Lameness is a general term that refers to a horse with an abnormal gait or stance. This is a common issue that requires assessment by a veterinarian to determine the cause and best course of action.
Common causes of lameness include strain or injury, acute or chronic laminitis, genetic traits, infection, metabolic issues, or neural disorders.
A timely lameness exam can identify the underlying cause and how to manage it to relieve pain and support longevity.
A lameness exam typically involves discussing the horse’s history, observing the horse at rest and in motion, performing flexion tests and using hoof testers to identify sources of pain. Further diagnostic tests may be needed if these assessments are not sufficient.
Lameness evaluations are also a crucial part of pre-purchase exams. Identifying possible lameness in a horse you are interested in purchasing allows you to determine if you would like to proceed with the purchase. If you purchase the horse, lameness exams can indicate what may become an issue in the future.
Types of Lameness
According to the American College of Veterinary Surgeons, lameness is defined as an abnormality of a horse’s gait or stance. Lameness is not a disease itself but is a clinical sign that can be caused by pain, restrained movement or neuromuscular dysfunction.
Lameness is usually caused by pain in the muscles, tendons, bones, ligaments, or joints. Less commonly, non-painful lameness can also occur from neurological dysfunction. 
Most lameness can be separated into the following categories:
- Front end lameness
- Hind end lameness
- Pain in the back and sacroiliac
- Compensatory lameness
- Neurological lameness
Front End Lameness
Front leg lameness is the easiest to see with even the untrained eye. Front end lameness produces the classic “limp” one would expect to see with a painful limb.
When looking to see if a horse is lame in front, look for two features of the gait:
- Head bobbing
- Differences in range of motion
When stepping on a painful limb, most horses will use the placement of their head to try to alleviate pressure on that limb. Horses will raise their head when they step on a sore limb to reduce pressure on that limb and lower it when they step with the non-painful limb.
When trotting your horse on a circle or straight line, pay attention to when they lift and lower their head. If you are only able to trot your horse on a circle, make sure you are looking at their gait in both directions, as they could be lame on both limbs. 
If a horse has a sore muscle or painful joint, it will likely exhibit a reduced range of motion, referring to how far a limb can move with little pain in a gait cycle. 
Horses should move their limbs evenly and smoothly during a gait cycle. Any hitching or unevenness can indicate pain. 
Hind End Lameness
Hind end lameness can be subtle, with most horse owners noticing that something is “off” without being able to put their finger on the source. Horses lame in behind may exhibit:
- An uneven rise and fall of the hips and buttock
- Differences in range of motion
Horses that are lame in behind will drop the hip on the sore side slightly more than the non-painful side and may produce odd-looking movement patterns in their hind limb joints to compensate for painful areas.
Like front-end lameness, horses will often show differences in their range of motion when lame in the hind legs. The lame leg may not come forward underneath the horse’s body or extend out as far behind the body as much as the non-painful leg. 
Back and Sacroiliac Pain
- Discomfort during grooming or pressure on the back
- Abnormally short strides
- Resistance to saddling or girthiness
- Behavioural issues during performance such as refusing fences, bucking, rearing, etc.
When a horse experiences pain or discomfort in one area of the body they often develop compensatory movements to alleviate pain in the affected area. For example, if the horse is lame in one forelimb it may alter its gait and weight-bearing to shift more weight onto the other forelimb.
Unfortunately, this can lead to compensatory lameness in the previously healthy limb. Compensatory lameness can be difficult to distinguish from the original source of lameness.
Asymmetry in the vertical movement of the withers can help distinguish primary and compensatory lameness when both front limbs are affected. 
Lameness due to a neurological disease can be subtle, extremely obvious or somewhere in between. It may begin in early life or following an infection.
Early in the disease progression, your horse may exhibit:
- Subtle abnormalities in their range of motion, which come and go
- Minor stumbling or tripping
- Issues retaining balance when turning in small circles
- Reluctance when transitioning from one ground surface to another
- Weakness and inability to balance when a leg is held up
Late in the disease progression, your horse may exhibit: 
- A wide stance when standing or walking
- Swaying back and forth
- Low muscle tone in the tail and anus
- Frequent falling
Lameness due to a neurological disease or injury is always very serious and needs a thorough work-up by your vet. Examples of neurological diseases that can cause incoordination include equine protozoal myeloencephalitis (EPM) and equine herpesvirus type 1 myeloencephalopathy.
Genetic conditions can also cause incoordination and lameness. One example is neuroaxonal dystrophy found in Morgan horses. Signs of these typically appear within the first 2 years of life and have a variable prognosis.
When performing a lameness exam, your veterinarian will follow a protocol that maximizes the likelihood of identifying the location of pain while minimizing the need for major diagnostic tests.
The American Association of Equine Practitioners uses the following scale to help owners and veterinarians identify the severity of lameness. On this scale, a grade of 0 means no lameness and 5 means extreme lameness.
- Grade 0: Lameness is not perceptible under any circumstances; manipulating the limbs does not produce gait abnormalities.
- Grade 1: Lameness is difficult to observe and is not consistently apparent regardless of circumstances.
- Grade 2: Lameness is difficult to observe at a walk or trot in a straight line but consistently apparent in certain circumstances.
- Grade 3: Lameness is observable at a trot under all circumstances.
- Grade 4: Lameness is obvious at a walk.
- Grade 5: Lameness produces a complete inability to bear weight or a complete inability to move.
The first thing your veterinarian will do is evaluate your horse’s medical history. They will want to know if your horse has any past lameness issues and what signs you have observed during the current episode.
This exam will include questions such as: 
- What type of exercise does your horse do? Did lameness first appear during exercise?
- How long has the horse been lame? Has it been stable or gotten worse/better?
- Have they been rested or exercised since lameness first appeared?
- Does lameness improve as they warm up to exercise?
- When is the lameness most consistently evident?
- Have you given any treatments? What were the effects?
- When was the horse last shod or trimmed? What is their typical farrier care?
- What abnormalities do you notice when riding or watching the horse?
Additional information such as your horse’s age, pedigree and past use can also be valuable to determine underlying contributing factors.
Depending on the type of work the horse does they may be more prone to certain lameness conditions. For example, racehorses are more prone to lameness associated with repetitive overuse such as foot bruising, fractures and suspensory injuries.
Knowing the type of work, intensity and training history will help your veterinarian understand your horse’s likelihood of certain injuries or conditions.
Observing Your Horse at Rest
Your veterinarian will want to study your horse while they are standing still on flat ground. They will evaluate your horse’s conformation, how they are weight-bearing at rest, and whether there are any obvious signs of strain. 
Observations will be made from a distance and up close. From farther away your vet can evaluate stance, frequency of weight shifting, unusual limb positioning, body conformation and body condition.
From up close, your vet can assess the feet for conformation and balance, hoof cracks, hoof size and abnormal wear. Joints and tendons can be inspected for swelling, and muscles can be inspected for swelling and/or atrophy.
Your veterinarian will emphasize comparing one side of the body to the other to identify the source of lameness.
Observing Your Horse in Motion
As part of diagnosing lameness, your vet will want to see your horse walk and trot in a straight line. They will observe your horse from the front, back, and sides as they walk and jog in hand.
They may want to watch your horse walk, trot, and canter in a circle to see how they move in the gait and how they transition between gaits.
Your vet will look for any gait deviations such as plating or winging, altered range of motion and abnormal placement of the feet.
This will help identify abnormal movement asymmetries in the body that can indicate the source and severity of lameness. Slight asymmetries in head and pelvic movements are a normal part of biological variability between horses, but larger asymmetries could indicate an issue. 
Assessments should be done under several circumstances to avoid over-interpretation, including on soft and hard surfaces, in a straight line and while lungeing. This will help distinguish between normal asymmetries vs asymmetries that indicate lameness.
Asymmetries might also not be the same in both directions. These natural asymmetries could mimic or mask limb lameness. Therefore, several observations during various forms of exercise should be made.
Your veterinarian will perform a thorough hands-on exam involving palpation of the hooves, limbs or other areas that may be sources of pain. They will pay attention to any areas of swelling, heat, or other physical abnormalities that could have resulted from an injury.
This should include systematic palpation of the pastern, fetlock and metacarpus/metatarsus. Palpation of muscles should also be done to identify areas of swelling or weakness.
Hands-on exams are usually done following observations at rest, although some veterinarians may also do this assessment following exercise. 
Application of Hoof Testers
If your vet thinks your horse’s hooves are sources of pain, they will perform a hoof test. Hoof testers are a blunt, scissor-like tool that can be used to apply pressure to certain areas of the hoof. If your horse has painful hooves, they will react to the applied force by pulling back or taking the foot away.
Horses that show sensitivity over broad areas of the sole might have a fracture in the distal phalanx, extensive bruising or laminitis. If the horse is sensitive in small, specific areas this could indicate localized bruising, puncture wounds or abscesses. 
Hoof testers can also indicate hoof wall issues, such as chronic laminitis or white line disease.
Flexion tests can help reveal lameness that may not otherwise be apparent. Your veterinarian will hold your horse’s leg flexed for a pre-determined period, anywhere from 5 to 60 seconds. 
They will then release the leg and ask you to immediately trot the horse in a straight line away from them. Your vet will watch for signs of pain, stiffness, improper weight shifting, or irregular movement.
This test can be used to identify severity of damage to an affected joint by assessing the horse’s response to light or firm flexion.
A scoring system should be used to track responses in various joints and to track improvement over time as your horse recovers.
If your veterinarian cannot pinpoint the exact cause and location of the lameness or if they think a major issue is causing the abnormal gait, they will likely suggest further diagnostic testing. These tests can offer a more precise explanation and help clarify which treatment would be most effective.
A nerve block is used when it is difficult to pinpoint the exact location of the pain. A local anesthetic will be injected into specific areas of your horse’s body to render them numb.
These locations are often near joints or particular parts of the hoof. Once the anesthetic has taken effect, you will trot your horse away from and towards the veterinarian to determine whether the horse is now sound.
If your horse trots away sound, the vet knows that the blocked area was the source of pain. If they trot away lame, this area was not of the issue and other tests are needed. 
If your veterinarian thinks that bone issues are the cause of lameness, they will suggest x-rays. Most x-rays can be performed at the barn, but x-rays covering large areas such as the back and sacroiliac may need to be performed at a veterinary clinic.
X-rays provide limited information regarding soft tissue injuries (i.e., tendon, ligament, bursa). If the issue involves soft tissue, your vet may need to perform an ultrasound. 
When performing an ultrasound, your vet will apply a jelly-like substance to your horse’s skin. This gel provides a medium through which the ultrasound waves can travel.
The ultrasound wand transmits ultrasonic waves into your horse’s tissues, producing an image. Your vet will examine the image for soft tissue irregularities. 
Rectal ultrasounds can also be performed if upper limb lameness is suspected. This exam can identify fractured vertebrae, muscle inflammation or irregularities in blood vessels that may be contributing to lameness. 
Scintigraphy (Nuclear Scanning)
If the source of lameness remains unclear, your vet may suggest a nuclear scan. This procedure requires injecting your horse with a radioactive substance and it is always performed in a veterinary hospital.
After your horse arrives at the hospital, they will be injected with a radioactive isotope called Technitium. Technitium is taken up in areas with abnormal inflammation or metabolic activity.
Your horse is then scanned with a Gamma camera that picks up areas of Technitium absorption, indicating “hot spots” of injury and pain. 
If your veterinarian has pinpointed the source of lameness to a specific joint but does not know the exact cause, they may suggest an arthroscopy. Under general anesthesia, a small scope is inserted into your horse’s joint to visualize the interior joint structures.
If a cause for lameness is found, surgery to correct the issue is often performed at the same time. 
Synovial Fluid Sampling
If joint infection or inflammation is suspected, your vet may suggest taking a synovial fluid sample.
Horses that show poor coordination or odd limb placement may have a neurological condition. A thorough neurological exam involves sampling the cerebrospinal fluid as well as genetic testing to identify known causes.
During a lameness exam, your vet may perform a tail pull test. A healthy horse will resist being pulled to one side by the tail. However, horses with neurological issues may appear weak and offer little resistance to being moved. 
One instance in which a lameness exam is warranted is during a pre-purchase exam (PPE). Buying a horse is an expensive undertaking, so many potential buyers will ask a vet to perform a PPE to highlight any issues the horse may have.
A PPE can determine if the horse is lame now and may speculate on the likelihood of becoming lame in the future. During a PPE, your vet will perform:
- A physical exam to identify past injuries and conformation issues
- Flexion tests
Veterinarians can tailor PPEs to the intended use of the horse. For example, a PPE for an upper-level dressage horse may look different from a PPE for a lower-level hunter. 
Preventing Lameness Issues
Many causes of lameness are avoidable with the right management program. You can reduce the likelihood of wear and tear on your horse by:
- Implementing appropriate feeding and exercise programs for growing horses
- Not pushing your horse past what they are conditioned for
- Feeling your horse’s legs every day for any heat and swelling
- Icing or cold hosing your horse’s legs after particularly hard work sessions
- Warming your horse up appropriately before working them hard
- Maintaining a healthy body condition
- Meeting their vitamin and mineral requirements
- Supporting your horse’s joints with scientifically validated supplements
Lameness can be complicated to diagnose and treat. Keep a vigilant watch for anything that may appear abnormal in your horse’s movements. Prompt diagnosis and treatment can save you money and keep your horse working well into their career.
If your horse is lame, work with an equine nutritionist to formulate a diet that supports joint health and recovery from lameness. You can submit your horse’s information online for a free evaluation.
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