Hyperadrenocorticism ‘Cushings’ Syndrome

Hyperadrenocorticism (HAC) or Cushings syndrome is one of the most common hormonal disorders diagnosed in dogs. Cushing’s syndrome is more commonly seen in older dogs.

There are two types of Cushings:

  1. Pituitary -dependent Cushings – This is the most common form of the disease (80%-85% of spontaneous cases), and is often caused as a result of benign tumour of the pituitary gland. This tumour causes the pituitary gland to produce large amounts of a hormone called ‘ACTH’ which stimulates the adrenal gland to produce excessive amounts of cortisol.
  2. Adrenal-dependent Cushings – This form is less common and occurs when a tumour develops on one or both adrenal glands and produces excessive amounts of cortisol.

The symptoms of Cushings syndrome develop when excessive amounts of cortisol are circulating around the body. Cortisol is a hormone produced by the a part of the adrenal gland called the cortex. Cortisol plays an important role in the normal body function including the following:

  • Mobilising nutrients
  • Aiding the body’s response to inflammation
  • Activating the liver to raise blood sugar levels
  • Help control the amount of water in the body

Symptoms of Cushings syndrome

However, excessive levels of cortisol in the body can cause numerous symptoms including most commonly:

  • Increased drinking
  • Increased urination
  • Increased appetite
  • Pot belly due to muscles becoming thinner
  • Hair loss, which is often symmetrical
  • Lethargy
  • Recurrent skin infections
  • Excessive panting


Cushing’s is diagnosed by measuring the level of cortisol in the body. There are several tests which your vet may recommend if they are suspicious your pet has Cushing’s syndrome.

1. ACTH Stimulation test

2. Low-Dose Dexamethasone Suppression Test

3. Urinary Cortisol: Creatinine Ratio

Treatment options

If the symptoms are being caused by a tumour on the adrenal gland, it can be managed surgically. However, a tumour on the pituitary gland is often impossible to treat surgically and needs to be managed medically.

Medical management involves administering your pet a tablet called ‘Vetoryl’ which contains the active ingredient Trilostane. Trilostane blocks the excessive production of cortisol. It is important to note that your the aim of treatment is to manage the condition successfully, which will enhance your pets’ quality of life.

Your pet will have to have regular bloods tests to monitor there cortisol levels as it is important that levels are not overly suppressed by the medical treatment. The efficacy of treatment is also assessed by monitoring changes in clinical symptoms, and monitoring electrolytes, urea and creatinine levels. At the start of treatment blood tests will be done at 2 weeks, 4 weeks and 12 weeks after starting therapy and thereafter every 3 months.