Common Causes of Lameness
From AQHA Corporate Partner Boehringer Ingelheim Animal Health USA
It’s a situation every horse owner dreads: you arrive at the barn to ride and see that your horse is lame. Whether it’s a subtle change in gait or a noticeable head bobbing, any sign of lameness is cause for concern. Most causes of lameness are not career-ending and can be treated, though some can be more serious. It’s important to be able to recognize the signs of the most common causes of lameness to ensure your horse has the best chance of recovery.
FOOT ABSCESS
A foot abscess, also referred to as a hoof abscess, is one of the most common causes of lameness. An abscess can occur when bacteria is able to enter the hoof through cracks in the sole, hoof wall or penetrating wound. Wet and/or muddy pasture conditions offer a greater risk for abscesses to develop, making this an especially common cause of lameness in the spring and fall.
Abscesses are quite painful and affected horses can be severely lame, sometimes seemingly out of nowhere. In many cases, horses may be “toe touching lame” and hesitant to put their full weight on the affected foot. A foot with an abscess will typically be very warm to the touch and a prominent pulse can be felt in the blood vessels just above the hoof.
Treatment of an abscess can include soaking in a mixture of warm water and Epsom salt, packing the hoof with a poultice and managing pain with medication. In some cases an abscess will drain on its own, but resolution can be sped up with a visit from your veterinarian or farrier to create a drainage path.
SUBSOLAR BRUISING
Subsolar bruising is another common cause of lameness that may occur when there is repetitive trauma to the horse's sole, most commonly due to working on hard ground. Poor hoof confirmation, such as thin soles or flat heels, can predispose a horse to subsolar bruising.
A horse with subsolar bruising may show persistent, mild lameness in both front legs as well as a reluctance to walk on hard ground. The horse may also appear to get better, but then exhibit lameness again the next day. In some cases, you may be able to see a visible bruise.1
Treatment of subsolar bruising often requires the teamwork of both a veterinarian and a farrier. A veterinarian will help to manage the pain, while a farrier can change the horse’s shoeing to help distribute some of the horse’s weight off the sole.
NAVICULAR SYNDROME
Navicular Syndrome is a broad term used to refer to horses with caudal heel pain related to the navicular bone or any of its supporting structures. The navicular bone is a small, flat bone that lies behind the coffin bone. Changes to this bone can also involve damage to the surrounding tendons and ligaments.2 The term Navicular “Syndrome” is used as there is no one problem, one cause or one solution for this issue in horses.
The onset of Navicular Syndrome is often gradual and typically presents as a chronic and progressive lameness in the front end. Initially, this lameness may only occur from time to time or on hard ground. While both front feet are typically affected, a horse may occasionally have one foot that is affected more than the other.3
The gold standard for diagnosis is an MRI in addition to radiographs.2
“An MRI allows us to see all of the soft tissue structures that may be affected by the disease, such as the deep digital flexor tendon, collateral sesamoidean ligament, impar ligament and the navicular bursa,” says Sarah Reuss, VMD, DACVIM, Equine Technical Manager, Boehringer Ingelheim.2
Because Navicular Syndrome can affect many different structures in the hoof, treatment varies case by case. Common treatments may include corrective shoeing, oral anti-inflammatories, systemic bisphosphonates and joint injections.
LAMINITIS
Laminitis is an extremely painful condition affecting the Velcro-like tissue that connects the coffin bone to the hoof wall (referred to as laminae).4 Weight –bearing is very painful for horses suffering from laminitis and they may rest in a rocked-back stance to take weight away from the area of most severe pain over the toes, in addition to exhibiting lameness at the walk or spending more time lying down.
Laminitis can be caused by many different diseases such as pituitary pars intermedia dysfunction (PPID), insulin dysregulation or sepsis. Ponies and older horses are more susceptible to developing this condition due to underlying endocrine disease. Severe lameness in one limb (as could happen with a fracture) can also result in “contralateral limb laminitis” in the other limbs that are bearing more weight.
“When the laminae are weakened, it can cause mild hoof soreness to complete separation of the coffin bone from the foot,” says Dr. Reuss.4 “Laminitis needs to be treated immediately to avoid permanent damage to the coffin bone and hoof.”
Treatment for laminitis is meant to reduce further progression of the disease and manage pain. Stall rest with deep bedding, NSAIDs, cold therapy and special farrier care are all common treatments for a horse with laminitis. Addressing any underlying diseases that caused the laminitis is integral. In severe cases, sling support may be necessary.4 Horses with laminitis should also avoid consuming grain and forage high in sugar and/or carbohydrates and maintain a healthy body weight.
OSTEOARTHRITIS (OA)
OA is a progressive deterioration of the structures of the joint that can develop in horses of any age. Degenerative joint disease usually begins with synovitis (inflammation of the joint fluid and joint lining), which if goes unchecked begins to cause cartilage damage and then irreversible bony changes. This typically occurs due to repetitive trauma from general wear and tear but can also develop subsequent to an acute injury like a fracture or infection.
“The main clinical sign of OA is lameness that can be a gradual onset or happen acutely,” says Dr. Reuss. “The lameness can be mild to severe, depending on the cause and location.”
Additional clinical signs may include heat and swelling around the joint and possible decreased range of motion.
While OA cannot be cured once bony changes have occurred, there are a variety of treatment options available to reduce pain and prevent further deterioration of the joint. These may include rest, systemic medications such as non-steroidal anti-inflammatory medications or hyaluronic acid and/or joint injections. When and with what substance(s) your veterinarian may inject a joint with varies from case to case. Horses with OA can still have a long and successful riding career with the proper care and management.
SOFT TISSUE INJURY
Soft tissue injuries are most often seen in performance and racehorses and refer to any damage done to a horse’s tendons or ligaments. Clinical signs may include swelling, pain and heat at the injured site in addition to lameness. Diagnosis, treatment and recovery timelines vary case by case and depend on the location and extent of damage. Initial treatments typically include cold therapy, applied-pressure bandaging and rest.
TRAUMATIC INJURY
Traumatic injuries are inclusive of anything from a wound or laceration to a fracture. Injuries such as wounds or lacerations are typically visible and easy to identify. It can be difficult to discern the severity of a wound or laceration, as some may appear dramatic without being severe, or appear mild but be life threatening if a joint or tendon sheath is involved. A veterinarian should be called whenever there is a traumatic injury to provide a proper assessment.
Fractures can also occur as a result of a traumatic event, or they can also be caused by repetitive loading during high-intensity work. A horse who has sustained a fracture from a traumatic event will typically exhibit severe non-weight-bearing lameness. Diagnostic imaging such as radiographs or computed tomography (CT) are crucial in the diagnosis of a fracture.
SUMMARY
Though having a lame horse is never something a horse owner wishes for, being able to identify the signs and potential causes means you’ll be able to help your horse start feeling better sooner. If your horse is exhibiting any signs of lameness, contact your veterinarian right away. They will be able to properly diagnose your horse and begin treatment. You can learn more about what to expect during a lameness exam here.
About Boehringer Ingelheim Animal Health USA
Boehringer Ingelheim Animal Health is working on first-in-class innovation for the prediction, prevention, and treatment of diseases in animals. For veterinarians, pet owners, producers, and governments in more than 150 countries, we offer a large and innovative portfolio of products and services to improve the health and well-being of companion animals and livestock.
As a global leader in the animal health industry and as part of the family-owned Boehringer Ingelheim, we take a long-term perspective. The lives of animals and humans are interconnected in deep and complex ways. We know that when animals are healthy, humans are healthier too. By using the synergies between our Animal Health and Human Pharma businesses and by delivering value through innovation, we enhance the health and well-being of both.
Boehringer Ingelheim Animal Health has deep roots in the U.S. From a start in St. Joseph, Missouri, more than 100 years ago, it has grown to encompass seven sites. Boehringer Ingelheim Animal Health’s portfolio contains widely used and well-respected vaccines, parasite-control products and therapeutics for pets, horses and livestock.
Learn more about Boehringer Ingelheim Animal Health USA at bi-animalhealth.com.
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REFERENCES
1 VCA Animal Hospitals, Bruised Sole in Horses. Available at https://vcahospitals.com/know-your-pet/bruised-sole-in-horses Accessed March 13, 2023.
2 University of Illinois Urbana-Champaign College of Veterinary Medicine, What I Wish Owners Knew about Navicular Syndrome. Available at https://vetmed.illinois.edu/2020/09/11/navicular-syndrome/ Accessed March 13, 2023.
3 VCA Animal Hospitals, Navicular Syndrome in Horses. Available at https://vcahospitals.com/know-your-pet/navicular-syndrome-in-horses Accessed March 13, 2023.
4 UC Davis Veterinary Medicine Center for Equine Health, Laminitis. Available at https://ceh.vetmed.ucdavis.edu/health-topics/laminitis#:~:text=Laminitis%20is%20inflammation%20and%20damage,rotate%2C%20leading%20to%20severe%20pain Accessed March 13, 2023.