This is a brief summary of several health problems common to PWDs and the health tests that exist to check for them.
Canine hip dysplasia is a very common degenerative joint disease seen in dogs, especially the larger breeds. Hip dysplasia is caused by looseness in the hip joint. The looseness creates abnormal wear and erosion of the joint and results in the development of arthritis. The dysplastic dog may have no pain or problems, or it may experience mild to severe discomfort.
Hip dysplasia is a polygenic trait. That is, more than one gene controls the inheritance. Environmental factors such as early spay/neuter, diet, or inappropriate exercise during bone development, can also be involved.
Treatment of hip dysplasia can be conservative or surgical. Conservative therapy consists of weight control, moderate exercise, and analgesics (pain relief medication). Another medical approach to the treatment of degenerative arthritis secondary to hip dysplasia involves the use of products called polysulfated glycosaminoglycans or PSGAGs.
Tests for Hip Dysplasia
The method used by the Orthopedic Foundation for Animals (OFA) has been the standard for many years. Radiographs are taken by a local veterinarian under specific guidelines and are then submitted to the OFA for evaluation of hip dysplasia and certification of hip status. The X-ray can be performed at any age over 4 months, but the OFA will give a "Preliminary" rating to dogs under the age of two and the dog should be re-evaluated at 24 months (or older). The radiographs are reviewed by three radiologists and a consensus score is assigned based on the dog's hip conformation relative to other individuals of the same breed and age. Hips are scored as normal (excellent, good, fair), borderline dysplastic, or dysplastic (mild, moderate, severe). Dogs with hips scored as normal will receive an OFA number.
OFA has an OPEN registry of the dogs that have passed. If you want to look up a specific dog, you can go to http://www.offa.org/, enter the dog's name or registration #, and click the search arrow to find that dog's results if s/he (1) was evaluated by OFA and (2) passed.
Another, more recently developed, test is the University of Pennsylvania Hip Improvement Program (PennHIP) test. Three radiographs are taken to measure the hip joint laxity. A score between 0-1 is assigned, with 0 being very tight hips and 1 being very loose. The test is not pass-fail, and the score is based on a measurement of the hip's distraction index (DI).
PennHIP has a closed registry, so the only way to get PennHip information is from the owner of the dog.
Progressive Retinal Atrophy (PRA) is a genetically transmitted eye disease found in about 80 breeds of dogs. It is caused by a recessive mutated gene. PRA causes the blood vessels of the retina to atrophy, or waste away.
Progressive Rod-Cone Degeneration (prcd) is currently the only form of PRA that can be tested.
Although prcd-PRA is inherited, it can be avoided in future generations by testing dogs before breeding. Identification of dogs that do not carry disease genes is the key. These "clear" dogs can be bred to any mate - even to a prcd-affected dog.
Test for prcd-PRA
A service company called OptiGen offers a DNA-based test for prcd-PRA. Tested dogs will receive one of three ratings:
- Normal/Clear (Pattern A *) - clear of the PRA gene
- Carrier (Pattern B *) - will not be affected but carries the gene
- Affected (Pattern C *) - may be affected
Other Eye Problems
Infrequently reported eye problems include cataracts, entropian eyelids, keratoconjunctivitis and PPM (persistent pupillary membrane).
These and other eye problems can be identified by an eye exam performed by a U.S. board-certified Veterinary Ophthalmologist. In the past the exam was referred to as a CERF exam because the test result was registered with the Canine Eye Registration Foundation (CERF). Effective November 1, 2012, the American College of Veterinary Ophthalmologists (ACVO) discontinued involvement with CERF, and transitioned affiliation to the Orthopedic Foundation for Animals (OFA). The new registry is called the OFA Eye Certification Registry or ECR, so the eye exam is now referred to as an ECR exam .
There are no differences in the eye examination protocol, and the resulting interpretation and classifications are the same. The eye certifications are valid for one year from the time of the exam.
A veterinary ophthalmologist can be found near you at the American College of Veterinary Ophthalmologists website: www.acvo.org .
Breeding animals should have a yearly eye exam and non-breeding dogs should have an exam at least every 3 years.
GM-1 Storage Disease
GM-1 Storage disease is a rare disease which is only found in humans and the Portuguese Water Dog. It is a recessive, genetic disorder that can be produced only when two carriers are bred together. The disorder is caused by a lack of an enzyme that allows the build up of toxic substances in the nerve cells.
Test for GM-1
Prior to July 21, 2013, the test to determine the genetic status of a dog for GM-1 was performed by the Neurogenetics Program of New York University. Since that date, the test has been done by OptiGen.
The test is performed on puppies as young as one week of age and on older dogs at any time. The test results rate the dogs as Non-Carriers or Carriers of the GM-1 gene. Carrier and Non-Carrier PWDs are all equally healthy dogs.
GM-1 is caused by a recessive mutated gene. See this chart for an explanation of the percentages of normal, carrier, and affected puppies produced by different combinations of breeding pairs.
Juvenile Dilated Cardiomyopathy (JDCM)
This is an inherited heart disease caused by a recessive mutated gene.
Test for JDCM
A DNA linked marker test for JDCM became available October 22, 2007, performed by the University of Pennsylvania. In 2010, the University of Pennsylvania announced the availability of a DNA gene-based mutation test for JDCM. All dogs previously tested via the linked marker test were run through the new gene-based test and the results were the same. All "1-1 probable normal" dogs are Normal, and all "1-2 probable carrier" dogs are Carriers.
Improper Coat (IC)
This trait is not a health issue, but rather affects appearance. Improper Coat (IC) is a recessive inherited trait that causes a significant change in the PWD coat. PWDs with improper coat do not have the coat described in the breed standard. Instead, their hair is usually straighter and shorter, laying close to the skin. Improperly coated dogs may also have some undercoat and are prone to shed.
Test for IC
In 2010 it became possible to DNA test dogs to find out their genotype for Improper Coat. This test is currently performed by OptiGen. OptiGen IC info...
Disorders caused by a Recessive Mutated Gene - Expected Litter Results for Breeding CombinationsReference this chart for an explanation of the percentages of normal, carrier, and affected puppies produced by breeding pairs with various combinations of health test results.
|Dog 1 Genotype||Dog 2 Genotype|
|Normal||All puppies = Normal||1/2 = Normal|
1/2 = Carriers
|All = Carriers|
|Carrier||1/2 = Normal|
1/2 = Carriers
|1/4 = Normal|
1/2 = Carriers
1/4 = Affected
|1/2 = Carrier|
1/2 = Affected
|Affected||All = Carrier||1/2 = Carriers|
1/2 = Affected
|All = Affected|
- "Normal" dog bred to a "Normal", "Carrier", or "Affected" dog
- "Carrier" dog bred to a "Normal" dog
- "Affected" dog bred to a "Normal" dog
It is perfectly ok to breed a dog that carries a recessive disease gene as long as it is bred to a non-carrier. The resulting puppies will not suffer from the disease (though some of them will be carriers of the mutated gene).
That said, the big picture must be taken into account. A breeding pair should not have incompatible test results for any disorder for which there is a DNA test available.