What is Cushing's Disease

Simply, Cushing's Disease is a disease in which the adrenal glands overproduce certain hormones. The correct medical term for this disease is hyperadrenocorticism.

The adrenal glands produce several vital substances that regulate a variety of body functions and are necessary to sustain life. The most widely known of these substances is cortisol (also known as cortisone), which helps to control the immune system and stress responses.

 

 

How does this disease occur?

There are three mechanisms by which this disease can occur. Regardless of the cause, the clinical signs are essentially the same.

• Iatrogenic. Iatrogenic Cushing's Disease means that the excess of cortisone has resulted from excessive administration of synthetic cortisones. This may occur from oral or injectable medications over a long period. Although the injections or tablets were given for a legitimate medical reason, their excess is now detrimental. Occasionally the use of ointment containing cortisone or its derivatives over a long period of time can result in excessive intake due to absorption through the skin or eyes or by the dog licking the product.

 

•  Adrenal Gland Tumour. Cushing's Disease may be the result of a benign or malignant tumour of the adrenal gland.

 

•  Pituitary Gland Tumour. The most common cause of Cushing's Disease (85% of all cases) is a tumour of the pituitary gland. The tumour may be benign or malignant. The tumour causes the pituitary to overproduce a hormone which stimulates the adrenal glands. Excessive cortisol secretion is the result. The tumour may be microscopic or quite large. Depending on the size of the tumour, the presence of signs other than Cushing's will be variable. Generally, if the activity of the adrenal gland can be controlled, the dog will live a relatively normal life. Unfortunately, this is sometimes not the case. However, many dogs with this form of Cushing's Disease can live normal lives for many years as long as they take their medication and stay under close medical supervision. Growth of the pituitary tumour would give the patient a less favourable prognosis.

What are the clinical signs?

The most common clinical signs associated with Cushing's Disease are:

• Drinking and urinating more, including toileting accidents

• Increased hunger / appetite

• Increased panting, even in cool conditions

• Pot-bellied abdomen

• Loss of hair, blackheads, darkening of skin, and hard scaly patches on the skin, especially the elbows, etc.

• Lack of energy, or interest in exercise

• Muscle weakness

• Easy bruising, or slow wound healing

Diagnosis

Firstly, a full physical exam, basic blood tests and a urinalysis will be conducted. Based on these results, further work-up is required. This will include specific blood tests, and possibly an ultrasound.

The two tests typically used are the ACTH Stimulation Test or the Low Dose Dexamethasone Suppression Test (LDDST).

The ACTH stimulation test is commonly used when there is significant evidence that your pet may have cushings, or to monitor the progress of diagnosed pets.

Where as the LDDST is typically used when a patients symptoms are unclear, as it is a more sensitive test.

Both tests will require your pet to stay in hospital for the day.

Treatment

Depending on the cause for your pets Cushings disease will determine the treatment options available.

Once diagnosed, your vet will work with you to develop an individual treatment plan for you and your pet.

Prognosis

Vets like diagnosing this condition. It is the most common hormonal disease we see in dogs, and the progression of the disease is incredibility slow.

The great news is that if your pet is diagnosed with Cushings, once treatment is started, their quality of life improves significantly.