Abstract. There is limited information describing species related pharmacogenetic differences in animals. Despite the lack of genetic information in veterinary medicine, breed specific responses to endogenous and exogenous substances have been reported across many species. This finding underscores the importance of obtaining insight into the genotypic and phenotypic variation present across breeds. This article provides a summary of the literature pertaining to canine breed differences in physiology, drug response, drug pharmacokinetics, and metabolic idiosyncrasies. The existing knowledge of pedigrees and the known phenotypes and genotypes of dogs provides important information for determining mode of inheritance, penetration, and other major characteristics of heritable traits. Understanding these breed differences will improve canine population predictions (for canine drug products) and may be of value when extrapolating toxicology data from dogs to humans.

Despite advancements in pharmacogenetics in human medicine, the incorporation of pharmacogenetics into veterinary medicine is still in its early stages of development. To date, efforts to understand the pharmacologic impact of genetic variation in veterinary species have largely focused on genes encoding for the membrane transporter, P-glycoprotein (P-gp). The emphasis on the role of P-gp is largely because of safety concerns associated with the use of some macrocyclic lactones in dogs. Because of the body of information available on this topic, we use P-gp as a platform for understanding the importance of population diversity in veterinary medicine. The impact of P-gp on drug pharmacokinetics and pharmacodynamics is considered, along with endogenous and exogenous factors that can modulate P-gp activity. The review includes discussion of how population diversity in P-gp activity can lead to susceptibility to certain diseases or alter patient response to environmental stress or pharmaceutical intervention. In addition, phenotypic diversity also needs to be considered, as demonstrated by the impact of P-gp up-regulation and drug resistance. The aim of this review was to set the stage for further exploration into the impact of genetic and phenotypic variability on drug pharmacokinetics, disease propensity, product formulation and drug response in both companion and food-producing animals.

Abstract. The challenge of measuring pain in veterinary medicine is compounded by the lack of fully validated, reliable methods to measure and assess pain in nonverbal patients. In human medicine, there are numerous, validated pain assessment tools (PATs) for assessing various, specific types of pain. The advances in human medicine pain management and numerous validated pain scales should serve as incentives and templates to facilitate similar advances in the development of validated PATs for use in dogs (and other species). The limited number of canine PATs constrains our ability to adequately and reliably assess pain. Improving the ability to quantify osteoarthritis and postoperative pain in dogs would enhance the development of analgesics for animals, advance the management of animal pain, facilitate the use of animal pain models in preclinical trials for human analgesics, and provide insight into the quantification of pain responses in humans who lack the ability to adequately communicate. This review describes the need for practical, valid, and reliable PATs for use in veterinary patients and discusses some currently available PATs commonly used to evaluate acute and chronic pain in dogs.

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