Below we have highlighted some topics that arise in discussion about neutering. Should I have my pet neutered? When should it be done? Shouldn't my bitch have a season or a litter before she is dressed? There is a lot of advice freely available by word of mouth or on the internet, so we would like to discuss some of the pros and cons from a veterinary perspective.

Every case and every animal is different and we encourage you to contact us to discuss the pros and cons of neutering for your pet. For most pets, our response to the question “should I neuter my pet”, is a resounding “yes”, but certainly for some others greater consideration should be given to their health, character, sex and breed before going ahead with the procedure.

Hygiene: animals with an oestrus cycle produce a discharge, or 'spotting', when they are in heat. In some bitches, this can be quite heavy.

Anaesthesia: isn’t anaesthesia dangerous?

Many clients are concerned about placing their pets under anaesthesia. It is true that anaesthetic accidents happen, but the incidence is extremely low. Modern anaesthetic agents are extremely safe and we take every precaution to ensure that your pet is suitably healthy to withstand both the anaesthetic and the surgical procedure.

Behaviour: will neutering change the behavior of my pet?

Yes, and no. For male animals, early neutering can help to reduce the development of ‘masculine’ behaviours such as aggression, overt sexual behaviour and marking/spraying. Neutering once these behaviours have become learned and established may not necessarily reduce the incidence or intensity of these behaviours.

Health: there are several malignant conditions of the reproductive tract, the incidence of which can be reduced or eliminated by neutering: cysts and tumours of the ovaries, pyometra (infection in the uterus or womb) and tumours of the mammary glands in females; prostatic hyperplasia, testicular and peri-anal tumours in males.

When your pet should be neutered.

If you are thinking to breed from your pet, please come to talk to us for help and advice on what to expect. Otherwise, we would not recommend neutering before six months of age for male and female dogs and cats. Why six months old? Neutering earlier than this can lead to a greater risk of: anaesthetic complications; urinary incontinence and complications in bone growth and development.

Neutering and the development of neoplasia (cancer) in dogs

Studies have shown that there are several types of neoplasia that are influenced by neutering. We will take each in turn:

Mammary neoplasia: this is the third most common tumour of female dogs with a reported incidence of 3.4%. It is malignant in about 50% of cases. There is a SEVEN-fold increase in the lifetime risk of developing mammary tumours in un-neutered bitches. Studies have shown that a bitch that has had two unmated seasons from birth has a 1 in 4 chance of developing mammary tumours. Dog breeds that appear to have a predisposition to mammary neoplasia are: Boxer, Brittany, Cocker Spaniel, Dachshund, English Setter, English Springer Spaniel, German Shepherd, Maltese, Miniature Poodle, Pointer, Toy Poodle and Yorkshire Terrier.

Prostatic neoplasia: this is an uncommon, highly malignant tumour of dogs with a reported incidence of up to 0.6%. Studies have shown that castration may as much as quadruple the risk of this condition.

Osteosarcoma: this is an uncommon, highly malignant tumour of dogs with a reported incidence of about 0.2%. Neutering may as much as double the risk of this condition. An exception to this is in some black and tan breeds, especially Rottweilers, who appear to have a genetic predisposition to this tumour with an incidence of 12.5%. Other breed that appear to have a predisposition to this condition are: Doberman, Great Dane, Irish Setter, Irish Wolfhound and Saint Bernard.

Haemangiosarcoma: this is an uncommon malignant tumour of dogs with a reported incidence of 0.2%. Neutering may double the risk of the form of this condition that affects the spleen. Breeds that appear to have a predisposition to this condition are: Boxer, English Setter, German Shepherd, Golden Retriever, Great Dane, Labrador, Pointer, Poodle and Siberian Husky.

Transitional cell carcinoma: this is a very uncommon malignant tumour of the bladder. Neutering may as much as quadruple the risk of this condition. Breeds that appear to have a predisposition to this condition are: Airdale, Beagle, Collie, Scottish Terrier, Shetland Sheepdog, West Highland White Terrier and Wire Fox Terrier.

Testicular neoplasia: this is a relatively common tumour of dogs with an incidence of 0.9%. Castration is curative.

For all of these tumours, with the exception of testicular neoplasia, no exact mechanism has been found to explain why neutering changes the incidence of neoplasia.

Neutering and incontinence in the bitch.

Urinary incontinence, now known as ‘urethral sphincter mechanism incompetence’, is a common side effect of neutering female dogs and occurs with an incidence of up to 20% of cases. The following tend to have a breed predisposition to the condition: Boxer, Doberman, Giant Schnauzer, Irish Setter, Old English Sheepdog, Rottweiler, Springer Spaniel and Weimaraner. No study has shown that spaying before puberty increases the risk of the condition, unless the bitch is less than three months of age. This condition is easily controlled with the use of a medication called phenylpropanolamine.

Finally, anecdotal evidence has suggested that bitches of some ‘at risk’ breeds, such as: Doberman, Old English Sheepdog, Irish Setter, Rottweiler and Weimaraner should be allowed to have at least one season.

Neutering rabbits

Female rabbits are particularly prone to a specific tumour of the uterus that has an incidence of 50-80% by the time the doe is four years old. Early neutering at 4-5 months is also recommended because she will store body fat in her reproductive tract as she gets older, which may complicate surgery later in life.

Neutering cats

Female cats are known as 'seasonally polyoestrus'. This means that they will come in and out of heat regularly during their mating season which, in the northern hemisphere, is roughly from January through to late autumn. Like dogs, we would recommend early neutering when they are about 6 months old.

Neutering ferrets

Recent studies have shown that there is a link between neutering of ferrets and the development of adrenal disease. In fact, early neutering of male ferrets (hobs) may actually accelerate the appearance of adrenal disease. Signs of adrenal disease may include hair loss, itchiness (pruritus), weight loss etc., although these signs are not unique to this disease. The use of implants (Suprelorin) can be effective in the early stages of this disease. These implants are now recommended as an alternative to neutering or vasectomy in hobs, and to neutering in female ferrets (jills), due to the possibility of adrenal disease. Implantation in the spring is recommended for the greatest duration of efficacy of the implant.

The implant is rapidly effective: starts about 2 weeks after implantation

The implant is resorbed over time - it does not need to be removed

The implant is safe and may be repeated as soon as signs of hormonal behaviours return

Some more information on Suprelorin may be found on the Virbac website, which has further links to webinars on ferret health and medicine.

As ever, if you have any further questions, please do not hesitate to contact us at the practice.

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