What Is Testing?
The term "testing" is bandied
about and can be used to cover any number of procedures. For this article,
and the way I use the term, it means using SIMPLE, NON-INVASIVE, READILY
AVAILABLE, INEXPENSIVE and PAINLESS screening tests to diagnose some of the
inherited health problems in Cavaliers, without having to wait until the dog
actually shows overt symptoms. The reason for testing should be to STOP
breeding Cavaliers that test positive for one or more of these problems.
WHAT
NEEDS TO BE TESTED FOR IN CAVALERS?
There are several inherited, non-congenital (i.e.
not present at birth), developmental health problems to which Cavaliers are
prone. These include heart problems, eye problems, patellar luxation
(slipping kneecaps), hip dysplasia, back problems, premature and partial
deafness, epilepsy (all forms, one of which is "Fly Catchers Syndrom"
they look like they're snapping at or trying to catch a fly that isn't there)
and autoimmune disease (things such as skin allergies, digestive problems, dry
eye, infertility/breeding problems, muscle and/or nerve disorders, thyroid
and/or blood platelet problems, etc.). The first four conditions are those
for which you can test.
It is possible that some of these things may be caused by other than genetic factors but unless there is absolute proof that they are caused solely by environmental influences, it is for the welfare of the BREED to assume they are inherited. Developmental genetic health problems take, on average, 2 to 6 years to show overt symptoms or to be diagnosable with a screening test. This is an average, they could show up later or earlier.
It is true that sometimes, with polygenic problems (controlled by more than 1 gene), environmental "triggers" cause the problem to become apparent. But these "triggers" cannot cause the problems if the dog does not carry the genes to produce them! It is the reason that some people who smoke cigarettes for years do not get lung cancer. They simply don't have the genetic make-up to develop it.
Genetic traits of all kinds do not necessarily show up in every generation, but can be passed "silently" through one or more generations before becoming apparent as a symptom or showing up via a screening test. You can see why continued testing, even if nothing "bad" has shown up for a while, is imperative. It is possible for tested-clear parents to produce offspring with one or more problems and likewise, parents with problems may produce offspring without them. On top of that, parents with only a mild, perhaps asymptomatic form of a problem can pass it on more severely to their offspring, BUT, odds are that affected parents will produce a higher percentage of affected offspring than unaffected parents. You must be ever so vigilant. While testing is no guarantee of good health, it is the best that responsible breeders can do at this point in time to improve the health of Cavaliers.
Be aware that if you linebreed or inbreed (i.e. breeding relatives together), as opposed to outcrossing (i.e. breeding unrelated dogs together), you increase the risk of producing genetic health problems even when the parents have been tested clear, because you are more apt to double up on the genes that cause the problems. Relatives have more genetic similarites with each other than with non-relatives.
WHAT
ARE THE SCREENING TESTS?
For heart problems in Cavaliers (the main one being
Mitral Valve Disease or MVD), their hearts are listened to annually with a
stethoscope by a veterinary cardiologist. The first indication that the
valve is starting to fail will be a murmur (a sound heard with a stethoscope).
For eye problems, Cavaliers have their eyes examined annually by a veterinary ophthalmologist.
For patellar luxation a regular veterinarian manipulates the Cavalier's patellas (kneecaps) with his hands following the guidelines set up by the Orthopedic Foundation for Animals (OFA). This is done annually.
For hip dysplasia a Cavalier has it's hips x-rayed by a regular veterinarian and these x-rays are sent to the OFA for diagnosis by board certified veterinary radiologists. If x-rayed under the age of 2 years, a preliminary report will be returned by the OFA. This procedure is then repeated at 2 years or older for final clearance (or failure). At that time a permanent OFA certificate with an OFA registry number on it is issued for any dog that is free of hip dysplasia and no further radiographs need to be taken. Only then will that dog be entered in the OFA's dysplasia control database, a very important step.
Don't ever forget that even when a Cavalier is tested clear for these 4 conditions, it should also be symptomless for the other, untestable, serious problems such as, but not limited to, back, deafness, epilepsy and autoimmune problems.
WHY
SHOULD THESE PARTICULAR TESTS BE DONE?
The tests I've listed are the ones that are most widely
accepted by the veterinary profession and concerned breeders. By having
everyone do the same tests in the same way you avoid comparing apples to
oranges. It is NOT up to each breeder to decide what level of testing, if
any, they choose to do. This should be left to the veterinary researchers.
They see large numbers of dogs, have the expertise to interpret their findings
and are not emotionally or financially involved with specific dogs.
Breeders do not turn to veterinarians to evaluate the conformation of their
dogs. Likewise breeders should defer to the preponderance of veterinary
research for decisions about the health of their dogs. No testing is
perfect but we should strive to have a single reasonable standard against which
to judge the health of all Cavaliers.
***
BREEDING DOGS is not a right, it is a privilege. As such there are responsibilities incumbent upon anyone who undertakes to do so. These responsibilities include the stewardship of the breed. What benefits the dogs must take precedence over what benefits the people.
This article is the express opinion of a
breeder of Cavalier King Charles Spaniels, Pat Winters, based on her years of
experience and factual information gleaned from many published articles and
books. Please note that breeding only dogs that have been cleared of hip
dysplasia, MVD, patellar luxation and serious eye problems and who are
symptomless for back problems, epilepsy, deafness and autoimmune disorders does
NOT guarantee your puppy will be healthy, BUT it has been firmly established by
genetic experts that continuously breeding generation after generation of dogs
that have been cleared and are symptomless for these defects WILL decrease both
the frequency and the severity of these diseases.
Also relevant to this page is a wonderful
article on the OFA site. Please visit this one as well.