Our Recommended Protocols

The NZVA policy on early desexing is “The NZVA supports the traditional age for desexing of dogs and cats. However, it recognises there is a case for desexing at a younger age in certain circumstances, eg animal welfare shelters, in the interests of population control.”

Veterinarians at Wellington SPCA have been carrying out early neutering operations on puppies and kittens in their animal shelter for many years. The SPCA protocols have been developed over a number of years in order to produce a system that is uncomplicated, easy to use, relatively cheap, and more importantly safe for the animals. Recovery from surgery is rapid enabling animals to be placed in new homes promptly. There are always risks associated with surgery and anaesthesia but these risks are minimised with experience and good technique.

A major advantage for the shelter is that all animals rehomed are desexed! It is important to bear in mind that without early desexing, many of the animals rehomed from shelters would be destined for a life of poor quality and/or early euthanasia.

The early desexing protocols currently used by Wellington SPCA veterinarians are outlined below. These may be of interest to other veterinarians who are asked to spay/castrate 7 to 14-week-old pups and kittens.

Patient Selection

Only operate on healthy patients. All candidates should have an examination prior to administration of a premed. The animals should have been wormed regularly as well, according to standard regimes.

Each patient should be weighed accurately in order to use the correct premed and induction agent. Each animal should be in good body condition, this is a more important criteria than absolute age.

Kittens have a smaller variability in body weights should be over 600 grams at about 7 - 8 weeks, in order to be suitable for surgery. Puppies with a much bigger weight range according to breed are better assessed on body condition than body weight.

Kittens

Premedication
Firstly “What does this animal require?”
The following dose rates are used at Wellington SPCA.
Acetylpromazine 0.02 - 0.1 mg/kg
Atropine 0.02 - 0.04 mg/kg

It is better to aim for the lower end of the scale. Premeds are timed to be administered roughly 30 - 60 minutes prior to surgery.

Pain relief- please contact Wellington SPCA for details

Males are then anaesthetised with propofol 1.25-1.75 ml.

Females then anaesthetised with propofol slowly i/v to effect (or ketamine/diazepam), before being masked or tubed for halothane or isoflurane.

Puppies

Premedication
Again “What does this animal require?”
The following dose rates are used at Wellington SPCA.
Acetylpromazine 0.02 - 0.1 mg/kg
Atropine 0.02 - 0.04 mg/kg
Pain relief - please contact Wellington SPCA for details
Premeds are timed to be administered roughly 30 - 60 minutes prior to surgery.

Anaesthesia is induced with propofol (about 0.04 ml/kg) before being intubated for maintenance on halothane or isoflurane.

(Note: For kittens and puppies, veterinarians at Auckland SPCA give the premedications buprenorphine 0.03 ml/kg, and atropine 0.1 ml/kg s/c, then anaesthetise half an hour later with a 50:50 mix of ketamine and Pamlin (diazepam 10 mg/ml) i/v to effect (about ½ ml for 4 kg pup) using a 25 gauge needle and 3 ml syringe. The animals are then intubated for halothane. This system is also very effective, with complications being very rare.)

Other tips:

It is important that only clinical healthy animals in good body condition are desexed.

Use 25 g needles for kitten veins, 23 g for puppies. Accurate syringes, (Tb syringes) are necessary when anaesthetising kittens.
Other points to note are that pre-anaesthetic preparation should include a minimal fast (3-4 hours) to avoid hypoglycaemia. Older animals (12 to 14 weeks) can be fasted 6-8 hours. After surgery, a small meal should be offered about an hour after the animal can stand.
Keeping litters together in a darkened, quiet environment before surgery helps decrease stress. Animals being neutered at a young age may be at the fear imprint stage.

Very young animals are prone to hypothermia due to their large body surface and limited fat reserves. Peri- and post-operatively it is wise to provide extra warmth with a heat pad, and this is particularly important during surgery. The animal should recover in a heated room, and wrapped in some insulating material such as towels.

Neutering male kittens can be a bit tricky. The testicles are small and sometimes found cranial to the scrotum. Occasionally they need to be massaged down into the scrotum.

Female kitten speys can very easily be approached via the flank. It helps to tie the upper leg back with a soft bandage. A ventral midline approach can be used, but needs to be cut further caudally than usual with older kittens.

Isoflurane is reported to be a safer inhalation agent than halothane because it requires much metabolism of the active ingredient (most is expired) and less depressant effect on thermoregulation.

Benefits of early neutering

Early age neutering is a useful tool to help control pet and stray animal over-population problems. From a shelter viewpoint it takes the onus off the adopters to comply with neuter contracts, and frees up finances and time spent trying to ensure compliance with neuter agreements. In the long run it also decreases the number of unwanted litters and consequently the number of animals presented to shelters for adoption or euthanasia.

From a veterinary and medical standpoint, early age neuters are physically quicker and easier to perform. The anaesthesia and surgery are less stressful on the animal and recoveries are faster. As with all dogs and cats neutered prior to puberty, there are decreased risks of certain medical problems later in life (eg mammary cancer, prostate problems).

Early age neutering appears to be advantageous to the animal-owner bond. A retrospective survey by the Medford, Oregon SPCA found that early age neutered dogs were less aggressive and had fewer medical problems than intact dogs (Kellington and Hannawalt, 1985), although there is also evidence to the contrary (see Clair Stafford – Heckel work?). In the Kellington and Hannawalt (1985) study, cat owners were happy with their early age neutered cats. It has been reported that animals neutered early are also calmer and gentler (Lieberman, 1987).
Despite the growing acceptance of early age neutering by many in the shelter and veterinary communities, there is still some opposition to the procedure. This opposition is often due to long held concerns about the long term effects on the animals involved, but these concerns have not been supported in clinical practice and there is little in the literature to support them.

Many of these objections relate to the possible effect of lack of reproductive hormones on the health and function of various body systems eg the urinary tract. However most veterinarians already recommend spaying females before their first heat, ie at 5 to 6 months of age, and neutering males at about the same age. This means that most traditional neutering operations are prepubertal. Neutering several months earlier should not make any significant difference since it is still within the phase of reproductive inactivity.

References

Faggella, AM and Aronsohn, MG, 1993, “Anaesthetic techniques for neutering 6- to 14- week-old kittens”, JAVMA, 202, 56-62.

Faggella, FM, 1997, “Early age neutering update”, Shelter Veterinarian Educational Program, American Humane Association, 45-49.

Joshua, JO (1965), “The spaying of bitches”, Vet Rec, 77, 642-647.

Kellington, T and Hannawalt, EH, 1985, “Study of the effects of early spay and neutering”, Medford Oregon SPCA, Reported May 1985.

Acknowledgments:
We are very grateful to veterinarians Jenny Waters, Wellington SPCA, and Doug Dreyer, Auckland SPCA, for providing information for this article, and to Roz Machon, IVABS, and Sandy Cooper, veterinarian Invercargill, for reviewing it.