Do ferrets have to mate or they’ll die? Fact or myth? I think this statement is a little mythical or perhaps sounds dramatic, but there is some truth behind it.  Let’s investigate this more.

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Female ferrets called “jills” are induced ovulators, meaning they need to mate to stimulate the ovaries to release an egg. If the jill isn’t mated, she doesn’t release an egg and so, hormonally, she remains in season, producing high levels of oestrogen (the female sex hormone). Prolonged high levels of oestrogen can cause health issues and lead to life-threatening complications and illnesses.

There are no known health implications for a male ferret (Known as a “hob”) not having access to mating although they can become violent if not mated, whilst in season, which has to be a consideration as ferrets prefer to live in social groups. 

When do Ferrets become sexually mature? 

Ferrets reach sexual maturity around 8-12 months of age. Jills are in season constantly from late March to early August if they are not bred, a period of 5 months.  

Male ferrets that have not been neutered (entire males) have a strong, musky smell when they come into breeding season, which may be for 6-10 months of the year. 

What health problems could occur if ferrets don’t mate?

Only mating or the end of the breeding season can bring the jill out of season. Remaining in season can cause severe health problems. 

Short-term health risks

Behavioural complications such as aggression in social groups (Aggression is particularly seen with in-season males that are not mated). 

Long-term health risks 

  • Oestrogen-induced anaemia 

This condition arises as a prolonged high level of oestrogen suppresses the bone marrow’s ability to produce new red blood cells, resulting in decreased production and eventually a deficiency of those red blood cells in the bloodstream. This is known as anaemia. As the role of red blood cells in the body is to carry oxygen around the body and keep it healthy, having a reduced volume of red blood cells to carry oxygen is obviously a serious problem. If the levels of red blood cells become very low, the brain and other vital organs can’t receive enough oxygen to function and so the condition becomes life-threatening. 

Symptoms of oestrogen-induced anaemia in ferrets include lethargy, weakness, loss of appetite, pale gums, and laboured breathing. If left untreated, then yes, it can – and often will – lead to death.

Not all unmated females develop prolonged seasons, in those that do, 50% develop anaemia. Overall, 30% of female ferrets in season will die if no male is available for mating, without veterinary intervention. 

  • Blood loss due to uncontrolled bleeding

High levels of oestrogen affect the bone marrow’s ability to produce platelets. Platelets are a component of blood that “plug” a blood vessel in the event of an injury to prevent excessive blood loss and bleeding. It is common for ferrets with long-term high oestrogen levels to bruise and bleed easily leading to death from uncontrolled gastrointestinal or organ bleeding. 

  • Infections 

High oestrogen levels reduce the ability of the immune system to fight infection due to suppression of the immune system and a reduction in the number of white blood cells – the body’s infection-fighting cells. These ferrets are more likely to get seriously ill if they become unwell with an infection. 

What are the options for treating Jills and bringing them out of season?

Surgical neutering/spaying 

Jills: The process of removing the ovaries and uterus under anaesthetic.

Advantages are preventing unwanted litter/breeding and removing the source of oestrogen, therefore the risk of life-threatening anaemia. 

Disadvantages of surgical neutering include a very high risk of developing hyperadrenocorticism also known as Cushing’s disease (Adrenal gland disease) later in life. 

Hyperadrenocorticism / Adrenal gland disease is one of the most common endocrine disorders of ferrets. As a result of an overactive adrenal gland or a pituitary gland tumour, producing too much hormone having an effect on the adrenal gland leading to it producing too much sex hormone. (Unlike in “true” Cushing’s disease where too much steroid is produced from the adrenal glands). 

Symptoms include hair loss, an enlarged vulva in females and difficulty urinating in males. 

Chemical / Hormonal treatment 

  • Injection 

Hormone injections sometimes known as the “jill jab” can be given at the start of the jill’s season, when signs are seen, or at the end of March before the breeding season starts. One such injection is a progesterone (pregnancy hormone) injection which “tricks” the body into thinking the ferret is already pregnant and thereby ending her season. In most cases, the injection lasts for the entire breeding season. The injection prevents the female from getting pregnant and avoids the possibility of life-threatening anaemia.

  • Implant 

Hormone implants such as deslorelin can be used in the form of a slow-release capsule inserted under the skin. Insertion of the implant is usually done under sedation or a brief anaesthetic. Implants can be used in males and females but are licenced for use in males only. This means the trials have been done to look at the safety and ability of the implant to create the desired effect (chemical neutering) in males, but not yet in females, although they are frequently used in both sexes. 

In jills, this form of treatment stops the female’s season and prevents her from being able to get pregnant. Treated males could still get females pregnant for 2 weeks after implantation. So they should be kept separated for this time. 

The implants in females can be placed at the start of spring and should last approximately 18 months, so should prevent her from coming into season (and therefore prevent her developing oestrogen-induced anaemia) or being able to breed throughout the duration of 2 breeding seasons. 

Mating the female with an entire Hob

Females are brought out of season “naturally” by mating her with a hob. This isn’t ideal as male ferrets are quite rough when displaying natural mating behaviour and so the female is commonly injured and stressed. Unwanted litters of kits would also be a by-product. 

Mating the female with a vasectomised Hob 

The female is bought out of season “naturally” by mating her with a hob who has been surgically altered. A vasectomy is a process of sterilising a male ferret by cutting the tubes that carry sperm from the testicles to the penis. This doesn’t affect the hob’s capability to mate. But it does prevent him from being able to get the jill pregnant. This practice has been common practice in the UK for many years, as its low cost and doesn’t require any specialist intervention. However, as stated above, mating in ferrets is naturally violent and injuries do occur. So this practice is no longer recommended. 

Summary – Do Ferrets Have to Mate or They’ll Die? 

Not mating can lead to life-threatening complications for female ferrets. Not all females will go on to develop these illnesses, but it is thought that they occur around 30% of the time, in unmated females. As induced ovulators with long seasonal breeding cycles, they are at high risk of developing consequences of high sex hormone levels if not mated or given veterinary intervention. 

Prevention of a prolonged season and therefore prevention of excessive sex hormone production that could lead to life-threatening complications such as oestrogen-induced anaemia include neutering, chemical/ hormonal treatments or mating with either an uncastrated or vasectomised male. 

In summary, yes ferrets can die as an indirect consequence of not mating. 

If you have any questions regarding keeping your Ferrets safe and healthy speak to your veterinarian who will be able to guide you further. You and your vet will be able to discuss the most appropriate course of prevention and treatment for your ferret and your own circumstances. If you have any health concerns regarding your ferret, seek immediate veterinary advice. 

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