Association of neutering with health and welfare of urban free-roaming cat population in Israel, during 2012-2014

•Physical condition of urban free-roaming cats was estimated during 2012–2014.•Body condition scoring (BCS) and external signs of disease were recorded (n = 4600).•Neutering was positively associated with obesity and negatively with skin lesions.•Neutering rate in the surroundings was associated with increased BCS of adult cats.•Prevalence of emaciation and severe disability/injury was highest in kittens. 'Trap-Neutering by gonadectomy-Return' (TNR) is currently becoming an accepted method for managing free-roaming cat (FRC) populations, especially in human habitation. However, data regarding its impact on cat welfare are limited. In order to determine the demographic risk factors for FRC morbidity, we followed FRC populations in the city of Rishon LeZion during 2012–2014. Their age status (kitten/adult), contraceptive status (neutered/intact), sex, body-condition-scoring (BCS 1-5/5; 1= emaciation, 5= obesity), skin lesions, and external signs of disabilities and injuries were recorded and analyzed. We fitted a mixed effects generalized linear model to each cat-condition. Overall, 4615 cat-observations were recorded, of which 692 were kittens, 2365 neutered adults and 1445 intact adults. In comparison to intact adults, kittens had a significantly higher prevalence of emaciation (BCS 1; OR of 4.61, CI95% 2.67–7.6, p