Ferrets - Reproductive Disease

What is the main reproductive disease in ferrets?

The main reproductive disease in ferrets is actually one associated with failure to reproduce! That is to say a female ferret which is not mated fails to ovulate and consequently suffers the effects of a persistently high blood level of oestrogen.

What signs should I look for?

Like cats, ferrets are what are known as induced ovulators, that is eggs are only released from the ovary after the vaginal stimulation associated with mating. Unlike cats the ferret is very affected by high levels of circulating oestrogen which occur just before oestrus. The main effect of this hormone when circulating at chronically high levels is to reduce production of blood cells by the bone marrow. This is most obviously seen in a lowering of red blood cells or erythrocytes giving anaemia. Signs of this are pale mucous membranes, seen most readily around the gums.

In fact, the more problematic reduction in circulating blood cells involves the platelets. A reduction in their number, or thrombocytopaenia, leads to haemorrhage. This can be seen most easily again in the gums but occurs in all mucous membranes and indeed in the gastrointestinal tract and internal organs. Haemorrhage is the most common cause of death in these hyperoestrogenic ferrets.

In chronically affected animals infections can occur because of a reduction in the white blood cells - the bone marrow produces the whole spectrum of circulating cells and thus problems are seen in the white as well as the red cells. The anaemia which occurs develops gradually and thus the ferret compensates and the signs of disease are subtle until fairly late in the condition.

Before any life-threatening blood disorders occur, however, the signs of persistent oestrus are obvious - a swollen vulva and possibly also some vulvar discharge. There may also be hair loss especially over the stomach and flank area.

The diagnostic tests required in such a case will, at a minimum, be a haemogram with red and white cell count as well as a platelet count. It might be argued that the vulval swelling is enough of a diagnostic signs and that blood tests are hardly required to confirm the diagnosis. What they do, however, is to show how severe the condition is and give some idea of the long term outlook, the prognosis, for the animal.

"The diagnostic tests required in such a case will, at a minimum, be a haemogram with red and white cell count as well as a platelet count."

The treatment for hyperoestrogenism is to stop oestrus. The most obvious way of doing this is to spay (surgically remove the ovaries and uterus) the animal. This is where the results of the blood sample are essential. An anaemic thrombocytopaenic ferret - that is to say one with dangerously low levels of red blood cells and platelets - is not a good candidate for surgery.

In such cases medical management is the best option - hormonal stimulation with human chorionic gonadotrophin or suppression with progestagen, is effective in the vast majority of cases. Once stabilised the ferret may then be a better candidate for surgery.

In cases where the anaemia is very severe blood transfusions can be given. When the PCV (packed cell volume or percentage of red blood cells compared to total blood volume) falls below 15% a transfusion will be required. It does not seem that ferrets have different blood groups as do people and dogs, so a blood crossmatch is not required. Between 5 and 10 mL of blood can safely be taken from an adult ferret and immediately transferred to the anaemic animal. If a vein is not readily available -as may be the case in extremely moribund animals - blood may be given into the marrow of a long bone by the technique known as intraosseous transfusion.

A ferret in this state of extremis will also require nutritional and fluid support - a high energy/ vitamin paste can be given and a subcutaneous, intravenous or intraosseous drip is also likely to be needed.

To prevent this situation, spaying can be recommended for those animals not likely to be needed for breeding. However, given the risk factors for adrenal gland disease it is now recommended that chemical/hormonal means of reproductive control may be considered instead.

What other diseases of the reproductive system are there?

Other diseases of the reproductive system are much rarer than persistent oestrus, but are clearly of paramount importance to the owner of an affected ferret. Pyometra, or infection of the uterus is very uncommon in ferrets and is treated, as in cats and dogs, by removal of the uterus and ovaries (ovariohysterectomy). This may also be a rare side-effect of progestagen given to suppress season. Similarly tumours of the ovary are rare although tumours of the testis have been reported. In these cases castration is required.

All signs of being in season or of hair loss or prostate enlargement in males may be due to adrenal tumours. So, if seen in neutered ferrets the adrenal glands should be investigated.