Gonadectomy in immature dogs: effects on skeletal, physical, and behavioral development

• Published in: Journal of the American Veterinary Medical Association Vol. 198; no. 7; p. 1193
• Main Authors: Salmeri, K R, Bloomberg, M S, Scruggs, S L, Shille, V
• Format: Journal Article
• Language: English
• Published: United States 01-04-1991
• Subjects: Adipose Tissue - growth & development; Age Factors; Animals; Behavior, Animal; Bone Development; Dog Diseases - etiology; Dogs - growth & development; Dogs - surgery; Eating; Estradiol - blood; Female; Growth Plate - physiology; Male; Obesity - etiology; Obesity - veterinary; Orchiectomy - adverse effects; Orchiectomy - veterinary; Ovariectomy - adverse effects; Ovariectomy - veterinary; Penis - growth & development; Random Allocation; Sex Characteristics; Sexual Maturation; Testosterone - blood; Vulva - growth & development; Weight Gain
• ISSN: 0003-1488
• DOI: 10.2460/javma.1991.198.07.1193

In a 15-month study, the effects of prepubertal gonadectomy on skeletal growth, weight gain, food intake, body fat, secondary sex characteristics, and behavioral development were investigated in 32 mixed-breed dogs. Male and female pups from 5 litters were randomly allotted to 3 groups: group I, neuter at 7 weeks (n = 14); group II, neuter at 7 months (n = 8); and group III, sexually intact dogs (n = 10). Growth plate closure was delayed (group I vs group III; P less than 0.000001; group II vs group III, P less than 0.000001) in all neutered dogs, as compared with sexually intact dogs. Growth plate closure was delayed longer (group I vs group II, P less than 0.000045) in dogs neutered at 7 weeks old, compared with dogs neutered at 7 months old. The rate of growth was unaffected by gonadectomy, but the extended growth period resulted in greater final radial/ulnar length in all male dogs and bitches neutered at 7 weeks. Gonadectomy did not influence food intake, weight gain, or back-fat depth. Penile development was immature in the adult group-I males (mean +/- SEM diameter of pars glandis = 11.1 +/- 1.0 mm), compared with adult group-II (16.3 +/- 0.5 mm) and group-III (21.0 +/- 2.2 mm) males. Subjectively, the prepuce and os penis of the group-I males were immature, compared with those of group-II and group-III males. Vulvar development in group-I and group-II bitches was less mature than vulvar development in the sexually intact bitches. Of 7 behavioral characteristics assessed, only general activity and excitability rated differently among treatment groups. All neutered dogs were judged to be more active (group I, P less than 0.004) than sexually intact dogs. Group-I males were judged to be more excitable (P less than 0.02) than group-III males. It was concluded that with respect to skeletal, physical, and behavioral development, the effect of neutering pups at 7 weeks old was similar to that of neutering pups at 7 months old.