Coping With Adrenal & Insulinoma

Robert Ryans describes the course of treatment given to Buffy

Adrenal gland tumours are a very common ailment in American ferrets and seem to be increasingly seen in UK ferrets too. Given this, all ferret owners should be aware of the signs of the disease and know what treatment options are available to them. To this end, I would like to share with you my own experience of adrenal tumours with my ferret, Buffy. I should state right away that I am not a vet, and not even a particularly experienced ferret owner, but hopefully my own experience will assist others.

I adopted Buffy from the Ulster Society for the Protection of Animals in August 2000, along with her companion Faith. We didn't know how old Buffy was, but she was a pretty energetic and inquisitive lady, and an age of around 3 years seemed a reasonable estimate. She was spayed a few months later, and has had yearly distemper vaccine shots as decided by my vet.

Buffy in August 2005
Buffy in August 2005

In the first few months of 2005 Buffy started to slow down a little, staying out for less than her by then standard one hour morning playtime. Since she was in otherwise good condition this didn't especially worry me at first, and I just put it down to her advancing age. Her tail was also losing fur, but since she had suffered from rattail most summers since I had her, this did not seem too worrying either. However, over the few months March- July it became clear that there was a more serious problem. Her activity levels continued to fall, she was losing weight, and her fur was getting very thin all over her body. She was also apparently very easily tired, and would get unsteady on her feet at times if she had been out for too long. When the fur loss finally resolved itself into the classical bilateral symmetric pattern it was clear that an adrenal gland tumour was involved.

Ferrets have two adrenal glands, near the kidneys. When tumours form they cause excess production of sex hormones, often causing neutered animals (both male and female) to appear to be in season, as well resulting in fur loss, lethargy, weight loss, etc. Mostly the tumours are non-metastatising, which means that if they can be extracted surgically then in principle a cure can be obtained. The majority of tumours are found in the left gland (anywhere from 65% to 90% depending on the study) - the reason for this is not known, but it is fortunate, since the left gland is relatively isolated and easy to access. The right gland is very close to several large blood vessels and while there are instances of many animals having successful surgery on right gland tumours, it is a much more complex operation and requires greater skill and experience on the part of the surgeon. There are some blood tests that can be performed on a ferret to test for adrenal disease, but the signs can be subtle and the tests apparently can produce false negatives. The pattern of fur loss in an adrenal ferret is usually diagnostic enough of the condition (as is the return to whole behaviour in a neutered animal).

After discussing the options with my vet, we felt that surgery was not an acceptable option for Buffy, due to her age. Even if she had been younger, if the tumours had been found on the right gland I would not have permitted the surgery to go ahead, given the greater risks involved. Instead, we decided to follow a 'management' philosophy, treating her with a hormone known as Melatonin. This is a naturally occurring substance, released by the body in response to darkness. Melatonin levels therefore vary in the ferret according to the length of day, and indirectly affect the moulting and breeding cycles. In a ferret, Melatonin treatments inhibit the production of excess hormones, thereby easing the symptoms of the condition, though it must be stressed that it is not a cure for the underlying tumours, merely a way to improve the quality of life of the animal, but this is a worthwhile result in an older animal.

Melatonin is freely available in health food shops in the US, but in the UK it is only officially available via prescription. However, some shops still stock it "under the counter", and it is straightforward to obtain it from various on-line health food stores. The human form of the drug is available in both tablet and liquid form, but must be given to the ferret each day, around 7-9 hours after sunrise so as to mimic the natural production of melatonin in the ferret in winter. Clearly, this is all a bit awkward, and I think most of us know how well some ferrets can resist taking any oral medication. Thankfully, there is another option, specially designed for ferrets. Ferretonin implants are subcutaneous melatonin implants, carrying a fixed dose which is designed to be slowly released over a period of months. It is inserted under the skin between the shoulder blades, in the same manner as an ID microchip. In most cases it can be inserted without sedation, and while it's not the most pleasant experience for the ferret (it's a relatively large diameter needle) it's much better than the alternatives, and a vet who is used to chipping animals will have no problems with the job. The implants come in a sterile package with the injector included. They have many advantages over the oral route - a much smaller dose is needed, since there are no problems of absorption through the stomach; there are no timing concerns; the quality of the drug is known; and finally there is no need for a daily struggle with a fed up ferret! Each implant lasts for about 3-4 months, depending on the size of your ferret and their metabolism, and do not need to be removed once expired.

Buffy in November
Buffy in November

The implants are only available from the US manufacturer, Melatek LLC. They will only deal with vets directly, and not with members of the public, but your vet can order the implants using their website. For non-US orders there is a minimum order of 4 units, but since this is about a year’s supply this is probably a good thing. The cost of the 4 implants, plus express shipping, came to about £170! Not cheap, but I felt it was the best option for my girl, so that's what was needed. However, if money is tight, the human tablets cost about £10 for around 150, which will last for several months.

Buffy in December fur starting to regrow
Buffy in December fur starting to regrow

Buffy had her first implant in mid-September 2005, by which stage her fur was in very poor condition and she had dropped to a lightweight 930g (compared to her usual 1060g). Within a few weeks there were positive signs - her appetite had increased and her weight was stable; there was evidence of new fur growth around her shoulder blades. Her activity levels had also increased to maybe 20-25 mins in the morning - still less than before, but better than the 10-15 that she had been capable of beforehand. By early December her tail fur had returned, she was over 1kg again, and her throat, neck, and side fur was growing back in. By late December she had a nearly complete covering of thick fur, and was looking very plump and content. Her second implant was inserted just before the New Year, and she still seems to be doing well, though she still has a few bald spots, one on her tummy, one on her head, and a band down her back above the tail. Hopefully these too will regrow, maybe not, but the little lady is still much better off than she was before! Therefore, as far as I am concerned, the implants have done what they said they would, and I would recommend anyone in my position to consider them as a treatment option for their own adrenal ferrets. Even in cases where surgery is possible, an implant can help with regaining hormone balance post- operatively.

I should at this point mention that in early December Buffy's problem with being unsteady got worse, with her being very weak for two mornings in a row. My vet examined her, and found no sign of infection or other physical problem. However, we decided to test her fasting blood sugar levels (by using a lance to prick her paw to obtain a few drops of blood, thereby avoiding sedation), and found that they were abnormally low. This was a classical sign of insulinoma, a condition caused by small tumours forming in the pancreas, which cause overproduction of insulin and thus suppress the blood sugar level.

Buffy 27th January 2006 Buffy 27th January 2006

Once more, we decided against surgery - insulinomas can be removed, but always return, so it seemed pointless in an already ill ferret. The most common treatment for the symptoms of insulinoma is Prednisone (Prednisolone). This is a very cheap medicine (it's used by humans, so generic versions exist) and costs about £4 for 30 tablets. Doses range from 0.5-2.5mg/kg twice a day. Within a few days of starting this regime at the lowest dose, Buffy was much more active, doubling her morning play time, and also coming out more in the evenings. She accepted it without hesitation, ground up and presented in a teaspoon of Ferretone. Since then she has had no recurrence of her periods of weakness, and long may it continue.

Dealing with illness in an older animal is difficult. We all want to give our pets the best treatment possible, and to try to cure everything. However, sometimes the cure may be worse than the disease, putting too much stress on an older body. It's a highly personal decision, but I think in the case of Buffy we have been right to try to maximise the quality of her remaining time, rather than subject her to major surgeries.

(From Ferrets First Issue no. 28e January 2006)

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