Page 338 - (DK) The Dog Encyclopedia

CARE AND TRAINING | INHERITED DISORDERS

Inherited disorders

An inherited disorder is one that is passed on from one generation to the next.
Such disorders appear more often in pedigree dogs and may be breed-specific.
Some common examples are described below.

THE RISK OF DISEASE AORTIC STENOSIS Another inherited blood clotting disorder
Smaller gene pools and widespread inbreeding A congenital defect, present from birth, is Von Willebrand’s disease, which affects
in the past have made pedigree dogs more aortic stenosis is a narrowing of the aortic many breeds of either sex. DNA tests are
likely than crossbreeds to be affected by valve in the heart. There may be no signs, available for some breeds.
inherited disorders. However, although the disorder being detected as a murmur
crossbred dogs may be at reduced risk, when a vet listens to the heart with a EYE PROBLEMS
they still have a chance of inheriting stethoscope at a puppy check. It may be Dogs can be affected by several inherited eye
disease-causing genes from either parent. investigated further (with radiography, conditions, including some that are easily
ultrasound, and ECG) or simply monitored, visible, such as entropion (right), and others
HIP AND ELBOW DYSPLASIA as only a few dogs can be treated surgically. that need internal examination of the eye
These two conditions occur mainly in Some dogs with aortic stenosis go on to using specialized equipment. An eye disease
medium-sized and large breeds. In dysplasia, develop congestive heart failure. that can occur in any breed and also in
structural defects either of the hip or the crossbred dogs is progressive retinal atrophy
elbow cause a joint to become unstable, BLOOD CLOTTING DISORDERS (PRA). In this disorder, there is degeneration
resulting in pain and lameness. Diagnosis is The most common inherited clotting of the retina—the layer of light-sensitive cells
based on the dog’s history, together with disorder (in both dogs and humans) is at the back of the eye—leading to loss of
joint manipulation and radiography. hemophilia, in which lack of an essential vision. An owner may become aware of PRA
Treatment may consist of pain relief, factor for blood clotting results in recurrent when a dog begins to display sight problems,
reducing exercise, and maintaining ideal bleeding. The faulty gene responsible is which at first may be only at night. PRA is
body weight. Various surgical options are passed on by affected males to their female diagnosed from examining the retina with an
also available, including total hip replacement offspring, who remain unaffected ophthalmoscope, and the vet may recommend
for hip dysplasia. After a set age (generally themselves but can be carriers of the gene. more specialized investigations. There is no
more than one year old), susceptible breeds Hemophilia can occur in both pedigree and treatment and loss of vision is permanent.
can be screened for hip and elbow dysplasia. crossbred dogs. DNA screening is available for some breeds.

Radiograph of hip
Screening is advisable before using a dog for breeding
when hip dysplasia is known to occur in the breed. This
involves submitting a radiograph of the dog’s hips for
scoring (see box below).

HIP SCORING

The hips are radiographed with the dog lying
on his back, hind legs extended straight out.
For best results, the dog may be given sedation
to keep him in the right position. Each hip joint
is given a score for six factors, covering
conditions from normal to severe. This gives
a maximum score of 53 for each hip—the
ideal is for as low a score as possible. Adding
the two scores together gives a total. When
selections are being made for breeding
purposes, it is best to choose a dog whose
total score is less than the current average
for that breed.

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