When is the perfect time to desex my pet?

Routine Desexing

Desexing has become a routine procedure in veterinary practice and is recommended to all pet owners to be performed at the age of 6 months (or thereabouts). Often owners have questions regarding the implications of desexing, what it  involves in terms of the procedure and also post-operative care, and the potential risks.

Shelters and rehoming facilities in Sydney often desex kittens and puppies at an earlier age than what we would generally recommend in general practice as the earlier they are neutered, the earlier they can be rehomed. With all anaesthetics, there is a risk of complication, and therefore – smaller animals have a higher risk of complication, especially as they have difficulty retaining warmth during procedures.

As anaesthetic knowledge and the pharmaceuticals we use have changed over the years, safer products have been found and more methods have been used to monitor anaesthetic depth and safety. By increasing the ways we monitor animals under anaesthetic, we are decreasing the chance of complications.

At Vet HQ we routinely use a capnograph (which monitors the carbon dioxide output and the volume of expelled air), ECG (electrocardiogram – which monitors the electrical output of the heart), blood pressure monitor and pulse oximetry (which reads the oxygen saturation of the hemoglobin). We also use physical signs to determine the depth of the anaesthetic to ensure they are kept at a stable state.

Our recommendation at VetHQ is desexing at 6 months of age. By this stage, most animals will have their full set of adult teeth and most, if not all, deciduous teeth have fallen out. If any deciduous teeth are retained (in particular the canine teeth in puppies), we will give you the option of having these removed whilst they are anaesthetized. If these teeth are not removed at desexing, and do not fall out on their own accord, there is a risk of overcrowding within the jaw, causing prehension difficulties when eating.

There is literature to suggest that desexing during the puppy stage, there is an increased risk of cruciate ligament disease (especially in bitches), but by the same comparisons there are numerous factors which account for partial and full rupture of the ligament.

For male dogs, the procedure is much quicker – the testicles are removed through a pre-scrotal incision and subcutaneous sutures and skin sutures are placed. Recovery is relatively quick and within24 hours they are usually bright and happy again – raring to go.

In males, the incidence of prostatic hyperplasia (enlargement) and neoplasia (tumours) , as well as testicular cancer increases with each year that they go without being neutered. Two of three testicular cancers are malignant and are often aggressive in nature – spreading rapidly to other abdominal organs quickly.

Another concern is that an animal will have stunted growth following  prepubertal gonadectomy has been refuted by multiple studies.

In contrast to intact dogs, pups spayed or neutered at 7 weeks of age and male pups neutered at 7 months of age had greater final radius and ulna lengths. The removal of hormonal influences on the growth plates of the long bones results in delayed closure, resulting in bones that are actually a little longer. However, no clinical significance to this difference in size has been found.

For female dogs, the procedure – a full ovariohysterectomy, is more involved. The two ovaries are located and removed, along with the entire uterine body.

A commonly asked question is whether desexed animals require hormone supplementation. There is no evidence to suggest that this is necessary – and this is essentially what we are trying to prevent as the estrogen and progesterone levels contribute to the incidence of mammary tumours. For each heat that a bitch experiences, the risk of developing mammary tumours increases.  The risk for mammary tumor development is approximately 0.5% for bitches speyed prior to their first estrus, 8% for those speyed after their first estrus and 26% for those speyed after two or more cycles.

The early desexing of large breed (breeds which at full grown adult weight are greater than 20kg) bitches can be related to hormonal incontinence – such that we recommend waiting closer to 9 months before desexing these animals.

For our feline friends, most are desexed at 6 months with no complications.  Some literature speculates that tom cats may have a higher chance of developing FLUTD (feline  lower urinary tract disease)  and other urinary tract conditions if desexed at an earlier age, however there is little evidence to support this theory.

In short, desexing is recommended as a routine procedure as the benefits of neutering far outweigh the postulated complications. Hip dysplasia, cranial cruciate ligament disease and development of long bones are multifactorial, and cannot be linked exclusively to desexing at 6 months (up to 9 months in large breed bitches).

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