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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.

Inflammatory bowel disease

Inflammatory Bowel Disease (IBD) is a chronic disease of the gut, or gastrointestinal tract. Most affected dogs have a history of recurrent or chronic vomiting and/or diarrhoea. They may lose weight but are otherwise normal. Most eat well or have an increased appetite, and appear normal.


Inflammatory cells invade the lining of the bowel causing thickening of the bowel. This interferes with digestion and absorption of nutrients and with normal movement of the bowel.

When the cells invade the stomach walls or upper small intestine vomiting develops. Infiltration of the small intestine causes watery diarrhoea and weight loss. Infiltration of the large intestine causes diarrhoea coated with mucus and fresh blood. The entire gastrointestinal tract is sometimes affected.

Something in the diet triggers the disease in some dogs. Bacterial proteins are involved in other cases. In most cases we cannot find any underlying cause.


IBD is diagnosed by ruling out other diseases. Blood tests rule out liver or kidney disease, pancreatic insufficiency and diabetes. Faecal tests rule out parasites like whipworms or giardia.

X-rays or ultrasound rule out some tumours or cancers in the abdomen.

If these tests are all clear we trial special low allergy, low residue or high fibre diets, depending on the part of the bowel most involved.  If bacterial overgrowth is present we trial various antibiotics until we see improvement.

If there is no improvement we biopsy the bowel and a pathologist identifies the type of cells involved, assesses the severity of the inflammation and checks for cancer cells.


If any diet has improved the condition we continue it.

Medication controls (not cures) the problem. We trial drugs like metronidazole, prednisolone and azathioprine until we find what suppresses the signs best. Most dogs stay on the appropriate drugs and diet for life.


Hyperthyroidism is a common disorder of older cats.  An overactive thyroid gland produces and secretes too much thyroid hormone putting pressure on all body organs. Any sex or breed of cat can be affected.

The signs of hyperthyroidism include:

  • Weight loss
  • Increased appetite
  • Hyperactivity and restlessness
  • Increased heart rate, associated with irregularities in rhythm, murmurs and high blood pressure
  • Increased frequency of defecation with occasional accidents inside
  • Increased thirst and urination
  • Occasional vomiting
  • Panting
  • Matted, greasy and unkempt coat
  • Enlarged thyroid glands on the neck

If we suspect that your cat has hyperthyroidism we send blood for measurement of the thyroid hormone, T4. We also check for secondary liver, heart or kidney problems.

We usually treat hyperthyroidism with tablets or drops and recommend radioactive iodine therapy once your cat’s system has settled down.

  1. 1. Anti-thyroid drug therapy

Anti-thyroid drugs interfere with the production and secretion of thyroid hormone. They control rather than cure the condition.

Carbimazole (brand name Neo Mercazole) tablets are given twice daily. We see mild and often transient side effects in a few cats on this medication. These include poor appetite, vomiting and lethargy. More serious side effects including a fall in the white blood cell count, clotting problems, or liver disorders occasionally result. If we find any serious side effects after 2 weeks of medication we switch to another treatment.

Many owners prefer methimazole as a gel applied to the inside of the ear or made up into a palatable liquid.

Hyperthyroidism often covers up kidney troubles in cats.  If your cat seems to be drinking or urinating a lot more on medication then alert us as soon as possible.

  1. 2. Radioactive iodine therapy

If kidney problems are not uncovered by anti-thyroid therapy then we suggest radioactive iodine, a more permanent cure for hyperthyroidism. Radioactive iodine only destroys the affected thyroid tissue and leaves adjacent normal tissue, including the parathyroid glands, untouched.

We refer you to a special facility at Canberra Veterinary Hospital for radioactive iodine therapy. Treated cats are kept in hospital for a week after the treatment until they are no longer a radiation risk to people.

Radioactive iodine treatment is curative and has no serious side-effects. Depending on the age of the cat at diagnosis the cost of treatment is similar to long term anti-thyroid drugs or surgery.

It is the only effective treatment for thyroid adenocarcinoma, the cancer that causes 1 to 2% of feline hyperthyroid cases.

  1. 3. Surgical thyroidectomy

Removal of the thyroid glands provides an immediate cure but has some nasty potential side effects so we don’t often recommend it.

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.