Understanding the genetic basis of canine anxiety: phenotyping dogs for behavioral, neurochemical, and genetic assessment

Dogs and Separation Anxiety

Karen L. Overall, MA, VMD, PhD, Steven P. Hamilton, MD, PhD, Melanie Lee Chang, PhD

Understanding the genetic basis of canine anxiety: phenotyping dogs for behavioral, neurochemical, and genetic assessment

Journal of Veterinary Behavior: Clinical Applications and Research, Volume 1, Issue 3, November–December 2006, Pages 124–141

Introduction: the Canine Behavioral Genetics Project (CBGP)

Behavioral problems account for the death, relinquishment, or the end of breeding careers of more dogs than does any other set of problems ( [Miller et al 1996], [Patronek et al 1996], [Salman et al 1998] and [Salman et al 2000]; Scarlett et al., 1999; [Shore et al 2003], [Mondelli et al 2004] and [Shore 2005]). Whereas many behavioral complaints involve management-related issues or dog-human temperament mismatches, the behavioral concerns that are most interesting to scientists and breeders alike are those with familial patterns.

A number of conditions have been identified as running in family lines of a number of breeds including, but not restricted to, generalized anxiety/fear, noise phobia, impulse/control aggression, conspecific aggression, predatory aggression, and obsessive-compulsive disorder ( [Overall 1994], [Overall and Dunham 2002] and [Overall 2005]). Most of these conditions appear sometime between one and two years of age, the social maturity period, during which neural systems are undergoing extensive developmental changes. The potential benefit of genetic counseling is clear, and the potential to make dogs “safer” and happier is substantial. Understanding the genetic bases of behavioral problems will lead to more humane treatment of dogs, fewer public health risks, an improved public perception of dogs as pets, and a considerable lessening in the recycled pet problem. Additionally, elucidation of the biological systems underlying pathological behavior will heighten our general understanding of the underlying molecular biology of behavior, allowing the dog to contribute to this rapidly evolving field.

Over 50 breeds across all seven AKC groups have family lines in which “fear/shyness/nervousness/panic/anxiety” is a major breeder-reported concern (Overall, unpublished). Within these breeds, this “trait” often follows familial lines, suggesting a heritable basis. This pattern has been noted for many physical conditions in dogs ( [Sutter et al 2004] and [Lark et al 2006]), but little emphasis has been placed on behavioral conditions because of the difficulty in defining a clear phenotype. Although recognition of other genetically mediated conditions is often straightforward, based on easily observable clinical phenomena that are defined by consensus (e.g., cancer, retinopathies, narcolepsy), assignment of behavioral phenotypes can be open to misclassification or misinterpretation ( [Overall 2005] and [Overall and Burghardt 2006]).

The broad goal of the CBGP is to explore the genetic background of anxiety-related behavioral problems in dogs. To do so, we must: (1) solicit the participation of owners of candidate dogs possibly affected by anxiety-related behavioral problems; (2) identify affected and unaffected dogs, using the necessary and specific diagnostic criteria to make a diagnosis of the condition; (3) confirm the presence of the relevant diagnosis in these dogs and if possible in their family lines, using reliable, repeatable, and validated behavioral measures involving questionnaires and videos; and (4) obtain DNA samples for genetic linkage and association analyses, along with the relevant pedigrees. In this article, we discuss the distinction between diagnosis and phenotype, and we describe our protocol for assessing behavioral phenotypes in dogs, addressing the second and third aspects of our project just discussed.