The Low Down on Cushing’s Disease in Dogs

Here at My Pet Nutritionist, we tend to see quite a few cases of Cushing’s disease. Some cases seem to occur as a result of corticosteroid treatment and others tend to come with a plethora of other symptoms and disease. Here we can cover all we understand about this disease from a conventional perspective, and then we can delve deeper into the natural support we tend to offer.

Cushing’s disease, also known as hyperadrenocorticism, is a condition in dogs where the adrenal glands produce too much cortisol; a hormone that helps regulate metabolism, immune response, and stress. There are two primary forms of Cushing’s disease in dogs as we currently understand, but various other forms which are perhaps less common. Let’s take a look at these, starting with the two primary forms.

1. Pituitary-dependent Cushing’s Disease (PDH): This is the most common form, accounting for about 85% of cases. It’s caused by a benign tumour in the pituitary gland (a small gland at the base of the brain) that stimulates the adrenal glands to produce excess cortisol.
2. Adrenal-dependent Cushing’s Disease (ADH): This form is less common and results from a tumour in one of the adrenal glands themselves. This tumour produces excess cortisol independently of the pituitary gland.
3. Iatrogenic Cushing’s Disease: This form of Cushing’s Disease is caused by the administration of corticosteroid medications (e.g., prednisone) for other medical conditions. Long-term or high-dose use of these medications can lead to symptoms similar to Cushing’s Disease. This is not a true form of Cushing’s Disease but rather a drug-induced condition, meaning it can be ‘reversed’. Once the corticosteroid medication is reduced or stopped, the symptoms usually resolve, though it’s important to do so under veterinary guidance.
4. Primary Adrenal Hyperplasia: In rare cases, a dog may develop Cushing’s Disease due to non-tumour-related hyperplasia (enlargement) of the adrenal glands, which leads to excessive cortisol production. This is less common compared to pituitary or adrenal tumours, and may occur due to chronic inflammation or trauma.
5. ACTH-Secreting Tumours Elsewhere: While the pituitary gland is the most common source of excessive adrenocorticotropic hormone (ACTH) production leading to Cushing’s Disease, there are rare cases where tumours in other parts of the body (such as the pancreas) can produce ACTH or ACTH-like substances, leading to Cushing’s- like symptoms.
6. Genetic or Congenital Causes: Although rare, some genetic or congenital conditions could potentially lead to Cushing’s Disease by causing the adrenal glands to produce excessive cortisol. However, this is not well-documented and is less commonly recognised or understood.

In summary, while tumours in the pituitary gland or adrenal glands are the most common causes of Cushing’s Disease in dogs, other less common scenarios, such as iatrogenic effects or rare forms of hyperplasia, can also lead to similar symptoms.

Symptoms of Cushing’s Disease

The symptoms of Cushing’s Disease can vary, but common signs include:

• Increased thirst and urination. Dogs may drink more water (polydipsia) and urinate (polyuria) more frequently.
• Increased appetite
• Excessive Panting
• Abdominal swelling: A “pot-bellied” appearance due to abdominal distension. The weight is usually carried differently to those who are simply obese.
• Hair loss: The coat may become thin or brittle, and dogs may experience symmetrical hair loss, sometimes all over!
• Skin changes: The skin may become thin and prone to bruising/discolouration or infections. Those with hair loss caused by Cushing’s Disease often have a black, scaly look about them.
• Lethargy and fatigue
• Muscle wastage, especially in the hind limbs
• Behavioural change, including increased irritability or changes in mood.

If you suspect your dog has Cushing’s Disease, your first step as a responsible pet owner is to seek veterinary assistance, where your dog’s symptoms can be investigated, and an appropriate diagnosis made. It is important to work with your veterinarian to build a suitable treatment plan for your pet.

It is also important to note that some of these symptoms can also commonly be seen in other disease, hence the importance of a veterinary consultation.

Causes and Risk Factors

The exact cause of Cushing’s Disease isn’t always clear, but several factors can contribute:

• Genetics: Certain breeds are more prone to developing Cushing’s Disease, including most commonly Dachshunds, Poodles, Boxers, and Beagles.
• Age: Cushing’s Disease is more commonly diagnosed in middle-aged to older dogs, typically between 6 to 12 years of age.
• Tumours: Tumours in the pituitary gland or adrenal glands are the primary cause of Cushing’s Disease. These tumours are usually benign but can lead to significant health issues due to the impact on hormonal production and the overproduction of cortisol.
• Gut Health: Gut health has a huge impact on Cushing’s Disease for many reasons. Gut dysbiosis (which occurs when there is an imbalance in the gut microbiome) can come hand-in-hand with Cushing’s Disease due to the fact that some types of bacteria found in the gut cause Cortisol degradation. In those with Gut Dysbiosis, the microbiome may lack enough of this bacteria, causing elevated Cortisol levels.
• Inflammation: any inflammation in the body is a risk factor of Cushing’s Disease. Cortisol is known to reduce inflammation, however levels are often so high in those with Cushing’s Disease, the body often enters a state of low-grade systemic inflammation. This generalised inflammation can lead to a host of other diseases including cardiovascular (heart) disease, diabetes, and bone mass issues such as osteoarthritis.
• Toxin Exposure: When we really look into the nitty gritty of toxin exposure, both internally and externally, we can see worrying factors that can cause Cushing’s Disease, and other endocrine diseases. Unfortunately, some toxins our pets (and their humans!) often come into frequent contact with, are known endocrine disruptors. Endocrine disruptors interfere with the balance of hormones in the HPA Axis, which can cause overproduction of the cortisol hormone, and also commonly presents as skin issues. You can read more about the HPA axis here.

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Diagnosis

Diagnosing Cushing’s Disease involves a combination of blood tests, urine tests, and diagnostic imaging (usually ultrasound or CT scans) to check for tumours and assess hormone levels.

The main tests used to diagnose Cushing’s Disease are:

• The ACTH stimulation test. During this test, a blood sample is taken, before the dog is given a synthetic ACTH-like drug, intravenously. Two hours after the injection is given, another blood sample is taken. Cortisol levels in both blood samples are compared with one another, to check how much cortisol the body has produced in the presence of the ATCH-like drug (which mimics the Adrenocorticotropic Hormone secreted by the Pituitary Gland). Your veterinarian will then interpret these results.
• The low-dose dexamethasone suppression test. For this test, a blood sample is taken before a low-dose injection of dexamethasone is administered. Dexamethasone is a glucocorticoid drug. Blood samples are also taken 4 hours after injection, and again at 8 hours after injection. The second and third samples are compared to the first sample, which will tell the veterinarian if Cushing’s Disease is present, and if so, what type. Pituitary and Adrenal types will show different results at 4 hour and 8 hours.
• The urine cortisol-to-creatinine ratio. This test measures the amount of cortisol in a dog’s urine. A sample of urine is to be taken from the dog in the morning. The sample is then split, and tested to find the concentration of both cortisol, and creatine. The ratio of Cortisol to creatinine will determine if your dog has Cushing’s Disease or not.

Conventional Treatment

Treatment options vary depending on the form of Cushing’s Disease and its severity, but include:

• Medication: Drugs like trilostane (Vetoryl) or mitotane (Lysodren) are used to help manage cortisol levels. This can be sometimes be helpful since those with Cushing’s Disease have an increased Cortisol release.
• Surgery: In cases of adrenal tumours, surgical removal of the affected adrenal gland might be recommended.
• Radiation therapy: For pituitary tumours that are not operable, radiation therapy can sometimes be suggested.

Management of Cushing’s Disease often requires lifelong treatment and regular monitoring by a veterinarian. If you suspect your dog might have Cushing’s Disease, it’s best to consult with your vet for a thorough evaluation before creating an appropriate treatment plan.

A Natural Approach to Cushing’s Disease

As always, our approach is often supported by veterinary care, so we tend to look at this as a complementary approach as opposed to alternative.

Here are some of our considerations:

• A Fresh Diet: whether it’s raw, or lightly cooked food, a fresh diet is the most gut-friendly option when it comes to feeding your dog. A healthy gut can reduce the risk of Cushing’s Disease, as the correct balance of gut flora in the microbiome means the bacteria capable of breaking down cortisol is present I the correct amounts.
• Stool and Mineral Tests: Running a stool test, to check for parasitic burdens, and bacterial overgrowths may be considered as a means of viewing a good picture of gut health. Having a mineral test performed on your dog may also be advisable to get a good look at gut health and mineral absorption – ensuring gut health is optimal can be a huge part of preventing Cushing’s Disease, as well as a part of managing it if your dog has a positive diagnosis.
• Testing Inflammatory Markers: As inflammatory markers are one of the elevated figures in the body of a dog with Cushing’s Disease, having these tested may be crucial to diagnosis of Cushing’s Disease; regularly checking these levels can also give an insight into how beneficial your dog’s treatment plan is.
• Check vitamin D status: Vitamin D deficiency is common in those with Cushing’s Disease. Vitamin D deficiency can present as hair loss, fatigue, musculoskeletal pain, and itching. Checking your dog’s Vitamin D status enable you to adapt your pet’s diet if required.
• Probiotics and Gut Healing Protocols: The gut is absolutely essential to keep healthy. It really is the main ‘hub’ of health in the body, and poor gut health, leads to other problems within the body – everything from hormone regulation to joint and skin health, brain health and calm behaviour, and so many more aspects of health. Our fantastic product, Gut Guardian is your all-in-one supplement for gut healing and microbiome boosting. Mucilage herbs are ideal for gut healing, while high quality soil based probiotics help the gut microbiome to flourish.
• Herbs that can help regulate cortisol levels, blood sugar balance and inflammation: you may wish to consider adding some beneficial supplements to your dog’s diet, including Ashwagandha (helps to lower cortisol levels), Cinnamon (helps to regulate blood sugar levels and reduce inflammation – aim for Ceylon Cinnamon!), Rhodiola (helps balance cortisol levels), Ginseng (anti-inflammatory properties), Liquorice Root (helps to regulate cortisol levels)
• Support to Detoxification: Detox, often best achieved using Milk Thistle, can help those with Cushing’s Disease, particularly when caused by tumours. The active compound in Milk Thistle, Silymarin, has properties which can help shrink these tumours!
• Reduce Exposure to Toxins: environmental toxins, including flea products, household cleaning products, and gardening products can have an enormous impact on glands and organs in the body, which in turn plays havoc with hormones. Eliminating exposure to these toxins may help reduce the symptoms of Cushing’s Disease.
• Liver support: Liver support may be a great consideration for those with Cushing’s Disease. While the dog rarely has major liver issues, the ALT score in a blood test can show as though the dog does have liver abnormalities. Our excellent liver-friendly supplement, Liver Guard is a beautiful blend of Milk Thistle, Methylated B Vitamins, and other beneficial organic herbs and minerals; essential for detoxification and liver support!

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To conclude our guide to spotting, diagnosing and treating Cushing’s Disease, and supporting the body with natural options, if your dog frequently shows any of the aforementioned signs and symptoms, book in with your veterinarian as soon as possible. If you feel you could benefit from some 1-2-1 support for your dog, consider booking in with one of our team!

Team MPN x