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Craig T. Roberts, DVM
The pre-purchase exam is often a confusing and varied experience for the horse owner. Standards of examination, duration and required components (i.e. radiographs, etc.) vary wildly from veterinarian to veterinarian and within discipline. Similarly, the emphasis of certain points of the examination is subject to great shifts based upon intended use, current level of training, age and intent for resale that all influence how the exam is reviewed. My intent here is to discuss technological advances and how they influence information that can be gathered on a pre-purchase exam. However, before launching into detailed discussion on particular pieces of equipment, I feel it is important to take a brief look and overview on the exam itself.
The pre-purchase has a place in deciding on whether to purchase an animal, but it must be put into perspective. The unique requirements of buying any animal may be more overwhelmingly important in the decision making factor. For example, if you are wishing to purchase a Grand Prix level Dressage schoolmaster, your market may be limited. There are not many horses that get to this level of accomplishment, due to the level of training required. Similarly, if they are competing well, they are very valuable and would not be sold as a “schoolmaster” to teach up and coming riders. Thus, the concept of finding one that is problem free is unrealistic. However, finding one that has problems that can be managed may be more likely. Thus, the concept of the pre-purchase as an examination of discovery to understand this horse’s unique problems and how to best consider management is important.
This brings me to my first major point.
The most advanced piece of equipment that you bring to the pre-purchase is your open mind (and the abilities of the veterinarian you are employing). In short, the ability to gather and interpret information.
No amount of advanced equipment and imaging can outweigh the value of this process. An essential part, of this process is good communication between you and the veterinarian. You are “renting” their brain and experience level for this examination. It is important that both you and the veterinarian are good communicators. After all, the decision to purchase an animal is ultimately yours. We, as veterinarians, are simply advisors as to the physical abilities and disadvantages of a particular animal and how these problems may relate now and in the future to your intended use of this horse.
The most successful pre-purchase exams are those conducted by experienced veterinarians who are good communicators and can confidently educate their clients about abnormalities uncovered in the process of the exam.
Understanding What Type of Exam You May Require
Ancillary testing procedures must be interpreted relative to the physical exam findings and relevant history of the animal being examined.
Selecting the Veterinarian
The needs of horse owners and competitors today have placed great demands on the abilities of veterinarians to assist them in their goals for having healthy, reliable competition horses. As such, many horse owners seek out advice from numerous sources in order to get answers to all of their questions. Gone are the days when a single veterinarian can and did meet all of the needs for all horse owners. Specialists in practice have emerged, emphasizing particular areas of equine care. This has evolved into multiple veterinarians being involved with the same horses, not only at the same farm, but especially as these athletes travel for competition. Meeting the needs of these horses, in order to best care for their ongoing needs, is essential to maintaining a consistent and reliable athlete.
Therefore, it is not unusual to believe that finding a veterinarian that has the expertise and technical ability to perform a pre-purchase to the standards of your expectations can be difficult. Especially as most pre-purchase requests often come with some sense of urgency and time limitations.
Remember that “the best” are often not readily available at a moments notice. Thus, researching veterinarians long prior to evaluating an animal may be warranted to ensure an in-depth pre-purchase exam is even an option prior to reviewing a particular horse.
Having prior personal experience with a veterinarian is probably the best way to have confidence in their abilities as an advisor. If this cannot be accomplished, selecting one whom your own veterinarian personally knows is the next best choice. If neither can be accomplished, be certain that their references are such that their suitability to pre-purchase a horse is credible. For example, do they belong to known organizations such as the AAEP? Are they in general practice or do they emphasize a field of veterinary medicine that is more relevant to your intended use? For example, a reproduction veterinarian would be more suited for a pre-purchase of a mare to be used significantly in embryo transfer. A veterinarian for performance horse/lameness needs may be better for a sport horse, etc.
Specific Equipment Advantages & Disadvantages
Radiology: What Images Can and Cannot Tell You
As the years of more advanced radiographic analysis of horses has progressed, the relative variation of what is “within normal limits” has changed many times over. Perhaps the most important change in interpretation has been the revelation that any radiographic change MUST be evaluated in conjunction with its current physical presentation. No example could be more relevant than front foot films and the vastly changing interpretation of navicular bones. In my short 14-year practice career thus far, I have seen navicular disease become navicular syndrome (a compilation of at least 10 different separate diagnoses), and now the in vogue phrase Caudal Heel Syndrome to encompass even more potential twists. Inevitably, as MRI becomes even more commonplace over the next decade I envision at least double the number of individual, more specific diagnoses we will be able to identify.
With all of this advancement in such a short period of time, two concepts remain clear. First, we are still re-interpreting information and learning at an alarming rate. Second, the relative importance of any radiographic find that is considered NOT “within normal limits” must be put into perspective based upon clinical findings in order to place appropriate relevance on the finding.
The most unique advancement in radiology has been portable digital radiology. Units such as the Eklin Direct Radiology system, made from Canon components, have allowed practical real time exams with very high resolution. These films can be acquired approximately every 3 seconds, making multiple film exams and rapid interpretation practical. Similarly, their DICOM storage format makes them legal documents and unalterable unlike other digital storage formats (jpeg, bit map, etc).
Waiting for radiographs to be developed, retaking images that are not acceptable for a multitude of reasons (poor positioning, technique, artifacts, etc.) and communicating the results has now been streamlined to a very efficient process with these machines, at the time of examination. As the images are digital, they can also be sent via the Internet for independent review, when required, by other veterinarians anywhere in the world. In short, digital imaging has taken radiology, a valuable tool, to an entirely new level while also making its information more rapidly available to review.
In contrast, standard radiographs do not give the same quality of resolution as digital machines, and require an “artist” to achieve good images consistently. Fluoroscopy, although presenting immediate data, has unacceptably low quality images and poor permanent record capabilities. Fluoroscopy also exposes the veterinarian and assistants to unacceptably high levels of radiation during the exam by today’s standards.
Some owners can be concerned that digital images may show “too much” and leave their prospective horses open for “over interpretation” based upon the images presented. In fact, it is just the opposite. The images taken are simply very high quality every time. These quality images are not new to our industry, but until now, it was harder to achieve them consistently in the field. “Over interpretation” comes from speculating on what is not readily apparent, not from what is readily visible. On this basis, it has been my experience that more horses have been left open to speculation on their radiographic exams due to poor image quality and artifacts on their images than good quality images that are artifact free.
As a final note on radiographs, remember that radiographs only image bone. In a joint, for example, bone is only the platform for which the joint is built. There are many soft tissue structures that are components of the joint that are NOT imaged, even with digital radiographs. Similarly, bone does not remodel or change relative to an abnormality very quickly. Bone, under abnormal stresses, may take weeks or months to appear differently on radiographs. Thus, we need to relate the films to the clinical exam and our understanding of the soft tissue components of each imaged area to fully interpret the relevance of any abnormalities seen on radiographs.
Ultrasound machines are less used during pre-purchase exams for a variety of reasons. In the musculoskeletal system, tendons, ligaments, cartilage and joint fluid can all be examined. However, many of these structures can appear normal on an ultrasound exam, yet be of some concern clinically. It is also very easy to create artifacts using an ultrasound that may, in fact, look like an injury. If this were not bad enough, the relative time and exposure it takes to become a skilled examiner with an ultrasound is also more difficult and less available to the veterinarian than any other piece of diagnostic equipment currently in use. Therefore, for all of the above reasons, I believe it is less likely to be offered or used during a pre-purchase exam.
If it is used, it is most likely to quantify an abnormality identified during the physical exam. Random scanning of tendons & suspensories, etc. should be discouraged as the relative likelihood of gathering useful information in absence of a clinical abnormality is low.
As more veterinarians become more skilled in its use and more capable equipment becomes commonplace, the use of ultrasounds may increase in musculoskeletal imaging. Once again, however, the findings should be closely correlated with the physical exam findings to understand their relevance.
In contrast, the ultrasound is an invaluable tool in a reproductive exam. Its use and interpretation have reached great heights in the last decade. I would recommend an ultrasound exam of the reproductive tract of any mare where breeding is going to be of high importance in the purchase decision.
Standing endoscopy is still a poor evaluation technique of the dynamic upper airway stability in the horse. For this reason, treadmill evaluation was developed. However, even in this exercising environment the results can be questionable & frustrating as repeating abnormalities seen in the field cannot be identically reproduced. Factors such as rider weight, head position, etc. are all poorly controlled in a treadmill environment. The point is that if upper airway abnormalities are suspected due to the horse making noise during a lunge line exam, etc., then a standing upper airway endoscopy exam is warranted, but not conclusive. It may well rule out obvious concerns, but there are a host of other problems, which will not be readily detectable in this manner. Fortunately, these conditions are rare, but you need to be aware of them.
Gastroscopy is of limited availability as a 3-meter scope length is need for the exam. Evaluating horses for stomach ulcers are uncommon on a pre-purchase, but should be considered if any historical information or related clinical finding warrants this type of investigation. Fortunately, gastric ulcers are usually easily managed. However, they do represent an often under diagnosed and poorly managed category of performance horse healthcare.
Nuclear scintigraphy, or bone scans, can have a place in a pre-purchase exam. Nuclear scintigraphy represents an entirely different approach to imaging by visually displaying areas of inflammation. Unlike any other piece of imaging equipment, it measures the metabolism of the horse. In this way it more consistently compliments the physical exam findings than any other piece of equipment. As such it can be an invaluable resource in searching for subtle abnormalities in the horse with a known problem. Unfortunately, the equipment is not readily available, expensive to operate and requires a horse remain at a referral facility for at least 24 hours in most cases.
This equipment is best used as a screening procedure for horses that may have subtle problems that would affect their peak performance. Very high-level performers may well be candidates for such an involved screening procedure where their ability to remain an outstanding athlete is paramount to the purchase decision, but few others demand such scrutiny.
In order for the diagnostics to be of value, two important facts need to be understood. First, the intensity of work the horse is in dramatically affects the testing outcome. Speed of the performance horse workout is more relative than low or high level performance within a discipline. Second, the age of the horse can dramatically influence results as well. Better image quality is seen in younger horses having a more active metabolism. Thus, an 18-year-old Dressage horse with a chronic history of having bending problems to the right is not a good bone scan candidate in comparison to the 2-year-old racehorse with a very recent, severe lameness which occurred during training. Based upon this understanding, it can yield good information but, again, is usually more involved than most pre-purchases require.
Although MRI will undoubtedly revolutionize our diagnostic abilities for lameness, it is unlikely to be a common pre-purchase tool. This is primarily due to the fact standing application of MRI seems to be of little value for anything other than foot images at this time. MRI under general anesthesia will be required for higher limb exams. Along these lines, MRI is time consuming and should only be considered for a small area that requires such advanced imaging. The concept of a “whole horse” MRI is a long way off. Similarly, the exposure to MRI cases is limited, thus these facilities, although cutting edge, cannot offer significant practical information at this time. This will all change rapidly but again, not in a practical format for the pre-purchase evaluation.
Drug testing has advanced, but there are limitations to this practice. Personally, I pull and hold blood for a minimum of 30 days after a pre-purchase. This is performed so that if an animal’s demeanor, soundness or general health take a dramatic down turn, their blood can be evaluated for specific drugs in light of these new clinical findings.
In reality, this is often best done to protect the seller’s reputation. It has been my experience that there are rarely cases where drugs were administered to help misrepresent an animal. However, horses that do not work out for buyers may cause some buyers to become suspicious or even disparage the seller’s reputation in absence of any hard evidence. Having a sample on hand often helps to verify or refute these types of claims.
A neurologic evaluation definitely should be part of the clinical exam. If abnormalities are found, it is best to stop the exam at that time. If no abnormalities are found, further neurologic testing should be avoided. This is primarily due to the fact that neurologic problems are a definite concern, but the diagnostic testing for definitively proving what disease process exists is not as clear cut. There is a more complicated explanation for all of this. However, for the purposes of this discussion we will limit to these statements. If further testing is requested, it should be on the seller’s behalf, not the buyers.
Other Bloodwork: Complete Blood Counts, Serum Chemistries, Thyroid Testing
In the absence of any clinical abnormality, routine bloodwork is unlikely to uncover a problem. Similarly, bloodwork done for Thyroid testing or other unusual abnormalities is often dubious at best. If a clinical abnormality is found, consider some sort of testing. Similarly, understand the relative value and credibility of some types of testing before spending money on them.
Communication to Other Veterinarians
It should be considered routine for the pre-purchasing veterinarian, if not your own, to contact your veterinarian and discuss the abnormalities and results first hand. Allowing access of your regular veterinarian to all testing information, radiographs, etc., should also be considered standard procedure.
In the end, a complete understanding of the abnormalities noted and their significance to your decision to purchase is ultimately guided by good communication and prioritizing these defects into the overall decision making process.
Finding the “perfect” horse may be less of a search for the ideal animal and more the realization that the veterinarian chosen may be less confident in identifying concerns or communicating information about the defects found effectively.
Regarding additional diagnostic testing, adding procedures does not mean the exam is necessarily any more thorough. With a lack of clinical evidence to support the need for these procedures, further testing is likely a “low yield” procedure for retrieving more useful information in many cases.
Perhaps my overall review has left you with a more negative and confused slant on the actual value of a pre-purchase. This was not my intention. I believe there is a lot of information to be gained in most cases. I merely wish to better educate you on the limitations of what can be done, and more importantly, shift the relative emphasis away from the new technologies for evaluation and back to the clinical exam, which should be the foundation for all decisions regarding purchase. No diagnostic procedure by itself can reveal significant information on its own merit. Rather, the entire exam and these procedures must be looked at in concert to draw conclusions. Similarly, there can be abnormalities not found even with the best of technologies applied. When the exam is completed, it comes down to intelligent thinking, good communication and experience that will ultimately serve to help make the best decision for your situation.