Breed-Specific Considerations

Historically, we have recognized that breed-specific physiology and clinical pathological normal values may vary. The evidence-based studies and literature to help guide decision making regarding specific breeds has been limited. Over the last several years, there has been important new information available on this topic.

There are several hundred distinct canine breeds and many more canine mixed-breed combinations, each with different genetics and diverse lifestyles.129,130 Breeds are recognized by phenotypic characteristics, but the accompanying inherited genetics also drive breed-specific physiology, anatomy, clinical pathology, and disease predisposition. As a result, visual identification of a dog’s breed and the initial record entry are not always correct. Therefore, it is important to be as accurate as possible when recording potential breed information (including mixed-breeds) to ensure accuracy in medical records. At least two-thirds of dog breeds have one or more recognized genetic disorders.131 The new popularity of “designer” breeds, i.e., purposeful crossbreeding, expands the need for breedspecific knowledge. The degree that purposeful canine crossbreeding reduces or magnifies certain genetic traits is not known. DNA testing in mixed-breed dogs may offer information allowing the veterinarian to be watchful for specific breed behavior tendencies or health concerns (e.g., orthopedic, cardiac, ophthalmologic, gastrointestinal or drug sensitivity).

Normal ranges for many test results are reported by species, but variations may routinely occur in selected breeds within a species, for example, red blood cell mass in sighthounds.132 Hospital- and laboratory-based reference ranges for specific breeds can be useful, but assuring the accuracy of data mining and data entry for specific breeds remains challenging.

Proper breed identification is essential for determining individualized care at all life stages. It is important at the first visit for practice teams to engage in breed-specific education with the pet owner. This dialog should include specific, directed evaluations and diagnostic tests at each life stage for the individual patient in order to detect occult disorders earlier. Various published resources describe breed-specific normal values and disease predispositions; understanding these parameters can help guide decisions for testing in different life stages.133–140 It can be beneficial for the practice team to designate a “champion” among the staff who is interested in breed-specific issues and can help educate other members of the team on the clinical relevance of breed identity.

Practitioners can increasingly and economically detect breed-specific anomalies with diagnostics that are available in-house. Routine diagnostics such as clinical pathology or imaging may be warranted to detect occult disorders earlier or prior to clinical signs in certain breeds. Examples include abnormal urine protein:creatinine ratio in Wheaton terriers or urinary bladder ultrasound in Scottish terriers. Some less-routine tests may be valuable among predisposed breeds, for example, tonometry and blood pressure.141–142 Besides early detection, these diagnostic tests are also important to establish a baseline for the individual patient. When a known breed of dog undergoes breed-specific screening, those results should be shared whenever possible in a public database, for example, collie eye screening or hip dysplasia screening.

An increasing diversity of DNA–based tests exists for dogs including consumer and medically marketed tests. Practice teams should evaluate insofar as possible any new test for its scientific merits and proven likelihood of disease predictability. Careful consideration must be given to the interpretation (predictive value) of genetic tests that screen for mutations.

Consider evaluating dogs for breed-specific issues that can be prevented or treated at the time of surgical sterilization under a single anesthetic episode (e.g., extracting persistent deciduous teeth, evaluating for unerupted first mandibular premolars, and performing prophylactic gastropexies).

Breed-specific individualized care is of special importance in active or potential working and service dogs where disease can both derive from and impact function.143–146 Because of the increased level of activity often seen with these dogs and their value increased frequencies of exams and diagnostic testing can be beneficial. A full lifespan approach should always be used with working or service dogs in the scheduling of elective procedures to reduce the total number of anesthetic episodes needed at each life stage.

The 2019 AAHA Canine Life Stage Guidelines are supported by generous educational grants from Boehringer Ingelheim Animal Health USA Inc., CareCredit, Elanco Animal Health, Hill’s ® Pet Nutrition, Inc., IDEXX Laboratories, Inc., Merck Animal Health and Zoetis Petcare.