Intratendinous Fibroma of the Superficial Digital Flexor Tendon within the Carpal Sheath of a Horse.

The research article details the case of a 20-year-old horse diagnosed with a rare tumor, called intratendinous fibroma, in its superficial digital flexor tendon. Despite efforts to treat the condition, the horse did not show significant improvement and was ultimately euthanized.

Introduction and Case Presentation

• The subject of the study was a 20-year-old British Warmblood gelding that experienced severe lameness in its right forelimb.
• The lameness had been gradually worsening after an intense dressage training session.
• An initial ultrasound showed a hypoechoic triangular region within the horse’s superficial digital flexor tendon (SDFT), a tendon located in the proximal metacarpal and palmar carpal region.

Initial Treatment and Observation

• The horse went through an eight-week <a href="/equine-rehabilitation-guide/" title="Equine Rehabilitation Programs: What to Expect When Your Horse is Recovering – [Guide]”>rehabilitation programme, but no significant improvement was seen in its clinical condition.
• A subsequent ultrasound showed that the affected area of the tendon had become enlarged.

Decision to Euthanise and Post-Mortem Examination

• Due to the severity of the lameness, the lack of response to treatment, and the worrying state of the horse’s well-being, the decision was made to euthanise the animal humanely.
• The affected SDFT was taken to the University of Liverpool for close examination after the horse’s death.

Histopathological Examination and Findings

• The post-mortem examination revealed a firm, irregularly shaped mass within the tendon.
• Upon histopathological examination, this mass was identified as a mesenchymal neoplasm, or a tumor arising from mesenchyme, the embryonic tissue that develops into connective tissues like bone and cartilage.
• This tumor was found to comprise of moderately atypical spindloid cells and displayed bizarre mitoses, making it a form of intratendinous fibroma.
• Intratendinous fibroma is a rarely occurring neoplasm in humans, but even more so in horses. This was only the third reported case in a horse, the first in an adult horse, and the first within the superficial digital flexor tendon.