What is Cushing’s Disease in Dogs? Treatment, Symptoms, and More!Reading Time: 5 minutes
Cushing’s disease is a common disease in humans, but it can also appear in dogs too! Cushing’s disease in dogs is often gone unheard of as most people are oblivious to the disease occurring!
Generalised by a hyperactive adrenal gland, Cushing’s disease in dogs is more serious then you might think. For this reason, it is important we have a comfortable idea of what it is and how it might present in your dog. If you think your dog has Cushing’s then read on to learn more!
What is Cushing’s Disease in Dogs?
Now you’re probably wondering what exactly Cushing’s disease in dogs might involve? Just as in humans, Cushing’s disease involves the over-production of the hormone cortisol. This is also referred to as hyperadrenocorticism. The adrenal glands are responsible for producing cortisol, along with several other hormones involved in homeostasis.
However, when something goes wrong and the adrenal glands start producing too much cortisol, several problems can arise. Cortisol receptors are numerous throughout the body, which means the levels of cortisol can have various effects.
Normal functions of cortisol involve the regulation of blood glucose levels and metabolism, response to stress and control of blood pressure. When abnormally high amounts of cortisol are being produced, these systems can be affected and clinical signs can appear. But before we get into the symptoms and signs of the disease, let’s explore a bit more of the science!
Cushing’s Disease: The Importance of the ACTH Hormone!
As mentioned earlier, cortisol is a very important hormone for various reasons. Though there are many other hormones alike, One being the adrenocorticotropic hormone (ACTH). This hormone is produced by the pituitary gland (in the brain) and is responsible for stimulating the release of cortisol from the adrenal gland. That’s right, hormones can act on hormones!
The release of ACTH is regulated by input factors such as external stress stimuli and blood sugar levels. For example, if blood sugar levels are low, this stimulates the Pituitary gland to release ACTH into the blood. This makes its way to the adrenal glands which causes an increased release of cortisol into the blood.
The increased cortisol levels cause a reaction in the liver to take place, converting fats and proteins into glucose. This glucose is released into the blood and in turn, increases your blood sugar levels! So you can imagine if there was a problem with the ACTH hormone production from the pituitary gland, the rest of the pathway would become altered.
To asses the functioning of the adrenal glands in response to the ACTH, the ACTH stimulation test can be performed. This indicates whether or not the adrenal glands are responding well or abnormally to the hormone and allows for appropriate treatment.
This involves an injection of ACTH into yours dogs muscle, and an hour later taking a blood sample. The blood sample will be measured for cortisol levels to asses how well the adrenal glands are responding to ACTH hormone.
This test is helpful in determining whether clinical signs are associated with problems in the pituitary gland, or adrenal gland response. In fact, Cushing’s disease in dogs is most commonly caused by problems associated with the pituitary gland rather than the adrenal! But how exactly does this occur?
What is Pituitary Adenoma?
Hopefully, you now have a rough understanding of how the pituitary gland and cortisol levels tie together. So what happens if the pituitary gland has a tumor? large, benign tumors of the pituitary gland are known as adenomas. The effect they have can depend on whether it is functional (secreting hormones) or non-functional.
Most pituitary adenomas are functional, meaning they are actively secreting the ACTH hormone. Non-functional adenomas don’t secrete a hormone, instead, they cause problems with the growing pressure they exert on surrounding brain structures. Though both types are typically benign, the functional tumors can have had a marked effect on cortisol levels.
Functional pituitary adenomas secrete ACTH, on top of the already actively-secreting pituitary gland. This causes an increase in ACTH hormone in the blood. Do you recall the effect of ACTH levels on the adrenal glands? It can dangerously increase the amount of cortisol being produced by the adrenal glands.
So excess cortisol is circulating! And excess cortisol in the blood is the characteristic of Cushing’s! Pituitary adenomas are actually the most common cause of Cushing’s disease in dogs!
3 Facts Pet Owners Need to Know About this Disease!
- Once successfully diagnosed, canine Cushing’s disease is very treatable!
- There are a range of signs this disease can present with, if you suspect something is abnormal, take your dog to the vet. better safe than sorry!
- Hyperadrenocorticism is more often seen in older dogs.
- Cushing’s disease is often confused as Addison’s disease. But the two are very different!
- This disease is most commonly seen in Yorkshire Terriers, Boston Terriers, Labradors, and even Australian Shepherds.
A Pituitary Gland Disorder: Causes of Cushing’s in Dogs!
The major causes of canines Cushing’s disease typically fall into two categories. There’s the pituitary-dependant type, the most common cause of canine Cushing’s disease.
As mentioned earlier this involves pituitary adenomas, claiming around 80% of cases. On the other hand is the adrenal gland-dependant cause. This involves tumors in the adrenal gland, responsible for around 20% of Cushing’s disease in dogs.
Generally, pituitary tumors have a good prognosis. As long as the activity of the adrenal glands can be controlled through the use of medicine. However, if these tumors grow and exceed 1cm, they are known as macroadenomas. Macroadenomas, due to their size, can put pressure on structures in the brain surrounding the pituitary.
This growing pressure will begin to cause associated neurological signs on top of the Cushing’s disease symptoms. These cases can become complicated and happen to around 15% of dogs with pituitary adenomas. Unfortunately, if your dogs start showing neurological signs, the prognosis typically takes a plunge.
Although only 20% of canine Cushing’s disease is caused by adrenal gland-associated causes, it is enough to be of importance! Adrenal gland tumors can also be either malignant (cancerous) or benign.
Those that are benign can be surgically removed which typically resolves the disease! However, those that are malignant can be a little more complicated. The malignant tumors can also be surgically removed from the adrenal gland, but this may only relieve the disease for a short while. Malignant tumors are always much harder to control and typically have decreased prognosis.
Luckily both causes of the disease can to some level be managed through either medicine or surgery! But before we dive into treatment, it is important the correct disease is diagnosed!
How Does A Vet Know If Your Dog has Cushing’s Disease?
There are a series of tests that can be done to confirm canine Cushing’s disease in your dog. But really the first step to diagnoses is up to you! Being aware of symptoms in your dogs can sometimes be the difference between life and death. For this reason it important you know the signs of the early disease! Signs may include:
- Increased urination
- Increased thirst
- A pot-bellied look
- Hair loss
- The thinning of the skin.
There may also be increased appetite, dry skin, and a weakened immune system. Though keep in mind your dog does not have to experience all these signs to suggest canine Cushing’s disease.
A dog may only show one or two signs! You are the best judge of whats normal for your dog, so if you think something is abnormal, don’t be shy, take him to the vet!
Cortisol Blood Test and More! Diagnostics is Key
If you decide your dog is showing signs of Cushing’s, your vet will likely perform a few diagnostic tests before handing out medication. Diagnoses are key! Because the Cushings disease symptoms are not specific to the disease, diagnoses can be slightly difficult!
Other diseases such as diabetes mellitus, kidney disease, and Addison’s disease can present with very similar clinical signs. General tests such as a complete cell count, serum biochemistry, and a urinalysis can help you vet differentiate between diseases.
However, a test more specifically for diagnosing Cushing’s disease in dogs is the low-dose dexamethasone suppression test. When healthy dogs are injected with dexamethasone (synthetic cortisol), their body responds by decreasing amount of ACTH being produced.
This, in turn, decreases the amount of cortisol in the blood. In a dog with Cushing’s disease, there will be no response to the dexamethasone and cortisol levels in the blood will likely increase. Another helpful test in diagnoses is petrosal sinus sampling.
Slightly more invasive, this involves taking a blood sample from the brain and measuring levels of ACTH. Thankfully, a combination of these tests, as well as the ACTH stimulation test, can be used diagnostically for Cushing’s disease in dogs. So you can be quietly confident with your vets decided diagnoses!
Can it Be Cured? Cushing Syndrome Treatment!
Unfortunately, there is no curable treatment available for canine Cushing’s disease! There is, however, very effect long-term Cushing’s disease treatment for managing the disease. Once the disease has been diagnosed, your veterinarian will construct an effective treatment plan for you and your pooch.
Most dogs are successfully treated with minimal medication side effects!
Prognosis: Can Your Pooch Still Live a Healthy Long Life?
They sure can! With the correct medication and treatment plan, most dogs go on to live a long and healthy life. With particularly larger tumors or malignant ones, the prognosis can often be affected. Luckily both these types of tumors are rare causes of Cushing’s disease, so most dogs have an excellent prognosis!
Own A Dog with Cushing’s? Here are 3 Tips for Pet Parents!
- Medications containing trilostane vetoryl are the only FDA-approved treatments for pituitary gland-associated Cushings disease. Vetoryl capsules are a common treatment used!
- Hyperadrenocorticism in dogs shouldn’t have any major effects on the quality of life for your dog. They are typically happy dogs and can live just as long as those not affected by the disease!
- Canine hyperadrenocorticism can’t be prevented! Other than the iatrogenic hyperadrenocorticism cases where it can be induced by steroid medicine, there’s not much to do with the prevention of the disease.
Is Your Dog’s Adrenal Gland going crazy? It Could be Hyperadrenocorticism!
Canine hyperadrenocorticism can be a bit daunting when you first learn of the diagnoses! But it’s important to remember its not the end for your dog. With the correct treatment plan and a supportive veterinarian, your dog will likely live a long, happy life!
Common Questions on this Adrenal Disease
What Causes Hyperadrenocorticism?
Can Cushing Disease be Cured?
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