Before You Breed:
Recommended Health Screenings for Breeding Stock
No breeder wants to breeds unhealthy dogs or dogs that have the potential to produce unhealthy offspring. But just like humans, dogs can develop genetic disease. Because purebreds have smaller gene pools, the overall number of genetic diseases they develop tends to be smaller than in random-bred dogs. But because of that same limited gene pool, genetic disease can all too quickly become entrenched in the breed. It is up to breeders to make and keep the breed healthy by performing health screenings on all their breeding stock.
The following health screenings are the CHIC (Canine Health Information Center) requirements for Rhodesian Ridgebacks:
HIPS and ELBOWS: Certification is required only once in the dog’s lifetime. The dog can be certified as free of dysplasia by a radiologist from any of the following independent registries:
(1) OFA - No earlier than 2 years of age for permanent evaluations. Preliminary evaluations can be done as early as 4 months, but must be repeated at 2 years of age or older for a permanent OFA number.
(2) Penn-HIP - Can be performed as early as 16 weeks.
(3) OVC (Ontario Veterinary College Hip and/or Elbow Certification) email@example.com or 519-767-5022.
To see the table of International Hip Score Comparisons, please click here.
EYE Evaluation: CERF (Canine Eye Registry Foundation) examination certifying the dog is free of genetic eye disease. Perform annually on dogs in breeding programs until age 9, at which time genetic eye disease is unlikely to manifest. Eye evaluations can start at any age.
THYROID Evaluation: For OFA certification, a dog must be 1 year of age and the following tests are required to ensure the dog does not have lymphocytic thyroiditis. For OFA clearance, these tests must be performed by an OFA approved lab:
An endocrinologist, pathologist and/or veterinarian with an expertise in canine thyroiditis may also have the following laboratory studies done:
While a dog is actively involved in a breeding program, it is recommended thyroid evaluations be done annually until age 6 and then again at age 8. If a dog is not involved in an active breeding program, but there is a possibility that he or she might be bred at a later age, it is recommended that a thyroid evaluation be done at least once at 2 years of age and again at 4 years of age in order to have a baseline for the TgAA, and then again before being used in a breeding program if it is more than a year after the last thyroid evaluation.
The most important value in the OFA panel when determining whether a dog has heritable thyroid disease (lymphocytic thyroiditis, also called autoimmune thyroiditis) -- as opposed to unexplained thyroid dysfunction (idiopathic hypothyroidism) -- is the Thyroglobulin Autoantibody (TgAA).
In lymphocytic thyroiditis, these autoantibodies slowly attack the thyroid gland until it is destroyed. This is what is inherited: the tendency of the immune system to trigger these abnormally elevated TgAA levels to attack the body itself. Later in life, after the thyroid is completely gone, the TgAA will return to a normal level because the autoantibodies have “done their job” and destroyed their target, the thyroid gland.
If a dog has a thyroid evaluation and there are abnormal values indicating reduced thyroid function (high TSH and/or low T-4) but the TgAA is normal/negative, that would indicate hypothyroidism from a cause other than lymphocytic thyroiditis. BUT if this thyroid evaluation was done for the FIRST time late in life, there is no way to be sure that the thyroid was not destroyed in an earlier TgAA surge. Instead, in this case, it is more likely the dog is in end-stage lymphocytic thyroiditis.
While a dog can become TgAA positive within a year, once that occurs, TYPICALLY the dog continues to have high/positive TgAA values for quite a while, USUALLY for several years. As a result, it is LIKELY that with normal TgAA values at age 2 and 4, repeat testing at a later age would identify lymphocytic thyroiditis. Obviously, there are no guarantees, but at least there would be more data available for a breeder to make a conscientious breeding decision. A consultation with a veterinarian with a detailed understanding of thyroid pathology is recommended.
Bottom line: In the vast majority of cases, idiopathic hypothyroidism is really end-stage lymphocytic thyroiditis, which is a heritable autoimmune disease.
Cardiac Evaluation: For OFA certification, the dog must be 1 year of age. This screening is required only once in a lifetime. The cardiac examination is done to identify murmurs that might indicate heart disease. This evaluation is recommended if there is a family history of cardiac disease. If a dog is murmur free, the dog is eligible for an OFA Cardiac certificate.
If a murmur is found, further evaluation is needed by a veterinary cardiologist to ascertain the cause of the murmur. Often dogs, just like humans, have innocent murmurs that are not pathologic. Cardiac certification can be given if the dog is cleared after echocardiographic examination, which includes Doppler echocardiography done by a veterinary cardiologist.
Hearing evaluation: Brain Auditory Evoked Response, or BAER, test is done to evaluate hearing. There is an incidence of deafness in Rhodesian Ridgebacks, but it is not common. This evaluation is recommended if there is a family history of deafness. This is a once-in-a-lifetime test that the Rhodesian Ridgeback should not receive until the dog is 1 year of age. This is in direct conflict with the OFA congenital BAER testing protocol, which requires the pup be 35 days old. Recent research has shown that in deafness in the Rhodesian Ridgebacks can develop any time in the first year of life, and Ridgebacks BAER-tested as hearing at 35 days may very well develop deafness later in puppyhood.