title: Effects of surgical and chemical sterilization on the behavior of free-roaming male dogs in Puerto Natales, Chile.
abstract: Population management of free-roaming domestic dogs (Canis lupus familiaris) is of interest due to the threat these animals pose to people, other animals and the environment. Current sterilization procedures for male dogs include surgical and chemical methods. However, little is known about how these procedures affect their behavior. The primary objective of this study was to investigate changes in selected behaviors following chemical and surgical sterilization in a male free-roaming dog (FRD) population in southern Chile. We also examined the association between serum testosterone levels and behaviors thought to be influenced by circulating androgens. A total of 174 dogs were randomly assigned to either a surgical or chemical sterilization group, or a control group. At the onset of the intervention period, 119 dogs remained and 102 dogs successfully completed the study. Each dog was monitored pre- and post-intervention using video recordings, GPS collars, and blood samples for the measurement of testosterone. Analysis of behavior revealed that surgically castrated dogs showed no reduction of sexual activity or aggression when compared to their pre-intervention behavior. Chemically sterilized dogs showed a statistically significant increase in dog-directed aggression, but no change in sexual activity. There was no change in home range size in any groups between the pre- and post-intervention measurement. We found no consistent association between levels of serum testosterone concentration and behavioral changes in any of the groups. This study presents the first detailed behavioral observations following surgical and chemical sterilization in male FRDs. The information generated is highly relevant to communities struggling with the control of FRDs. Complementary studies to further our understanding of the effects of male sterilization on the behavioral and reproductive dynamics of FRD populations are needed.
authors.affiliation: The Global Alliance for Animals and People, Pasaje Los Arrayanes 333, Valdivia 5110624, Chile; Veterinarians without Borders/Vétérinaires sans Frontiéres Canada. Electronic address: elena.garde@thegaap.org.
authors.forename: E
authors.initials: E
authors.lastname: Garde
authors.affiliation: The Global Alliance for Animals and People, Pasaje Los Arrayanes 333, Valdivia 5110624, Chile; Veterinarians without Borders/Vétérinaires sans Frontiéres Canada.
authors.forename: G E
authors.initials: GE
authors.lastname: Pérez
authors.affiliation: Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PEI C1A 4P3, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Vanderstichel
authors.affiliation: Human-Animal Relationship and Animal Welfare Laboratory-Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale", Campo Boario, 46100 Teramo, Italy.
authors.forename: P F
authors.initials: PF
authors.lastname: Dalla Villa
authors.affiliation: Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Serpell
mesh_terms: D000374:Aggression / Q000187:drug effects; D000818:Animals; D001120:Arginine / Q000008:administration & dosage / Q000494:pharmacology; D002629:Chemosterilants / Q000008:administration & dosage / Q000494:pharmacology*; D002677:Chile; D004285:Dogs / Q000502:physiology* / Q000601:surgery; D005163:Factor Analysis, Statistical; D005942:Gluconates / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D009919:Orchiectomy / Q000662:veterinary; D012726:Sexual Behavior, Animal / Q000187:drug effects; D013245:Sterilization, Reproductive / Q000379:methods / Q000662:veterinary*; D013739:Testosterone / Q000097:blood
chemical_list: D002629:Chemosterilants; D005942:Gluconates; D013739:Testosterone; D001120:Arginine; C030691:gluconic acid
keywords: Behavior; Factor analysis; Free-roaming dogs; Sterilization; Testosterone; Zinc-gluconate