Have you noticed your senior dog drinking more and urinating more frequently than usual? If so, one of the many conditions your veterinarian may test for is Cushing's Disease.
Also known as Cushing's Syndrome, this is a condition in which a dog's adrenal glands overproduce specific hormones, the best known of which is cortisol. Cushing's Disease is a serious and incurable condition, but it's one that can be controlled to allow your dog to continue living a happy and full life.
Let's take a closer look at the telltale symptoms of Cushing's, what causes the disease, and how your vet can help you manage your dog's health.
Signs and Symptoms of Cushing's Disease
A common and easily noticeable indicator of Cushing's Disease is increased thirst and urination. For example, you may notice that your dog, who can usually "hold it" all night long without having to visit the bathroom, all of a sudden needs to answer the call of nature in the middle of the night.
This will also usually be accompanied by an increased appetite, so watch for signs of your pet eating more than usual, which is caused by elevated levels of cortisol. General lethargy and a reluctance to exercise are also common, while a poor coat is another surefire sign.
Dogs with Cushing's Disease may also develop a distinctive pot-bellied appearance, resulting from increased fat levels within the abdominal organs. As the disease progresses further, muscle loss, skin lesions, and hair loss can occur.
However, these symptoms don't just develop overnight and will, instead, occur over time, often over the space of 12 months or more. As a result, owners sometimes mistake the signs of Cushing's Disease for little more than the natural consequences of aging, so the disease could be well advanced before it's even diagnosed.
With this in mind, regular veterinary check-ups are an important protective measure and if you notice any Cushing's symptoms, get your pet examined by a vet!
The Science of Cushing's Disease
The scientific name for Cushing's Disease is hyperadrenocorticism. A dog's adrenal glands, located near the kidneys, produce a range of vital substances that help regulate a dog's body functions. The best-known of these hormones is cortisol, and Cushing's Disease occurs when there is an overproduction of cortisol.
There are three different types of Cushing's Disease that may affect your dog, and the disease can occur naturally or as a result of excessive steroid use. The three causes of the condition are:
- Pituitary gland tumor. This is the most common cause of the disease and is responsible for around 85 percent of all cases. The tumor can be benign or malignant, but either way it causes the overproduction of a hormone that prompts the adrenal glands to produce cortisol. The good news is that if the adrenal gland's production of cortisol can be controlled, dogs with this type of Cushing's Disease can generally live long and healthy lives. However, if this tumor grows in size it can affect your dog's brain and lead to a wide range of neurological symptoms, causing some much more serious problems for your pet.
- Adrenal gland tumor. A tumor in the adrenal gland can also cause Cushing's Disease. If the tumor is benign, it can be surgically removed to cure the condition. However, if the tumor has already spread then it may not be possible to have it surgically removed.
- Iatrogenic. The third form of Cushing's Disease results from the prolonged or excessive use of steroids, which, in turn, can result in excessive cortisol levels. Though oral or injectable steroids may have been initially given for a legitimate medical reason, their over-use can have serious consequences.
Diagnosis and Treatment of Cushing's Disease
It's widely thought that Cushing's Disease is much more common than we realize, but due to the complex and expensive testing required to detect it, the condition often goes undiagnosed.
If your vet suspects Cushing's Disease, he or she will conduct blood and urine tests and then may use an adrenocorticotropic hormone (ACTH) stimulation test to confirm the condition. This latter test involves your pet giving blood samples before and after being given an injection of ACTH — if a dog's cortisol level starts out high and climbs even further after the injection, the Cushing's Disease diagnosis is verified.
Another test, which examines the dog's response to the hormone dexamethasone, can also be used, while ultrasounds will help your vet check for a tumor.
Treatment varies depending on the cause of the disease. For pituitary gland tumors, which make up the vast majority of cases, most dogs are treated with oral medications designed to selectively destroy a portion of the adrenal cortex. The aim is to ensure that cortisol levels remain normal, but careful monitoring is required to ensure that the drugs don't completely destroy the cortex.
In the case of adrenal gland tumors, surgery may cure benign tumors but is a complicated procedure, and is unlikely to be effective for malignant tumors. Iatrogenic Cushing's Disease can be treated by the controlled discontinuation of the steroid being given, and further medication may also be required to combat any effects the disease has had on the adrenal glands.
The key thing to remember is that a diagnosis of Cushing's Disease is not a death sentence. Dogs with the condition can go on to live normal and happy lives, so speak to your vet about how to best manage your pet's health.
By a Labrador Retriever lover Tim Falk
Published: 05/04/2018, edited: 04/06/2020