Adrenal gland disease is, unfortunately, a common disease of pet ferrets in the United States. Most affected ferrets are greater than 2 years of age. Many researchers believe that it is due to the close relationship between the ferret’s reproductive organs and the adrenal glands. Early neutering or spaying may result in a compensatory growth in the adrenal glands that leads to the tumor. Other possible risk factors may include diet and genetics.
What are adrenal glands? Why do ferrets need them?
- Adrenal glands are part of the endocrine system. They are located right next to/above the kidneys.
- They consist of a cortex and a medulla.
- Their main responsibility is to regulate the stress response through the synthesis of corticosteroids (i.e. cortisol) and catecholamines (i.e. adrenaline).
What is the adrenal cortex and what does it do?
The adrenal cortex is divided into 3 zones:
- Zona glomerulosa: Main site for production of mineralocorticoids, namely aldosterone
- Zona fasciculata: Mainly responsible for producing glucocorticoids (cortisol)
- Zona reticularis: Produces androgens (estrogen, testosterone)
Stages of Adrenalcortical Disease in Ferrets
- Adrenal hyperplasia: Increase in the size of the adrenal cells resulting in an increase in the amount of hormones produced by the adrenal cortex
- Adrenal adenoma: Benign tumor arising from the cortex of the adrenal gland
- Adenocarcinoma: Malignant (cancerous) tumor arising from the cortex of the adrenal gland
Signs of Adrenal Disease in Ferrets
- Hair loss (alopecia), especially starting with the tail and rump
- Females: vulva swelling
- Males: enlarged prostate, difficulty urinating
- Increased sexual aggression (males often grab and drag females by the nape of the neck)
- Muscle atrophy
- Pruritus (itchiness)
- Thinning of the skin
How is adrenal disease diagnosed in ferrets?
- Clinical signs
- Ultrasound–a non-invasive way of visualizing the internal organs
- Blood sampling of hormone levels
- Medical Management
- Deslorelin: A newer treatment, similar to Lupron, is the deslorelin acetate (Suprelorin) implant. Like leuprolide, deslorelin mimics GnRH and blocks adrenal stimulation. The advantage of deslorelin over leuprolide is that the implant lasts for up to 2 years in the average ferret. Additionally, there is some evidence that deslorelin can shrink adrenal tumors or slow their development. Update late 2014: The availability of deslorelin has become problematic for many veterinarians, as it is currently on backorder.
- Melatonin: Ferretonin is a melatonin implant about the size of a grain of rice that is injected under the skin of your ferret between the shoulder blades. Melatonin is a natural inhibitor of GnRH.
- By inhibiting GnRH, the production of LH and FSH is reduced preventing their negative effect on the adrenal gland.
- The implant is broken down by the body and eliminated and thus must be administered repeatedly with the return of adrenal disease signs (i.e. hair loss).
- Lupron: The hormone leuprolide acetate (lupron) is commonly used. Lupron mimics the effects of a hormone called GnRH (gonadotropin releasing hormone). This ultimately causes the body to stop producing GnRH, thus decreasing stimulation of the adrenal glands. Hormone injections are usually repeated once every 4-8 weeks. When lupron is used, the symptoms of adrenal gland disease may resolve. However, the enlarged gland is itself unaffected and may continue to increase in size, and in some cases, a malignant tumor may develop. Update late 2014: The availability of lupron has become problematic for many veterinarians.
- Surgical Management: Surgical removal of the affected gland is the preferred treatment. Surgery allows direct inspection of both adrenal glands as well as the other internal organs. If abnormalities are noted in one or both adrenal glands, they can be removed, and any other abnormalities can be addressed at the same time. The left adrenal gland is typically easily removed without complication. The right adrenal gland lies very close to a major blood vessel called the caudal vena cava, making removal more difficult.In these cases, cryosurgery may be used to remove the gland without the risk of hemorrhage. While surgery is curative in the majority of ferrets, it is important to know that in some cases, recurrence or re-growth of an adrenal mass may occur.
The use of drugs (mitotane, ketoconazole, or streptozocin) currently used to treat hyperadrenocorticism in humans, dogs, and cats is unsuccessful in ferrets as it targets a different layer in the adrenal cortex that is not affected with ferret adrenal disease.
Can adrenal disease be prevented?
Newer research has shown that giving Lupron injections once yearly during the ferret’s natural breeding season may prevent the onset of adrenal disease as the ferret matures. Timing is critical!
- Male ferrets should receive a dose of Lupron in January.
- Female ferrets should receive a dose of Lupron in mid-February to mid-March.
- These injections are annual for the life of the ferret, unless it has received a deslorelin implant within the past 18 months.
- Injections can be started as young as 6 months. No ferret is too old to start these annual injections.