Did you ever get warned that kissing a stranger was like kissing everyone they had ever kissed too? Sadly, the same advice applies to our dogs too! Luckily when we’re talking about canine oral papillomas, they can’t be transmitted to humans, but these warts are caused by a virus which can be passed between dogs. So what’s the lowdown on canine papillomas? And why do our dogs get them? Here at My Pet Nutritionist, they seem to be the topic of the year so let’s take a look at them in a little more detail. What is the Canine Papilloma Virus? Warts in dogs are caused by infection with canine papilloma virus (CPV). They appear as lesions mostly found on the lips and muzzle and have a cauliflower like appearance. They can also grow on the oral mucosa which can affect eating and swallowing. In most cases, they are left untreated and may resolve within 3-12 months of presentation. CPV is transmitted through direct contact with another infected canine, and it spreads relatively easily. But as it’s a virus, its understandable that it most commonly strikes dogs with weakened or underdeveloped immune systems (which is why they are more common in younger dogs). The virus will also more easily settle in injured skin, so if a dog suffers with pre-existing skin issues they may be at an increased risk. The Immune System 101 When the body is invaded by bacteria, a virus or parasites, an immune alarm goes off, setting off a chain reaction of cellular activity in the immune system. Specific cells are deployed to help attack the invading pathogen. Those cells often do the job, and the invader is destroyed. But sometimes, when the body needs a more sophisticated attack, it turns to a more specialised set of cells. These cells are like the special ops of the immune system—a line of defence that uses past behaviours and interactions to tell it exactly how to deal with the threat. Through exposure to the virus, he body learns how to deal with it, which is why older dogs don’t always develop lesions even if they are living with another dog who does. But as we know, there are many things that can affect how well the immune system is functioning. Lifestyle and environmental factors can dictate if the immune system is fast and efficient, or whether it’s as much use as a chocolate teapot. What can affect immune function? Sleep Sleep is widely studied for its evolutionary benefits. It is crucial for most daily functions and in humans suffering sleep restriction, they have attention lapses, slowed working memory, reduced cognition and depressed thought. Studies have shown a significant reduction in activity in dogs experiencing sleep restriction. Findings Here One of the main purposes of sleep is to consolidate memories or learning. This has also been found true in dogs. Learning affects sleep structure which ultimately decides whether you retain the information or not. Interestingly, in studies, those dogs allowed to sleep after learning a new command were more likely to retain the command at a later date, than dogs allowed to walk or play. So, if you want to train your dog, they need their sleep. Findings Here But it is clear that sleep and the circadian rhythm significantly influence immune functions. It is thought that sleep facilitates the function of immune cells and also their redistribution to lymph nodes. In addition, in clinical studies, sleep on the night after experimental vaccinations produced a strong and persistent increase in the number of antigen specific cells and antibody titres. This suggests that sleep plays a role in immunological memory. Findings Here Under laboratory conditions, dogs will sleep around 13 hours per day. But this is very generic. Older dogs will sleep more as they tend to experience periods of broken sleep. Puppies too will sleep a lot more – generally 18-20 hours. Stress Since the dawn of time, both us and our dog’s ancestors have been subject to evolutionary pressure from the environment. The ability to respond to environmental threats or stressors such as predation or natural disaster enhanced survival. In mammals, these responses include changes that increase the delivery of oxygen and glucose to the heart and skeletal muscles. We know this as the stress response, or rather more specifically the fight or flight part of the stress response. But this serves as a redirection of resources, and data clearly suggest that chronic stressors suppress cellular and humoral responses in the immune system. In short, stress lowers the body’s response to viral load. Have you ever noticed that that pesky cold sore rears its ugly head when you’re feeling a little run down? That said, acute stressors (lasting a couple of minutes) upregulate certain immune pathways. This makes total evolutionary sense. In addition to the risk inherent in the situation, like a predator, fighting and fleeing carries the risk of injury and subsequent entry of infectious agents into the bloodstream or skin. Any wound in the skin is likely to contain pathogens that could multiply and cause infection. Stress-induced changes in the immune system that could accelerate wound repair and help prevent infections from taking hold would therefore be beneficial. The key is balance. Both us and our pets are designed to tackle short term stressors, the issue is when they become chronic and continually deplete our resources. Diet The immune system has a number of cells it can call upon, but these cells need to be made somewhere. In addition, for the messages to get sent around the body and for the antigens to be effectively neutralised, other cofactors and compounds are needed. Whilst the body is incredibly smart and can synthesise certain compounds itself, the majority of them need to come from somewhere and this somewhere is largely the diet. In addition, an activated immune system further increased the demand for energy during periods of infection. The Ultimate Raw Feeding Guide for Dogs Furthermore, the majority
Here at My Pet Nutritionist, we take a holistic view of your pet’s health. So, whilst we focus primarily on nutritional adjustments we can make, we look at everything else that is going on for your pet too. Not surprisingly we find that stress is a key player in many of the concerns brought to us. Most of us are familiar with the concept of stress, but do we truly understand the mechanism and the far-reaching impact it has on the body? Stress is huge, so we’ll try to condense it as much as we can. Stay with us. Despite the biological stress response being around for millennia, we first started paying attention to the actual response in the early part of the 1900s. Walter Cannon was the first Professor of Physiology at Harvard, and he was particularly interested in how the body managed to maintain its balance even when faced with things that could threaten it’s being. Building on this, Hans Selye established that no matter the stressor, each body (and brain) experienced the same cascade of responses. He also proposed that during the response to one stressor, our ability to withstand another is diminished. We often reference his theory when we discuss trigger stacking – and we’ve all been there – that day, when you miss your alarm, you spill the milk as you’re putting it in your coffee, then you lose your keys – and your ability to manage challenges that day just seems reduced. But on a biological level, we also see that when we are going through particularly stressful times, our immune system isn’t quite as nifty as dealing with threats and so we start picking up bugs and that old faithful cold sore rears its ugly head. The same concept applies to dogs, and if you sadly share your life with a reactive dog, you’ll see trigger stacking in them too. Equally, if they live with chronic stress, their immune function may go rogue too. This is why we always consider stress levels in those dogs who suffer with inflammatory skin issues. What is Stress? The official response starts in the brain. The amygdala, being the part of the brain that deals with emotions, sends a message to the hypothalamus which is like the command centre of the body. It communicates with the rest of the body through the autonomic nervous system which controls involuntary body functions like breathing, blood pressure and heartbeat. The autonomic nervous system is then split further into two branches, the sympathetic nervous system, and the parasympathetic nervous system. These are the systems that we are particularly interested in in the stress response. The Sympathetic Nervous System This system is known as the fight or flight system. We can think of it like the gas pedal of the stress response. This system: Dilates pupils – to see oncoming danger, Inhibits saliva production, Dilates bronchia, Increases heart rate, Inhibits the activity of the digestive system, Relaxes urinary bladder, This system is like a redistribution centre. When the body is faced with a stressor that can challenge body homeostasis, it redirects resources to re-balance. Blood is sent to the limbs to mobilise and why waste energy on food digestion? But this is where we see many issues. As we know, to absorb and utilise nutrients the digestive system needs to do its job. If the stress response is inhibiting the action of the digestive system, then it can’t do what it needs to. As part of sympathetic response, corticotropin-releasing-factor (CRF) is released. The name isn’t particularly important, but it seemingly plays a considerable role in altering gastrointestinal functions. It has been found that CRF: Inhibits gastric acid secretion Inhibits small intestine transit Increases intestinal permeability Increases visceral sensitivity Gastric Acid Secretion Gastric acid is a digestive fluid formed in the stomach, produced by parietal cells. The highly acidic environment in the stomach causes proteins from foods to lose their folded structure (denature) which exposes the peptide bonds. It is therefore a key player in protein digestion. Gastric acid secretion is regulated by the parasympathetic nervous system via the vagus nerve and by the hormone gastrin which stimulates the parietal cells. There is also an increased risk of infection with reduced gastric acid secretion. Low or no gastric acid can reduce the disinfectant properties of the gastric lumen. Gastric acid suppression is also associated with the development of food intolerances and allergies. Findings Here Small Intestine Transit The small intestine is chiefly involved in the digestion and absorption of nutrients, it receives pancreatic secretions and bile through the hepatopancreatic duct to aid its functions. In the stress response, it is thought that this mechanism encourages vomiting to expel potential pathogens, as in the large intestine, transit time is increased, again to aid expulsion. Poor motility can lead to small intestine bacterial overgrowth (SIBO) which is frequently implicated in nutritional deficiencies, malabsorption, weight loss and bowel changes like diarrhoea. Findings Here Intestinal Permeabilit The intestinal barrier is made up of tight junctions which allows the absorption of nutrients whilst limiting the transport of potential harmful antigens. Early stress and chronic stress have been seen to increase intestinal permeability both through TJ function and mucous degradation. Animal studies have demonstrated that early life stress impairs development of mucosal barrier function, becoming a predisposing factor to intestinal disorders in adult life. However, these stress induced changes do seem to respond to probiotic intervention. Probiotics have been seen to restore colonic tight junction integrity and enhance the mucus barrier. This is largely because stress impacts the bacterial community found in the gut. Studies have shown that early life maternal separation, for example, results in a significant decrease in fecal lactobacillus numbers, three days post separation. Mothers who report feeling stressed have a significantly higher number of proteobacteria and lower lactic acid bacteria. Findings Here Visceral Sensitivity Evidence suggests that long term stress facilitates pain perception and sensitises pain pathways. There is a clear gene-environment interaction which
Vitamin B12, also known as cobalamin, is a water-soluble vitamin which means no matter how much it is absorbed; any excess will be excreted via urine. It is critical for a range of functions in the body and if you have looked in any multivitamin aisles in the supermarket, it is one of the well-known B complex vitamins. A common deficiency in human vegetarians,disorders of cobalamin metabolism are seemingly increasing in small animal medicine. The causes of deficiency range from chronic gastrointestinal disease to hereditary disease, but what is clear is the health impact of low levels. Suboptimal B12 levels result in: Blood cell count abnormalities Disorders of lipid and protein metabolism Failure to thrive Anorexia Lethargy Vomiting Mood disorders/cognitive decline Slow healing Shortness of breath Muscle weakness Unsteady movement Increased homocysteine levels Functional folate deficiency Because the human body’s stores of B12 can seemingly last 3-6 years, low levels may take a while to be noticed. This seems to be true in our four-legged friends too. So, without further ado, let’s take a look at why it’s so important. Vitamin B12 is essential for DNA and RNA synthesis and for cellular energy production. All cells in all bodies need to know what they are doing and they need energy to do them! There are no known naturally occurring bioactive forms of B12 in plant sources. This is because B12 is synthesised by the bacteria in the gastrointestinal tract of animals, and then absorbed by the host animals. B12 is concentrated in their tissues, which is then eaten by other animals. Sources of B12 include red meat, fish, dairy and eggs. This is why human vegetarians and vegans are often low in it. Once ingested, dietary protein is partially digested by pepsin (digestive enzyme) and hydrochloric acid (HCI). Here Cbl (cobalamin) is released and binds to another protein called haptocorrin. Haptocorrin is then digested by pancreatic proteases (things that breakdown protein); freeing Cbl which can then bind to intrinsic factor. This then forms the B12 complex which travels through the small intestine. Here, there are receptors for intrinsic factor. The complex is internalised into the ileal enterocyte, and then released into the plasma, binding to a plasma protein. B12 is then delivered to those body parts that use and need it. And, there are certain many parts of the body that need and use it. Methionine Cycle B12 plays a vital role in the methionine cycle, which is involved in a range of cellular functions, particularly converting homocysteine to methionine. Methionine can be converted into sulphur-containing molecules which protect tissues,modify DNA, and ensure correct functioning of cells. Methionine also plays a role in creating new proteins in the body, which is essential when older proteins degrade. Whilst it has a role in a range of functions, there have been suggestions that cancer cells too are methionine dependent. Yet, when methionine is replaced with its precursor homocysteine, cancer cell growth is inhibited. Findings here That said, methionine is a key player in producing glutathione. Glutathione is often referred to as the body’s master antioxidant. It is composed of the three amino acids cysteine, glycine and glutamate. Glutathione is an important part of the body’s defence systems. Free radicals are like the exhaust fumes of work, work that the body carries out on a day to day basis. An imbalance in free radicals can result in oxidative stress, something which glutathione can alleviate. Glutathione depletion is often linked with low immune function and increased infection. It has also been found to be protective of skin, lens, cornea and retina damage. Findings here The balance of homocysteine is important,and B12 (along with B6) has the greatest effect on those levels. High levels of homocysteine are often linked to the early development of heart disease, along with Alzheimer’s (in humans), birth defects, blood clots, endothelial damage, and stroke. Resistance to Insulin Mouse studies have suggested that restricted B12 and methionine resulted in an increased resistance to insulin. Insulin is the gatekeeper for glucose getting into cells. Without insulin, glucose remains in the blood without a party to go to. It is argued that the restriction resulted in the lower availability of molecules that are vital to the process of DNA methylation (regulator of gene expression). These gene expressions were modulators underlying the development of resistance to insulin. Findings here Lipid (Fat) Metabolis Low levels of B12 have been noted to increase levels of adiposity, triglycerides, and total cholesterol. It is suggested that deficiency inhibits the oxidation of fatty acids. In these cases, there is also an increase in pro inflammatory cytokines. Findings here The dysregulation of lipid metabolism raises another interesting element. The nervous system has a rich lipid composition. Myelin sheaths are sleeves of fatty tissue that protect nerve cells. These nerve cells carry messages around the body. This is why low levels of B12 can lead to peripheral neuropathy. Without sufficient B12, the myelin sheath is damaged (demyelination) resulting in the disruption of nerve signals between the spinal cord and different parts of the body. This is the same mechanism that occurs in degenerative myelopathy. Whilst it is generally deemed a genetic condition in dogs (specific to certain breeds), in human studies, low levels of B12 have been associated with the condition. B12 deficiency is often a differential diagnosis to degenerative cervical myelopathy in humans too. Findings here Humans with low B12 often report progressive tingling in fingers and toes, without the ability to speak, it is unclear whether these symptoms affect our dogs too, but certainly poses food for thought in itchy cases. Findings here Anaemia The most recognised deficiency of B12 is anaemia. B12 is involved in the formation of healthy red blood cells; anaemia is when the body doesn’t have enough of them. Pernicious anaemia is usually a result of malabsorption of B12 due to a lack of intrinsic factor, the protein found in the stomach. Without enough B12, the red blood cells don’t divide normally (thanks to
