Pre-pubertal neutering: the long-term impact on cats

Neutering at four months and younger compared to six months put cats at no greater risk of increased body condition score (BCS) or bodyweight gain as cats age in real-life settings, new research has found.

The study, which compared clinical measurements of BCS and bodyweight for owned kittens neutered at four months and younger, five months and six months, found no differences between the groups throughout adulthood into their senior years, indicating that cats neutered pre-pubertally are at no greater risk of obesity in adult life than those neutered at six months.

Investigating health outcomes

The research follows calls for more long-term studies investigating health outcomes for cats neutered pre-pubertally by some in the veterinary profession¹. As neutering is a known risk factor for obesity in adult cats, some may be worried that younger neutering may increase the size of this risk.

Data for the research was obtained through the Bristol Cats Study², a longitudinal study following kittens registered between 8 to 16 weeks old throughout their lifetime, and part funded by Cats Protection. This first of its kind project has collected regular owner-reported data, alongside clinical measurements on more than 2,000 individuals, in a bid to gain insight into feline health, behaviour and welfare.

Other findings from the study, published in Vet Record³, include evidence that BCS and bodyweight were dependent on age, increasing up until nine years old then declining. Sex-related differences in BCS and bodyweight were also found, with females having a lower BCS and bodyweight than males – a difference which was more pronounced in summer and autumn. This highlights that season should be an important consideration within clinical practice when assessing bodyweight changes – particularly for female cats.

The difficulties of assessing BCS in cats with long hair were also highlighted as a potential challenge for veterinary professionals. Hair length was found to be associated with BCS, but not bodyweight, suggesting inaccuracies in estimations, with long hair associated with lower BCSs. Recommendations for accurately assessing growth and development in cats with long hair in particular would include the use of both BCS and bodyweight.

Population management through four-month neutering

In a time where financial constraints and issues with capacity are facing both owners and vets, a move to four-month neutering may be an effective way to manage cat populations.

A modelling paper published by Cats Protection researchers demonstrated that even when neutering rates remain constant, shifting the age of neutering towards four months rather than the historically recommended six months could reduce the number of free-living unowned cats⁴. Alongside the known beneficial impacts of neutering on longevity, long-term prevention of disease and the reduction of owner-reported undesirable behaviours, pre-pubertal neutering at the general population level can be viewed as a positive cat welfare intervention.

Growing body of evidence

The study adds to a growing body of evidence which suggest no greater concerns around neutering cats at four-months old compared to the historical standard of six months.

Cat-Kind, a collaborative of animal welfare organisations, has collated a summary of scientific evidence on key areas of concern for neutering cats earlier than six months which can be accessed online⁵. The Cat-Kind website also hosts other resources, such as video resources and a directory of veterinary practices which promote four-month neutering.

• This article appeared in Vet Times (2025), Volume 55, Issue 33, Pages 16-17

Author

Rae Foreman-Worsley is an associate researcher at Cats Protection, specialising in feline welfare, behaviour and epidemiology.