Definition
Hypreadrenacortacism is excessive production of cortisone by the adrenal cortex.
The Adrenal Gland
The adrenal glands sit above the kidneys and are responsible for producing and balancing electrolytes and cortisol for the body.
The inner core of the adrenal gland is called the ‘medulla’, and is responsible for the production of electrolytes.
The outer layer is called the ‘cortex’ and is responsible for the production and balance of cortisol. The Cortex is stimulated to produce the cortisol by a chemical called ‘ACTH’, which is produced by the pituitary gland in the brain.
Causes
There can be two different causes of hyperadrenacortacism:
1) Pituitary Dependent Hyperadrenocorticism:
This condition is caused by over-stimulation of the adrenal cortex by the pituitary gland. This type of hyperadrenacortacism accounts for approximately 85-90% of cases, and is caused by a benign or malignant tumour of the pituitary gland.
2) Adrenal Cortex Tumour:
Mainly seen in middle aged to older dogs. Only 15-20% of tumours found are malignant. Only a biopsy will be able to determine the difference. Generally, only one of the adrenal glands is affected.
Clinical Signs
Signs will vary between cases but can include:
- Hair loss
- Exercise intolerance
- Increased thirst
- Panting
- Increased production or urine
- Thin skin
- Increased appetite
- General weakness
- Abdominal distension
- Lethargy
- Deficiency, or complete loss of hair
- Neurological signs
Diagnosis
There are several blood tests that can be used to diagnose hyperadrenocorticism
ACTH Stimulation test
- An initial blood is collected from the patient.
- A synthetic version of ACTH is given intravenously.
- A second blood sample is then collected one hour after the injection.
- The blood is then sent to the lab to test the Cortisol levels
This test is also used to monitor the patient progress during the mediation.
Low Dose Dexamethasone Suppression
Test
- An initial blood is collected from the patient.
- A small dose of Dexamethasone (Cortisol) is given intravenously.
- Blood samples are then taken at 4 hours and 8 hours after administration.
- The blood is then sent to the lab to test the Cortisol levels throughout the test.
In a healthy patient, the immune system should stop producing cortisol and suppress the Dexamethasone. In a patient with ‘cushings’ the cortisol levels will continue to rise.
Abdominal ultrasound
Once cushings has been diagnosed, an abdominal ultrasound may be required to determine if it is ‘pituitary dependent hyperadrenocorticism’ or an ‘adrenal cortex tumour. The ultrasonographer will examine the adrenal glands for possible tumours.
Treatment
Medication is available that can help affected animals live out their years with a healthy hormonal balance.
Lysodren is a drug that works by destroying some of the adrenal cells that produce the cortisol. The goal, when treating, is to reduce and normalise cortisol levels without creating a cortisol deficiency.
A stable medicated patient can live a long and normal life.
If an adrenal cortex tumour has been diagnosed, it is possible to surgically remove the adrenal gland.
Home Care
Medication will be life-long but may be reduced to once weekly dosages.
Owners need to monitor water intake and look out for loss of appetite, vomiting and/or diarrhoea, which are all signs that your animal’s cortisol levels may have fallen too low.
Regular blood tests and medication dose adjustments will probably be required.
