Adrenal glands are hormone-producing organs, situated in front of the left and right kidneys; they are tiny but very important.
Dogs can suffer if the glands overproduce cortisol, this is called hyperadrenocorticism, also known as Cushing’s Disease.
The opposite is also possible, where the adrenal glands do not produce enough hormones. This disease is called hypoadrenocorticism, also known as Addison’s Disease.
Cushing’s Disease
Cushing’s disease is the more common condition. The symptoms can be varied per patient, but often include drinking and urinating excessively, some dogs may have trouble holding on at night! Also, dogs may be hungrier, more lethargic, panting more, unable to exercise, as usual, development of a “potbelly”, skin problems such as thin skin, skin infections, ratty tail etc. Often the symptoms develop slowly over time, and sometimes we assume our pet is “just getting old”.
Of course, other conditions may also present with some of these symptoms, so the first step in the diagnosis is for the vet to do a full physical examination, followed by screening blood and urine tests. These blood tests may prompt us to follow up with further tests (blood and/or imaging tests such as abdominal ultrasound) to confirm the diagnosis.
The two main causes for the development of Cushing’s Disease are:
1. Pituitary Dependent Cushing’s Disease. In this case, the pituitary gland in the brain overproduces a hormone (called ACTH) which overstimulates both adrenal glands into overproduction of cortisol. This is the most common cause of Cushing’s.
2. Adrenal Tumours. In this case, one adrenal gland becomes out of control, starts overproducing cortisol and the other adrenal gland can even shrink in response.
It is important to properly diagnose the Cushing’s Disease, before starting treatments.
In the case of an adrenal tumour, referral to a specialist centre can be arranged to assess if surgical removal of the affected adrenal gland is an option. Otherwise, medical management is possible as well, the best choice for the patient needs to be discussed between vet and client.
In the case of Pituitary-Dependent Cushing’s disease, treatment with medications to suppress the adrenal glands is the treatment of choice. This does require careful monitoring of patient and bloods to make sure we are not under- or overdosing.
Addison’s Disease
Addison’s disease is much less commonly diagnosed. In the case of Addison’s disease, the adrenal glands are not producing enough hormones. Usually, there is a deficiency in cortisol as well as in aldosterone. Aldosterone is involved in the regulation of fluids and electrolytes in the body, and cortisol, a stress hormone, is involved in the regulation of the body’s sugar levels, and metabolism to provide fuel for the body when the body needs it urgently. It also suppresses the immune system.
Symptoms of Addison’s can be vague, with gastrointestinal symptoms such as vomiting, diarrhoea, loss of appetite, weight loss, and signs of weakness, shivering, and lethargy. These signs can come and go. The vagueness of the symptoms can make it more difficult to diagnose, and after a physical examination screening blood and urine tests are needed, with a specific blood test (called an ACTH stim test) to confirm the diagnosis.
Some pets may present in an “Addisonian crisis”, which is a medical emergency, with the sudden appearance of severe symptoms such as severe depression, and lethargy, collapse, vomiting and diarrhoea, a slow and possibly irregular heart rate, not eating, and possibly a low temperature.
Once diagnosed, Addison’s disease can be treated with supplementation of the adrenal hormones that are lacking. Regular monitoring is required to make sure we are giving an appropriate dose of the medication, and it is important to realise that in periods of stress, (such as boarding, travel, moving house etc.) some dogs may need a higher dose of medication – to be discussed with your vet, but overall the prognosis of this disease is quite good.