NEUTERING RABBITS
By Virginia Richardson MA VetMB, MRCVS
There are many reasons why we should be offering rabbit neutering to our clients as a routine procedure. With the advent of the anaesthetic Isoflurane rabbits can be anaesthetised safely. The rabbit does not usually object to Isoflurane induction through a face mask, and breath holding does not seem to be a problem. As 98% of the gas is eliminated through the lungs there are no aftereffects of anaesthesia. As more veterinary surgeons become familiar with the surgical procedures, neutering should no longer be considered a high-risk operation.
Reasons for Neutering
Female Rabbits
- By the age of 5 years up to 50% (some studies suggest 95%) of female rabbits have a chance of developing uterine adenocarcinoma.
- Uterine infections (pyometra) are common in females over a year of age.
- Spaying removes all the behavioural problems associated with sexual maturity, such as nesting, mounting, aggression, spraying and mood swings.
- Neutered rabbits are easier to litter-train.
- Neutered females can live in the company of males (preferably also neutered).
- Prevents unwanted litters.
- Castration eliminates the behaviour changes associated with sexual maturity such as mounting, spraying and aggression.
- Neutered male can live with a female (preferably neutered).
- Easier to house-train, and less smell (essential if a house rabbit).
- Prevents unwanted breeding.
The ideal timing for surgery is as the rabbit reaches sexual maturity. Males can be castrated as soon as the testicles descend (around 3-4 months of age). Females can be spayed at 6 months. Some smaller breeds may mature earlier and miniature does may be capable of breeding at 4 months, and may require neutering at this time.
Pre-operative preparation
Rabbits should not be starved prior to surgery. They are unable to vomit, and studies show that they return to eating post-operatively faster if they have not been starved.
Ovariohysterectomy
This is performed in a similar fashion to other small animals. A standard mid-line incision is made into the abdomen. The uterus is located and identified with its duplex cervix and uterine horns. The uterus and ovaries are usually supported by an amount of adipose tissue. The ovaries must be adequately exposed, as often they are buried deep in the adipose tissue. The ovarian vessels must be clamped, and ligated with absorbable suture. The tissues around the ovary are fairly friable, but the blood vessels tend to coagulate readily. The uterine body should be ligated with a transfixing suture below the double cervix. Care must be taken not to include the ureters which run close to the uterine body at this point. The peritoneum and abdominal muscles are closed with a simple interrupted absorbable suture, such as Vicryl. The skin can be closed with a subcuticular absorbable suture (this prevents chewing) or a non-absorbable simple interrupted suture. The latter may be chewed by the patient, although as the skin usually heals rapidly as long as the sutures are in for a few days the incision will heal.
Castration
Castration of the male is done with a standard canine approach, a midline incision is made anterior to the scrotum. The testicles are pushed into the incision wound, and castration is via the open method. The inguinal ring must be closed to avoid post-operative herniation of the abdominal contents. The skin can be closed with an absorbable material, using either a subcuticular or simple interrupted suture pattern.
Post-operative Care
After surgery the rabbit is given a single antibiotic injection. Further antibiosis is unnecessary. The rabbit should be allowed to recover in a warm environment, and allowed access to food and water. For the first few days the rabbit should be bedded on a soft surface, such as "Vetbed", towels or lino, to prevent abrasive bedding materials interfering with the wound. If indicated suture removal is done 10 days after the surgery.
Pairing and Loss of Negative Sexual Behaviour
The castrated male can be paired with a female after 2/3 weeks. Residual stored sperm should be gone by this time. The average time for negative sexual activity (spraying, mounting and aggression) to start lessening is two weeks. The average time for all such behaviour to have gone is two months. It may however be up to four months in larger breeds.
The spayed female should not be placed with a male (neutered or unneutered) for two weeks as during this time he could damage her by mounting her. Negative sexual behaviour in the female lessens and may go completely in two weeks. A neutered pair that live together will occasionally mount each other during their lifetime together and generally form a close pair bond.