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12/12/12

Information about neutering age: when to neuter a dog

The following subsections discuss current desexing age recommendations and how they have been established as well as the pros and cons of early age (8-16 weeks) neutering.

Current desexing age recommendations.


In Australia and throughout much of the world it is currently recommended that male dogs are neutered at around 5-7 months of age and older (as far as the "older" goes, the closer to the 5-7 months of age mark the better - there is less chance of your dog developing a testicular or testosterone-dependant medical condition if he is desexed at a younger age). 

The reasoning behind this 5-7 month age specification is one of anaesthetic safety for elective procedures.

When asked by owners why it is that a dog needs to wait until 5-7 months of age to be desexed, most veterinarians will simply say that it is much safer for them to wait until this age before undergoing a general anaesthetic procedure. The theory is that the liver and kidneys of very young animals are much less mature than those of older animals and therefore less capable of tolerating the effects of anaesthetic drugs and less effective at metabolising them and breaking them down and excreting them from the body. Younger animals are therefore expected to have prolonged recovery times and an increased risk of suffering from severe side effects, in particular liver and kidney damage, as a result of general anaesthesia. Consequently, most vets will choose not to anesthetize a young dog until at least 5 months of age for an elective procedure such as neutering. 

Whether the 5-7 month age specification for general anaesthesia is valid nowadays (2008 onwards), however, is much less clear and is currently the subject of debate. The reason for the current desexing-age debate is that the 5-7 month age specification was determined ages ago, way back in the days when animal anaesthesia was nowhere near as safe as it is now and relied heavily upon drugs that were more cardiovascularly depressant than modern drugs (e.g. put more strain on the kidneys and liver) and required a fully-functioning, almost-adult liver and kidney to metabolize and excrete them from the body. Because modern animal anaesthetic drugs are so much safer on young animals than the old drugs used to be, there is increasing push to drop the age of desexing in veterinary practices. This puts us onto the topic of early age neutering (see next section - 3b).

Are there any disadvantages to desexing at the normal time of 5-7 months of age?
  • Just as there are disadvantages of desexing an animal at a very young age (see section 3b), there are also some disadvantages associated with desexing at the normal age of 5-7 months:
  • Some people find it inconvenient to wait until 5-7 months of age to desex. 
  • There is a chance that an early-maturing dog may be able to mate and sire unwanted pups before this age.
  • For people who choose to have their pets microchipped during anaesthesia, there is an inconvenient wait of 5-7 months before this can be done. If it gets lost prior to this age, the unchipped dog may fail to find its way home. 
  • Many of the behavioural issues commonly associated with entire male animals may become manifest before the time of the desexing age recommendations (e.g. cocking the leg to urinate). These behavioural problems may persist even after the animal is sterilized.

Neutering puppies - information about the early spay and neuter of young dogs (puppy desexing).


As modern pet anaesthetics have become a lot safer, with fewer side effects, the debate about the recommended age of canine neutering has been reopened in the veterinary world with some vets now allowing their clients to opt for an early-age spay or neuter, provided they appreciate that there are greater, albeit minimal, anaesthetic risks to the very young pet when compared to the more mature pet. In these situations, cat and dog owners can opt to have their male and female pets desexed as young as 8-9 weeks of age (the vet chooses anaesthetic drugs that are not as cardiovascularly depressant and which do not rely as heavily upon extensive liver and kidney metabolism and excretion).

NOTE - in 1993, the AVMA (American Veterinary Medical Association) advised that it supported the early spay and neuter of young dogs and cats, recommending that puppies and kittens be spayed or neutered as early as 8-16 weeks of age. 

The advantages of the early spay and neuter of young dogs:

Certainly, there are some obvious advantages to choosing to desex an animal earlier rather than later. These include the following:
  • People do not have to wait 5-7 months to desex their pets. The procedure can be over and done with earlier.
  • Dogs neutered very early will not attain sexual maturity and will therefore be unable to sire any pups of their own. This role in canine population control is why most shelters choose to neuter early.
  • It makes it possible for young pups (6-16 weeks old) to be sold by breeders and pet-shops already desexed. This again helps to reduce the incidence of irresponsible breeding - dogs sold already desexed cannot reproduce.
  • For owners who choose to get their pets microchipped during anaesthesia, there is no inconvenient wait of 5-7 months before this can be done.
  • Some of the behavioural problems and concerns commonly associated with entire male animals may be prevented altogether if the pup is desexed well before achieving sexual maturity (e.g. cocking the leg to urinate).
  • From a veterinary anaesthesia and surgery perspective, the duration of surgery and anaesthesia is much shorter for a smaller, younger animal than it is for a fully grown, mature animal. I take about 3-7 minutes to neuter a male pup of about 9 weeks of age compared to about 10-15 minutes for an older animal.
  • The post-anaesthetic recovery time is quicker and there is less bleeding associated with an early spay or neuter procedure.
  • From a veterinary business perspective, the shorter duration of surgery and anaesthesia time is good for business. More early age neuters can be performed in a day than mature dog neuters and less anaesthetic gas is used on each individual, thereby saving the practice money per procedure.
  • Routine, across-the-board, early spay and neuter by shelters avoids the need for a sterilisation contract to be signed between the shelter and the prospective pet owner. A sterilisation contract is a legal document signed by people who adopt young, non-desexed puppies and kittens, which declares that they will return to the shelter to have that dog or cat desexed when it has reached the recommended sterilisation age of 5-7 months. The problem with these sterilisation contracts is that, very often, people do not obey them (particularly if the animal seems to be "purebred"); they are rarely enforced by law and, consequently, the adopted animal is left undesexed and able to breed and the cycle of pet reproduction and dumped litters continues.
The disadvantages associated with the early spay and neuter of young dogs:

There are also several disadvantages to choosing to desex an animal earlier rather than later. Many of these disadvantages were outlined in the previous section (3a) when the reasons for establishing the 5-7 month desexing age were discussed and include:
  • Early age anaesthesia and desexing is never going to be as safe as performing the procedure on an older and more mature dog. Regardless of how safe modern anaesthetics have become, the liver and kidneys of younger animals are considered to be less mature than those of older animals and therefore less capable of tolerating the effects of anaesthetic drugs and less effective at metabolising them and breaking them down and excreting them from the body. Even though it is very uncommon, there will always be the occasional early age animal that suffers from potentially life-threatening side effects, in particular liver and kidney damage, as a result of young age anaesthesia.
  • There is an increased risk of severe hypothermia (cold body temperatures) and hypoglycemia (low blood sugar) occurring when young animals are anesthetized. This hypothermia predisposition is caused by the young animal's increased body surface area (higher area for heat to be lost), reduced ability to shiver and reduced body fat covering (fat insulates against heat loss). The predisposition towards hypoglycemia is the result of a reduced ability to produce glucose from stores of glycogen and body fat as well as the fact that these stores of fat and glycogen are smaller in the young animal.
  • Loss of testosterone production at a very early age, as a result of desexing, may result in extremely immature development of masculine characteristics and a significantly reduced body musculature.
  • Early neutering may result in retained juvenile behaviours inappropriate to the animal's age later on.
  • Desexing equates to a loss of breeding potential and valuable genetics. Many breeders choose to only desex their dogs after they have had some time to grow (after all, it is not possible to look at a tiny puppy and determine whether or not it will have the right color, conformation and temperament traits to be a breeding and showing dog). This allows the breeder time to determine whether or not the animal in question will be a valuable stud animal or not. Early age neutering prevents breeders from being able to accurately determine which pups will be valuable stud animals (it is too early to tell when they are only puppies). 
  • Pups neutered very early will be completely unable to extrude their penises from their preputial sheaths throughout life. This can potentially result in urinary hygiene problems and an increased risk of preputial urine scalding and prepuce infections throughout life.
  • Early spaying and neutering will not 100% reduce pet overpopulation and dumping problems when a large proportion of dumped animals are not merely unwanted litters, but purpose-bought, older pets that owners have grown tired of, can't manage, can't train and so on. Those people, having divested themselves of a problem pet, then go and buy a new animal, thereby keeping the breeders of dogs and cats in good business and promoting the ongoing over-breeding of animals.

Author's note: at the time of this writing, I was working as a veterinarian in a high output animal shelter (RSPCA) in Australia. Because shelter policy was not to add to the numbers of litters being born irresponsibly by selling entire animals, all dogs, including puppies, were required to be desexed prior to sale. Consequently, it was not unusual for us to desex male and female puppies and kittens at early ages (anywhere from 9 weeks of age upwards). Hundreds of puppies and kittens passed under the surgeon's knife every year on their way to good homes and I must say that the incidence of post-operative complications that were a direct result of underage neutering was exceedingly low. 

Please remember, however, that if you do decide to have your pet neutered at an early age, you do make this choice at your own risk. Current veterinary recommendations do still state that pet cats and dogs should be neutered at 5-7 months of age and that there is a greater risk (albeit minor) of young animals suffering from operative or post-operative complications as a result of general anaesthesia.

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