Gonadectomy is widely used to treat and prevent behavior problems including the aggressive behavior of dogs. The aim of this study was to determine whether aggressive behavior toward familiar people, strangers, or other dogs was significantly different in dogs gonadectomized at various ages vs. intact dogs using the Canine Behavioral Assessment Research Questionnaire (C-BARQ) with multivariate analysis. Of 15,370 initial surveys, those for dogs reported to have been gonadectomized at less than 6 weeks of age or to correct a behavior problem, and those with incomplete answers to questions regarding independent or dependent variables were excluded, leaving 13,795 for the analysis of aggressive behavior toward familiar people: 13,498 for aggressive behavior toward strangers and 13,237 for aggressive behavior toward dogs. Aggressive behavior was defined (a) using mean scores for all questions on the C-BARQ for aggressive behavior (range 0–4) and (b) comparing dogs with no aggressive behavior (all questions answered 0) to dogs with moderate or severe aggression (at least one score of 2, 3, or 4). Data for intact dogs were compared with those for dogs gonadectomized at 6 months or less, 7–12 months, 11–18 months, and >18 months. Neither gonadectomy nor age at gonadectomy showed an association with aggression toward familiar people or dogs. However, there was a low but significant increase in the odds of moderate or severe aggression toward strangers for all gonadectomized dogs compared with intact dogs, but this effect was driven entirely by data for dogs gonadectomized at 7–12 months of age, which were 26% more likely to demonstrate aggression toward strangers. This large, comprehensive study of the relationships between gonadectomy and aggressive behavior in dogs demonstrates that when the many factors affecting aggressive behavior are considered, there is no evidence that gonadectomy at any age alters aggressive behavior toward familiar people or dogs, and there is only a minimal increase in aggression toward strangers. Given the increasing evidence of significant negative health effects of gonadectomy, there is an urgent need to systematically examine other means of preventing unwanted procreation, such as vasectomy and hysterectomy.

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Working dogs help to keep society and individuals safe, secure, and healthy. To perform their varied functions, it is critical to select dogs that are structurally sound and capable of demonstrating power, coordination and agility. Characteristics such as size and substance, head and axial skeletal structure, chest size and conformation, and thoracic and pelvic limb angulation should be evaluated to select the optimal combination of characteristics to suit the tasks to which each dog will be assigned. This review provides guidance on how to evaluate each of these structural components and discusses the contributions of those body parts to a working dog's function.

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We study orbits in potentials with central cusps, emphasizing the spheroidal equidensity (SED) potentials generated by mass distributions with spheroidal equidensity surfaces. The most prominent bifurcations are those related to 1:1 and 4:3 resonances between radial motions and motions perpendicular to the central plane. We find that 1:1 resonances can cause the thin tube orbit, as well as the equatorial plane orbit, to become unstable. We concentrate on period-tripling bifurcations because they appear to be the least understood. We study them via a class of analytic maps. This study suggests that stable period-three orbits generally arise de novo in stable and unstable pairs via a turning-point bifurcation, and not through a bifurcation from the thin tube at a 120 degree rotation angle. The stable period-three orbits typically have only a short span of existence before becoming unstable to a period-doubling instability through a supercritical pitchfork bifurcation.

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OBJECTIVE To compare health and behavior outcomes for dogs that underwent vasectomy or ovary-sparing spay (hysterectomy) with sexually intact dogs or dogs that had undergone traditional castration or spay. SAMPLE 6,018 dog owners responded to a web-based survey between November 3, 2021, and January 7, 2022. PROCEDURES Participants were asked demographic questions and to provide information about 1 or more dogs (living or deceased). Options for reproductive status were as follows: sexually intact, castrated, spayed (ovariohysterectomy or ovariectomy), vasectomy, or ovary-sparing spay (hysterectomy). Participants were asked questions about orthopedic and other health problems, cancer, and problematic behavior. Logistic regression models, survival analyses, and descriptive statistics were used to assess relationships between reproductive status and outcomes. RESULTS Owners provided valid surveys for 6,018 dogs, including 1,056 sexually intact, 1,672 castrated, and 58 vasectomized male dogs and 792 sexually intact, 2,281 spayed, and 159 female dogs that had undergone ovary-sparing spay. Longer exposure to gonadal hormones, regardless of reproductive status, was associated with reduced odds of general health problems and both problematic and nuisance behaviors. CLINICAL RELEVANCE TTo our knowledge, this study provides the first data on health and behavior outcomes of vasectomy and ovary-sparing spay in dogs and is the first to compare these outcomes to sexually intact and gonadectomized dogs. It adds to accumulating data on the mixed benefits and risks of removing the gonads to prevent reproduction and emphasizes the importance of developing an informed, case-by-case assessment of each patient, taking into consideration the potential risks and benefits of spaying or neutering and alternative reproductive surgeries.

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