A Prospective Cohort Study Investigating the Impact of Neutering Bitches Prepubertally or Post-Pubertally on Physical Development

Abstract

No previous large prospective cohort studies have been identified that have investigated the impact of the surgical neutering of bitches before or after known puberty on their growth and physical development. This study was designed to examine the data on physical development, vulval size, and conformation for bitches neutered by ovariohysterectomy before puberty (PPN, n = 155) or after puberty (control, n = 151) using a prospective cohort study design. Data were gathered at 6- and 17-months of age using bespoke physical assessment forms and digital images of the vulva. PPN bitches had greater changes in height measurements (mean difference = 2.039, SEM = 0.334, 91% CI = 1.471 to 2.608, p < 0.001) and smaller changes in the measurements of vulval length (mean difference = −0.377, SEM = 0.079, 91% CI = −0.511 to −0.243, p < 0.001) and width (mean difference = −0.221, SEM = 0.063, 91% CI = −0.328 to −0.113, p < 0.001) between 6- and 17-months of age than for the control bitches. Although not significant, the PPN bitches were taller (mean 58.5 vs. 56.6 cm) and heavier (mean 28.3 vs. 27.3 kg) with smaller vulval size measurements (mean vulval length 2.8 vs. 3.2 cm, mean vulval width 1.7 vs. 2.1 cm) at 17-months of age. At 17-months of age, significantly more PPN bitches had vulvas that appeared juvenile (Yates’ Chi-square = 14.834, D.F. = 1, p < 0.001) and recessed (Yates’ Chi-square = 7.792, D.F. = 1, p = 0.005) at the physical assessment, and significantly more PPN bitches had vulvas that appeared ‘recessed/inverted’ on the examination of digital images (Chi-square = 9.902, D.F. = 1, p = 0.002). The results from this study suggest no contraindications to prepubertal ovariohysterectomy for large breed bitches. However, any longer-term health implications of these differences in physical development need to be investigated and better understood prior to recommendations being made.

Later-age neutering causes lower risk of early‐onset urinary incontinence than early neutering–a VetCompass target trial emulation study

“…Given an estimated 75% of bitches in the UK will be neutered during their lifetime [ 4 ], the associated risks from neuter decision-making are magnified at a population level. Evidence for the optimal age to neuter bitches remains inconsistent [ 5 ], although it has been suggested this decision should be made on a bitch-by-bitch basis, in line with the breed-specific effects for age of neutering [ 6 ].…”

The Impact of Pediatric Neutering in Dogs and Cats—A Retrospective Study

“…However, some of the stated findings about the impact of neutering on the long-term health and well-being of animals seem to be contradictory in the different literary sources [9][10][11]. Specifically, in the case of female dogs, the optimum age of when to neuter is a contentious matter amongst veterinary professionals [12], and delaying the procedure until after the first heat is still an alternative used by many veterinarians, even with the lack of scientific data supporting this as a preferable approach [13]. Furthermore, the situation is even more complex regarding bitches that are available for adoption in animal shelters since pediatric neutering is essential to eliminate the risk of unwanted litters [14].…”