Eyes are the most valuable resources you have to evaluate hoof soundness. Training your eyes to “feel” as you assess the hoof and limbs is an invaluable skill.
Fingers must betrained to sense changes in tissue firmness and flexibility as you palpate the muscles, joints, limbs and feet.
Hands must be trained to sense changes in joint range of motion and sensitivity to manipulation.
Plastic wedges allow you to position the foot as it would be after trimming or shoeing. This allows you to see the effect of your work before you create it.
Hoof testers are effective and useful tools. “The most efficient, productive method to differentiate the site of pain in the foot is the very careful application of hoof testers. The instrument must be designed to detect all sites of pain and the operator must be skilled in the instrument’s use... A diagnosis of navicular disease is made when the site of pain is isolated to the middle third of the frog,” according to G. Marvin Beeman, DVM, of Littleton, Colo.
Farriers frequently find the need to use hoof testers to determine what area in the horse’s foot might be painful. Often the farrier’s examination is made prior to the veterinarian’s and may be useful to identify conditions in the foot that may need veterinary attention.
Every farrier and veterinarian should have a good hoof tester and know how to use it. Some strength is required to operate any hoof tester properly. Hoof testers should have some spring in them and fit the foot being tested. Consis-tency and position of force application is most important.
Farriers must be careful in stating their findings and should not place themselves in the position of diagnosing and prescribing foot ailments. They should state they find that a horse is sensitive to pressure in a certain area of the foot and a specific shoe may be of benefit in relieving pressure and pain in that area. Veterinarians should recognize the value of mechanical support to medical therapy.
The drawings in this article show the proper position of the jaws of the hoof tester in determining soreness in various areas (Figures 1 and 2). Always compare the sore foot to a sound one. Some horses are very sensitive to pressure while others are not.
Degree Of Lameness
Lameness can be graded using a system used by Dr. Nils Obel and adapted by the AAEP (American Association of Equine Practitioners). Here are five grades or degrees of lameness:
Grade 1: Difficult to observe; not consistently apparent regardless of circumstances (such as weight carrying, circling, inclines, hard surfaces, etc.).
Grade 2: Difficult to observe at a walk or trot in a straight line; consistently apparent under certain circumstances (such as weight carrying, circling, inclines, hard surfaces, etc.).
Grade 3: Consistently observable at a trot under all circumstances.
Grade 4: Obvious lameness; marked nodding, hitching or shortened stride.
Grade 5: Minimal weight bearing in motion and/or at rest; inability to move.
1 Radiography (X-ray) is usually necessary to confirm a physical diagnosis of the lower limb. A radiograph is a picture of the number of X-rays passing through the animal’s body and the parts that are the densest (bone and teeth) absorb the most X-rays. Less dense parts (muscle, fluids, fat, etc.) absorb a lesser amount and air absorbs the least amount. The variation in absorption records images of body parts on radiographs (Figures 3, 4, 5).
2 Local and regional anesthesia, including bursa, joint and nerve blocks, may be necessary to separate the differential diagnosis of an obscure lameness case into a definitive diagnosis. Effective use of nerve blocks in the diagnosis of lameness is only possible by thorough study of nerve distribution and variations.
3 A rectal exam is occasionally used to diagnose obscure hind leg lameness due to pelvic fracture(s).
4 Laboratory analysis of blood, urine, feces, spinal or synovial fluid as well as tissues is also available to veterinarians to produce a definitive diagnosis for any given problem.
5 A videotape recording with slow motion and stop action capability is most useful when the camera is at ground level. A zoom feature can fill the screen with only the lower leg and foot contacting the ground. Looking at the whole horse is also important to see body posture and head carriage.
6 An ultrasound can be used to measure bone density and strength. It may also be used to check tendon and ligament condition. This may be especially valuable in young horses and horses in training.
7 Arthroscope examination (and surgery) allows the veterinarian to look into the joint of the horse to find pathology that radiographs fail to show or to evaluate joints before surgery is performed. Arthroscopy has been used on limb joints, most commonly the carpal, fetlock, stifle and tarsal joints, to find pathology that could not be seen on radiographs.
8 Xerography allows the veterinarian to examine soft tissue injuries. The picture is light blue and is like a positive of a radiograph negative.
9 Thermography (heat sensing) is a means of detecting and recording infrared radiation emitted from an object directly related to its temperature. Its principal use in veterinary medicine has been the detection of soring in show horses and tendinitis in race horses.
10 Gait analysis using force sensors, treadmills, etc., can be used to detect variations in pressure applied to the ground by lame limbs. Changes in pressure on the various parts of the bottom of the hoof can also be detected. Sensors can be mounted on the shoe or a force plate.
11 Nuclear scintigraphy uses a radiographic tracer to assess blood flow and bone cell growth. A tracer, usually technetium 99m-labeled methylene diphosphonate is injected and a “dynamic” image is projected through a rapid sequence of images by an expensive gamma camera as the tracer passes through the circulatory system of the horse. This allows examiners to detect any changes in blood flow to an area in question which may have been damaged. After several hours, alterations in bone metabolism can be detected as well. It is mostly used in the diagnosis of equine joint disorders but can be used to detect damage in internal organs (Figures 6, 7).
12 Magnetic resonance imaging (MRI) combines the sensitivity of scintigraphy with the benefits of viewing cross sectional anatomy (multiplanar imaging) and the ability to detect differences in contrast in the various examined soft tissues. It’s been used to determine severity of tendon and ligament damage as well as detecting brain damage in horses.
Develop the basic skill tools of observation, palpation and manipulation. Obtain helpful diagnostic tools that fit in with your level of farriery practice.
Refer cases that are obscure to equine veterinarians when clients have the desire and means to explore more costly diagnostic procedures. Don’t overlook the obvious and consult with the client throughout the process. Present the possibilities and let the client choose and compare the cost to value.
Doug Butler of LaPorte, Colo., is an American Farrier’s Association Certified Journeyman Farrier and a Fellow of the Worshipful Company of Farriers. He is also the owner of Butler Publishing and Farrier Services (1-800-728-3826). He holds a doctorate in veterinary anatomy and equine nutrition and is the author of the widely used textbook, “The Principles of Horseshoeing II.”