Cushing’s Disease (hyperadrenocorticism) is a hormonal disease which arises when the adrenal glands produce too much of the steroid hormone, cortisol. Whilst the hormone cortisol is needed by every cell in the body, too much cortisol can have serious harmful effects.
Cushing’s Disease (hyperadrenocorticism) is a hormonal disease affecting dogs (and other animals)
It is caused by an overproduction of the steroid hormone, cortisol
The symptoms of Cushing’s are varied and range from drinking and urinating more than usual, to skin changes, panting and a ‘pot belly’ appearance.
What are the Adrenal Glands?
The adrenal glands are found at the top of each kidney. They are part of the endocrine system, making and releasing important hormones into the bloodstream that then travel around the body. These s hormones are a type of protein, and they help control many body functions that are critical for survival. One of the most important hormones produced by the adrenal glands is the steroid hormone cortisol.
The adrenal glands receive signals from the pituitary gland in the brain to tell them when to release cortisol.
What is Cortisol?
This hormone has many functions, from helping your dog respond to stress and stimulating its appetite, to regulating the body’s immune (infection fighting) system.
Cortisol is a stress hormone. It is released from the adrenal gland during times of stress to help prepare the body as part of the ‘fight or flight’ response. The body reacts to this increase in cortisol by speeding up metabolism (energy production) so that sugars and fats can be made available to provide energy for “fight or flight”. The body will also respond to the higher cortisol by dampening down the immune system, so less energy gets used up on fighting infections and more on dealing with the current stress facing the body.
This is fine normally, but when the adrenal gland is continually producing too much cortisol as a result of Cushing’s this can cause problems in the long-term. It can make your dog more prone to infections (due to the immune system being dampened down), become more prone to diabetes (due to the high levels of sugars being produced for energy) and can cause changes to the skin.
What causes Cushing’s Disease?
There are three main causes for Cushing’s disease. It is important that we know which of the three causes your dog has because the treatment for each of these will be slightly different.
Pituitary-dependent Disease
This is the most common cause of Cushing’s in dogs - about 85% of cases. A tumour in the pituitary gland - the part of the brain which sends signals to the adrenal gland to tell it to release cortisol - means that too many signals are sent, and the adrenal glands make too much cortisol
Adrenal-dependent Disease
A tumour in the adrenal gland itself makes excess cortisol. This is a much less common cause.
Iatrogenic Disease
This can happening dogs who have been on long-term steroid treatment, such as for allergic skin problems. It is usually because the dog has been on too high a dose of steroids for too long a period of time.
What are the signs of Cushing’s?
The signs of Cushing’s can be quite varied and vague. Dogs will usually show one or more of the following signs:
Increased drinking
Increased weeing
A larger, rounder tummy (“pot-bellied” appearance)
Hair loss (quite often down both sides) and poor coat quality
Skin changes – thinning skin, darkened skin (hyperpigmentation), or ongoing skin infections (pyoderma)
Increased appetite
Lack of energy or tiring easily on exercise
Panting
Repeated urinary tract infections or cystitis
Dogs with untreated or undiagnosed Cushing’s disease can go on to develop other more serious conditions. These include:
Diabetes
Blood clots – which commonly lodge in the lungs
Pancreatitis (inflammation of the pancreas)
High blood pressure
Kidney damage
Cushing’s disease is complicated and all cases are different, so if you wish to discuss your dog’s Cushing’s disease, one of our vets will be happy to help!
