Inherited Condition in Dogs and Cats

Exam 3

Polydactyl

Autosomal dominant trait

Preaxial polydactyl- cats

Extra dew claws- dogs

Preaxial polydactyl

Extra digits on the medial side of the limb

Primarily in front feet only

Commonly referred to as “Hemmingway cats”

Elbow Dysplasia

Polygenetic condition

Osteochondrosis of the elbow joint

One or both limbs can be affected

Environmental factors also contribute- Diet, fast growth

Condition begins in young dogs

front limb lameness

typically requires surgical correction

Orthopedic Foundation of America keeps a database of screened breeding dogs

Many breeds affected

Osteochondrosis

OCD = abnormal cartilage development

medial humeral condyle, fragmented medial coronoid process, ununited anconeal process, and incongruent elbow are all potentially affected sites of the joint

Common breeds effected by elbow dysplasia

Labs, Golden, Rotties, Bassets, German Sheperds

Hip Dysplasia

Polygenetic condition

Subluxation of the hip joint- Loose joint leads in a young dog leads to osteoarthritis in an older dog

One or both limbs can be affected

 Environmental factors also contribute- Diet, fast growth, excess weight, Previous trauma to the hip

Difficult to eliminate due to unidentified genetic marker

Large and giant breeds

OFA certification prior to breeding

Intervertebral Disc Disease

Found in chondrodystrophic breeds

Abnormality of the annular cartilage around the intervertebral disc

The abnormal cartilage allows protrusion of the inner nucleus pulposus in spinal column

Pressure on the spinal column results in: pain, ataxia, paralysis

Chondrodystrophic breeds

Basset, dachshund, corgi

long backed breeds

mode of inheritance has not been identified

Brachycephalic Syndrome

Syndrome that has occurred due to phenotypic selection for certain breeds

Results in: elongated soft palate, everted laryngeal saccules, stenotic nares, hypoplastic trachea

Only three of these can be corrected surgically

Any of these conditions increase airway resistance which leads to: Increased airway noise, exercise intolerance, increased cardiovascular workload, collapse, death

Brachycephalic breeds

• English bulldog, Boston terrier, French bulldog, Pug

Mitral Valve Dysplasia

Inherited defect of the mitral valve- Exact mode of inheritance unknown

Results in backflow of blood from the left ventricle into the left atrium

Eventually leads to heart failure

Diagnosed with auscultation, radiographs, and cardiac ultrasound

Cavalier King Charles Spaniels predisposed to this condition

Dilated Cardiomyopathy

Inherited cardiac abnormality of certain large breed dogs

Exact mode unknown but sex—linked gene suspected- Increased incidence in males

Age of onset: middle age to older

Initially no obvious symptoms as the heart muscle dilates, but eventually results in heart failure

Arrhythmias can occur and lead to sudden collapse or death

Screening echocardiograms and Holter monitoring in pre-disposed breeds is recommended

Asymptomatic dogs should not be bred

Breeds predisposed to cardiomyopathy

Doberman Pinschers, Boxers, Great Danes, Irish Wolfhound, Saint Bernard

Collie eye anomaly

Disorder affecting the structures of the eye that can result in blindness

Chororetinal dysplasia – thinning of the choroid

Coloboma – defect in the optic disc

Retinal detachment

Staphyloma – thinning of the sclera

Autosomal recessive

Breeding stock should be evaluated at 5-6 weeks of age

Collie breeds affected by the collie eye anomaly

Collie

Border Collie

Shetland sheepdog

australian shepherd