Canine Hyperadrenocorticism
(Cushing's Syndrome)

Contents

What is hyperadrenocorticism?
Clinical signs of hyperadrenocorticism
The diagnosis of hyperadrenocorticism
Treating hyperadrenocorticism
Vetoryl - the treatment of cushing's syndrome

What is hyperadrenocorticism?

Hyperadrenocorticism or Cushing’s sydrome occurs when a dog is chronically exposed to high levels of the hormone cortisol. Cortisol is produced by 2 small glands situated near the kidneys known as the adrenal glands. The production and release of cortisol from the adrenal glands is controlled by the hormone ACTH (adrenocorticotrophic releasing hormone). ACTH is produced by a pea-sized gland at the base of the brain called the pituitary gland. Cortisol is normally released into the bloodstream at times of stress to prepare the body for a “fight or flight” response. In dogs with Cushing’s syndrome, cortisol is produced excessively all of the time and this eventually results in the development of the clinical signs of the syndrome.

There are 2 forms of hyperadrencorticism

Pituitary-dependent hyperadrenocorticism (PDH) is the most common form (85% of cases) of the syndrome and occurs due to the development of a slow growing tumour in the pituitary gland. This tumour produces large amounts of the hormone ACTH.

Adrenal-dependent hyperadrenocorticism (ADH) occurs when a tumour producing large amounts of cortisol develops in one or possibly both of the adrenal glands.

Both tumours result in excessive amounts of cortisol in the blood and over time the clinical signs of Cushing’s syndrome will develop.

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Clinical signs of hyperadrenocorticism

Hyperadrenocorticism (Cushing’s syndrome) is usually seen in the older dog. Initially the signs may be attributed to normal ageing.

A dog with hyperadrenocorticism will often:

• Drink large amounts
• Urinate frequently
• Eat ravenously
• Have a “pot belly”
• Have thin skin and hair loss
• Develop muscle wasting
• Be lethargic

A dog may not necessarily have all of these symptoms.

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The diagnosis of hyperadrenocorticism

Blood tests are performed to confirm a diagnosis. Cortisol levels in the blood of both normal dogs and dogs with hyperadrenocorticism fluctuate greatly throughout the day. As a result, a diagnosis cannot be confirmed by simply measuring the concentration of cortisol in a dog’s blood. Instead, one of the most commonly used tests to aid in the diagnosis of hyperadrenocorticism , the “ACTH stimulation test” is routinely performed. This test assesses the capacity of a dog’s adrenal glands to produce cortisol. This type of test requires the owner to leave the dog with the veterinary surgeon for a few hours or for a whole day.

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Treating hyperadrenocorticism

Treatment requires reducing the level of cortisol in a dog’s blood.  A dog will need to take medication for life in order to halt and contain the debilitating effects of this syndrome.  Given the complexity of the syndrome, it is important that a dog is carefully monitored at every stage.  The veterinary surgeon will need to perform tests at regular intervals to assess progress and to make sure of the dog’s well being.  The owner is advised to keep checks on his/her dog and note any changes or new symptoms.

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Vetoryl - the treatment for cushing's syndrome

Vetoryl is the only veterinary licensed treatment for canine hyperadrenocorticism in the UK.

Vetoryl contains the active ingredient trilostane that blocks the synthesis of cortisol by inhibiting an important enzyme which is key to that synthesis.  Since Vetoryl is a short-acting drug, it needs to be taken every day. 

Clinical trials have shown that Vetoryl is more effective if it is taken with food in the morning.  The most common signs associated with Cushing’s syndrome such as increased drinking, eating or urination tend to improve quickly – often within two to three weeks after commencement of treatment.  However skin changes including hair loss may take many months to improve.

Vetoryl therapy is only effective if a dog is carefully monitored.  Regular revisits to a veterinary surgeon are necessary to assess progress.  In the early stages after diagnosis, it is strongly recommended that a dog is tested and assessed at 10 days, 4 weeks and 12 weeks.  Thereafter, a dog should be examined by a qualified veterinary surgeon every 3 months.

Click here for detailed information about Vetoryl.

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