Page 678 - ONLINE PROCEEDING BOOK WSAVA 2017
P. 678

An Urban Experience
WSVA7-0467
WSAVA HEREDITARY DISEASES
10 MOST COMMON HEREDITARY DISEASES IN DOGS
J. Bell1
1Cummings School of Veterinary Medicine at Tufts University, Dept. of Clinical Sciences, North Grafton- MA, USA
10 MOST COMMON HEREDITARY DISEASES IN DOGS
Jerold S Bell DVM
Cummings School of Veterinary Medicine at Tufts University, USA jerold.bell@tufts.edu
Genetic diseases common in mixed-breed and purebred dogs are typically associated with evolutionarily
ancient disease-liability genes. These emerged prior
to the separation of breeds and are dispersed in
the domestic dog genome. Pedigreed breeds may
have varied incidence of disease, depending on the frequencies of liability genes in their gene pools. The hallmark of inherited disease is predictability of onset and progression. Recognizing predictable triggers and modifying factors that in uence the expression of genetic disorders can help improve diagnosis, treatment, and control.
Insurance claims and centralized hospital databases monitor the most frequent disease presentations, which helps veterinarians understand the most frequent genetic diseases. The most frequent conditions are complexly inherited and involve combinations of multiple genes
and environmental factors. Genetic diseases should be recognized in practice because they must be treated as chronic illnesses—not episodic diseases.
Allergic Skin Disease
Manifestations of allergic skin disease (e.g., chronic in ammatory otitis, recurrent hot spots, pruritus) are the most frequent disease presentations in clinical practice. These presentations are commonly seen in mixed-breed and purebred dogs, with some breeds having a higher incidence than others. A study of atopic dermatitis in Golden and Labrador Retrievers showed heritability (i.e., percent of liability due to genetic in uence) at 47%, which also indicates a signi cant environmental contribution. A molecular genetic study of atopic dermatitis in German Shepherd dogs identi ed an associated segment of chromosome 28.
No genetic-liability tests are available. Predictable seasonality can be recognized in 15% to 62% (median, 30%) of allergic dogs with chronic presentations. For these patients, interventional measures to manage
pruritus should be prescribed before it progresses to clinical disease.
Canine Hip Dysplasia
Hip dysplasia, which occurs across all mixed-breed
and purebred dogs, is the most common inherited musculoskeletal disorder. Of all dogs for which radiographs are submitted to the Orthopedic Foundation for Animals (www.ofa.org), 14.6% are rated as dysplastic. This is a low estimate, as clinically apparent cases may not be submitted for evaluation. Small dogs with hip dysplasia usually do not show the pain and discomfort seen in larger dogs, demonstrating a size–weight relationship to clinical presentation. Radiographic diagnosis is made through ventrodorsal view or distraction index.
Palpable hip laxity can predict hip dysplasia and later osteoarthritic changes. A gentle Ortolani procedure during puppy examinations and palpation for hip laxity under anesthesia during neutering should be performed. Dogs with severe laxity identi ed at an early age may bene t from interventional surgery.
Estimated breeding values and genotypic breeding values based on DNA marker panels are being experimentally developed to assist with selection for hip normalcy. Breeders should select for familial breadth and depth of normalcy as seen in vertical pedigrees.
Brachycephalic Obstructive Airway Syndrome
Brachycephalic obstructive airway syndrome (BOAS)
is a disorder of breathing dif culty in short-snouted
and “bully” breeds. Breeds with the highest prevalence include Bulldogs, French Bulldogs and Pugs. BOAS occurs because of a mismatch in the proportions of the skull and soft tissue in the nose and pharynx. Clinical signs include dyspnea, exercise intolerance, heat intolerance, abnormal and increased respiratory noise, cyanosis, syncope and death. In one study, 16.7% of high-risk dogs died of respiratory failure at an average of 8.6 years of age.
This syndrome includes stenotic nares, an elongated soft palate, everted laryngeal saccules, laryngeal collapse and/or a hypoplastic trachea. Brachycephalic dogs
may present with facial skin fold dermatitis and corneal ulceration. For dogs experiencing signi cant morbidity, corrective surgery can include rhinoplasty for stenotic nares, soft palate resection, and laryngeal saccule removal. Breeders should select for dogs that do not show signs of BOAS and that have a de ned muzzle, a normal-diameter trachea (ratio of lumen diameter at the thoracic inlet to the width of the proximal third rib should be ≥2 on a lateral radiograph), and wide nostrils.
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42ND WORLD SMALL ANIMAL VETERINARY ASSOCIATION CONGRESS AND FECAVA 23RD EUROCONGRESS


































































































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