Dr. Patricia J. Provost
Initial evaluation includes assessment of conformation and foot balance, palpation of the neck, back, and limbs including the joints, tendons and ligaments. The veterinarian will look for changes in symmetry, in range of joint motion, in tendon and ligament size, for abnormal swelling of joints and tendon sheaths, and painful reactions to the palpation and manipulation.
The horse will then be observed at the walk and trot while being led in a straight line and eventually at all gaits on a lunge line and/or under saddle. At the walk how the limb is carried and how each hoof is placed is assessed. Lame horses are best seen at the trot. At this gait differences in limb stride length and weight distribution among the four limbs can be determined.
Some conditions become more obvious when the animal is trotted in a circle, or on soft or hard footing. For these reasons the animal is usually lunged to both directions on both hard and soft footing. Manipulation of the joints will also be used to rule-out potential joint problems. Concentrated stress on an already sore joint will exacerbate lameness when the horse is then trotted out. Horses with normal joints will take only a few stiff steps and then again appear sound.
Discovery of Lameness
In most instances this is grounds for termination of the prepurchase evaluation. There are instances in which mild degrees of lameness are acceptable, however. Horses that have been successfully performing week after week at the same job and are being bought with the intention to continue to do the same job deserve further scrutiny providing the management of the horse will not change significantly. Mild to moderately lame horses that are being retired from high level competition are another example of horses that may require the benefit of the doubt and a closer look. And of course if the animal is being purchased for reproduction, certain types and degrees of lameness can be overlooked.
With the permission of the seller, anesthetic injections can be performed to localize the origin of the lameness if it is unclear. The expertise that your veterinarian has will help to guide you regarding which horses, despite their unsoundness, may prove to be serviceable for your intended use. Unbroken horses, young horses in early training, and horses that have had little exercise in the immediate past should not be lame. If for some reason (temperament, ability) the buyer is still interested in the lame horse, it might be wise to have the horse examined again at a later date to determine if the problems have resolved, remained static or become worse.
Radiographs (X-rays) are typically taken of the limbs only unless something else on physical examination warrants otherwise. Which limbs and what structures will be determined by the intended use of the animal, the current use of the animal (targeting injuries commonly seen with a particular sport or breed), and whether a specific question arose on the lameness or physical examinations. Radiographs can be taken of all limbs in their entirety but this is costly.
In most instances, radiographic examinations can be limited to the front feet, pasterns, fetlocks, hocks, and if the horse is young, the stifles. Radiographs of the knees are usually not warranted unless the horse has been a racehorse. Radiographs of the shoulder, elbow and hip are rarely necessary. The cost of the animal being purchased and whether or not the horse is being bought to resell will also influence the number and type of radiographs being taken. Bony abnormalities seen on the radiographs will be interpreted by the veterinarian in light of the intended use of the animal and his current level of soundness. The veterinarian may decide to send the radiographs to a radiologist or a surgeon for a second opinion. If the significance of a lesion is questionable, this second opinion is well worth the wait.
Endoscopy of the Upper Airway
The pharynx and larynx of a horse should be evaluated by endoscopy if the intended use requires speed and endurance, marked flexion of the head/neck, or if the horse produces a noise when exercised. Horses that have or have had a history of nasal discharge or cough should also be evaluated.
An ECG is performed when a horse has an irregular heart rhythm or heart rate and in high-level performance horses that are not performing to their capabilities.
A complete blood count can be used to rule out anemia and current infectious processes.
A serum chemistry can be used to rule-out some types of liver, kidney, intestinal and muscle problems.
Equine infectious anemia/Coggin's test is a requirement for all horses. Do not purchase a horse unless it has a current negative test.
Equine protozoal myeloencephalitis (EPM) titer a blood sample that can be submitted for a rapid screening test. A positive test does not mean that the horse has EPM but only that it has been exposed to the organism. However, a negative test means that the horse has an 88 percent chance that it does not have EPM. In horses showing clinical neurologic signs that have a positive blood EPM titer, a sample of the cerebral spinal fluid (CSF fluid) can be submitted to specific laboratories for further testing.
A fecal parasite exam should be performed on horses that have unknown backgrounds and deworming histories. Parasites can be responsible for loss of condition, poor hair coat, weight loss, anemia and some forms of colic.
A contagious equine metritis culture should be negative for horses that will be transported abroad.
A negative equine viral arteritis blood titer is required on horses being transported abroad.
Blood as well as urine samples may be collected to screen for behavior and performance altering drugs. Samples can be analyzed for anesthetics, anti-inflammatory drugs, antibiotics, tranquilizers and muscle relaxants. A drug screen that would rule out the presence of most performance altering drugs costs on average $150. This may be a worthwhile investment if the buyer does not know the horse or the seller that they are dealing with.
Ultrasound, Thermography and Nuclear Scintigraphy
These represent a group of diagnostics that can be pursued to determine the significance of musculoskeletal disorders. Your veterinarian may recommend them if he/she feels that they are necessary to prognosticate the serviceability of the horse.