What is Hyperadrenocorticism?

Hyperadrenocorticism (HAC), also known as Cushing's disease, occurs when the adrenal gland produces excess adrenal steroids (most commonly cortisol).  It can be caused by abnormal pituitary gland function or adrenal gland tumors.  This disease slowly progresses and the early signs are often unnoticed.  Some of the symptoms include increased appetite, increased drinking and urination, reduced activity, and a swollen abdomen.  Extensive laboratory tests, radiographs (x-rays), or ultrasound may be needed to diagnose the condition, find its cause, and plan treatment.

How is it treated?

Some animals respond to medical management while others need both surgical and medical treatments.  In most cases, control, rather than cure, is the outcome of treatment.  Medical treatment consists of either mitotane (Lysodren) or trilostane.  Patients must be monitored closely while on these medications.  If adrenal hormones are suppressed too much, a condition called Addison's disease develops, which can be life threatening if untreated.  Non-invasive adrenal tumors are best removed surgically.

What is the prognosis for Hyperadrenocorticism (HAC)?

Average life expectancy ranges from 36 months to longer with good regulation.  Clinical signs and the development of concurrent disease like diabetes may shorten this time.  When HAC is caused by a pituitary tumor, the tumor may grow and put pressure on other parts of the brain causing neurological symptoms and ultimately death.  It is common to see infections of the skin, urinary tract, and liver due to the high levels of circulating steroids that suppress the immune system.  A personalized treatment plan can be provided by your veterinarian with regards to the best treatment protocol for your pet.


  • Increased drinking and urination
  • Increased appetite
  • Panting
  • Lethargy
  • Abdominal distention
  • Muscle weakness
  • Mild hair loss
  • Hair that won't grow back
  • Mild to moderate skin infections
  • Persistent early stages
  • Weight loss
  • Muscle wasting
  • Moderate to severe hair loss
  • Severe skin infections
  • Thin skin
  • Chronic eye infections
  • Worsening dental disease
  • Chronic urinary tract infections
  • Incontinence
  • Bladder stones
  • High blood pressure
  • Calcium deposits in the skin
  • Blood clots in the lungs
  • +/- Diabetes
  • Addisonian crisis - weakness, vomiting/diarrhea, heart arrhythmias, seizures
If your pet exhibits any of the following symptoms immediate veterinary assistance is needed regardless of the disease.
  • Difficulty breathing
  • Prolonged seizures
  • Uncontrollable vomiting/diarrhea
  • Sudden collapse
  • Profuse bleeding - internal or external
  • Crying/whining from pain