Tendon sheath inflammation in horses: recognise and treat it

What is tendon sheath inflammation?

With tendon sheath inflammation, the tendon sheath — the fluid-filled tube surrounding the tendon — becomes inflamed. This differs from a direct tendon tear, but can lead to one if the injury is ignored. The inflammation usually develops through overloading, a sudden wrong movement, or prolonged work on hard or uneven surfaces. Young horses in training are particularly vulnerable, as are horses that are pushed too hard too quickly after a rest period. The tendon sheath fills with excess synovial fluid, leading to the characteristic swelling around the tendon.

Symptoms you can recognise immediately

• Warm, soft swelling around the tendon or tendon sheath, often on the hind legs
• Lameness ranging from barely visible to clearly noticeable at the walk
• Pain when light pressure is applied to the affected tendon
• Stiffness after standing still, which sometimes improves with movement
• Visible swelling that does not fully disappear after rest

Diagnosis: more than just feeling

Your vet confirms the diagnosis via ultrasound. This shows whether the tendon sheath contains only fluid or whether there is also fibre damage within the tendon itself. Fibre damage requires a longer recovery period — think 3 to 6 months of rest versus 4 to 8 weeks for a straightforward tendon sheath inflammation without fibre damage. Some vets combine ultrasound with flushing of the tendon sheath via scoping if an infection is suspected. Make sure you save the ultrasound images and diagnosis report in the EquiSight horse profile, so you can easily compare progress at follow-up checks.

Treatment options at a glance

Treatment depends on the severity. Mild cases respond well to rest and cooling; more serious cases require medical intervention.

• Immediate rest: at least 2 to 4 weeks of box rest for mild inflammation
• Cooling: ice packs or water cooling 2 to 3 times per day, 20 minutes per session
• NSAIDs: anti-inflammatory drugs such as phenylbutazone or meloxicam prescribed by your vet
• Flushing or injection: in serious cases the vet flushes the tendon sheath or injects corticosteroids
• Controlled rehabilitation: a gradual programme of in-hand and lungeing work before returning to the saddle

Rehabilitation: building up gradually pays off

One of the biggest mistakes is returning to normal work too soon. Even if the horse moves clinically sound, the tendon is only truly healed once the fibres show no abnormalities on ultrasound. Build up the workload in steps: start with 10 minutes of in-hand walking per day and add 5 minutes each week. After 6 weeks of quiet in-hand walking, you can move on to short blocks of lungeing at walk. Use the calendar in EquiSight to track your rehabilitation schedule and set reminders for ultrasound check-up moments.

Preventing recurrence: practical tips

• Always warm up for 10 to 15 minutes at walk before moving to trot or canter
• Train preferably on a soft, even surface and limit work on hard ground
• Use leg protection suited to your type of training: bandages or boots for use during exercise, not as a standard day-in-day-out measure
• Watch weight: excess weight significantly increases the load on tendons
• Introduce periodic ultrasound checks for horses with a history of tendon issues