Vomiting is one of the most common reasons owners take their dog to the vet. Here at My Pet Nutritionist it is a common symptom too, but it is often misperceived for regurgitation. There are a number of reasons for both, and they are very different mechanisms. So, let’s first establish the difference between vomiting and regurgitation, and focus specifically on reasons why your dog may be regurgitating. What’s the difference between vomiting and regurgitating? Vomiting is an active process, where the dog is forcefully ejecting the contents of their stomach or intestines. It is often preceded by sound. Food is usually at least partially digested, or it may be bile that comes up. In vomiting you will notice signs of nausea, like drooling or lip licking. Regurgitation is more passive and usually happens while a dog is eating or shortly afterward. There is usually no sound beforehand. Regurgitation is often just water or undigested food. Regurgitation can be common if a dog eats something that is too large – think large bones or chews. Some dogs will attempt to re-ingest it as soon as they’ve regurgitated it. But there are also some other reasons for regurgitation. 1) Stress Stress is a response in the body –and it is similar across humans and dogs. When exposed to a stressful trigger, the sympathetic nervous system fires up. During this process, resources are directed away from the digestive system and so digestive function is compromised. This can lead to the development of acid reflux which is one of the more common reasons for regurgitation. Stress has also been seen to affect oesophageal sensitivity. During stress, corticotropin releasing hormone plays a key role. This hormone is regularly implicated in hypersensitivity (which is why conditions like IBS are more common in those who are anxious or stressed). But what it means is that the oesophagus is more sensitive to mechanical distension, chemical stimuli and more, which may lead to regurgitation. 2) Reduced Mucosal Integrity In the same strand, mucosal integrity also influences oesophageal hypersensitivity. Just like we have a barrier in the skin and gut, we also have an oesophageal one. It too is made up of tight junctions and has its own plethora of defence mechanisms, including a mucosal barrier. But the presence of acid, in cases of acid reflux can injure the oesophageal epithelium and so, in turn, it damages the mucosal barrier, along with the tight junction formation. During attempts to repair, the inflammatory response is called to action, and animal studies into oesophageal damage have suggested it is a double-edged sword. This inflammatory response has been seen to lower oesophageal pressure through its action on smooth muscle which, not only allows for further reflux of acid,but also then delays acid clearance. Findings Here. The take home here is to restore mucosal integrity as soon as possible and modulate inflammation with ingredients such as l-glutamine, slipper elm, deglycerised and marshmallow root. Gut Guardian 3) Good Stress You may notice that your dog is more likely to regurgitate if they eat too soon after exercise. There is such a thing as good stress, but the response in the body will be the same. When your dog is running, chasing and playing, they are asking their body to move away from homeostasis. Their body will need compounds at a higher rate than what they are needed at rest. It therefore places their body under stress and so, resources are redirected. Digestion is no longer a required function and energy conversion is more important. The sympathetic nervous system is the functional stress response, the parasympathetic nervous system is the commande rthat walks into a room and states, “as you were!” But this command can take time to be heard, and so, if your dog eats too soon after exercise, the entirety of the parasympathetic nervous system hasn’t yet got the message. Without a fully functioning digestive system,it propels the food back out again. Always be mindful of when you choose to offer meals to your dog. 4) The Food Being Fed Regurgitation immediately after eating is in fact relatively common in dogs – but this doesn’t mean its normal. From experience, we often link it to the type of food being fed, as often in many cases, when the food is changed,the regurgitation stops. This can be for a number of reasons,but in short, the body isn’t liking what is going in. The enteric nervous system (ENS) is a subset of the autonomous nervous system and can function independently of the central nervous system. The enteric nervous system innervates the entirety of the digestive system and ENS neurons become hyperexcitable in the presence of toxins, bacteria, inflammatory and immune mediators. Animal studies have demonstrated hyperexcitability of ENS neurons after sensitization withmilk ingestion, leading to mast cell degranulation and histamine release. What caused the sensitisation in this study isn’t relevant, the note to make is that hyperexcitability can occur after sensitization, leading to aberrant enteric function. And so, it pays to consider an inflammatory/immune component in cases of chronic regurgitation. An elimination diet may be useful in this case. Check out our blog for more information. Here Equally, an easily digestible recipe such as white fish, can help, if fish is well tolerated. Low Fat Fish Of interest here is the crosstalk between the microbiome and the enteric nervous system. ENS nerves are thought to detect microbial products because germ-free animals exhibit significantly altered enteric function. A healthy microbiome is therefore crucial for the correct digestive messages to get where they need to go. To support your dog’s microbiome, check out our blog: Here 5) Structure There are cases where the structure of the oesophagus can result in frequent regurgitation. This can be a developmental abnormality or blockage. A thorough exam would be necessary to establish the severity of any structural issue. Summary In many acute cases of regurgitation, acid reflux often comes intoplay. If you would like to learn more then check out
Coprophagy,the technical way of saying a dog’s (or other animal’s) tendency to eat their own or other animal’s poop, is possibly more common than you may think, and certainly an issue we are told about here at My Pet Nutritionist. Throwback to the 1940’s and 1960’s and studies on rabbits and rats respectively suggested that it occurred due to vitamin synthesis and the frequency depended largely on nutritional requirements during growth or aging. So, much like Chinese whispers, we have come to the understanding that our dog is eating their poop because they are deficient in something. Findings here. You could stop reading there and have an answer to your question, but you would be wrong. Firstly, your dog isn’t a rat or a rabbit. There’s a little more to this less than desirable habit, so let’s delve a little deeper. What is coprophagy? Coprophagy is common in rats, rabbits, guinea pigs and chinchillas. Rabbits even excrete two types of faeces; hard and soft. Soft faeces are re-ingested but hard faeces are not. If rats are prevented from the act, then they require dietary supplementation of thiamin, biotin, pantothenic acid, folic acid, Vitamin B12 and Vitamin K. Findings here. Based on this information, if you were to notice a dog commonly eating their own poop you would consider that they too did it for nutritional reasons. But it all comes down to the digestive system. In rodents and rabbits, bacterial synthesis of nutrients occurs in the lower gastrointestinal tract. Here, little absorption occurs. By eating their own faeces, it gives them another shot at absorbing the nutrients, for want of a better description. So why do dogs eat their own poop? Well, it has its own name, so it’s nothing new. Canine conspecific coprophagy is regularly mentioned to vets and use alike, and is a regular search term on the world wide web. Some argue that it is a sign of an underlying medical issue,for example: 1) Enzyme deficiency As we know, a key part of the digestive process is enzymatic breakdown. Without key enzymes, food will pass through undigested. There is a school of thought which suggests the dog will eat their own faeces, to give themselves another chance at digesting the food and utilising the nutrients; exactly like the rodents did. 2) Increased appetite There are certain conditions which increase appetite, like diabetes and thyroid issues and so in an attempt to meet their ravenous needs, a dog will eat anything in sight! On the same side of this coin – there are others that argue a dog will eat his own faeces if he is being underfed. That said, the number of obese dogs is increasing year on year, so, before you alter his feeding amounts, check out our blogs: Here and Here. Others argue that it’s not necessarily a health issue, but more a psychological issue. Some have noted that it can occur in bored dogs; whether the dogs are simply amusing themselves, or in fact it’s attention seeking behaviour. For example, many owners don’t like dogs eating poop, so when they spot it, they give the dog attention;despite it being a negative interaction. Think of it like the child who misbehaves as soon as the parent takes that important phone call. However, in order to get a handle on the true reason, a study was conducted that looked at the diet of coprophagic dogs, it looked at house-training, their eating habits and what behaviour modifications had successfully been used in managing it. Findings here. This study found that the diet of the dog had no significant impact,therefore suggesting no nutritional basis for the behaviour and coprophagic dogs were just as easily house-trained as non-coprophagic dogs; so, they still maintained a typical aversion to faeces like most dogs. Interestingly, those dogs who ate their own poop, were more readily described as greedy eaters. Sadly, the success rate of behaviour modification to stop the dog eating their own poop was close to zero. Let’s see if their like of other animal’s poop sheds anymore light on the reasoning behind this particular behaviour. Why do dogs eat cat poop? The most likely explanation is that whatever hasn’t been absorbed by the cat during their digestion, attracts the dog to eat the poop. In some commercial cat foods, compounds are added to make the food palatable; these aren’t always absorbed by the cat, so they just come out the other end. Why do dogs eat another dog’s poop? There’s little evidence to suggest a nutritional basis for eating another dog’s poop. The factors relating to a dog eating faeces include: Greedy eating Breed group (hounds and terriers are more likely to do so) Multiple dogs in the house Eating dirt Eating cat stools It doesn’t appear to make a difference whether they are eating their own, or another dog’s poop – if they are going to eat poop, they’re going to eat poop. Why do dogs eat wild animal poop? When you’re out on your walks with your poop eater, he’s probably found rabbit or horse poop. Why are they drawn to it? The explanation could lie in their plant-eating habits! With horses and rabbits being herbivores, are dogs seeking the plant content of their poop? Again, grass-eating is not linked to nutritional deficiency or illness. Some owners perceive it as a way for dogs to make themselves sick. But dogs fed commercial, table scrap or raw diets were no more prone to grass or plant eating than the others. The answer to this question takes us back to their ancient beginnings. Plant-eating seemed to play a role in controlling internal parasites. Plant material passes through the intestinal tract, wrapping around worms and thereby clearing them out. Findings here. The parasites would then be found in the faeces, which leads us to another reason why a dog would eat poop – to keep their den clear of parasites. Some domestic dogs take themselves off to the furthest point
Whilst we often reference lip licking in anticipation food, there are a number of reasons why dogs especially, may demonstrate this behaviour. Some may even surprise you. So, let’s take a look at some of the more common reasons for lip smacking, or licking, that we see here at My Pet Nutritionist. 1) Anticipation of Food! We can head back to Pavlov and his dogs to put this behaviour into context. Most of us are familiar with the concept of conditioning that Pavlov introduced – he paired a bell with food, and eventually, the dogs would salivate in anticipation of the food, just by hearing the bell. This increase in salivation will encourage lip licking to help manage the extra fluid in the mouth! But what is also interesting is that food also stimulates the reward system in the brain – and the physical response to this type of reward is often saliva – again, the lip licking is a mechanism to manage the extra fluid in the mouth. 2) Lip Licking in response to stress! Not surprisingly, stress can result in hypo (too little) and hyper (too much) salivation! Either way, lip licking is often the result. On the one side, activation of the sympathetic nervous system (fight or flight), redirects resources and in doing so, digestive functions are sacrificed. As saliva is an important part of the digestive process, production is therefore reduced. The resulting dry mouth can encourage lip licking behaviour. Licking is also a maternal behaviour – they would clean and groom their offspring, soothing them during the action. Many dogs demonstrate licking behaviour because it elicits positive responses. It is well demonstrated that those born to Mothers who engaged in grooming/licking behaviour, are more resilient to stress, and develop more appropriate coping mechanisms. Findings here That said, increased salivation can be implicated in certain health issues that are exacerbated by stress – here salivation may be a side effect of an underlying issue, like acid reflux. 3) Acid Reflux Acid reflux is where stomach acid ends up somewhere it shouldn’t. As we know, the body is pretty nifty and has a few tricks up it’s sleeve to deal with rogue compounds. In response to the irritant in the oesophagus (stomach acid), salivary glands can over produce in an attempt to neutralise it. Ironically, acid reflux can be a result of reduced salivary production in the first place. There are a number of causes of acid reflux, poor lower sphincter functioning, abnormal oesophageal clearance, altered mucosal resistance and delayed gastric emptying (which is why it can be implicated alongside stress). If you would like more information about tackling acid reflux, then check out our blog here. 4) To smell better! Dogs use their tongues to enhance their sense of smell. When they lick a surface their transfer molecules via their tongue to olfactory receptors and then to the vomero nasal organ. When a dog keeps their nose wet, they are lowering the surface tension of the scent molecules so they can be translated better! Dogs are incredible at detecting minute traces in their environment – this also applies to information from us humans. We must consider whether our dog is attempting to gain more information about those around him when he is licking his lips. 5) Gastrointestinal Disorder Lip licking is often paired with nausea,along with excess salivation, lack of appetite, increased swallowing and lethargy. For this reason, it is often considered that lip licking is more likely associated with some gastrointestinal disorder or discomfort. One particular study sought to investigate this. Dogs demonstrating excessive licking behaviour were studied. In 14 of 19 licking dogs, gastrointestinal abnormalities were noted. They included: Delayed gastric emptying Irritable bowel syndrome/disease Food intolerances or allergies Pancreatitis Gastric foreign body Giardia Researchers concluded that full gastric health should be considered in any dog presenting with excessive licking behaviour. Findings here If you would like a head start on supporting your dog’s digestive health, then check out our blogs here: The Dog’s Digestive System 7 Steps to Optimal Gut Health for Your Pet Natural Guide for Pets IBD Pancreatitis and a Natural Nutrition Regime 6) Disorders of the Mout Gum disease is an inflammatory condition,symptoms include bad breath, drooling along with mouth and tongue inflammation. Sadly, bacteria can be translocated from the mouth into the rest of the body, often causing secondary infections and issues. For more information on dental care for your dog check out our blog here. But disorders of the mouth aren’t limited to periodontal disease. They can also include lip disorders found in those breeds with dropping upper lips and lower lip folds (like spaniels,bulldogs and St. Bernards). The lips accumulate moisture, becoming the perfect breeding ground for harmful bacteria. The lip folds can become fowl-smelling,inflamed, uncomfortable and swollen, resulting in your dog licking them to try to soothe them. Keeping these folds is therefore essential to your dog’s health! As is supporting their skin and oral microbiome. Please check out blog on puppy microbiome here. Your dog can also develop lip wounds – from a rogue branch or grass seed that has gotten wedged. If you are concerned about your dog’s lip licking behaviour – checking in their mouth is a good place to start. These are the more common reasons why your dog may be licking their lips, but they are not the only ones. Your dog may lip his lips for any one of the following reasons: Medication side effect Infectious disease Car sickness Reluctance to swallow (irritation/blockage) Inflamed tonsils Structural defects in the mouth Metabolic disorder (liver or kidney issues), Natural Guide To Liver Disease and Natural Nutrition Guide to Kidney Disease. Abscess. Disorder/blockage of the salivary glands Pain Whilst we can’t change the structure of your dog’s mouth, we have a wealth of experience tackling gastrointestinal disorders in the canine. If you are concerned about excessive lip licking in your dog and are wondering where to start, check out our services to see
In 1988 a hospital launched a “healthy eating day” in its staff canteen at lunchtime. One dish contained red kidney beans, and 31 portions were served. At 3pm one of the customers, a surgical registrar, vomited in theatre. Over the next four hours10 more customers suffered profuse vomiting, some with diarrhoea. All had recovered by next day. No pathogens were isolated from the food, but the beans contained an abnormally high concentration of the lectin phyto haemagglutinin. What on earth are these we hear you wonder? Well, lectins are often described as an anti-nutrient and as they are found in potatoes, beans, lentils, peas, soybeans, nightshade vegetables and grains, we thought we’d give you the 411 on them. Lectins are carbohydrate binding proteins present in most plants, especially seeds and tubers like cereals, potatoes, and beans. Their original purpose was protection. They would produce an inflammatory response in the animal that ate them – so they wouldn’t eat them again. Humans and Dogs are largely unable to digest them, but friendly bacteria in the gut can lend a hand. Until recently their main use was as histology and blood transfusion reagents, but in the past few decades we have realised that many lectins are (a) toxic, inflammatory, or both; (b) resistant to cooking and digestive enzymes; and (c) present in much of our food Well, it’s not sounding good is it! The really disturbing finding came with the discovery in 1989 that some food lectins get past the gut wall and deposit themselves in distant organs. At high dietary levels, it is thought that lectins cause damage to the structure of the brush borders of the small intestine. In lectin fed rodents, the mucosal membrane in the small intestine was stripped, compromising the gut integrity. This compromise has also been linked to abnormal bacterial proliferation. Findings here As we know, the gut wall does exactly that – keeps things in and keeps things out! It requires tight junction integrity to ensure rogue particles of food don’t get where they shouldn’t. Whenever and however this integrity is compromised, inflammation ensues! The other issue here is that lectins are also seen to inhibit the repair of resident gut epithelial cells. Sadly, not only do rogue particles get where they shouldn’t, but so do the lectins and because of their binding properties, lectins stimulate antigens on cells that do not normally display them like pancreatic islet and thyroid cells – what this means is the body will attack cells it normally wouldn’t because of the confusion. This is why lectins are sometimes implicated in autoimmune disorders, including cases of rheumatoid arthritis. Lectins and Rheumatoid Arthritis A normal IgG (type of antibody) molecule possesses carbohydrate side chains, which end with the molecule galactose. In rheumatoid arthritis much of the galactose is missing, so the next molecule along—N-acetyl glucosamine—is exposed instead. Wheat lectin has an affinity for this molecule, and so binds (when it normally wouldn’t with the terminal molecule inits normal place). This is why glucosamine has found it’s way as an anti arthritic supplement – wheat lectin can be blocked by N-acetyl-glucosamine. Lectins and Urinary Tract Infections In a similar premise, D-mannose is a sugar with a similar activity to N-acetyl-glucosamine. This too binds to lectins found on some microorganisms. Some bacteria responsible for urinary tract infections contain lectins specific for the sugar mannose and use these lectins to bind tightly to mannose -rich tissue in the bladder walls – therefore initiating infection. D-mannose supplementation provides a decoy for these bacteria. Lectins and Gluten There is also the idea that gluten can act as a lectin with toxic properties for intestinal cells. Together with the gut-associated lymphoid tissue and the neuroendocrine network, the intestinal epithelial barrier plays a role in the tolerance and immunity to non-self-antigens. Zonulin is a protein that helps regulate permeability in the gut by opening and closing tight junctions. Zonulin has been shown to be upregulated in many autoimmune diseases and it appears that gluten may be a strong trigger of zonulin. Lectins and Histamine Lectins also cause discharge of histamine from gastric mast cells which stimulates acid secretion. We need acid secretion to aid digestion, but it’s like the story of Goldilocks again – we need just enough, not too much (or too little). Not only does histamine stimulate acid secretion, but it has also its own little purpose in the body, chiefly the immune response. So, not only do we have rogue particles escaping due to poor gut integrity (thanks to lectins), but we also have increased histamine production, when then increases the likelihood of cross-reactivity. In short, tricking the body into thinking it needs to react to something it most likely doesn’t. Can you see why lectins are often dubbed the great mimics? They confuse the body into doing all sorts of things. They also appear to mimic insulin. Now, insulin is needed in the body, it helps get glucose to where it needs to be, but do we really need things mimicking it? Not when “Low concentrations of wheat germagglutinin (plant lectin) enhance the specific binding of insulin to receptors of fat cells and liver membranes.” Findings here In this case, imitation is not the sincerest form of flattery. But there are other reasons why lectins are deemed anti-nutrients. Animal and cell studies have found that active lectins can interfere with the absorption of minerals, especially calcium, iron, phosphorus, and zinc. Legumes and cereals often contain these minerals, so the presence of lectins may prevent the absorption and use of these minerals in the body. As we have already explored, lectins can also bind to cells lining the digestive tract which may also disrupt the breakdown and absorption of nutrients and affect the growth and action of intestinal flora. However, on the other side of the scale, lectin containing foods are sometimes associated with lower rates of cardiovascular disease and diabetes, because they are rich in fibre. So, what do we do? Lectins are most potent in their raw
An elimination diet – the wand of all wands. Or at least we would like to think so. Here at My Pet Nutritionist, we regularly utilise elimination diets in our healing plans. But there is often some confusion over their purpose and how best to use them. So, we thought we’d cover, what they are, what they hope to do, and what they can’t do. What is an elimination diet? An elimination diet, also known as exclusion diet, is a diagnostic procedure used to identify foods that an individual/animal cannot consume without adverse effects. Adverse effects may be due to food allergy (IGE), food intolerance (IGG), other physiological mechanisms, or a combination of all of the above. The point to note here is that it is a diagnostic tool – not a long-term lifestyle and in some cases, a means to give the immune system a welcomed break. People often look at certain foods being the culprit or the saviour. But what’s really happening is the bodies inability to deal with certain antigens effectively. As we know, the immune system functions like a radar – always on the lookout for potentially harmful compounds. But, through regular activation it can become hypersensitive and seemingly forget that it does have a tolerance capacity too. Immune Tolerance In the body, there are two types of immune tolerance, one is self-tolerance, and this prevents the development of autoimmune disease. The body accepts its own cells and doesn’t try to kill them (so kind!). But there is also this idea of induced tolerance. Induced Tolerance Induced tolerance occurs when the immune system actively avoids responding to an external antigen. This tolerance is induced by previous encounters with that antigen. An example of induced tolerance is a deliberate manipulation of the immune system to avoid the rejection of transplanted organs or to provide protection from allergic reactions. But induced immunity needs a fully functioning immune system to make the right calls at the right time – this is the basic premise of why we want to carry out an elimination diet. To see what foods might elicit a reaction. Through the removal of antigenic compounds (the foods potentially wreaking havoc), you remove the adverse responses pulling on resources and you can then spend time supporting the various systems in the body, including the immune system, to get your ducks in a row. Why would you do an elimination diet? An elimination diet is often the first port of call for dogs suffering with allergies, intolerances, inflammatory conditions and also behavioural issues. This last point often raises a few eyebrows –but as we know, immune responses are intricately linked with the brain and subsequently behaviour. We not only have sickness behaviour, which makes us hunker down and prevent the spread of virus (evolutionary purpose for survival), but pain simply makes us, and our dogs, miserable. In cases of irritable bowel syndrome, there is a noted visceral hypersensitivity too, which in a nutshell means an even higher sensitivity to pain (and sadly an increased propensity to be miserable). The take home? Allergies, intolerances and inflammatory conditions are all an immune response. So, the point is to lighten the load on the immune system. But we can’t forget there are differences between allergies and intolerances. A food allergy or other allergic response is caused by an IgE antibody reacting towards that allergen. IgE binds to mast cells to promote histamine release. This is an immediate response and in some to certain food allergens can be fatal (anaphylaxis). Hives or instant rashes and swelling can be seen. IgA is an antibody that lives in mucous membranes, inside nasal cavities, and lungs. It helps to protect the respiratory tract as a first line of defence. IgM is the first immunoglobulin that is encountered in an infection, or vaccines for the first time. IgG is the work horse antibody; it is the soldier, the memory antibody. This is what gets drafted when your dog is exposed to something they have already figured out a response to. When you have a food intolerance, we tend to discuss it in terms of IgG. Symptoms usually begin within a few hours of eating the food that you are intolerant to. Yet, symptoms can be delayed by up to 48 hours and last for hours or even days, making the offending food especially difficult to pinpoint. IgG’s are mostly raised from the barrier mucosa in the digestive system. After a meal, there are both antibodies and complexes of food antigens bound to specific IgG’s. These complexes are quickly cleared by the reticuloendothelial system. Clinical observations suggest that due to gut inflammation and permeability (leaky gut), the digestive system is unable to digest the proteins effectively which subsequently raises IgG response to certain foods. We know that chronic intestinal inflammations and permeability are related to and possibly responsible for food IgG sensitivity. 90% of food reactivity comes from IgG’s. Just to confirm, intolerances can be changeable but allergies tend to be for life and only account for around 10% of food reactivity. IgG’s come in different categories but to keep it simple, they are generally defined as cyclic or fixed. A common IgG reaction is cyclic and can take around 3 months to disappear/change. A fixed Intolerance tends to linger for longer and can take around 6 months to disappear/change. So how do we move forward? We prime and reset the digestive system, and this includes starting with an elimination diet but also gut healing and immune balancing protocols. We follow the 4 R’s. – Remove – carry out an elimination diet. Remove offending foods, one at a time and note changes in symptoms. Quite often, even offending foods can be reintroduced at a later stage. – Repair – support immunity and gut healing with ingredients like slippery elm, de-glycerised liquorice, glutamine, andN-acetyl-glucosamine. It is also important to consider how existing medications are affecting gut healing for example, steroid use impairs intestinal absorption which is linked to several gastrointestinal dysfunctions. But, because of their anti-inflammatory and immunosuppressive activities,
Would you believe that around 70% of the consultations we carry out here at My Pet Nutritionist are surrounding allergies? The reasons for this are largely multi-factorial and bigger than the scope of one blog article, but as in the words of someone much smarter than us – you’ve got to start somewhere – so we thought we’d explore histamine in a little more detail. What it is, what it does, if indeed it is found in foods and whether there is anything, we can do to reduce the load. So, let’s get cracking. What is histamine? Histamine is a transmitter in the nervous system and a signalling molecule in the gut, skin, and immune system. It is synthesised from the amino acid histidine which is in fact an essential amino acid for humans and dogs. Before we knew better (and in some labs we still don’t), animal studies established that histidine deplete diets result in dog death! Findings here Histamine is primarily associated with the functioning of the immune system. During an immune reaction, histamine is released and contributes to the physical changes necessary for the immune system to fight the pathogen, including the increase in blood pressure, temperature, swelling, and constriction in the lungs. Like all things in the body, histamine needs receptors for it to do its job and there are especially high concentrations of histamine receptors found in the lungs, skin, blood vessels, and gastrointestinal tract. Histamine is stored in granules in mast cells throughout the body and as we know mast cells mediate inflammatory responses such as hypersensitivity and allergic reactions. The granule protects the histamine; if histamine could float freely it would degrade very quickly. Histamine is released from those granules in response to tissue injury resulting from cold, heat, toxins, and trauma. As noted, there are numerous histamine receptors throughout the body. H1 and H2 receptors are of most interest in the hypersensitivity and allergic response (but there are H3 and H4 too). H1 receptor binding results in a range of actions. Peripheral sensory neurons are acted upon which causes itching and sometimes pain. Intestinal smooth muscle is affected causing constriction, cramps and possibly diarrhoea. H1 receptor binding can result in secretory mucosa causing bronchi and nasal mucus. Lastly the pulmonary smooth muscle can be affected resulting in constriction. There are some tissues that have both H1 and H2 receptor binding sites. This includes the cardiovascular system. Histamine binding here drops blood pressure by widening the blood vessels. It also increases heart rate. There are also dermatological effects resulting in increased permeability. This is often described as the triple response resulting in the reddening of the skin, wheal formation and an irregular “halo” flare, also known as hives. H2 receptor binding sites are more commonly seen in the stomach itself. Histamine can bind to parietal cells stimulating the secretion of gastric acid. This is why antihistamine medication is sometimes implicated in digestive dysfunction due to the lower secretion of gastric acid – which is ironic, when partially digested proteins can then become antigenic. H1 receptors are involved in type 1 hypersensitivity reactions (involves immunoglobulin E – IgE – mediated release of antibodies), H2 are involved in Th1 lymphocyte cytokine production, H3 are involved in blood-brain barrier function and H4 are also expressed on mast cells exacerbating histamine and cytokine generation. The long and the short of it, histamine stimulates inflammation and is a prominent contributor to hyper sensitivities and allergic disease (but it is only one of many mediators of allergic disease). Histamine kick starts the processes to get rid of the offending particle/s – whether this is to sneeze pollen from your nose, or to expel food allergens from the gut, but it also plays a role in wakefulness, appetite, and endocrine homeostasis. So, histamine is in fact necessary to maintain homeostasis (balance in the body). But there can be too much of a good thing. Histamine is released to carry out a function and then it is removed by a few different pathways. The enzymes we are particularly interested in are diamine oxidase (DAO) along with histamine-N-methyltransferase (HNMT). DAO inhibition or disruption can result in disproportionate amounts of histamine in the body which can result in a range of GI symptoms along with cardiovascular, respiratory, and skin complaints. Disruption of HNMT function, on the other hand, tends to affect the nervous system. HNMT inactivates histamine by transferring a methyl group, so methylation is a key process in maintaining HNMT activity. Methylation is a relatively simple process, but it occurs billions of times every second! It underlies the proper function of virtually every body system. It is dependent on certain key nutrients like folate in its active form, methyl folate, B12 and B6. There are a number of factors that can affect methylation, from nutrition to genes, but stress and vaccination is a major drain on it. The stress response is a sequence of processes that relies on methylation, depleting key nutrients as it goes. Therefore, if methylation isn’t efficient, HNMT isn’t efficient, and histamine can become imbalanced affecting behaviour, sleep, appetite, immune function and digestion. A range of factors can increase histamine in the body such as infections, B12/folate deficiency, magnesium deficiency, stress, inflammation, trauma and exercise. Not only that but certain gut bacteria produce histamine. DAO and HNMT can become flooded when there is a high histamine load, subsequently affecting breakdown. Histamine load can be increased by the ingestion of high-histamine foods too, but the release of it can also be promoted in the body, by foods we know as liberators. The following list is of foods to avoid if opting for a low-histamine approach to hypersensitivity, whilst getting to the bottom of things. Fermented foods (kefir, sauerkraut etc, prebiotics) Tripe Vinegars (including ACV) Long-stored nuts Beans and pulses Canned foods Citrus fruits Banana Wheat germ Spinach Canned fish (salmon can contain more histamine than most) There is also discussion around yeast behaving as a histamine generating catalyst, so the general rule
The Universe inside your Puppy Here at My Pet Nutritionist we always focus on microbrial health, so we delve into it’s importance for your puppy to hopefully set them up for life. Microbes have been around for billions of years, humans – less than a million and we all know there is much disagreement over the domestication of our faithful furry friends. Microbes can multiply in minutes, survive and thrive in every habitat on earth, and technically, they’ve killed more people than all wars combined. But, without them, we actually couldn’t survive. Microbes are like a bad version of Ed Sheeran, you need me, I don’t need you. The body is in fact like a mini ecosystem. It has many different microbial communities throughout the body. They live inside; in the lungs, nose, urinary tract, and digestive tract, but they also live on; they are all over the skin! Because you sadly have jobs that need to get done today, we’re just going to do a whistle stop tour of the three main microbial communities and how we can support them in the puppy. First up, the skin microbiota. Not surprisingly, the skin microbiota plays a role in skin conditions like atopic dermatitis and even some skin cancers. Check out our blog on atopic dermatitis in pets here. In the dog, there are different communities found in different areas of the skin; there are also clear differences in diversity between healthy and allergic dogs. The skin provides one of the first lines of defence in the immune system, but in two ways. Not only does it have its physical structure to keep things in, and things out, but the community of microbes on the skin also protect against potentially harmful pathogens. The good guys can engulf the bad guys before they gain entry into the body, but they can also compete for nutrients and resources, to prevent the bad guys from thriving. In utero, foetal skin is thought to be sterile. But colonisation of microbes occurs during and immediately after birth. As the newborn puppy moves through the birth canal, he is exposed to a variety of bacteria from Mum. Once puppy is born and grooming begins, Mum passes even more over to her offspring. Mum health is therefore imperative – not only for the diversity she possesses but also her emotional health. Stressed Mum’s are less likely to engage in grooming behaviour, so if she isn’t grooming her offspring, she’s not passing her microbes to them. The environment greatly influences the microbiome of the skin. There are noted variations in skin microbial communities between those living rurally and those in urban areas. There is also an increase in chemical use associated with urban living, which also influences the composition of the microbiome. Diversity is significantly reduced with the use of detergents and antibacterial cleaning products. Potentially pathogenic taxa are also increased as there are fewer good guys to keep the bad guys in check. This is why skin issues like acne or dermatitis are deemed western diseases; they simply just aren’t found on the skin of indigenous tribes or on that of individuals from non-industrialised societies. What is also interesting is that there is also a clear distinction between male and female microbiome, therefore suggesting hormonal influences. This poses food for thought in the neutered pet and how their microbiome is subsequently affected. Unnecessary use of antibiotics also affects the skin microbiome, along with excessive use of grooming products and of course nutrition. The Oral Microbiota There is a collection of microbes found in the mouth; these are the ones that result in bad breath or dental issues. Again, they pose a first line of defence against ingested potentially harmful pathogens. But they also play a role in metabolising certain nutrients. It is clear that the oral microbiota found in dogs differs significantly from humans – some researchers have even gone as far as saying that a human bite would be more dangerous than a dog bite in terms of wound infection potential. Findings here The oral microbiota is gaining more attention and for good reason – there are associations between oral microbiota composition and weight gain, much like we have with the gut microbiota. So, caring for the mouth cavity is just as important as caring for the gut, and colonisation, like in the skin occurs at and shortly after birth – and certainly within the teething period! Data is relatively new, but in human realms, to support oral health, the guidelines regularly include avoiding ultra-processed foods along with high-sugar foods (think high-fructose corn syrup found in many dog treats and processed foods). Guidelines also promote dental hygiene –for our puppies and dogs, raw, meaty bones are a great opportunity to support dental health. Remember to choose appropriately sized bones for puppies – soft bones like chicken necks or wings. They must always be raw – cooked bones pose a splinter risk! The Gut Microbiota/Microbiome When we reference the microbiome, we are considering the microbial community found in the whole of the digestive tract. Generally, the further down we go, the more bugs we find. SIBO or small intestinal bacterial overgrow this when there are too many bugs in the small intestine. We want the majority of them in the large intestine. Each puppy and dog have a unique microbiome – just as we do. It’s like a fingerprint. How cool is that? But it just goes to show that if there is dysbiosis (imbalance of good to bad guys) – there is no one silver bullet. For our puppy, we are in a great position to support optimal gut health from the beginning (not withstanding gene interactions). When we talk about the microbiota or microbiome, we are not just talking about bacteria, but fungi and viruses which live inside the gut too. This is totally normal – the good guys with the right tools can keep the bad guys in check. This community can metabolise nutrients (ruminant
What You Need To Know About The Dog’s Digestive System Here at My Pet Nutritionist, most issues that we are faced with involve the need for some form of gut healing. And so, we thought we’d pop a handy guide together, to explain the function of the digestive system, and how it all works. We like to think of it as a journey that food goes on, so, pop on your seatbelt, and come along for the ride. Gut Healt Gut health relates to the whole of the digestive tract, which officially starts in the mouth and ends with, surprisingly, the rear end, or more biologically accurate, the rectum and anus. In humans, digestion begins in the mouth. We physically break down food with our teeth, and salivary enzymes get to work. This is slightly different in the dog. The structure of their teeth means they are equipped for ripping and tearing, and then swallowing larger chunks of foods, whereas us humans have flat surface teeth made for grinding. A dog’s saliva also has a different composition to humans. Studies have demonstrated 2,532 different proteins between human and canine saliva. Canine saliva plays more of a role in protecting against inflammation and functioning as an anti-microbial. Dogs also have lower amounts of amylase than humans and there appears to be no, or very little, salivary amylase present in canine saliva. It is regularly concluded that because a dog is carnivorous, amylase activity in the species is not as dominant. Findings here For this reason, digestion in the dog really starts in the stomach. As food travels down the food pipe (oesophagus), it passes through the lower oesophageal sphincter. These sphincters are important, as they keep parts of the digestive system separate; if they don’t shut or open properly,there may be complaints like acid reflux. The stomach is like a washing machine; it physically churns food around, but it also releases enzymes, acid, and hormones to break it down into a usable form. An enzyme is a protein that speeds up chemical reactions in the body. Digestive enzymes speed up chemical reactions that break down food molecules into something that can be used by the body. Pepsin is an enzyme released in the stomach, from what we call chief cells. It serves to digest protein. The stomach also releases hydrochloric acid, more commonly known as stomach acid from the parietal cells. This highly acid environment causes proteins to lose their characteristic folded structure which exposes the bonds of the protein. Pepsin (having been activated by the stomach acid) can then get to work on these bonds. Stomach acid also inhibits the growth of many microorganisms which is helpful to prevent infection. Digestive hormones are also made in the stomach (and small intestine, but we’ll get there later). The two G’s are released in the stomach, being gastrin and ghrelin. Gastrin stimulates the release of stomach acid when it senses the stomach has been stretched. Ghrelin on the other hand, also produced in the stomach tells the brain that the body needs to be fed; it increases appetite. In the stomach, food is turn into a substance known as chyme, and this moves to the small intestine. The small intestine is full of tiny, carpet like projections called villi and microvilli, which increases the surface area of the organ. These projections allow for nutrient absorption. In short, they allow whatever is in the small intestine to reach circulation. The pancreas feeds into the small intestine and is like the factory of the digestive system; producing enzymes and hormones to further digest the chyme. The pancreas produces: Lipase – think lipid, breaks down fat. Protease – think protein, breaks down protein. Amylase – helps to break down starch. It also produces a range of hormones: Insulin – promotes the absorption of glucose from the blood into the liver, fat and skeletal muscle cells, Glucagon – the messenger which tells the liver to release stored sugar, Gastrin and amylin – whilst most of the G is release in the stomach, some is made in the pancreas too. Amylin helps control appetite and stomach emptying. To further assist with digestion, bile acids are made by the liver, and stored in the gallbladder. Bile is secreted into the small intestine and helps with fat digestion and absorption. To this end, they are also important for the digestion and metabolism of fat-soluble vitamins. As we move through the small intestine, we hit another gateway known as the ileocecal valve. This gateway acts like a watchdog. If it notices under-digested food coming through, it hits what we know as the ileal brake, halting the movement of the upper gut movements. This is a crucial feedback system for nutrient absorption in the small intestine. There is a link between this mechanism and peptideYY, which is produced in the last part of the small intestine known as the ileum. This hormone inhibits intestinal transit (for better absorption of nutrients) and has been associated with higher-fat levels,which is why fat in the diet is associated with higher levels of satiety. Findings here And then we are into the large intestine. The large intestine is responsible for four main things: Hydration The large intestine reabsorbs fluid and electrolytes. Here the contents from the gut turn from liquid to solid (that runny poop – hasn’t spend enough time in the large intestine for some reason). The Microbiome Here resides the microbiome. That community of microbes that is gaining a lot of attention, for good reason. There are microbes found throughout the GI tract, but the majority of them are found here. These guys can make vitamins, amino acids (building blocks of protein), hormones and chemical messengers. They train the immune system, strengthen the gut barrier, communicate with other vital organs including the brain, prevent invasion from the bad bugs, influence gut movement and function and love eating fibre! Nutrient Absorption Whilst most of this occurs in the small intestine, thanks to the
The primary two functions of the skin is to act as a protective barrier and an immune barrier, between the body and its external environment, it keeps everything in, and prevents the entry of pathogens and allergens. Here at My Pet Nutritionist, we have heavily focussed on the skin function and allergies so let’s take a look. A defective skin barrier is a key feature of the chronic inflammatory skin disease, atopic dermatitis and it has been noted that the protein filaggrin has a pivotal role in skin barrier function. Mutations with the FLG gene, which encodes filaggrin, strongly predisposes to conditions including atopic dermatitis and secondary allergic diseases. Whilst we always find these revelations in human literature, we have found that this also applies to dogs. So, let’s take a look at filaggrin in a little more detail and how there is a possibility that the skin issues faced by your dog may have a genetic origin. What is Filaggrin The term filaggrin, derived from filament-aggregating protein, was first coined in 1981 to describe a class of structural protein that had been isolated from the stratum corneum (the outermost layer of the epidermis of the skin). Filaggrin is formed from the breakdown of profilaggrin, a protein contained in the granular layer of the upper epidermis. Filaggrin is vital for skin cells to mature properly into the tough, flat corneocytes that form the outermost protective layer of our skin known as the cornified cell envelope (CCE). It does this by binding together the rigid keratin filaments that form a structural skeleton within the cells. As a result, the cells collapse and become flattened. The CCE is constantly renewed by new cells formed in the basal layer of the epidermis. These gradually work their way to the top of the skin layers where they become corneocytes. They will then shed. Surrounding the corneocytes you will find a layer of lipids, which coat the CCE, keeping the skin waterproof, protected and supple. This also provides a protective layer, keeping out irritants and allergens. Without filaggrin, the CCE does not form correctly. Corneocytes dry out, and the lipid layer is lost. This results in dry, cracked skin and a permeability to the skin. Atopic dermatitis is characterised by these symptoms, and data has revealed an association between loss of functions of the filaggrin coding gene and this condition. In short, these conditions are more commonly noted in those with a mutant gene, than those without a mutant gene. What is particularly interesting is that the environment plays a role, not only in developing atopic disease, but also directly in FLG expression. It is regularly noted that exposure to irritants can reduce epidermal FLG levels and lead to an acquired filaggrin deficiency. The FLG deficiency, be it genetically determined or acquired, causes an altered epidermal structure and an impaired barrier function. Sadly, this allows penetration of environmental allergens into the skin, including house dust mites, pollen, bacteria, irritants, and toxicants but it also results in sensitisation of the host. The resultant alteration of the epidermis by way of increased pH, altered lipid secretion, modification of keratinocytes and reduction of antimicrobial peptides also then paves the way for the perfect environment for other bacteria and fungi to thrive, leading to recurrent skin infections, which you’ll have likely observed in cases of canine atopic dermatitis. Environmental and Inflammatory Factors known to alter the amount of Filaggrin: Humidity It seems there is a correlation between indoor humidity and disease severity. In human studies, in those children with atopic dermatitis and FLG mutations, their skin lesions are more often located in air-exposed skin areas. Interestingly, children with atopic disease experience a reduction in disease severity after one month spent in a humid climate. It seems that filaggrin and more filaggrin proteolysis is required in a dryer environment and for that reason, it is often concluded that children predisposed to atopic dermatitis should be encouraged to increase their indoor humidity. Findings here Mechanical damage Mechanical damage includes stretching, compression, and friction on skin cells. It not only affects the barrier function of the skin but also induces various immune responses, triggering inflammation at the site of the stress on the skin. For example, scratching of itchy lesions exacerbates the skin inflammation in atopic dermatitis. This increase in inflammatory mediators has been seen to down regulate filaggrin expression. Skin Irritants Studies have demonstrated that profilaggrin expression can be down regulated after application of experimental sodium lauryl sulphate (SLS). In the 6 hours post exposure, it was noted that SLS in fact induced skin barrier defects. Findings here SLS is what’s known as a surfactant. This means it lowers the surface tension between ingredients, which is why it’s used as a cleansing and foaming agent. You will find SLS in a range of human products and may find it in some dog grooming products. It is generally what makes them foam. Human Products: Hand sanitiser Makeup remover Liquid hand soap Shampoo Conditioner Styling gel Bubble baths Dental care products like toothpaste Anti-itch creams Sunscreen You may also find it as a food additive in certain products, it is used to mix acids with other liquids, or as an emulsifier or thickener. Dog Grooming Products: Shampoo Conditioner Detangler Conditioning balms Deodorising sprays Cologne It is also worth noting that some shampoos specifically prescribed or advertised for use in atopic disease also contain SLS, amongst other ingredients. The issue is that when products reduce filaggrin expression, it disrupts the skin barrier, making it permeable to other toxicants and irritants, creating a vicious cycle. What you choose to apply to your dog’s coat and skin is just as important as what you put into their body through their diet. Not only that, but whilst you may not be applying human products directly to your dog, they may come into contact with them through exposure to soft furnishings or you. In the hopes to create a mechanical barrier, without harsh chemicals being used, there are certain topical products
Constipation is the infrequent or difficult passage of faeces. As pet owners, we may pay more attention to the size, colour and consistency of bowel movements and not necessarily notice that our companion hasn’t “gone” for a while. The first hint we may notice is straining when out on a walk with our dogs, or our cat spending more time in the litter tray than usual. When they do go, faeces are dry and hard. Constipation is something that we are asked about regularly here at My Pet Nutritionist, so let’s take a look at what actually occurs in the digestive tract in cases of constipation, what can cause it, and some top tips for managing it. The Digestive Syste Unlike us humans, our pets lack salivary enzymes and so the digestion of their food doesn’t really start until it hits the stomach. As food travels down the oesophagus, it goes through a gateway known as the oesophageal sphincter before getting to the stomach. The stomach is like a washing machine, it churns the food and releases detergent-like compounds to break the food down. Food is turned into a smoothie like consistency known as chyme, which then makes its way to the small intestine. The small intestine is covered in tiny,carpet-like projections known as villi which are vital for nutrient absorption. In short, these villi allow the goodness found in the food to get to the rest of the body. But for that to happen, the chyme needs to be broken down further. Here is where the pancreas comes in. The pancreas is like a factory, it produces enzymes that help to digest food, along with hormones that help control how much sugar is in the blood too. The liver also produces bile acids which are secreted into the small intestine from the gallbladder to help with digestion and absorption of fat. Just to make sure digestion is targeted from all angles, the lining of the small intestine also contains enzymes that break down food too! After the small intestine has done its job, the unabsorbed bits (including fibre) move into the large intestine. But it must go through the ileal brake first. This is like a watchdog; if it spots under-digested food coming through, it tells the upper-gut movements to shut down their party. The large intestine also plays a role in nutrient absorption, simply because it houses trillions of microbes that can help digest things that have so far been indigestible. These microbes also produce messenger molecules to the brain, reducing inflammation and signalling satiety amongst other functions. The large intestine also reabsorbs fluid and electrolytes. During this process,the contents in the gut turn from liquid to solid, so the longer the food remains here, the more water is absorbed and therefore the more solid it is. Sloppy poops spend significantly less time here. At the end of the large intestine, the rectum stores and compacts the waste, before the brain receives the signal to release the accumulated waste though the anus. But how does food move through this system? As the intestine looks much like a computer game from the 1980s, we’re pretty sure gravity isn’t completely in charge. Well, it isn’t. The movement of food through the system is largely thanks to a carefully curated orchestra of muscle contractions. On of these programmes is peristalsis, which are wavelike contractions. Earthworms actually use this mechanism to drive their movement. The other is segmented contractions which generally occur in the small intestine. In the large intestine, mass movements propel the chyme/faeces towards the rectum. What is particularly interesting is that the gut can function independently of the brain, so it can do all of this without any conscious thought. Digestion forms part of the parasympathetic nervous system, appropriately dubbed rest and digest. This leads us into our first possible cause of constipation… Stress When the body feels stressed, resources are redistributed to organs and functions that need them. Sadly, the digestive system is not one of them. Stress can result in a temporary halt to digestive function (of course,stress can also result in projectile diarrhoea, but we never said the body was an easy study did we!). Without the nod to continue its work, waste can sit, waiting for the signal to release. Changes in Routine The digestive system also displays circadian rhythm variations. There is evidence that peristalsis has its own routine. Gastric emptying rates are slower in the evening, and the migrating motor complex (think of it as the road sweep after a car accident, clearing the small intestine between meals) is slower at night too! Not only that but the liver seems to have its own circadian regulation to synchronise with periods of feeding and fasting. Findings here Factors which inform circadian rhythm: Light Mealtimes Sleep Exercise Temperature If your pet has recently experienced changes to their mealtimes, walk times, or had disrupted sleep, this could play a role in their changing bowel habits. Dehydratio This is particularly relevant to cats. They historically have a low thirst drive and sadly, chronic kidney disease is a risk factor for constipation (diagnosis is increasing year on year). As we noted earlier, the large intestine reabsorbs fluid, and it is here that generally dictates how solid the poop is likely to be. The body always wants to maintain homeostasis, so it will always try to balance its levels. For the cat who isn’t gaining much moisture from their diet, there isn’t much water to reabsorb in the large intestine, but by gum, it will try! This is why we always advocate a fresh food diet for your pet. Always have fresh, filtered water available too. A worthwhile read on cats, hydration and kidney disease here. Obstruction Obstruction can be as sinister as it sounds, blockages caused by foreign objects like toys, plastic bags or elastic bands, but it can also be a medical obstruction caused by a tumour, abscess or granuloma. That said, as pets regularly groom themselves, they
Any quick search on the internet will populate a range of breeds that are seemingly notorious for being fussy eaters. If you have a basenji, husky or yorkie, it looks like you’re signed up for a lifetime of stressful meals. Except here at My Pet Nutritionist, we don’t believe everything we read on the internet. Whilst all those breeds could indeed be fussy eaters, so can many more. And they are. It is perhaps one of the more common questions we are asked, “how can I get my dog to eat?” Being a fussy eater can be technically defined as an eating disorder, and there are a number of causes. From behavioural to biochemical, let’s take a look at the complex world of the fussy eater. The Function of Eating Food components are the main sources of energy for the canine body. Not only that, but it provides the compounds needed for each cell to do its job. As the body carries out its tasks, it uses fuel and compounds, as reserves run low, signals bounce around the body to kickstart feeding behaviour. This is hunger, a physical need to eat. Appetite is quite simply the desire to eat. Hunger and appetite can be at odds. You may want to eat, but not need to, and you may need to eat, but not want to (in times of stress for example). Appetite and hunger are largely controlled by the brain and a range of hormones. The Brain In the brain sits the hypothalamus. Through its connection to the pituitary gland, it modulates the endocrine system. It is involved in a range of daily activities including temperature regulation and energy maintenance. We know it plays a role in eating behaviour as several lesions to small areas of it can result in overeating and under eating. The lateral hypothalamus is defined as the feeding centre and the ventromedial hypothalamus is defined as the satiety centre. This is largely an oversimplification, but it certainly demonstrates the role. The hypothalamus receives information from the digestive system like stomach extension, chemical nature of ingested food and the metabolic activity of the liver and uses it to maintain energy balance. It also receives information from the emotion/reward system. Food is a rewarding object that induces pleasant emotions. Findings here The amygdala is largely responsible for this. Studies have demonstrated that when the reward value of food decreases, so too does eating motivation. Sadly, these studies often include the injection of lithium after eating, of which causes discomfort. But it does raise an interesting point in terms of the fussy eater in your life. We’ll revisit this later. Food reward is elicited by several events that occur before it even passes through the oesophagus, namingly the appearance and shape of the food, the taste and smell and then the pleasure of swallowing the food. We know this because in tube-feeding studies, reward sensations are reduced. In short, when subjects were no longer allowed to taste or chew it, they did not want to eat it. That said, in sham studies, when animals are denied nutrition because everything swallowed leaks out of a tube connected to the oesophagus, they eat and swallow more than usual, but they are still unsatiated. This tells us just how complex eating behaviour actually is. And provides food for thought for the gluttonous dog (on the other side of the scale). Hormones Hormones are probably the most talked about in terms of eating behaviour. You’ve all likely come across leptin and ghrelin. Leptin is produced in adipose cells, or fat cells. So, the more fat cells there are,the more leptin. In short, the more fat available in reserves, the less you need to eat. If you have no fat cells, you need to conserve your energy until you next find food. Leptin crosses the blood-brain barrier, and there are high numbers of leptin receptors found in the hypothalamus, brain stem and other regions of the brain. Rising leptin in a fed state inhibits food intake by suppressing a range of peptides involved in eating behaviour. Ghrelin is predominantly secreted in the stomach and it too modulates cells found in the hypothalamus by increasing excitatory inputs and decreasing inhibitory inputs. Here we are talking about neurotransmitters. These chemical messengers modulate much of our and our pet’s behaviour and they either make something do something or stop something from doing something. Whilst dopamine can be both inhibitory and excitatory, ghrelin is seen to have a large influence on the release of dopamine via increases in cell excitability. As dopamine is involved in reward and motivation, ghrelin is thought to target the motivational functions geared to gaining food and to select those which are more rewarding (high calorie). Findings here In eating disorders, dopamine is one of the neurotransmitters that gets a lot of attention. In times of reduced food intake (fussy eating), dopamine neurons are activated, in the short-term rewarding the lack of food. It is considered that it is a physiological response in an attempt to increase motivation to forage for food. Findings here However, there are also other mechanisms in which the dopaminergic system comes into play for the fussy eater. A central feature of the dopamine neuron response is that it is triggered by unexpectancy. After receiving an unexpected reward like food (or how many likes our recent post has got on social media) a dopamine surge is elicited. When this becomes a regular occurrence, the dopamine signal is triggered by the conditioned stimulus in predicting the reward. However, the dopamine system does not respond when the reward is received. If the reward is predicted, then not received, there is a dip in dopamine activity. What this means, is that your dog may do the song and dance ready for their bowl of food, but then walk a way as soon as it is placed in front of them. The reward they predicted (tasty food), isn’t what was received. The other neurotransmitter that gets a
If you’ve just rinsed your dog off after a meander through the woods, then their licking is likely grooming behaviour. But, here at My Pet Nutritionist, we often see dogs who excessively lick causing abrasions and hair loss. Whilst it’s often indicative of an irritation, there are in fact some other reasons why your dog may start licking in the absence of a jaunt through a muddy puddle. Let’s take a look at some of the more common causes. 1) Stress Yes – stress can take the blame for this one too! Stress is like the wonder woman of life – is there anything she can’t do? For anyone who has spent time investigating dog behaviour, you’ll know that lip licking in particular is a sign of stress. An interesting theory here suggests that because stress depletes essential nutrient resources, lip licking is in fact a sign of malnutrition. Deficiencies in a range of nutrients like vitamin B2, B3, B12, iron, and Vitamins A, C and K and Zinc have all been known to cause irritation and inflammation in and around the mouth and lips. The licking is thought to be an attempt to soothe it. Findings here However, other suggestions explore the idea that the lip licking mechanism is thought to soothe the stress response by activating the parasympathetic nervous system. Yet, this mechanism can apply to licking of all body parts, not just the lips. The stress response is dominated by the sympathetic nervous system; it increases heart rate, widens eyes in order to assess the threat better and redirects resources in order to deal with it. Once the threat has passed, the parasympathetic nervous system kicks in and re-balances. The chief of the parasympathetic nervous system is the vagus nerve, and chewing, along with licking is considered to activate it. Through the action, attention is redirected and focussed on that particular task, not what is making them stressed. Findings here Licking is also deemed a self-soothing behaviour through its association with oxytocin. Oxytocin is a hypothalamic nonapeptide linked to increased levels of social interaction, well-being and anti-stress effects. Oxytocin is released by sensory stimulation (touch) and promotes the release of dopamine whilst decreasing the cascade of stress response mechanisms throughout the brain and body. Oxytocin also modulates the activity of serotonin which as we know is a key hormone in mood stability, feelings of well-being and reward. An element of this could have also been learned behaviour from their mother. Licking and grooming behaviour is a key feature in determining neural changes and fear responses in offspring. Those from low licking mothers tend to show a greater stress-response and proceeded to be low-lickers themselves (if they were female and had their own litter). The same also occurred for high lickers. Findings here The bottom line? Excessive licking could be a response to stress faced by your dog. Watch out for other signs of stress like: Panting in the absence of exercise Salivating in the absence of food Pacing Inappropriate toiletting Unusual vocalising Out of character behaviour Wide eyes Flat ears Abnormal tail placement Work to remove the trigger and support them with other stress reduction strategies. Also, be mindful that chronic stress can deplete essential nutrient resources. our Calm Complex can help support the above signs of stress. 2) Pain Pain is an uncomfortable feeling that gives us and our dogs an indication that something isn’t as it should. Not only are many breeds incredible at hiding pain (it wouldn’t have helped them in evolutionary terms), but they also lack the ability to converse. Whilst we would all love to think we have this form of communication with our dogs, we can miss things, especially if they are pretty crafty at hiding them! The sensation of pain is a necessary function that warns the body of potential or actual injury. Whilst we may think that dull ache in our lower backs is merely an inconvenience, it’s a rather reliable indication that our office chair possibly doesn’t suit us. Pain occurs when a nociceptor fibre detects a painful stimulus on the skin or in an internal organ. This detection is picked up by other receptors in the spinal cord and brainstem and then transmitted to the various areas of the brain. This is done through the incredible work of neurotransmitters. There exists both inhibitory and excitatory neurotransmitters. Those that make things happen, and those that apply the brakes. Inhibitory neurotransmitters are involved in the modulation of pain; including enkephalins and endorphins, serotonin, noradrenalin, GABA, acetylcholine and oxytocin. Excitatory neurotransmitters acting without an inhibiting system results in pain. Which is why pain killers primarily prevent the release of some excitatory neurotransmitters (and can in fact make you or your dog drowsy). When we look at the neurotransmitters involved, it’s possible to see why our dogs may start licking an area that is painful to them. Through touch they can stimulate the release of oxytocin (a modulator of pain). Not only that but self-trauma (excessive licking) is thought to promote the release of endorphins, which are also pain modulators. Findings here This demonstrates how dogs can get into a vicious cycle, they want to lick to soothe, but the more they lick, the more trauma they cause, resulting in more licking. There is also the possibility, that what could have started as a pain response, could turn into irritation, or what started as irritation, could turn into pain and continue the cycle. 3) Itch Itch is a sensation felt on the skin, which causes the desire to scratch. Although initially it could be as simply as scratching something to remove it, itching can become stressful when excessive. When tissues are stimulated by allergens, histamine is released from mast cells. Histamine makes the blood vessels expand, driving blood to the area creating that common swelling among other responses. Specialised nerve fibres are stimulated; when these are processed, the scratching or rubbing reflex is stimulated. The main mediators for the itch
