Prevalence, comorbidity, and breed differences for anxious dogs
A large study sheds light on anxious behaviors in dogs by evaluating their penetrance within the domestic canine population, the patterns by which certain traits occur in tandem, and the genetic stronghold for these behaviors.
Anxious dogs can pose as a problem for not only their owners, but also for themselves. Anxiety in dogs is linked to many unwanted behaviors, including aggression and hyperactivity, that can sometimes land these pets in shelters.
Previous studies have found the most common canine behavior issues to be excessive barking, inappropriate elimination, aggression, fear, and destructiveness.1,2-5 About 1 in 5 dogs display a fear of strangers, dogs, or new situations,6,7 while 20% to 50% exhibit excessive sensitivity to noise.6-10 Comorbidity between noise sensitivity and separation anxiety has been reported.6,11
Although extensive previous research has laid the foundation for the epidemiology of canine behavior problems, that work is hobbled by small sample sizes, meager breed representation, and limited numbers of traits studied.
The current study, conducted by genetics researchers in the University of Helsinki’s Department of Veterinary Biosciences, provides a broader picture by collecting 13,715 responses from owners of 264 canine breeds to questions regarding 7 anxiety traits.12
The data were harvested through an online questionnaire that inquired about noise sensitivity, (delineated into fireworks, thunder, and gunshots), fear (of dogs, of strangers, of novel situations), fear of surfaces/heights, hyperactivity/impulsivity/inattention, compulsive behavior (self-biting, surface licking, excessive drinking, pacing, fly snapping, staring, tail chasing), aggression (toward family members, toward strangers), and separation-related behavior (destroy/urinate, vocalize/salivate/pant).
The gender ratio of the dogs was roughly 50-50, with the following breed types predominating: Bernese mountain dog, border collie, Finnish Lapponian dog, German shepherd, Labrador retriever, Romagnolo, Lapponian herder, miniature schnauzer, rough collie, smooth collie, Shetland sheepdog, soft-coated wheaten terrier, Spanish water dog, Staffordshire bull terrier, and mixed-breed dog.
In total, 72.5% of dogs reportedly displayed some type of troubling behavior. Noise sensitivity was among the most prevalent anxiety trait, with 1 in 3 dogs exhibiting excessive fear of at least 1 sound; reaction to fireworks was most common. Fear was the second most common trait, with a rate of 29%; within this realm, fear of other dogs predominated.12
The scarcest traits were separation-related behavior and aggression; aggression toward human family members was more common than aggression toward strangers. Ironically, previous studies showed aggression to be the most polarized behavioral problem reported among patients referred to veterinary behavior clinics,2,3,5 perhaps because many owners consider aggression serious enough to warrant professional consultation.
Comorbidities for different anxiety-related attributes were prevalent in this survey. Fear and noise sensitivity, perhaps because of their individual universalities among domestic dogs, were often annexed to other anxiety disorders. The most common comorbidity was fear, especially in aggressive and hyperactive/impulsive dogs. The second most common was noise sensitivity, particularly in fearful dogs. Separation-related behaviors, hyperactivity/impulsivity/inattention, and compulsive behavior are also tightly joined. The connection between impulsivity and compulsion may be due to a failure of response control mediated by basal ganglia.13
Because of comorbidity patterns, relative risks for different behaviors can be determined by the presence of other traits. For instance, dogs exhibiting separation-related behavior were over 4 times more likely to be hyperactive/impulsive and 3.4 times more likely to be inattentive. Likewise, aggressive dogs were fearful 3.2 times more often, while those showing separation-related behavior were 2.8 times likelier to be fearful.
Male dogs were more prone to aggression, hyperactivity/impulsivity/inattention and, to a lesser extent, separation-related behavior. Females had a higher prevalence of fearfulness.
The rate of noise sensitivity—particularly to thunder—increased with age, as did aggression and fear of surfaces/heights. Conversely, hyperactivity/impulsivity/inattention, tail chasing, and self-biting declined with age.
Significant breed differences and predispositions were evident across all behavioral traits. Notably, nearly 11% of miniature schnauzers had a history of aggression toward strangers, compared with less than 1% of Labrador retrievers. Over 9% of Staffordshire bull terriers engaged in tail chasing, but none of the lagotto Romagnolos in the study displayed this habit. Fear was the most common behavior issue in Spanish water dogs, Shetland sheepdogs, and mixed breeds, but was seldom reported in Labrador retrievers.
Hyperactivity/impulsivity were most commonly reported by owners of German shepherds, Staffordshire bull terriers, and mixed breeds, but were rarely seen in rough collies and miniature schnauzers.
Some traits were shared by several breeds but expressed differently in each. For instance, compulsive behavior was trademarked by German shepherds and Staffordshire bull terriers, but the former manifested it by pacing and excessive drinking, while the latter engaged in tail-chasing. In border collies, compulsiveness took the form of light chasing and staring. Likewise, mixed-breed dogs showed their separation anxiety by destroying or soiling the house when left alone, whereas wheaten terriers were more likely to vocalize, salivate, or pant.12
Breed-specific patterns also came to light. For example, border collies showed only moderate behavioral impairment across the board, except for compulsive staring and fly snapping, which they manifest at high prevalence. The behavioral landscape of the Staffordshire bull terriers in the study overwhelmingly consisted of compulsive behavior and hyperactivity/impulsivity/inattention.12
The findings in this study are consistent with those of previous research, and the sheer number of dogs in the present report lends further credence to past work. The obvious limitation of the study herein is that the sample is self-selected and, therefore, may not be representative of the Finnish canine population at large. Secondly, traits were categorized into low, moderate, and high brackets, but these were based on frequency of signs rather than severity, except in the cases of aggression, separation-related behavior, and hyperactivity/impulsivity/inattention.
The breed trends in behavioral properties of the study group highlight the genetic governance over the way a dog behaves.
Dr. Capuzzi is a small animal veterinarian and journalist based in the Philadelphia area.
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