As the name suggests, purchase exams are an exploratory process designed to evaluate the physical condition of a horse before you commit to a purchase. It is performed by a veterinarian and is, before anything else, a comprehensive physical examination.

When is it appropriate to use ancillary, or supportive, tests for any particular examination? If you are investing more in a horse, should you request "extra" tests? If you have doubt about a certain condition, should you explore possible future problems? What tests are necessary before you decide to buy?

The decision to proceed beyond the physical examination is based upon and limited by several factors. These include: The intended use of the horse; the recommendation and capabilities of the examining veterinarian; the needs, wishes, and financial resources of the buyer; the approval of the seller; constraints such as weather, facility, qualified assistance, and the behavior of the horse.

Needless to say, these factors vary from case to case. In many instances, no supportive diagnostics are needed. However, you should know what your options are, especially when you have concern for a certain condition, and these should be discussed with the examining veterinarian.

X rays commonly are included in purchase examinations, especially of performance horses. Their primary use is in high-probability areas, or so-called "seeds of disease." Confusion occurs when a clinically sound horse, or one which shows no outward signs of problems, is said to have questionable findings on his or her radiographs. In such cases, have the examining veterinarian explain, not predict, these findings to you. You can determine whether or not these implications should influence your purchase.

Nuclear Scintigraphy
While used infrequently in purchase examinations, nuclear scintigraphy, or "bone-scanning," provides an image on film of inflammatory "hot spots." Because it can be expensive and is not accessible to most practitioners, this type of imaging should be used as an adjunct to help determine the significance of certain radiographic findings.

Examination of the upper airway with an endoscope is frequently part of the purchase exam in horses producing suspect respiratory sounds and those whose intended use demands maximum respiratory function, such as racing Thoroughbreds. Your veterinarian will use a flexible, fiberoptic instrument to allow for a safe, rapid, and effective evaluation of the nasal passage and throat for both actual and potential respiratory problems.

Both quick and non-invasive, an ultrasound examination of suspect soft-tissue structures, such as tendons, can help determine the significance of apparent abnormalities. If you are planning to purchase a mare for breeding purposes, an ultrasound or transrectal palpation may also help determine the horse's capabilities of reproducing.

Immunologic Testing
This test measures the presence of antibodies in the horse's blood to specific diseases. The most frequently performed immunoassay in a purchase exam is the Coggins test, considered diagnostic for equine infectious anemia (EIA). For many other infectious diseases, however, immunoassays do not provide a definitive diagnosis in clinically normal horses. For this reason, the relevance of any immunoassay and the implications of the possible results should be discussed with the examining veterinarian. For most interstate and international transport and certain insurance coverage, specific immunoassays are required.

Drug Testing
You can test for the presence of pain-killing or mood-affecting medications during the time of the examination. While the technology of drug testing has become very sophisticated in recent years, significant limitations to detecting all drugs exist. Before including this in your exam, discuss it with your veterinarian.

Genetic Testing
Though somewhat expensive, this is sometimes indicated for certain purchase examinations. For example, the identification of horses carrying the gene for HYPP (hyperkalemic periodic paralysis) is important to many buyers.

Other testing is included in the purchase examination to assist in appraising the horse's overall health status. Depending on the intended use for the horse and possible suspicions you may have when evaluating the horse, you can have a variety of tests performed at the discretion of the examining veterinarian. Examples of such tests include: Complete blood count, fecal parasite egg count, serum chemistry profile, tissue biopsies (skin lesions or cellular status of a broodmare's uterus), electrocardiography (to detect cardiac arrhythmia), or electromyography (absence of normal muscle function, such as in the tail).

There are other "extras" that can be included in the purchase examination. As technology continues to grow at a rapid pace, no doubt many new examination techniques will emerge. It is up to you as a buyer to consult with the examining veterinarian to determine which ancillary tests are best for you on a case-by-case basis. Consider factors such as expense and turn-around time. Most importantly, consider these "extras" as supplemental to the fundamental physical examination, not a replacement for it.

About the Author

Harry Werner, VMD

Harry W. Werner, VMD, is a Connecticut equine practitioner with special interests in lameness, purchase examinations, wellness care, and owner education. Dedicated staff, continuing education and technological advances enable his practice to offer high-quality patient care and client service in a smaller, general equine practice environment. A committed AAEP member since 1979, Dr. Werner is has served as AAEP Vice President and, in 2009, as AAEP President, and he is a past president of the Connecticut Veterinary Medical Association.

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