Cushing’s Disease in Dogs

Symptoms of Cushing’s Disease and Treatment

Overview of Cushing’s Disease in Dogs

Cushing’s disease in dogs, or hyperadrenocorticism, is a condition of the adrenal glands in the endocrine system whereby the body overproduces the hormone cortisol. Dogs, like human, require certain amounts of cortisol to maintain their immune system, normal stress levels, and body weight, among other things.

However, the production of too much cortisol can adversely affect the health of canines. A consistent release of an excess of cortisol can cause one or many of the following health issues:

• Consistent infections throughout the body
• Increase in blood pressure
• Increase in blood sugar
• Extreme thirst and hunger (due to low levels of glucose)
• Deterioration of bone and muscle mass
• Sensitive, thinning skin and fur

Cushing’s in dogs is a much more prevalent condition than previously believed due to it being largely underdiagnosed. Expensive and involved diagnostic testing is mostly to blame for underdiagnosis of the condition. There is currently no one single diagnostic test that has been found to accurately detect Cushing’s disease in dogs 100% of the time.

Cushing’s disease is seen more frequently in middle-age and older dogs that are 8 years or older. Dog breeds prone to Cushing’s disease include Poodles, Boston Terriers, and Boxers.

Symptoms of Cushing’s Disease in Dogs

The symptoms associated with Cushing’s disease in dogs are routinely mistaken for natural signs of aging. Even more, it can take up to one year for the symptoms to manifest in their entirety. Out of all the symptoms, an increase in the tendency to urinate and consume water is the most prevalent sign of Cushing’s disease in dogs.

Some of the more noticeable and common symptoms of Cushing’s disease in dogs are:

• Consumption of large amounts of water
• Excessive urination (especially at night)
• Increase in appetite
• Protruding belly (pot-bellied)
• Sensitive skin
• Loss of hair
• Inactivity and subsequent weight gain
• Darkened appearance of the skin

Cushing disease dog behaviors are difficult to identify given how closely they mirror other conditions. However, a careful examination of your pet and a recording of its health history will be done by your vet to determine this. If Cushing’s disease is suspected, diagnostic tests are ordered.

Diagnosing Cushing’s Disease in Dogs

Some of the following diagnostic assessments are utilized in an attempt to establish the presence of Cushing’s disease:

• A low-dose dexamethasone suppression test (LDDST)(more typical)
• Chemistry tests to evaluate functioning of organs (liver, kidney, pancreas)
• Blood count
• Urine and possibly fecal samples
• Electrolyte panels
• Thyroid tests
• Cortisol tests
• Recording of blood pressure levels
• ECG of the heart (less typical)
• Antibody count (less typical)

If Cushing’s disease is detected in your furry friend, your vet may recommend weekly or monthly routine check-ups to keep tract of the progression or regression.

What Causes Cushing’s Disease in Dogs?

Many of the symptoms of Cushing’s disease and treatment that follows are dependent on the root causes.  There are two main causes of Cushing’s disease (CD).

1. Pituitary-Dependent. This form of Cushing’s disease occurs after a benign tumor on the pituitary gland is discovered. This represents the most common diagnosis, with 80% to 85% of all cases stemming from this type. The pituitary gland, which is at the base of the brain, supplies what is known as the adrenocorticotrophic hormone (ACTH). The ACTH stimulates the adrenal gland, which releases cortisol. The presence of a tumor causes cortisol to be released in excess, causing potentially major issues.
2. Adrenal-Dependent. This alternative form of Cushing’s disease occurs when a tumor is found on one or both of the adrenal glands. The tumor may be benign or malignant in nature. 15% to 20% of all cases stem from this type.

Both of these types contribute to an excess of cortisol in the dog’s system that triggers the onset of the condition. Besides the main two ways canine Cushing’s disease in dogs develops, there is another less common form known as Iatrogenic Cushing’s syndrome. Although this syndrome occurs naturally, extended use of steroidal medications have been proven to facilitate this alternative form of the disease.

Commonly used steroid medications such as cortisone and prednisone are used to treat swelling, allergies, and disorders of the immune system. These medications are absorbed into the bloodstream, which can bring about Iatrogenic Cushing’s syndrome. Fortunately, if this occurs, the disease usually goes away if all steroid use is discontinued.

How Long Does a Dog Live with Cushing’s Disease?

The remaining length of life following a diagnosis of Cushing’s disease in dogs depends on several factors. The common consensus among veterinarians concerning prognosis is that, even with dog treatment for Cushing’s, a canine’s chance at a long life is slim.

While the condition is rarely ever cured entirely, it can be managed medicinally and otherwise to ensure the dog has a pleasant life with minimal pain. In terms of the prognosis in technical terms, most dogs with the condition live up to two years post-diagnosis, with a slim 10% living four years post-diagnosis.

Treatment for Cushing’s Disease in Dogs

Prognoses of dogs with smaller tumors (usually tumors of the pituitary gland) are better due to the fact they are able to take medication to combat it. Medications such as trilostane (Vetoryl) and mitotane (Lysodren) have been found to be effective.

Trilostane and mitotane are orally administrated medications that work to carefully eradicate the faulty parts of the adrenal gland in order to enable the pituitary gland to release a healthy amount of cortisol. If cortisol levels do not reach a normal state after a set time, it can be assumed the tumor is failing to respond to the medication. Other modes of treatment may then be suggested.

Larger tumors (especially if they are malignant) naturally have a poorer prognosis. The only true cure is to remove it, but the techniques currently in use are risky and further developments in terms of methods of removal are needed.

Even though the symptoms of Cushing’s disease and treatment seem to be on the dismal side, the largest population of dogs diagnosed with the condition are of old age. It follows that many within this population more often die of age-related reasons rather than Cushing’s disease itself.