Ferret Adrenal Gland Disease
Adrenal gland disease is a common problem in ferrets in the US. There are many theories on why this is happening, from early age neutering, to diet, to being housed indoors and not having access to natural light and day/night cycles. Luckily, there are surgical and medical treatment options for your ferret if they develop a problem with the adrenal glands. Keep reading to learn more about the adrenal gland, clinical symptoms, diagnosis, and treatment options!
What is an adrenal gland?
The adrenal glands are 2 small glands that are located near each kidney in the abdomen. The adrenal glands are made of 5 distinct layers in ferrets, but we only understand the function of 3 of the layers. The layer called the zona reticularis is responsible for releasing sex hormones is the important layer in ferret adrenal gland disease.
The Brain, The Reproductive Tract, and The Adrenals
So now we know what the adrenal gland is, but how does it cause disease in ferrets? The part of the brain called the hypothalamus secretes a hormone called GnRH. GnRH then signals the pituitary gland in the brain to secrete another hormone called LH. LH then signals the testicles and ovaries to secrete sex hormones and inhibin. Inhibin sends a signal back to the brain that enough sex hormones have been released and it can stop releasing LH.
In neutered ferrets (males and females), the ovaries and testicles are no longer present to send the signal back to the brain to stop releasing LH and GnRH, so these hormone levels continue to rise. The adrenal glands, ovaries, and testicles all start from the same progenitor cells during early embryonic development. This means the adrenal glands also have sex hormone-releasing potential that wakes up in neutered ferrets with adrenal disease as the adrenal gland enlarges. With no signal to stop the hormone release, ferrets with adrenal tumors just keep releasing sex hormones that cause the clinical symptoms of adrenal gland disease.
In ferrets that are neutered young, often at 4-6 weeks of age in the US, the incidence of adrenal gland tumors is nearly 25%. In the Netherlands where ferrets are typically neutered at 1 year of age, the incidence of adrenal disease drops to 0.55%. In Europe and Australia, where ferrets are rarely neutered and often housed outdoors, adrenal disease is seen even less frequently than in the Netherlands.
Clinical Symptoms of Adrenal Gland Disease in Ferrets
- Hair loss, starting on the tail and then progressed up the abdomen and chest. Hair loss is present on both sides of the body. This can start as seasonal hair loss, then becomes year-round.
- Itchy skin, mainly between the shoulder blades
- Thin skin
- Enlarged vulva in females
- Difficulty urinating or defecating in males as a result of an enlarged prostate
- Aggression, more often seen in male ferrets, where they try to pin down and bite the other ferrets on the back of the neck
How can my vet diagnose adrenal gland disease?
- Diagnosis is often made based on consistent clinical symptoms and possibly feeling an enlarged left adrenal gland (the right gland is located higher in the abdomen and not as easy to feel).
- The University of Tennessee has a blood panel called the Ferret Adrenal Panel that detects elevated sex hormone levels.
- Radiographs may show an enlarged and mineralized adrenal gland and enlarged prostate in males.
- Ultrasound by an experienced vet or radiologist can locate and accurately measure enlarged adrenal glands.
My ferret has adrenal gland disease. What can we do for him?
Surgery is certainly an option for adrenal gland disease in ferrets. The right adrenal gland can be hard to remove as it is located next to a large vessel (caudal vena cava), and often invades it. This makes a severe, potentially fatal, bleeding event during surgery a real risk. Surgery is considered curative if the affected gland can be completely removed. However, up to 38% of ferrets will develop adrenal disease in the remaining gland. Removing part of the gland or removing both glands can be considered.
Deslorelin is an injectable medication to control the symptoms of adrenal gland disease in ferrets. This is a GnRH analog that causes gradual reduction to the GnRH receptors in the pituitary gland, which leads to lower levels of LH being released and less stimulation to the adrenals to secrete the sex hormones. This medication is available as an implant (think of a microchip) that is inserted under the skin on the back of the neck and is slowly absorbed. Clinical symptoms begin to improve in 2 weeks and can be controlled for about 16-17 months. The implants are replaced when clinical symptoms recur.
Leuprolide Acetate is another GnRH analog and works similarly to Deslorelin. This is a liquid medication given as an injection into the muscle and needs to be repeated every 4 to 8 weeks.
Melatonin implants are another option. Melatonin is thought to reduce GnRH release, which reduces LH release and sex hormone release. These implants need to be repeated every 6 months.
Male ferrets may need additional medications to help reduce the prostate size.
Some ferrets develop anemia (low red blood cells) as a result of their adrenal gland tumor and may need additional medications to help improve the red blood cell levels.
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