Cushing’s Disease in dogs is one of the most common endocrine problems that pups can deal with. Considering how common it is, it may surprise you that it is also one of the most overlooked medical conditions in dogs. Cushing’s commonly occurs in dogs that are entering their golden years. Sadly, pet owners often think their beloved doggo is just aging, because they mistake the symptoms of Cushing’s disease for natural aging.
Every doggo dad or doggo mom should familiarize themselves with Cushing’s Disease in dogs. If left untreated, the disease could become life threatening. That’s why it’s important to learn the symptoms and learn how to prevent it. Most important of all: know that if your pup has Cushing’s Disease in dogs, chances are you will have to manage it for the rest of their life!
What is Hyperadrenocorticism or Cushings Disease in Dogs?
Cushing’s disease, also known as Hyperadrenocorticism, is an endocrine disorder. When you hear “endocrine”, you should think “glands”. Well, glands and hormones to be more precise. As with all other systems within the body (canine or human), as soon as there is an imbalance, things begin to malfunction.
Cushing’s disease is one such imbalance. It is what happens when, for a number of possible reasons, the body produces too much cortisol. Cortisol is produced in your dog’s adrenal glands (the ones that sit on your dog’s kidneys), along with other steroid hormones like cortisone.
Cortisol has a couple of very useful functions, such as regulating body weight, keeping blood sugar under control, and let’s not forget the famous (and very useful) Fight or Flight response that this stress hormone triggers. Cortisol does, however, become a problem when the body starts producing too much of it. Ergo, the “hyper” in hyperadrenocorticism. Canine Hyperadrenocorticism is not fun for anyone as the elevated cortisol levels can cause a farmyard of problems.
There is a long list of manifestations and clinical signs of Cushing’s disease: increased hunger, increased thirst, and hair loss to name but a few. The cause: an excess of systemic (on the inside) cortisol.
The 3 Types of Cushing’s Disease in Dogs:
1. Pituitary-Dependent Hyperadrenocorticism
Pituitary-Dependent Hyperadrenocorticism (PDH) is the most common type of Cushing’s disease in dogs. It is caused by a pituitary tumor, which in most cases, is benign. One of the pituitary gland’s most important jobs is control other glands in the endocrine system, glands such as the adrenal glands.
How does the pituitary control the adrenal glands? Easy. The pituitary gland produces Adrenocorticotropic Hormone (ACTH). This hormone stimulates the production of cortisol in the adrenal glands. However, the pituitary gland gets its wires crossed when there’s a tumor present and will send the wrong signals to the adrenal glands. Consequently, the adrenal glands receive abnormal amounts of ACTH and produce cortisol like it’s going out of fashion.
PDH is the cause of 80% – 85% of Cushing’s cases in dogs. Benign pituitary tumors make up the bulk of those percentages.
2. Adrenal-Dependent Hyperadrenocorticism
Adrenal-Dependent Hyperadrenocorticism (ADH) accounts for the other 15% – 20% of cases of Cushing’s disease in dogs. With PDH, the problem lies in the malfunctioning of the pituitary gland. The adrenal glands are simply taking orders.
With ADH, the problem lies with the adrenal glands themselves. ADH is also caused by tumors, this time, within the adrenal glands. The tumors in adrenal glands have a much higher probability of being malignant. A 50% / 50% chance to be exact.
If the adrenal tumors are malignant, there is a possibility that they may metastasize, meaning they will multiply and spread.
3. Iatrogenic Hyperadrenocorticism
This last type of Cushing’s is not a disease technically speaking, but along with PDH and ADH, it also falls under the term “Cushing’s Syndrome”. Iatrogenic Hyperadrenocorticism has nothing to do with either the pituitary gland or the adrenal glands. Instead, modern medicine is to blame for this syndrome.
Most pet parents will (hopefully) know that giving certain medications to dogs over extended periods of time can cause serious damage. These medications, such as corticosteroids, work wonders to treat conditions such as inflammation, immune disorders, allergies, and even cancer. In addition, Corticosteroids are actually given to dogs with hypoadrenocorticism (i.e. their bodies don’t produce enough cortisol).
If there is a misdiagnosis and the dog’s body does produce sufficient cortisol, adding corticosteroids to the dog’s system will cause the same abnormalities as Cushings disease in dogs does.
Cushing’s Disease Symptoms
Symptoms of Cushing’s Syndrome in dogs are easily overlooked because there are so many of them. On top of that, many of the symptoms are common signs of completely unrelated conditions.
If your dog shows one or more of the possible Cushing’s symptoms, take them to the vet to be checked out. The prognosis for Cushing’s Syndrome isn’t great, so the earlier you catch and diagnose it, the more time you can buy for your doggo.
Here are some of the more common tell-tail symptoms of Cushing’s Syndrome:
- Increased appetite – Even the most obedient dog will begin foraging, begging and stealing food
- Weight gain
- An extended “pot-belly”
- Weak and wasting muscles
- Polydipsia – Increased thirst
- Polyuria – Increased urination. Your house trained dog will suddenly start having piddles inside.
- Incontinence – Leaking wee
- Excessive panting
Other signs of Cushing’s syndrome are:
- White, scaly patches – especially on the elbows
- High blood pressure
- Hair loss – Cushing’s disease in dogs can cause their hair to become much thinner, and in some cases, dogs will lose hair everywhere except on their legs and their head.
- Darkened skin
- Thin skin
- Bruised skin
- Urinary Tract Infections – This could become a recurring condition
Rare signs of Cushing’s Syndrome in dogs include:
- Neurological abnormalities
The Causes of Cushing’s Disease in Dogs
All cases of Cushing’s Syndrome either occur naturally or are a result of the adverse effects of certain medications.
Pituitary-dependent Hyperadrenocorticism is caused by a tumor (in most cases benign) in the pituitary gland at the base of the brain.
Adrenal-dependent Hyperadrenocorticism is caused by a tumor (benign or malignant) in the adrenal glands on the kidneys.
Iatrogenic Hyperadrenocorticism is caused by an excess of corticosteroids, given to a dog at high doses for an extended period of time. Steroids are never a long term solution for treating medical conditions. You aren’t doing your dog a favor by keeping them on steroids.
Which Dogs are More Likely to Develop Cushing’s Disease?
First off, there are a few factors which may increase the likelihood of a dog developing Cushing’s disease. These factors are age, breed, and gender.
(Naturally occurring) Cushing’s disease is more common in middle-aged and older dogs. Dogs are diagnosed with Cushing’s disease at an average age of around 11 years. The symptoms of Cushing’s disease are often mistaken for signs of old age, so this isn’t too surprising. Dogs younger than 6 are diagnosed with naturally occurring Cushing’s Syndrome only the the rarest of occasions.
Breed and Size
Poodles, Boxers, Dachshunds, and Terriers are more prone to developing Cushing’s disease. The disease does not discriminate though and can affect dogs of any breeding. Or lack thereof.
Size seems to be a factor in dog’s developing pituitary tumors (pituitary-dependent hyperadrenocorticism or PDH). Adrenal tumors (Adrenal-dependent hyperadrenocorticism or ADH) are equally common in dogs of all sizes, but 75% of dogs with PDH weigh less than 44 lbs.
PDH is equally common in dogs of either sex, but ADH, strangely enough, is more common in females.
Diagnosing Cushing’s Disease in Dogs
Diagnosing Cushing’s is a multi-step process. Unfortunately, there is not one test that will confirm whether a dog has Cushing’s, and if so, what type of Cushing’s the dog has. Cushing’s shares common symptoms with a range of other illnesses. Unless there are severe tell-tale symptoms that point to it, veterinarians will first check for other illnesses before assessing for Cushing’s.
The average age of a dog with Cushing’s is 11 years. With this said, many of these dogs probably developed Cushing’s before the age of 11 but their parents did not know it at the time.
Your veterinarian will first:
- Take a full history of your dog’s health
- Perform a physical exam
Based on your dog’s medical history and the physical exam, if your veterinarian suspects that your dog may have Cushing’s Disease, there are a series of tests which can help to confirm their suspicions. These tests can help vets not only to diagnose the disease, but also to differentiate between PDH and ADH.
Here are some of the tests which veterinarians may perform upon suspicion of Cushing’s Disease:
- Blood count
- Fecal analysis
- Urine analysis – When testing for Cushing’s with a urine analysis, vets check the urine cortisol : creatinine ratio. If there is a high cortisol ratio, it’s a sign that you may be dealing with Cushing’s.
- Abdominal ultrasound – This will not only help to confirm the presence of adrenal tumors and their size, but it can show whether or not the tumors are metastasizing.
- CT Scan
- Thyroid function test – Hyperadrenocorticism (HAC) affects Thyroid gland function. The symptoms of Cushing’s disease and hypothyroidism are very similar. Consequently, Vets often misdiagnose Cushing’s dogs with hypothyroidism.
- Low-dose dexamethasone suppression (LLDS) test – A dog’s cortisol levels are established by means of a blood test. The dog is then injected with a small dose of Dexamethasone, suppressing the Adrenocorticotropic hormone (ACTH), which stimulates cortisol production. Blood samples are taken 4 hours and again 8 hours after the dog was injected. The cortisol levels are analyzed in each of the blood samples. The production of cortisol is not suppressed by the inhibiting of the ACTH in dogs with Cushing’s disease. In normal dogs, their cortisol levels are lower after the dexamethasone injection.
- High dose dexamethasone suppression (HDDS) test – This test will help your veterinarian tell whether your dog is dealing with pituitary or an adrenal tumor.
- ACTH stimulation test – The ACTH stimulation test serves to help vet’s test for Cushing’s and Addison’s disease in dogs. The vet will take a blood sample and check your dog’s cortisol levels. They will then inject your dog with ACTH. In dogs with Cushing’s, the ACTH stimulation will cause the adrenal glands to release its excess cortisol (if there is any). More blood samples are taken over a few hours. Cortisol levels are analyzed in each of the various samples.
Cushing’s Disease Treatment
Sadly, there is no quick fix for Cushing’s disease. Treatment can often be expensive, aggressive, and complicated, especially if you are dealing with more than just Cushing’s. Trying to balance a dog’s hormones is a complicated task because, well, chain reaction. Cause and effect.
Treating Cushing’s Disease in Dogs with Veterinary Medicine
Cushing’s is one of those diseases in which 50% of vets won’t treat if the dog’s symptoms aren’t severe. Especially in the case of PDH. Vets will generally recommend that you monitor the dog, but they will hold out on treatment until the treatment is beneficial. Meaning the symptoms are doing more harm than the meds might. Most Cushing’s medications have serious side effects, so vets don’t like to hand it out lightly.
Without delay, here are some of the medications vets might recommend for treating pituitary-dependent Hyperadrenocorticism in dogs:
Vetoryl treats both PDH and ADH in dogs. Vetoryl capsules work by suppressing the cortisol production in the adrenal glands. Dogs generally respond quite quickly after starting the treatment. A dog’s Vetoryl intake needs to be regularly monitored and assessed, even if their symptoms are improving. This will be a life-long treatment.
Like Vetoryl, Lysodren inhibits the production of cortisol by suppressing the adrenal gland. Dogs taking this drug often experience many adverse side effects, which is why vet’s will only prescribe it when it is absolutely necessary and in the best interest of the dog. Dogs with Functional Adrenocortical Tumors are often prescribed Mitotane.
Radiation therapy is an aggressive approach, but it has proven to be very successful in shrinking pituitary tumors. It is one of the more common treatment plans for dogs with pituitary tumors which measure over 8mm vertically.
Other medications include:
Ketoconazole for Dogs
Ketoconazole is actually an anti-fungal medication, but it can help to keep Cushing’s under control in 50% to 66% of dogs. It inhibits the production of glucocorticoids and slows down the circulation of cortisol in the system.
Ursodiol for Dogs
Ursodiol is not directly speaking a drug used to treat Cushing’s in dogs. It is however, a popular choice for treating liver disease and gallstones in dogs. Dog’s with Cushing’s Disease are 29 times more likely to develop gallstones, so this is a drug to keep in mind if your dog has Cushing’s.
Denamarin for Dogs
Denamarin is a supplement which supports the liver. Liver problems are very common in dogs with Cushing’s disease. Hardly surprising how this condition throws the whole body out of whack. As soon as you add Denamarin to your dog’s diet, it should help support their liver function.
Surgical Treatment for Adrenal Tumors
In the best-case scenario, medication can not only suppress adrenal gland tumors, but can also help to shrink them. In the worst-case scenario, the adrenal tumors are malignant, inoperable, and have spread to other parts of the body.
Vets use medications such as Trilostane and Mitotane to treat and manage adrenal tumors. However, your vet will have to surgically remove the tumors if the medication doesn’t work.
The surgery is by no means risk free, but if all goes well, adrenal-dependent hyperadrenocorticism (ADH) is the one type of Cushing’s disease which is curable.
Treating Iatrogenic Hyperadrenocorticism
In comparison to treating “true” Cushing’s disease, treating Iatrogenic Hyperadrenocorticism is relatively simple. With that said, if it’s done incorrectly, it can have devastating consequences.
Medication causes this form of Cushing’s Syndrome in dogs. Therefore, the obvious thing to do, is stop giving them the medication.
However, never ever stop giving your dog their corticosteroid medication without consulting your veterinarian first! You will have to wean a dog with Iatrogenic Hyperadrenocorticism off of the medication slowly. If you don’t, it is likely to result in an Addisonian Crisis (or Addison’s Disease).
The Tricky Thing About Treating Cushing’s Disease in Dogs
First off, diagnosing and treating Cushing’s disease is not often a simple affair. Take for example, the combination of Cushing’s and Diabetes Mellitus. Both diseases have common symptoms. A dog can have one of the two diseases or they can have both simultaneously. In cases where dogs have both, vets will need to stay sharp.
Two common symptoms of Cushing’s disease. If the dog is drinking excessive amounts of water, they are also flushing their system. Flushing the system, the kidneys in particular, prevents a buildup of toxins (which is very important for diabetic dogs). Should the vet treat the Cushing’s, the dog might stop drinking so much water which would result in a build-up of toxins… You can see where this is going. It is conditions such as Cushing’s and Diabetes which really pack a powerful punch for the argument of a holistic approach to treating illnesses in dogs. It simply makes sense.
Holistic and Natural Treatment Options
Holistic treatment and natural remedies are a great option for many dogs with Cushing’s disease. Unless the dog’s symptoms have progressed to a dangerous level, there is no reason why pet parents shouldn’t try treating the disease naturally and holistically.
Lastly, here are a few treatment options and supplements for pet parents who want to take a holistic and natural approach to treating Cushing’s Disease in their dogs:
- A healthy, balanced diet
- Homeopathic remedies such as Burdock, Dandelion, or Milk Thistle. Anything that supports the liver, kidneys, immune system, and can aid in bringing the body into a state of homeostasis is a win.
- Lignans – Lignans are plant extracts that have a range of nutritional benefits. Lignans lower cortisol levels naturally in dogs with Cushing’s. Many pet parents swear by Lignans, so its worth giving this supplement a try.
- Melatonin – Melatonin levels are lower in dogs with Cushing’s Syndrome. Adding it as a supplement to your dog’s treatment plan will mean added support for hair growth, as well as reduced stress and anxiety. Be sure to choose a product made for dogs. Human Melatonin doses are far higher and most likely unsafe for dogs.
- Pet Alive Cushex Drops by Native Remedies – They have a range of drops to treat the various problems associated with Cushing’s disease.
While the prognosis for dogs with Cushing’s disease isn’t great, there are so many ways to keep a Cushingoid dog’s tail wagging. However, all things considered, medication, supplements and tons of love will go a long way in making them comfortable and allowing them to be their happy doggo selves.