in life to evaluate trends.
One important distinction between genotypic and phenotypic testing is that genotypic test results do not change over time and so don't need to be repeated, whereas phenotypic results do change over time so need to be periodically reevaluated. For example, diabetes mellitus is a relatively common chronic disorder in both dogs and cats. In dogs, it is likely a complex genetic disorder in which several susceptibility genes affect overall genetic risk in a breed‐specific manner. Thus, some breeds might be considered at increased risk, including keeshonden, Australian terriers, golden retrievers, miniature schnauzers, pugs, Samoyeds, etc. It cannot currently be predicted with a DNA test, and phenotypic testing with blood glucose levels and urinalysis can either be used to confirm a diagnosis or, preferably, can be used proactively to screen animals at potential risk to identify the prediabetic animal and attempt to alter the course of the disease. To identify such trends regarding the slow progression of such chronic diseases (including glaucoma, hypothyroidism, etc.), veterinary teams need to determine trends by periodically reevaluating relevant phenotypic tests.
Mrs Thompson presented her 2‐year‐old Doberman pinscher, Brutus, for routine evaluation and vaccination. Brutus had genetic testing as a puppy and was found to be “affected” on a DNA test for dilated cardiomyopathy. Initially Mrs Thompson was quite concerned and considered relinquishing Brutus to a shelter, but the veterinary team at ABC Animal Hospital helped put things in perspective.
It was true that Brutus had the PDK4 (DCM1) mutation that was associated with an increased risk for dilated cardiomyopathy, but she now understood that the mutation did not cause the disease (it was just associated with increased risk in a certain cohort of Doberman pinschers), was not the only mutation associated with the disease, and that there were also other factors that could influence cardiomyopathy onset in a complex manner. In fact, she also read about some diets that could possibly be associated with the disease in a number of different breeds.
The team at ABC Animal Hospital helped establish a sensible ongoing screening protocol with their local veterinary cardiologist, and Mrs Thompson felt quite relieved that they had identified a risk factor, but now had a sensible program in place to make sure Brutus would have the care he needed.
In most pets, a combination of genotypic and phenotypic testing is needed for the early detection of disease conditions.
Genotypic testing allows the earliest identification of risk, but does not always mean that the pet will develop disease.
In most instances, genotypic testing is used as a health screen rather than a disease screen.
Phenotypic testing can confirm a diagnosis, but typically later in the course of disease.
Veterinary teams need to be able to effectively counsel clients as how a combination of genotypic and phenotypic testing can help deliver excellent healthcare across a pet's lifespan.
Abbreviation
DNA Deoxyribonucleic acid
Recommended Reading
1 Ackerman, L. (2011). The Genetic Connection, 2e. Lakewood, CO: AAHA Press.
2 Ackerman, L. (2019). An introduction to pet‐specific care. EC Vet. Sci. 4 (1): 1–3.
3 Ackerman, L. (ed.) (2020). Pet‐specific care. In: Five‐Minute Veterinary Practice Management Consult, 3e, 260–263. Ames, IA: Wiley.
4 Ackerman, L. (2020). Proactive Pet Parenting: Anticipating pet health problems before they happen. Problem Free Publishing.
5 American Animal Hospital Association‐American Veterinary Medical Association Preventive Health Guidelines Task Force (2011). J. Am. Vet. Med. Assoc. 239 (5): 625–629.
6 Bell, J., Cavanagh, K., Tilley, L., and Smith, F. (2012). Veterinary Medical Guide to Dog and Cat Breeds. Jackson Hole, WY: Teton NewMedia.
7 Companion Animal Parasite Council. www.capcvet.org
8 Partners for Healthy Pets. www.partnersforhealthypets.org
9 Shaffer, L.G., Geretshlaeger, A., Ramirez, C.J. et al. (2019). Quality assurance checklist and additional considerations for canine clinical genetic testing laboratories: a follow‐up to the published standards and guidelines. Hum. Genet. 138: 501–508.
10 Stull, J.W., Shelby, J.A., Bonnett, B.N. et al. (2018). Barriers and next steps to providing a spectrum of effective health care to companion animals. J. Am. Vet. Med. Assoc. 253 (11): 1386–1389.
3.12 Orthopedic Screening
Jason C. Nicholas, BVETMED (Hons)
Independent Consultant, Author and Speaker, Co-founder, Preventive Vet, Portland, OR, USA
3.12.1 Summary
From congenital and early‐onset conditions, such as angular limb deformities (ALD), luxating patella (LP), and hip dysplasia (HD), to developmental conditions that show up later in life, like degenerative joint disease (DJD) and osteoarthritis (OA), orthopedic conditions can cause significant pain, dysfunction, and secondary complications in our canine and feline patients. Such conditions can also cause emotional distress, logistical complications, and financial strain for our clients. Proactive screening and early client education and intervention are crucial to help avoid or mitigate the problems associated with orthopedic conditions both for our patients and our clients.
On the other hand, a reactive approach typically results in affected patients suffering unnecessarily until such time that their owners recognize a problem and present their pet for evaluation. By this point, treatment options may be more limited or prognosis for the best level of return to function and good quality of life (QOL) may already be reduced.
Orthopedic conditions in cats and dogs can be more common than many people realize and they can often have a significant negative impact on the comfort and QOL of affected animals. Orthopedic conditions can cause a host of problems, both for the affected pet and also for their people. Associated problems can include:
pain (potentially with a resulting change in behavior, including development of aggression and noise aversions)
loss
