So, your dog has been diagnosed with Cushing’s disease. What is this disease and how can it affect your pet? Hyperadrenocorticism, commonly known as Cushing’s disease, is a hormonal disorder that affects dogs. It occurs due to the overproduction of cortisol, a steroid hormone, by the adrenal glands. The condition can develop either spontaneously or as a result of prolonged administration of corticosteroid medications. A veterinarian commonly will suspect Cushing’s based on the patient’s appearance or from the history that the pet owner gives us during their appointment.
Common symptoms of Cushing’s disease in dogs may include:
1. Increased thirst and urination
2. Excessive appetite
3. Weight gain and pot-bellied appearance
4. Muscle weakness and loss
5. Hair loss and thinning coat
6. Development of a pendulous abdomen
7. Skin infections
8. Panting and heat intolerance
9. Lethargy and reduced activity
10. Enlargement of the liver
All dogs can get Cushing’s disease, but the following breeds have an increased risk:
- Poodles
- Dachshund
- Small terriers (Yorkshire, Jack Russell, Staffordshire)
If we suspect Cushing’s disease, we will recommend a test called a Low-Dose Dexamethasone Suppression test. It’s a test that assesses the patient’s negative feedback loop in regard to cortisol. This feedback loop is capable of causing rapid changes in blood cortisol levels in response to the body’s needs. However, in a pet with Cushing’s syndrome, this controlling mechanism is not working correctly. The dexamethasone suppression tests use the negative feedback mechanism in order to diagnose the presence of Cushing’s disease. The two adrenal glands produce and store cortisol. Normally, cortisol is released from the adrenal glands in times of stress and prepares the body to respond rapidly and appropriately to the stress. With Cushing’s disease, an excessive amount of cortisol is circulating all the time.
There are two primary forms of hyperadrenocorticism in dogs: pituitary-dependent hyperadrenocorticism (PDH) and adrenal-dependent hyperadrenocorticism (ADH).
1. Pituitary-Dependent Hyperadrenocorticism (PDH):
PDH is the most common form, accounting for around 85% to 90% of Cushing’s cases in dogs. It occurs when there is an enlargement or tumor in the pituitary gland, a small gland located at the base of the brain. This tumor causes the pituitary gland to produce excessive amounts of adrenocorticotropic hormone (ACTH), which stimulates the adrenal glands to overproduce cortisol.
2. Adrenal-Dependent Hyperadrenocorticism (ADH):
ADH occurs when there is a tumor or abnormal growth in one or both of the adrenal glands, which are located near the kidneys. These tumors can be either benign (adenomas) or malignant (adenocarcinomas). In ADH, the tumor cells produce excess cortisol independent of ACTH stimulation.
Treatment options for hyperadrenocorticism depend on the underlying cause. Most commonly, a medication called trilostane is commonly used to manage Cushing’s disease. This drug works by suppressing the production of cortisol and controlling the symptoms. Regular monitoring and dose adjustments are necessary to maintain proper cortisol levels.
Luckily, Cushing’s isn’t a disease that is an emergency for your patient. However, it is a disease that leads to chronic immune suppression due to circulating steroids in the patient, making other disease more likely, such as pancreatitis, diabetes and skin disease. It is a disease that can be controlled and a patient with Cushing’s can lead a normal life and have a normal life span if treated and managed appropriately. If your pet has Cushing’s or if you’re concerned about your pet having Cushing’s, let us know and we can help give your pet back the quality of life they deserve.
Adam Thompson, DVM
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