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pstinard · 01-04-2018, 07:47 AM

Hi. I decided to start a separate thread here on the welfare implications of spaying and neutering dogs rather than hijacking a thread in the General forum. I started by doing a research literature search on the effect of spaying and neutering on the behavior of dogs and found about a dozen relevant articles. Of these, I discarded the ones where the discussion was only incidental to the article, older articles, as well as articles that were only about small studies. I found this really REALLY good review article from May of 2017 that I thought was the best of the best: https://avmajournals.avma.org/doi/pd...ma.250.10.1155

This article will undoubtedly be behind a paywall for most Yorkietalk readers, but I have access to the full article, so I will post the section on the effect of spay/neutering on behavior in its entirety. There are other good sections on the effect of spay/neutering on health issues such as cancer, ACL tears, and luxating patella that I'll either post later or summarize if there is interest.

Here is the section on behavior:

(Definition of terms: gonadectomy = spaying/neutering. OHE = spaying.)

Behavior

Inappropriate or unacceptable behaviors disrupt the human-animal bond and are one of the most common reasons for relinquishment or rehoming of dogs. Because some owners pursue gonadectomy to prevent or resolve behavioral problems of their pets, they should be given realistic expectations for potential postsurgical behavioral changes.

Gonadectomy and the resultant decrease in gonadal steroid hormones typically result in a marked reduction or elimination of sexually dimorphic behaviors, including roaming, hormonal aggression (fighting with other males or females), and urine marking. In males, the age at castration or duration of the behavior does not change the likelihood that surgery will alter these unwanted behaviors.

The literature provides consistent results regarding the effects of gonadectomy on behaviors driven by testosterone or estrogen; however, studies involving behaviors not directly related to gonadal steroid hormones have resulted in mixed findings. Although the most serious bite injuries in the United States involve sexually intact dogs, gonadectomy has not been found to be a useful measure to prevent aggressive behavior in male or female dogs. Gonadectomy consistently reduces only intermale aggression and may actually contribute to increased aggression in female dogs. In a study conducted to evaluate canine patients referred for management of behavioral problems, sexually intact males and neutered females were significantly more likely to be referred because of aggression and stimulus reactivity than were neutered males and sexually intact females. A prospective controlled study of German Shepherd Dogs revealed increased reactivity to unfamiliar people and unknown dogs following OHE performed between 5 and 10 months of age, compared with results for dogs allowed to remain sexually intact. A study based on responses of 150 owners of dogs to questionnaires administered at the time of spaying and again 6 months later revealed a significant increase in dominance aggression toward family members by bitches following OHE, compared with the response of sexually intact female dogs of similar age and breed assessed at the same time periods. Female puppies that already had displayed signs of aggression were at highest risk for an increase in dominance aggression following gonadectomy, and there was little risk of increased aggression in older dogs that had not already displayed aggressive behavior. Therefore, consideration should be given to postponing OHE in female puppies with a history of aggression.

Differences in study designs and results create additional challenges when the potential consequences of gonadectomy on behavior are evaluated. Investigators of 1 study reported decreased activity in 50% of male dogs neutered as adults, contrary to results of an earlier study in which there was no indication that neutered male dogs become more inactive or lethargic. Additional differences were for dogs gonadectomized at 7 weeks or 7 months of age, which were judged to be more excitable than were sexually intact dogs. When dogs gonadectomized before or after 5.5 months of age were compared, those neutered before 5.5 months of age were more likely to display noise phobias and sexual behaviors. However, separation anxiety, urination due to fear, and the likelihood a dog would escape were less likely. Male puppies neutered prior to 5.5 months of age had increased aggression toward family members and also were more likely to bark excessively at visitors or household members. In another study conducted to evaluate gonadectomy in dogs before or after 24 weeks of age, investigators concluded that there was no increase in the incidence of behavioral problems or return rate to shelters for prepubertally gonadectomized dogs. Vizslas gonadectomized before 6 months of age reportedly have an increase of undesirable behaviors related to fear and anxiety. Investigators of that study did not evaluate sexual behaviors such as mounting and urine marking. When bitches of various breeds spayed between 2 and 4 years of age were compared with a sexually intact control group, no behavioral differences were observed during the 2 months after gonadectomy.

Interpretation of the literature related to behavioral changes after gonadectomy is further complicated by various definitions of aggression as well as comparisons of similar-appearing but potentially unrelated behaviors (eg, aggression, reactivity or energy level, and excitability). It is also possible that gonadectomy was recommended for some dogs as part of a behavior treatment plan, which would artificially increase the number of spayed or neutered dogs with behavioral problems. Because of these complicating factors, additional research is needed before conclusions can be confidently made about the effects of gonadectomy beyond the reduction of reproductive behaviors. Specific evaluation of potential behavioral consequences of surgery during critical periods of behavioral development could help guide general recommendations on the most appropriate time for gonadectomy of puppies.

01-04-2018, 07:47 AM	#1
pstinard YT 3000 Club Member Join Date: Apr 2013 Location: Urbana, IL USA Posts: 3,648	2017 review article on welfare implications of spay/neutering in dogs. Hi. I decided to start a separate thread here on the welfare implications of spaying and neutering dogs rather than hijacking a thread in the General forum. I started by doing a research literature search on the effect of spaying and neutering on the behavior of dogs and found about a dozen relevant articles. Of these, I discarded the ones where the discussion was only incidental to the article, older articles, as well as articles that were only about small studies. I found this really REALLY good review article from May of 2017 that I thought was the best of the best: https://avmajournals.avma.org/doi/pd...ma.250.10.1155 This article will undoubtedly be behind a paywall for most Yorkietalk readers, but I have access to the full article, so I will post the section on the effect of spay/neutering on behavior in its entirety. There are other good sections on the effect of spay/neutering on health issues such as cancer, ACL tears, and luxating patella that I'll either post later or summarize if there is interest. Here is the section on behavior: (Definition of terms: gonadectomy = spaying/neutering. OHE = spaying.) Behavior Inappropriate or unacceptable behaviors disrupt the human-animal bond and are one of the most common reasons for relinquishment or rehoming of dogs. Because some owners pursue gonadectomy to prevent or resolve behavioral problems of their pets, they should be given realistic expectations for potential postsurgical behavioral changes. Gonadectomy and the resultant decrease in gonadal steroid hormones typically result in a marked reduction or elimination of sexually dimorphic behaviors, including roaming, hormonal aggression (fighting with other males or females), and urine marking. In males, the age at castration or duration of the behavior does not change the likelihood that surgery will alter these unwanted behaviors. The literature provides consistent results regarding the effects of gonadectomy on behaviors driven by testosterone or estrogen; however, studies involving behaviors not directly related to gonadal steroid hormones have resulted in mixed findings. Although the most serious bite injuries in the United States involve sexually intact dogs, gonadectomy has not been found to be a useful measure to prevent aggressive behavior in male or female dogs. Gonadectomy consistently reduces only intermale aggression and may actually contribute to increased aggression in female dogs. In a study conducted to evaluate canine patients referred for management of behavioral problems, sexually intact males and neutered females were significantly more likely to be referred because of aggression and stimulus reactivity than were neutered males and sexually intact females. A prospective controlled study of German Shepherd Dogs revealed increased reactivity to unfamiliar people and unknown dogs following OHE performed between 5 and 10 months of age, compared with results for dogs allowed to remain sexually intact. A study based on responses of 150 owners of dogs to questionnaires administered at the time of spaying and again 6 months later revealed a significant increase in dominance aggression toward family members by bitches following OHE, compared with the response of sexually intact female dogs of similar age and breed assessed at the same time periods. Female puppies that already had displayed signs of aggression were at highest risk for an increase in dominance aggression following gonadectomy, and there was little risk of increased aggression in older dogs that had not already displayed aggressive behavior. Therefore, consideration should be given to postponing OHE in female puppies with a history of aggression. Differences in study designs and results create additional challenges when the potential consequences of gonadectomy on behavior are evaluated. Investigators of 1 study reported decreased activity in 50% of male dogs neutered as adults, contrary to results of an earlier study in which there was no indication that neutered male dogs become more inactive or lethargic. Additional differences were for dogs gonadectomized at 7 weeks or 7 months of age, which were judged to be more excitable than were sexually intact dogs. When dogs gonadectomized before or after 5.5 months of age were compared, those neutered before 5.5 months of age were more likely to display noise phobias and sexual behaviors. However, separation anxiety, urination due to fear, and the likelihood a dog would escape were less likely. Male puppies neutered prior to 5.5 months of age had increased aggression toward family members and also were more likely to bark excessively at visitors or household members. In another study conducted to evaluate gonadectomy in dogs before or after 24 weeks of age, investigators concluded that there was no increase in the incidence of behavioral problems or return rate to shelters for prepubertally gonadectomized dogs. Vizslas gonadectomized before 6 months of age reportedly have an increase of undesirable behaviors related to fear and anxiety. Investigators of that study did not evaluate sexual behaviors such as mounting and urine marking. When bitches of various breeds spayed between 2 and 4 years of age were compared with a sexually intact control group, no behavioral differences were observed during the 2 months after gonadectomy. Interpretation of the literature related to behavioral changes after gonadectomy is further complicated by various definitions of aggression as well as comparisons of similar-appearing but potentially unrelated behaviors (eg, aggression, reactivity or energy level, and excitability). It is also possible that gonadectomy was recommended for some dogs as part of a behavior treatment plan, which would artificially increase the number of spayed or neutered dogs with behavioral problems. Because of these complicating factors, additional research is needed before conclusions can be confidently made about the effects of gonadectomy beyond the reduction of reproductive behaviors. Specific evaluation of potential behavioral consequences of surgery during critical periods of behavioral development could help guide general recommendations on the most appropriate time for gonadectomy of puppies.