Tendinitis is a troublesome disorder for many owners and trainers of highly competitive horses. In fact, some horsemen feel injury to the tendons and ligaments threatens an equine athlete's career more than fractures. The "bowed tendon" involves inflammation of the superficial flexor tendon, where an unsightly "bow," or bulge, will appear most often in the forelimb.


Tendinitis usually appears following fast exercise. There is a myriad of causes, including poor conditioning, fatigue, poor racetrack/arena conditions, persistent training when inflammatory signs are present, improper shoeing and even poor conformation.

Tendinitis occurs with a primary lesion of ruptured tendon fibers causing hemorrhaging or edema, where large amounts of fluid accumulate. Onset can be acute or chronic. Acute tendinitis causes severe lameness and a "bow" that is hot, painful and swollen. In chronic cases, subtle clinical signs may appear intermittently.


Treat with cold packs and non-steroidal anti-inflammatory drugs (NSAIDs). Edema may be mobilized using laser or therapeutic ultrasound. Prevention of re-injury also should be considered, with possible management adjustments made to training schedule, training environment and foot balance.


Fortunately, ultrasonography has improved the diagnosis and rehabilitation of tendinitis. Unlike palpation, diagnostic ultrasound allows direct visualization of tendon architecture. The horse initially should be graded for lameness and an ultrasound evaluation of the affected tendon should be performed. The veterinarian will take a cross sectional view and a long axis view of the tendon and observe the following--changes in size of the tendon, changes in echogenicity (or the extent to which the tendon gives rise to reflections of the ultrasonic waves) and changes in fiber patterns of the tendon.

During this initial examination, the veterinarian will determine the degree of tendon fiber disruption. The amount of exercise is based on the severity of this lesion.

The horse should be examined three to five times following the initial diagnosis. During these examinations, lesion healing will be evaluated ultrasonographically. The parameters of the lesion will be measured and compared to the initial measurements. Amount of exercise will increase as the tendon improves.

Successful cases usually require eight to nine months of rest and rehabilitation to return to previous work load. Advancing too quickly often results in worsening of the lesion, while advancing too slowly results in loss of productive athletic use of a horse. The purpose of controlled exercise rehabilitation is to maximize the tendon's functional repair. Gradually increasing the work load provides stimulation to the tendon to continue the healing process. I always keep in mind that the tendon is relatively weak after injury and slowly gains strength over six to eight months of rehabilitation.

About the Author

Carol Gillis, DVM, PhD, Dipl. ACVSMR

Carol Gillis, DVM, PhD, Dipl. ACVSMR, is a graduate of UC Davis School of Veterinary Medicine. She was the owner of a sport horse practice for 8 years during which time she became one of the first equine practitioners to perform ultrasound examinations on the musculoskeletal system of horses. Dr. Gillis returned for an equine surgery residency at UC Davis. Following completion of the residency, she obtained a PhD in equine tendon and ligament pathophysiology. Concurrently she established the equine ultrasound service at UC Davis, pioneering ultrasound of the musculoskeletal system at the University, and developing courses and wet labs to train terinary students, residents and veterinarians how to perform and interpret ultrasonographic examinations. She is the author of over 50 scientific publications in journals such as the American Journal of Veterinary Research and the Journal of the American Veterinary Medical Association on the subject of equine soft tissue injury diagnosis and treatment, and recently was an author of Equine Sports Medicine and Surgery, the definitive reference book on the topic. Clinically, Dr. Gillis has performed more than 22,000 ultrasound examinations of the horse and subsequently guided treatment of problems identified.

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