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Since pet‐specific care is about anticipating problems before they happen, typically through surveillance, screening tests are paramount to the process. The main categories of screening tests are based on phenotypic and genotypic assessment (see 3.11 Integrating Genotypic and Phenotypic Testing).

Genotypic tests assess a genetic mutation or marker to determine disease susceptibility. Such genetic tests measure either the presence of an actual genetic variant or genetic markers that appear to be associated with phenes. Genetic tests typically measure a specific variant associated with disease, while genomic tests may be used for more complex diseases in which there may be interactions among genes, and between genes and the environment; information may be assessed for disease susceptibility, prognosis, or likely response to therapy.

When it comes to genetic testing, there are many DNA tests that can be run, either individually or as part of a panel (http://bit.ly/2YWXBsc). For those that are only concerned with a single medical issue, individual genetic tests can be conducted. From a medical perspective, the most valuable information typically comes in the form of genetic panels in which multiple genetic tests are run at the same time (see 3.11 Integrating Genotypic and Phenotypic Testing). This will evaluate for dozens of medical conditions, as well as for certain traits (e.g., conformation, color, etc.). Sometimes specific breed profiles are requested, evaluating only conditions common in a specific breed, although with the new “chip” technologies, it is as inexpensive to run a complete panel with dozens or hundreds of tests as it is to run a handful of tests common in a specific breed. In almost all cases, it makes more sense (financial and otherwise) to run the complete profile rather than try to guess which tests might be most relevant. However, after running such a panel, it is necessary for the hospital team to determine which tests are actually relevant for each individual pet (see 3.8 Genetic Counseling).

Phenotypic tests are those that measure a detectable abnormality or variance from normal, rather than a genetic variant. This includes most of the tests we routinely use, such as hemograms, biochemical profiles, urinalysis, radiography, etc. For example, while genotypic tests can identify some variants of primary open‐angle glaucoma susceptibility at birth, phenotypic tests that rely on measurements of intraocular pressure (IOP) identify glaucoma when IOP increases above an established reference interval (range) for the breed.

Nutrigenomics will likely also play more of a role in healthcare with improved technology. There are several direct‐to‐consumer testing possibilities that purport to tell consumers how their eating habits could be associated with genetic predisposition and how sensitive they are to certain foods. Because of complicated environment–gene interactions, how individuals metabolize foods, and the role of the gut microbiome (see 4.6 Role of the Microbiome), this would be potentially complicated to interpret in pets.