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Cat Cushings Disease

"Cushing’s disease or hyperadrenocorticism is a rare condition. In cats it is associated with a hormonal disturbance. This may be due to tumors of pituitary gland and adrenal glands, or is correlated with insulin resistant diabetes mellitus. Cushings disease in cats may also occur due to extended glucocorticoid therapy. Symptoms of Cushings disease in cats includes It is characterized by polyuria (frequent urination), polyphagia (excessive eating) & polydipsia (abnormal thirst). Depression, lethargy, alopecia (hair loss), fragile skin and other or secondary complications may indicate the severity of the condition. Diagnosis involves laboratory tests and screening. Treatment involves surgical resection of the adrenal glands, and is preferred course of action along with the use of drugs. A cats prognosis is made on based on the treatment plan selection and if there are any secondary complications. If these complications exist, then the prognosis is usually "grave""

Cause of Cat Cushings Disease:

Hyperadrenocorticism (cushings disease) is the overproduction of cortisol, a glucocorticoid secretion of the adrenal gland, which is monitored by Adrenocorticotrophic hormone (ACTH), which is produced by the pituitary gland. Any factor which makes the level of cortisol increase in the body leads to feline Cushings disease. Some of these factors are; 

  1. Insulin resistant Diabetes Mellitus; Diabetes mellitus, especially when due to a resistance to insulin, is thought to be the primary cause of cat Cushing’s disease. Almost 80% of Cat Cushing’s cases are concurrent with insulin resistant diabetes mellitus. Coritsol levels in the body are closely related to insulin level and the resistance of body towards insulin. 

  2. Pituitary and Adrenal gland Tumors; In most cases, pituitary and adrenal gland tumors result in an increase of in hormonal secretions, by increasing the number of cells responsible for release. 80% of pituitary tumors, and 20% of adrenal gland tumors and cancers result in hormonal cell hyperplasia (abnormal increase in the number of normal cells). 

  3. Corticosteroid Therapy; Corticosteroids are commonly used an an anti–inflammatory drug in veterinary practice. These drugs and especially cortisol, if it is used in excess and larger doses for quite some time can lead to the development of Cat Cushings disease

Signs and Symptoms of Cat Cushings Disease:

Cat Cushing’s disease is more common in females, and is seen in cats who are age 10 – 11 years or more. Polyphagia (excessive eating), polydipsia (increased thirst) and polyuria (frequent urination in larger volumes) are three primary signs of the disease. On clinical observation, the abdomen may appear enlarged, the coat may appear scruffy and patchy with distributed alopecia (hair loss). The skin may become fragile and get torn with slight bruising. Secondary infections and the correlation with insulin resistant diabetes mellitus should be considered while probing a cat's history.

Diagnosis of Cat Cushings Disease:

Clinical signs, symptoms and a cat's history can be helpful in confirming early suspicion of Cushings disease in cats. These may not help as they do not conclusively lead to Cushing's since symptoms are relatively common. In order to confirm Cushings disease in cats, detailed laboratory tests are required. Different laboratory tests like those of biochemistry profiling, ACTH Stimulation tests, a Dexamethasone Suppression test and measuring the urine creatinine to cortisol ratio are some of the diagnostic tests can reveal the actual cause of the disease will differentiates feline Cushings disease from other conditions.

Ultrasonography is helpful in examining the adrenal glands, its size, position and any tumors.

Treatment of Cat Cushings Disease:

Once feline Cushing’s disease is confirmed by laboratory and radiographic imaging, all efforts should be pursued to control cortisol production in the body. It is not an easy task to attain; as there are many other complications and side effects correlated with a treatment plan.

Adrenolectomy or surgical removal of one or both adrenal glands in the body is the only successful treatment option for Cat Cushing’s disease. There are some post surgical complications, like delayed wound healing, bacterial complications and the need to use glucocorticoids and mineralocorticoids for rest of the cat's life.

Medical therapy or the use of drugs is another option, but unfortunately it is not very effective. Even long term management and therapeutic plans can fail at the end.

Metyrapone is one drug used to resolve Cushing’s disease in cats. 65 mg/Kg per oral administration is recommended. There are some issues with this drug, as it is not readily available and surgery is still required even after its use. It is also recommended that it be administered prior to surgery. Ketaconazole and Mitotane are other options for treating Cat Cushing’s disease, but it cannot be administered for long term treatment, as it may cause severe side effects in cats, such as renal (kidney) failure.

There is a homeopathic remedy available that helps address the symptoms of cushings disease in cats. The product, Cushex, contains several herbs that are specially selected to target adrenal health and balance in pets. Each ingredient of this natural remedy has a specific role to play in maintaining adrenal function, normal corticosteroid, fluid and electrolyte levels. See the manufacturers site for supporting studies and additional information. While not a cure, it may help alleviate some of the symptoms of the disease, helping cats live a better quality of life.

Prognosis for Cushings Disease in Cats:

Usually the prognosis is termed “Grave”, due to the severity of the disease and other complications a cat may experience after an onset of Cat Cushing’s disease. It is also due to the ineffectiveness of available treatment options.

 

References:

The Merck/Merial Manual for Pet Health (Home Edition)

2. Gary D. Norsworthy, et all. “The Feline Patient: Essentials of Diagnosis and Treatment” (Wiley – Blackwell Publishers. 2007) 136 – 137

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