Spayed Female Dogs May Have Reduced Communication Skills

Spayed female dogs show reduced responses to human communication signals.

Posted Feb 27, 2019

The spaying of female dogs and neutering of male dogs is an extremely common practice in North America: 83% of owned dogs are spayed or neutered in the United States. This is certainly not a universal practice and desexing is not looked upon as such a good thing in Europe. In Sweden, only about 1% of dogs are spayed or neutered, and only about half of the dogs in Hungary and Britain are altered. In Norway, it is against the law to perform such surgeries unless there is a medical reason.

In North America, various animal welfare and humane societies argue that spaying and neutering are the most effective means of population control for dogs. Many high-profile campaigns sponsored by groups such as PETA advocate that all pet dogs should be desexed to reduce the number of unwanted dogs that end up abandoned or in shelters. However, a number of surveys have shown that the majority of pet owners who have their dogs surgically altered do so not for population control, but because they believe that these operations will reduce aggression and some other behavioral problems in their pets. Unfortunately, as scientists have begun to look at the actual behavioral outcomes of dogs who have undergone these operations, the picture emerging is that spaying and neutering generally has negative, rather than positive, behavioral effects. As an example, one pair of studies, involving 15,984 dogs, found that both male and female dogs showed a marked increase in aggression and fearfulness following spaying and neutering.

Up to now, the major focus of scientific studies on the behavioral effects of desexing has been on emotional changes and overt aggressive responses toward the dog's owner, strangers, and other animals following such surgical interventions. However, because some research has found that the removal of the ovaries of rats has negative effects on learning, memory, and social recognition in female rats, some researchers have begun to look at the social-cognitive effects of spaying in female dogs as well. Some of this recent research has already shown that spaying reduces a female's ability to deal with spatial problems, such as solving mazes.

Dom Crayford photo — Creative Content License
Source: Dom Crayford photo — Creative Content License

A recent study from Italy has discovered a completely different problem in the behavior of female dogs that have undergone an ovariectomy. The team of investigators was headed by Anna Scandurra of the Department of Biology at the University of Naples Federico II. The concern of this set of researchers has to do with the fact that, in the absence of ovaries, a number of psychologically significant hormones are missing in female dogs. These hormones play a role in social behaviors including bonding, and socially motivated attention toward both humans and other dogs. [These are the same types of hormones believed to be responsible for more affectionate, empathic, and caring behaviors in human females, as compared to males.] To demonstrate the consequences that this change in body chemistry can have on dogs, the research team tested 40 female pet dogs that had never been pregnant. The dogs were Golden Retrievers and Labrador Retrievers. Both breeds are known to be highly sociable and responsive to human communication signals. In the test groups, there were 18 intact females and 22 spayed females.

The task which was used involved simple problem-solving based on attention to human gestures. Specifically the dogs were presented with two bowls and the experimenter would point to one. If the dog responded by going to the indicated bowl she was rewarded with a bit of sausage. In addition to the number of correct responses that each group of dogs made, researchers also recorded the number of times that the dogs failed to make any response at all, as well as the amount of time that they took to respond (the response latency).

One of the reasons why a pointing task was chosen is because it not only involves problem-solving but also demonstrates attention and communication skills. Pointing is a language-like signal which attempts to say something about where in the environment there might be something of interest. To be effective, the individual watching the pointing must pay attention, accurately interpret, and then respond to the pointing signal. The guess was that in the absence of some of the female hormones produced by the ovaries, the spayed dogs would be less socially attentive and responsive to gestures meant as communication. Therefore, it was expected that the spayed females would not do as well in such a task involving social cues in the form of gestures. This turned out to be the case.

The intact females were 1.5 times more likely to correctly choose the bowl which was being pointed at than were the spayed females (75% versus 50%). The spayed females appeared to be less socially reactive since they were nearly 3 times more likely to simply not respond at all than were their intact counterparts (38% versus 13%). This diminished response to social cues was also shown in the latencies since it took three times longer for the spayed females to respond (when they responded at all) than the females with intact ovaries (averaging 3 seconds versus 1 second).

In the discussion of their results the authors claim that their data provides "clear evidence of impaired communicative skills in ovariectomized dogs." In other words, these researchers conclude that spayed female dogs simply don't pay as much attention to people, are less socially responsive, and don't react as accurately to human communication gestures as do sexually intact female dogs.

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Anna Scandurra, Alessandra Alterisio, Anna Di Cosmo, Antonio D’Ambrosio and Biagio D’Aniello (2019).  Ovariectomy Impairs Socio-Cognitive Functions in Dogs. Animals, 9, 58; doi:10.3390/ani9020058

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