Health Screening: An Historical Perspective

by Mary Anne Zanetos

In recent years, considerable emphasis has been placed on the use of specific tests prior to breeding as a tool for improving health. Is this a new phenomenon?  What can we conclude about the adoption and use of health screening tests?  Are voluntary programs working?  Does the situation warrant legislation to force breeders to do the right thing?

Let’s examine current perception and practices regarding health testing as reported on the 2002 GDCA National Health Survey. This is believed to be the largest national single breed survey of its kind. The survey included 519 households and data on 1564 adult Great Danes and 4773 puppies. (See complete results at: http://www.gdca.org/health/healthsurvey.htm )

Not only did the survey show that Great Dane breeders are adopting certain screening tests as the norm, but large numbers report using screening test results, or lack thereof, in making breeding decisions. Nearly three-quarters of households (73%) perform one or more health screening tests on their own dogs. Of the 330 households performing screening tests requiring annual re-certification (CERF, OFA Thyroid, OFA Cardiac), 204 (62%) performed only initial testing while 126 households (38%) repeated these screening tests on one or more subsequent occasions. Although there is definitely room for improvement in re-certification of eye, thyroid and cardiac tests, a majority of breeders are utilizing these screenings.   

When asked whether they had eliminated any of their own dog(s) from breeding based on screening test results, 64% of households reported they had not, while 36% had. It is unclear, however, whether the 36% eliminated dogs based on: (a) an unsatisfactory test result; (b) inability to locate a tested dog’s result in a public database; or (c) absence of testing.

Use of Health Screening Tests for Breeding Stock

                  The table below provides details on the use of the various types of health screening tests.

Health Screening Attitudes and Practices

These data provide strong evidence that GDCA and affiliate club members and other opinion leaders are, in fact, adopting
health screening voluntarily. They don’t need the GDCA to mandate health screening by making these tests a condition for Futurity eligibility. To do so risks creating a backlash which might increase the number of dogs tested, yet in the long run, undermine the actual USE of screening results as a tool for improving bloodstock.

The Orthopedic Foundation for Animals (OFA) provides another source of data on health screening. OFA’s aggregate reports include all dogs whose results were submitted to OFA, regardless of whether the dog passed or the owner permitted the
results to be published.

Although some breeders do not use screening tests at all and others seem to be adopting them at a slow pace, time trend graphs of the number of screenings submitted to OFA,   by year, for Hips, Cardiac and Thyroid show substantial progress.
OFA data show conclusively that Great Dane breeders are performing these tests to a much greater degree than in the past, and that the rate of adoption of these tests has accelerated in recent years. 

      Figure 1 shows the number of Great Danes submitting OFA hip x-rays, by year, from 1974-2004.  

     Figure 2 shows the number of Great Danes submitting OFA cardiac tests, by year, from 1995-2004.  1995 is the initial

     year  for this program. 

             

    Figure 3 shows the number of Great Danes submitting OFA thyroid tests, by year, from 1995-2004.  1996 is the initial

    year for this program. 

  Data for the three tables above was provided by Mr. Eddie Dziuk, Orthopedic Foundation for Animals on 8/24/05. 

Is health screening really a new-age phenomenon or have top breeders traditionally looked for ways to acquire information on their breeding stock?

Let’s examine OFA’s records.  The table below shows kennel names of breeders performing OFA hip evaluations three decades ago. They are broken into two time periods: 1970-74, the earliest time for which published records are available,
and the second half of that decade, 1975-79, now 7-9 generations back in today’s pedigrees. The list below is not exhaustive, but includes breeders with recognizable kennel names and one or more Great Danes with OFA hip evaluations in the 1970’s.

It is obvious that many of the most prestigious and successful kennels are listed above. These breeders produced the bloodstock behind many of today’s top breeders.  Is this sheer coincidence? Or does the fact that these old-time breeders carefully evaluated their dogs long before health screening became “fashionable” (and marketable) contribute to the longevity and current success of those breeding from these lines? Perhaps early adoption of hip x-rays was indicative of a set of
attitudes and practices associated with critical and honest evaluation of breeding stock, rather than concern over hip joint conformation, per se. Did these highly successful breeders need the GDCA to tell them to use hip radiographs to evaluate invisible aspects of conformation? I think not. They did it simply because they cared about the future of the breed they entrusted to us.

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