Tag Archives: cortisol

Cushing’s disease

In dogs with Cushing’s disease the adrenal glands overproduce some of the body’s regulators, particularly cortisol.

What are the signs of Cushing’s disease?

The most common signs of Cushing’s disease are marked increases in appetite, water consumption and urination. Lethargy, panting and a poor hair coat are also common. We often see a pot-bellied or bloated abdomen due to increased fat within the abdominal organs and thinning of the muscular abdominal wall.

What causes Cushing’s disease?

The three major causes of Cushing’s Disease:

  1. A tumour of the pituitary gland, that stimulates the adrenal glands to produce excessive  amounts of cortisol.
  2. Excessive administration of synthetic cortisones cortisones such as prednisolone, triamcinolone or dexamethasone may cause Iatrogenic Cushing’s disease.
  3. An adrenal gland tumour is an uncommon cause of Cushing’s Disease.

If we suspect Cushing’s Disease we run a blood test to check your dog’s general health. An enzyme called Alkaline Phosphatase (ALKP) is often high in dogs with Cushing’s disease. A Low Dose Dexamethasone test (LDDT) confirms or denies Cushing’s disease.

To determine which type of Cushing’s disease your pet has, we ultrasound the adrenal glands and/or do an endogenous ACTH blood test.

What are the treatment options?

Pituitary Tumour: This is the most common cause of Cushing’s disease. There are two treatment options for it. Trilostane is our drug of choice. A daily capsule of Trilostane reduces the production of cortisone and another important hormone, aldosterone.  We monitor your dog’s response to Trilostane with a test called the ACTH stimulation test. Too little Trilostane won’t reduce appetite or water consumption but too much will cause illness.

If your dog has liver or kidney disease we may suggest treatment with Mitotane (also known as Lysodren). This drug destroys part of the adrenal gland. Careful monitoring and good communication with your vet is necessary during the initial intensive treatment to achieve good results and avoid life-threatening adrenal damage.

Although the pituitary tumour remains present and continues to stimulate the adrenal gland if the tumour is small successful control for many years in most dogs is possible.  If the tumour is large, it may invade surrounding brain tissue and cause other signs, but this is rare.

Iatrogenic Cushing’s Disease: To treat this type of Cushing’s disease we must stop the synthetic cortisone in a very controlled way. If we stop intensive cortisone treatment abruptly your dog may lose his appetite, vomit, develop diarrhea and collapse. The suppressed adrenal gland takes a while to regain normal production of cortisol.

Treatment of an Adrenal Tumour:

Adrenal tumours tend to invade surrounding tissue but if we can surgically remove it all and it is not malignant your dog will regain normal health. Otherwise we treat adrenal tumours with Trilostane also.

Cushing’s disease

What is Cushing’s Disease?

The adrenal glands overproduce cortisol in dogs with Cushing’s Disease. Cushing’s disease is also known as Hyperadrenocorticism.

What causes Cushing’s disease?

The three causes of Cushing’s Disease are:

  1. A pituitary gland tumour which overproduces the hormone that stimulates cortisol production in the adrenal glands. The size of the tumour and its malignancy varies widely. Signs of brain problems develop if the tumour is large, but this is unusual. Most dogs with this form of Cushing’s Disease live normal lives for many years as long as they take their medication and stay under close medical supervision.
  2. Excessive administration over long periods of time of synthetic cortisones like prednisolone, triamcinolone or dexamethasone causes Iatrogenic Cushing’s disease.
  3. An adrenal gland tumour is an uncommon cause of Cushing’s Disease. Surgical removal treats this form of the disease

How do I know if my dog has Cushing’s?

  • A marked increase in appetite
  • Increased water consumption and urination
  • Lethargy, panting and a poor hair coat
  • A pot-bellied or bloated abdomen

How is it diagnosed?

If we suspect Cushing’s Disease we run a blood test to check your dog’s general health.  An enzyme in the test called Alkaline Phosphatase (ALKP) is usually high in dogs with Cushings.

If ALKP is high then we do a Low Dose Dexamethasone test (LDDT) which will confirm or deny Cushings Disease.

To determine which type of Cushing’s disease your pet has, we ultrasound the adrenal glands and do an endogenous ACTH blood test.

Although some of these tests are expensive, they are necessary to allow us to accurately target the treatment.




We often prescribe cortisone for allergies and immune related diseases. Prednisolone, Macrolone or Antihistalone tablets contain a form of cortisone called prednisolone.  Short or long acting cortisone injections contain dexamethasone.

After 5 days of prednisolone tabs every day the adrenal glands start to slow their production of natural cortisol. It is safe to stop after 5 days of daily tablets but if we prescribe a longer course follow our instructions carefully.  Usually we recommend every other day tablets so that the adrenal glands keep functioning.

On a long course of prednisolone do not stop giving the tablets suddenly. Your pet may not be able to step up the production of cortisol fast enough to cope with an emergency, like a dog attack, a new pet or illness, and may collapse.

Side effects of cortisone include:

  • Increased fluid intake
  • Increased urine production
  • Increased appetite

Longer term and more serious side effects of cortisone include:

  • Cushings disease signs like a pot belly, flakey skin, enlarged liver and weak legs
  • Diabetes mellitus

Cortisone and anti-inflammatories given at the same time cause stomach ulcers.  We give anti-inflammatories such as Previcox, Deramax, Rimadyl, Metacam and Meloxicam for postoperative pain relief or arthritis. Please make sure your vet knows that your pet is on anti-inflammatories already.

A short acting dexamethasone injection rarely causes more than a mild increase in fluid and food intake.

We only inject long-acting dexamethasone if your pet is difficult to medicate or if your cat has a chronic condition that is not responsive to other cortisones.  Cats are generally more resistant than dogs to the side-effects of cortisone but very occasionally long-acting dexamethasone tips a weak heart into failure.