There's a lot of information online debating the optimal age to de-sex a cat.
We adopted two 16-week-old kittens, a brother and sister, from a shelter. They were already desexed.
I am wondering how the early de-sexing of these cats may have affected them.
Early-Age Desexing (also referred to as EAD), has been a widely accepted practice in Australia over the past decade. It was originally tried in the US in the 1980s and has since been adopted by the vast majority of pet welfare organisations throughout Australia, including the RSPCA (which is often at the forefront of Animal Rights issues and the formation of best practice guidelines, that become adopted by our Governments).
There has been research and debate about the benefits and risks of EAD and the consensus here, seems to be that, overall, the benefits of EAD on pet cats is far greater than possible drawbacks.
As cats can come into season as early as four months, early desexing prevents any unwanted litters that may be born when the, previously recommended 6 - 8 months of age desexing was practiced.
EAD has been known to provide a variety of health benefits for cats, including the reduction of urinary tract health problems and some cancers. It has also been shown to help reduce behavioural problems pet owners experience, as the result of sexual maturation, including spraying and wandering.
On the down side, cats that are desexed before 16 weeks of age are prone to growing larger, which is not to be confused with obesity. It is also, not recommended for small animals < 1 kg.
On a personal note the majority of the pets I have owned and cared for through welfare organisations have all been desexed prior to 16 weeks of age and I have noticed that these pets have not suffered the same degree of behaviour issues that can be associated with sexual maturity. From a health point of view, I haven't experienced a complication as a result of this.
Early Age Desexing for Dogs & Cats – Blessing or Curse?
According to a comprehensive study by the University of Queensland, advantages of Early Age Desexing include:
shorter recovery times
minimal blood loss
cats and dogs desexed early tend to be bigger as adults, because bone maturity is delayed
reduced frequency of urinary disease in cats (3% vs 17% for late desexed). Urinary disease is a key cause of illness in older cats and this is a major change
reduced aggression in cats and dogs, even compared with the positive effects of later desexing (1)
From the RSPCA Australia:
... over the past decade, desexing at an earlier age (from eight weeks onwards) has become more common. This is known as early-age desexing or EAD. The RSPCA has been desexing kittens and puppies in its shelters at this earlier age for many years, and based on this experience and the cumulation of considerable scientific evidence, the RSPCA considers EAD to be a safe and effective strategy for the wider community to prevent unplanned/unwanted litters in cats and dogs.
...
Desexing surgery is faster and easier when carried out on younger patients as their anatomical structures are less developed. There is less tissue trauma and less tissue handling involved, the surgery incision site is smaller, and bleeding is reduced and minimal. It also takes less time to prepare the animals for EAD surgery which means less time under general anaesthesia. The anaesthetic recovery and wound healing times are also shorter, providing further animal welfare benefits. EAD significantly reduces the risk of mammary cancer in both dogs and cats. These benefits are in addition to all of the commonly accepted benefits associated with general desexing, such as a reduction in wandering/roaming and undesirable sexual behaviours such as mounting and urine spraying.
References
Pets Australia (1)
Report on Validity and Usefulness in Early Age Desexing in Dogs and Cats
Department Primary Industries & Fisheries
Queensland, Australia PDF
In addition to Skippy's excellent information, one thing I've noticed is that there's a much higher likelihood of hormonal issues with later-desexed animals. If the cat or dog is mature when the operation happens, their hormonal balance tends to "freeze" at the point where they were spayed or neutered.
I've seen this lead to compulsive over-eating, permanent "in heat" behavior, and other similar issues.
The cats I've lived with that were fixed before maturity (usually before 4 months - the vets I went to would spay a cat from 12 weeks on, and neuter "as soon as the testicles dropped enough to see them" (this was my brother-in-law, who is currently a vet in the Brisbane, Australia area)) never had any of these issues.
Also, the cats I've lived with who were fixed young tended to be more affectionate and kittenish throughout their life where those fixed older tended to be less inclined to bond strongly with humans.
