ADRENOCORTICAL DISEASE (HYPERADRENOCORTICISM)
Author: Michelle Brunton
What is Adrenal Cortical disease (Hyperadrenocorticism)?
Adrenocortical disease (Hyperadrenocorticism), also known as Adrenal Disease, is a common ferret illness which usually affects middle aged to older ferrets (four to seven years old).
This condition is caused by tumours or lesions forming on either one or both of the adrenal gland(s) causing the glands to produce excessive amounts of a steroid called cortisol. The glands may be overactive due to hypertrophy (exaggerated growth), benign tumours (adenoma) or a malignant form of cancer (carcinoma). The good news is most adrenal tumours are benign, meaning they will not spread to other places.
Adrenal glands are part of the endocrine system. Located in the abdomen, near the kidneys, adrenals are small glands. There are two glands, one on the right, and one on the left. The majority of tumours are found in the left gland which is fortunate, since the left gland is relatively easy to access. The right gland is very close to several large blood vessels, making it dangerous to remove. The function of these glands is rather complex and vital, including:
Produce of reproductive hormones, oestrogen and testosterone
Produce Cortisol (stress hormone) and Adrenalin
Regulate blood pressure
Metabolise food correctly
There is a high prevalence of adrenal disease in ferrets in America which is associated with the practice of spaying and neutering at an early stage (often around 6 weeks of age). In the UK, adrenal tumours in ferrets are much less common, although the frequency of diagnosis is increasing.
Fur starts to thin out Ferret will eventually become completely bald
Clinical signs Of Adrenal Disease in Ferrets
Ferrets of all ages can develop adrenal disease. Common signs of adrenal gland disease include:
Hair loss or progressive symmetrical alopecia is the most common symptom – This often starts with the tail and rump. Occasionally, this is mild and starts with just a little thinning of the coat, commonly starting the base of the tail. The hair loss can start to progress up the body. It can be minimal, seasonal based, or fluctuate and eventually leave the ferret nearly bald. Complete baldness can happen in as little as 5 weeks. (Ferrets can often get fur loss on the tail, known as Rat Tail, however this usually happens around moulting time and is confined to the tail. The tail can develop scaly skin, sparse, bristly hair, and blackheads. This is a very unattractive but harmless condition with no known cause)
In entire animals the hair may regrow outside of the breeding season, only to be lost again the following spring
Loss of coat condition, which feels brittle to the touch and/or orange coloured patches of skin
Pruritus (constant itchiness and scratching) - Pruritus is the sensation of itchiness that prompts an animal to scratch. Beside obvious scratching, licking, biting, and chewing, your ferret may also have red, swollen skin, hair loss, or open wounds in the affected areas. (Ferrets are naturally itchy creatures and love a good scratch. Look for any abnormal behaviour and check for infestations of mites or fleas before assuming this is adrenal disease)
Vulva swelling in females - Adrenal often causes neutered ferrets (both male and female) to appear to be in season.
Enlarged prostate in males, often leading to dysuria (difficulty urinating). This can become an emergency situation in male ferrets if the prostate becomes large enough to block the passage or urine through the urethra. A ferret straining to urinate is an emergency situation and needs a vet as soon as possible as blockages can be fatal.
Increased sexual aggression - both sexes of ferrets may exhibit increased sexual behaviours such as mounting or dragging other ferrets in the group. This is similar the aggression shown during mating season. Neutered ferrets showing seasonal behaviour should be seen by a vet.
Thinning of the skin - Along with thinning of the coat, the skin can become fragile, which may result in bruising and irritation.
Lethargy – A ferret that appears weak and doesn't move around the cage is needs immediate medical attention. Less severe lethargy, such as a noticeable decrease in activity level and interest in playing, when handling they act almost limp in your hands, which a healthy ferret would not do.
Weight loss – any weight loss outside of the usual seasonal weight fluctuations should be investigated by a veterinary professional.
Abdominal muscle atrophy may be noticed as a pot-bellied appearance. - It is important to note that lethargy and muscle atrophy may be associated with other diseases found in ferrets.
If Adrenal disease is diagnosed, blood glucose levels should be checked, as some ferrets with adrenal disease may have concurrent insulinoma.
Ferrets may present with some or all symptoms, which can make it hard to recognise that a ferret may be developing adrenal disease. It is important to understand what is normal for your ferret (such as rat tail, how active and energetic they usually are, etc.…) so that you can see any changes to their usual behaviour. If your ferret is sleeping more than usual, looks physically different (outside of normal moulting changes) or generally presents any behaviours outside of the norm, then it is important to get them checked by a veterinary professional.
Ferret with clinical signs of adrenal hair loss Typical hair loss starting from the tail to the head
Why Ferrets Develop Adrenal Disease?
A key factor in ferrets developing Adrenal disease is attributed to neutering. Ferrets are seasonal breeders. During the breeding season a gland within the brain called the pituitary gland is responsible for producing sex hormones. Neutering does not stop the production these hormones as it does in other species, meaning that the hormones produced can cause cellular changes occur within the adrenal gland varying from the gland growing in size to turning into an invasive tumour (adenocarcinoma).
Adrenal disease caused by early neutering is much more prevalent in America due to the breeding process of Marshall ferrets.
In the USA most ferrets are bred by Marshall Ferrets, a breeding farm in New York, who neuter ferret kits at five to six weeks of age. The average lifespan of a US ferret is far less that its UK counterpart at four to five years. Mostly this is due to them being spayed or neutered at a young age so that they can be sent to pet shops for sale.
In the UK it is illegal to sell an animal below 8 weeks old (except for mice, rats, hamsters, etc… that mature much quicker). Most veterinary practices in the UK will not neuter a ferret below the age of 6 months.
Based on research from the US, many vets will not neuter ferrets, preferring to offer chemical neutering, jill jabs and vasectomy. This advice is not based on any research undertaken in the UK where ferrets are more mature and less likely to develop adrenal because of neutering.
This is a difficult situation as failure to spay or neuter can also result in life-threatening illness.
While the majority of ferrets that develop adrenal have been neutered there are still many entire ferrets that develop the disease. It is also worth noting that the symptoms of Adrenal do not usually present until middle to later life and these symptoms can be managed so that the ferret has a normal life expectancy whereas a ferret is in immediate danger from a gynaecological life threatening illness.
Another consideration for entire males is aggression and hormonal behaviour can cause injury to other ferrets and many entire males need to be housed separately during the mating season. Vasectomising a male does not remove hormonal behaviour and, while it may reduce the likelihood of unwanted breeding, this is a very difficult surgery and is frequently unsuccessful.
Diet, Genetics and Housing
Very little research has been carried out to establish if poor diet and genetics contribute to ferrets developing adrenal disease. Ferrets are obligate carnivores and need to be given a good healthy diet to stay healthy.
Genetics and breeding can play a big part in ferret health and the pathology of illnesses. Inbreeding and poor genetic makeup could potentially explain the prevalence of adrenal disease in unneutered ferrets and many of those who develop symptoms that are neutered may have developed them anyway due to their genes.
There is a theory that ferrets kept as indoor pets develop the condition because their natural hormonal cycles are altered due to the artificial lighting in homes for periods of time longer than 8 hours. This over exposure to light stimulates the production of hormones from the Hypothalamus and the pituitary gland.
The fact that adrenal gland disease is less common in the United Kingdom can therefore be explained by the fact that many ferrets are still being kept outdoors without being neutered.
Diagnosing adrenal disease is usually quite easy. A veterinarian will examine the ferret and, based on the symptoms, they will likely perform a few tests to rule out other illnesses and diseases that may present similar symptoms. It is important to rule out these other disorders by performing diagnostics, which can include blood work, radiographs and an ultrasound. The vet may also take X-rays of the animal to identify any cysts in its genital tracts or to detect an enlarged spleen or liver.
Occasionally, the enlarged adrenal gland is palpable and ultrasonography may help in this assessment, although this is not always possible due to the location of the adrenal glands and the fact that a tumour may be very small or deep within the gland.
The vet may check for low blood sugars or check for specific hormones in the blood such as estradiol and progesterone, an elevated level of these hormones is a good indicator of adrenal disease and their measurement is believed to be one of the most reliable means of diagnosis.
Fur loss and thinning around lower back (Picture of unneutered male with adrenal)
There are two main treatment options for ferrets with adrenal disease:
Deslorelin: Deslorelin is an implant that can be placed beneath the ferret's skin in a simple, quick procedure performed by a vet. This implant acts on the pituitary gland in the brain, slowly releasing hormones over time to suppress the negative effects of the hormones released by the adrenal gland. The small implant lasts for up to two years in the average ferret and the larger implant can last three to four years. There is some evidence to show that Deslorelin can shrink adrenal tumours or slow their development.
The favoured option for treatment by most UK vets is to implant instead of surgically neutering ferrets.
Left: before implant Right: Same ferret after implant
Before implant (course and brittle fur) Same ferret after implant with Deslorelin
Before Implant with Deslorelin After Implant with Deslorelin
Surgery to remove the affected gland(s) is the only way to completely cure Adrenal disease however this is difficult and risky. In some cases there is recurrence or re-growth of the tumour. For older ferrets the risks are greatly increased and the vet may advise against it.
The benefit of surgery is that it allows the vet to inspect both adrenal glands as well as the other internal organs. If tumours are found in one or both adrenal glands, they can be removed, thus curing the disease.
The left adrenal gland is typically easily removed and in most cases the tumours are prevalent in the left gland. However, the right adrenal gland lies very close to a major blood vessel called the caudal vena cava. In these cases the risk of haemorrhage and death is higher and removing the entire tumour may not be possible.
The diagnosis of Adrenal disease may be very upsetting but in most cases it is very treatable. Most ferrets live for many pain free and happy years with adrenal gland disease. With treatment and regular check-ups with a veterinarian, as well as monitoring and treatment for any secondary infections or disorders you will get to enjoy many more years with your ferret.