Lameness Exams
Lameness is a generalized term for an abnormal gait in a horse and can occur for a wide variety of reasons. Determining the cause of a lameness is not always straightforward, and a lameness exam may involve a variety of diagnostic steps and treatment options.
Key Points:
- Lameness exams utilize evaluations of the horse at rest and while in motion under different conditions
- Local anesthesia of nerves (“blocking”), radiographs and ultrasound are common diagnostic tools for lameness in the field
- Complicated lamenesses may require additional testing done in a referral setting
A lameness exam consists of multiple parts, including both at rest and dynamic evaluations. Your veterinarian will examine your horse at rest, their conformation, weight-bearing, and thorough palpation of musculoskeletal structures, tendons, and ligaments to look for any abnormalities, swelling, heat, or pain on palpation. The use of hoof testers to apply pressure to different regions of the foot may also be part of an at-rest exam.
In a dynamic exam, your veterinarian will evaluate your horse in motion under a variety of conditions. This could include at a walk or jog in-hand on multiple types of surfaces (soft footing vs. hard ground), in straight lines and/or on a lunge line. Your veterinarian may view the horse moving from multiple angles – straight on from the front or back, and from the side. Some lamenesses may only be evident when under saddle, and your veterinarian may need to see the horse ridden to evaluate the lameness.
When evaluating a horse for lameness, a standardized scale of grading from 0 to 5 is often used to categorize the severity of the lameness.
0: Lameness not perceptible under any circumstances.
1: Lameness is difficult to observe and is not consistently apparent, regardless of circumstances (e.g. under saddle, circling, inclines, hard surface, etc.).
2: Lameness is difficult to observe at a walk or when trotting in a straight line but consistently apparent under certain circumstances (e.g. weight-carrying, circling, inclines, hard surface, etc.).
3: Lameness is consistently observable at a trot under all circumstances.
4: Lameness is obvious at a walk.
5: Lameness produces minimal weight bearing in motion and/or at rest or a complete inability to move.
Flexion tests are a part of a dynamic exam where your veterinarian will flex and hold different portions of the lower limbs to try to accentuate a lameness and narrow down where the lameness is stemming from.
Local anesthesia or “blocks” may be utilized to further narrow down the location of a lameness. By strategically anesthetizing different nerves in the lower limb in a particular order until the lameness is improved, blocking is a common diagnostic procedure to pinpoint where a lameness may be coming from, may be used rule out certain areas of concern, or where further diagnostics may be needed.
Further diagnostics in the field for lameness can include radiographs and ultrasound. These tools are most helpful to be utilized when a lameness has been localized to a specific area of concern or suspicion.
Once a cause for the lameness has been identified, your veterinarian can work with you to develop an appropriate treatment plan for your horse.
Certain lamenesses can be incredibly hard to diagnose. They may not block out using local anesthesia, may not have changes on radiograph or ultrasound, may be extremely subtle, or may involve multiple limbs. With difficult lameness cases, referral to a hospital for additional diagnostics including nuclear scintigraphy (bone scan), MRI, PET scan, or CT may be warranted.
