Cushing's Disease in Cats

Cushing’s disease affects your cat’s adrenal glands. If your cat develops this condition, his adrenal glands will produce more of the hormone cortisol than his body needs. While cortisol is an integral part of overall health, too much can lead to serious illness and even death.

Your cat’s endocrine system is as complex as any human’s. When it is functioning correctly, your cat is healthy and happy. However, there are some conditions that affect the endocrine system that can cause your cat to experience negative symptoms. Cushing’s disease is such a condition, although it is rare in cats.

Your cat will exhibit specific symptoms if he develops Cushing’s disease. Here is a detailed overview of the most common symptoms seen in domestic cats:

• Lethargy
• Increased thirst
• Excessive urination
• Unusual sexual behavior or changes in sexual behavior
• Weight gain
• Unhealthy overall appearance
• Overeating
• Distended abdomen
• Weakness
• Nausea
• Vomiting
• Hair loss 
• Thin skin that is easily torn or broken
• Enlarged liver
• Panting

No matter what the cause of Cushing’s disease in cats, the symptoms are always the same. There are three ways cats can be affected by this debilitating disease. The following is a description of each condition that can cause this disorder to occur:

Tumor of the Pituitary Gland

This is the most common cause of Cushing’s disease in cats. In all cats diagnosed, 85 percent will have a tumor on the pituitary gland. This tumor may be cancerous or benign, but all tumors stimulate the gland to overproduce the hormone cortisol. Most pituitary gland tumors in cats are not malignant but must be dealt with to get hormone production under control. 

Iatrogenic

If your cat develops Cushing’s disease due to the administration of too many steroid medications, he has Iatrogenic Cushing’s disease. This can occur when your cat receives steroids such as prednisolone, dexamethasone or prednisone. It does not matter whether this medicine is given in tablet, liquid or injection form. While steroids have beneficial uses, serious and sometimes deadly consequences can occur if your cat receives excessive amounts.

Tumor of the Adrenal Gland

Cushing’s disease can also occur in cats that have a tumor of the adrenal gland. This tumor can be benign or cancerous. Some cats have a favorable outcome if the tumor is benign and is successfully removed during surgery. Malignant tumors may also be removed during surgery, but the outcome depends largely upon whether the cancer has spread to any other parts of the body or vital organs.

It is extremely important for your veterinarian to properly diagnose the cause of Cushing’s disease in your cat. The outcome depends on treatment of the condition. Your doctor will take a brief medical history from you regarding your cat’s health. He will gather information such as birth history, date of symptom onset and the types of symptoms your cat is experiencing.

After taking a medical history, your doctor will examine your cat. He will observe his demeanor, motor skills, and alertness. Your cat’s temperature, respiration rate, and heart rate will be checked and recorded as well. He will also draw blood to run laboratory tests. A CBC or complete blood count, biochemistry profile and urinalysis will be performed. If your doctor suspects Cushing’s disease, he will also run tests to check your cat’s hormone levels, including cortisol.

Diagnostic imaging tests are often used to determine if there is a tumor on the pituitary or adrenal gland. A standard X-ray may be used or more detailed tests such as a CT scan or MRI may be ordered. If your doctor is concerned that a tumor is malignant and has spread, an abdominal ultrasound may also be performed.

The treatment of Cushing’s disease in cats depends on the cause of the condition. If the condition has occurred due to excessive steroids, it is important for the doctor to wean your cat off the medication slowly. Stopping these medications suddenly can cause a variety of health problems. In most cases, this may stop the symptoms associated with Cushing’s disease but the original problem your cat was being treated for may return. 

Adrenal gland tumors can be difficult to remove successfully because of the location of the gland in your cat’s body. However, it the tumor is benign and is safely removed, your cat may have a good outcome.

Pituitary gland tumors are often treated with medications such as trilostane or Lysodren. These drugs are considered to be chemotherapy drugs and are not a cure, but the condition can be managed over the long term in some cats.

Your cat’s recovery from Cushing’s disease will depend on the cause of the condition and the treatment your doctor recommends. Since this condition is rare in cats, it is often misdiagnosed. However, some cats go on to recover and live several years after diagnosis.