The Australian Shepherd is a healthy breed compared to many, but the breed is not without hereditary problems.
Hereditary Skeletal Defects:
Hip dysplasia (HD) is found in all dog breeds and is basically a poor development of the hip joints. This disease is not caused by a single pair of genes, but instead is "polygenic." This means many gene pairs determine the condition and development of the hip joints. This disease is difficult to understand and to determine the genetic inheritance involved is equally complex. Additionally, there are environmental factors that can produce HD in dogs with no genetic predisposition for the disease.
The incidence of HD is reduced by careful selection of breeding stock. Dogs with HD exhibit symptoms from lameness varying from slight to very severe crippling. The lameness is usually noted between six months to a year of age, or in the dog's older years (clinical dysplasia). Some dogs never show lameness at all but, nonetheless, have the disease (radiographic dysplasia). These dogs run, jump, and play vigorously, but still carry the disease and can pass it along in its clinical form to their offspring.
HD can only be diagnosed through x-rays analyzed by a competent veterinarian. The Orthopedic Foundation for Animals (OFA) has served for many years as the diagnostic expert for this disease. X-rays submitted to the OFA are sent to three independent veterinary radiologists for a consensus opinion. OFA will not certify a dog free from HD until the animal is two years old. Dogs may be x-rayed for a preliminary evaluation earlier than two years, but because of the progressive nature of the disease, certification is only granted when x-rays taken after the second birthday are submitted.
The OFA has been compiling statistics on Australian Shepherds since January 1974. From that time through December 1999 a total of 14,915 Aussies have been evaluated. 6.4 percent were diagnosed as dysplastic. That may sound like a small percentage but it is about one out of every 15 dogs, or one puppy in every two litters. This statistic comes from dogs owned by conscientious breeders and owners who use the OFA, and not the general population, so this low percentage is probably inaccurate amongst the breed in general. More telling is the number of dogs OFA rated as having "excellent" hip joint conformation. From 1974 through 1980 the incidence of excellent-rated dogs was 10.5 percent, compared to 8.6 percent diagnosed dysplastic. In 1994 and 1995 the incidence of excellent-rated dogs rose to 15.8 percent while the incidence of dysplasia dropped to 5.1 percent.
Conscientious breeders will breed only OFA certified individuals and guarantee their pups to be free of HD. The hip status of littermates and half-siblings is also important. An animal diagnosed as having HD should never be bred. Dogs who are HD clear and OFA evaluated as fair, good, or excellent but who have close relatives with HD should be bred only with the understanding they may produce HD affected offspring.
For further information and applications to submit x-rays, write or call the OFA. A booklet is available for $3.00.
Orthopedic Foundation for Animals
2300 Nifong Blvd.
Columbia, MO 65201
(573) 442-0418
The "Penn Hip" method is another type of hip tests. It differs from OFA-style diagnosis in the position the dogs hip are placed in for x-ray and in the certification. Penn Hip does not offer a true certification; instead, hip laxity is measured. Hip laxity is a reference to how closely the head of the femur and the acetabulum of the dog's pelvis articulate. A rating from zero to one is assigned. The closer to zero, the better the dog's hips are judged to be.
Hereditary Eye Defects:
The Aussie can be affected by eye defects varying with degrees of heritability. A regular veterinarian cannot certify that a dog is free of eye diseases. A licensed veterinary ophthalmologist specializes in diseases of the eyes. When a dog is examined by a veterinary ophthalmologist and diagnosed free of diseases the owner will receive a form for the Canine Eye Research Foundation (CERF). The owner submits the form to CERF and receives a certification number declaring the dog free from eye defects.
Progressive Retinal Atrophy (PRA) is a very serious eye disease caused by a recessive gene. The end result is complete blindness. Affected dogs inherit the gene from both parents, so both parents must be carriers. All the puppies from an affected dog will either have the disease or be carriers. This disease may not show up until later in the dog's life. In suspected bloodlines, yearly eye exams by a veterinary ophthalmologist are crucial to preventing the on-going spread of the PRA.
Another eye defect in the Australian Shepherd is Collie Eye Anomaly (CEA) which is also hereditary and results in blindness. CEA is inherited from both parents and results in varying degrees of blindness over time. A DNA test to determine a dog's genetic makeup with regard to the CEA gene was developed by Dr. Alan Wilton in Australia. All Black Rock dogs are now screened for CEA as puppies. Dogs who are CEA carriers can be selectively bred to normal dogs without fear of producing puppies that will eventually go blind. Two carriers, however, can not be bred together since that combination holds a significant probability that at least one puppy in the resulting litter will be CEA affected. A DNA test for CEA is $250. Additional information can be found at: WWW.optigen.com
A defect that can be seen without special equipment is the Iris Coloboma, also called a subluxated pupil. It is especially noticeable in blue eyes and on excessively white trimmed dogs. The inheritance of this defect has not been identified although studies have shown it occuring in families. In these eyes the pupil appears to extend into the iris (colored part of the eye) often with a jagged edge. The ASCA breed standard calls for the pupil to be well defined and perfectly positioned. If the pupil is not perfectly round and in the center of the eye, the eye is not normal. Most dogs with Iris Coloboma appear to function normally, but since there is evidence of inheritance affected dogs should not be bred.
Juvenile cataracts are a serious defect and also result in blindness. This disease is distinct form of cataract, and not the result of old age sight degeneration or senile cataracts.
Other inherited diseases have been observed in the Australian Shepherd to some lesser degree than those discussed here.
