High severity

Fistulous withers (Supraspinous bursitis)

Fistulous withers is chronic inflammation or infection of the supraspinous bursa over the withers — it can drain through fistulous tracts. It is not sweeney (shoulder muscle atrophy / suprascapular nerve), not poll evil (nuchal bursa at the poll — a different place), and not kissing spine (back/spinous processes). A photograph cannot diagnose fistulous withers. A still cannot tell fistulous withers from a saddle sore, withers abscess, trauma swelling, or poll evil. Diagnosis is a vet exam. The skin scan is a first look at the withers skin/swelling to share with a vet, not a fistulous-withers test, and there is no fistulous-withers scanner.

Symptoms to watch for

Swelling, heat, or pain at the withers — the swell is a clue, not a still-photo verdict

Draining tracts or discharge over the withers after a poorly fitting saddle or trauma

A withers swelling that can look like a saddle sore, a withers abscess, trauma swelling, or poll evil — a still cannot tell them apart (poll is a different place)

Heat or a draining opening at the withers — a reason to book a vet, not a photo verdict

Pain at the withers after saddle or withers trauma — location is a clue, not a diagnosis

Some horses show only swelling at the withers at first; draining tracts can come later — that is a vet visit, not a photograph

Common causes

Chronic inflammation or infection of the supraspinous bursa over the withers, which can drain through fistulous tracts
Poorly fitting saddle or trauma at the withers — the history is a clue, not a diagnosis
Not sweeney (shoulder muscle atrophy / suprascapular nerve), not poll evil (nuchal bursa at the poll — a different place), and not kissing spine (back/spinous processes)
Not a saddle sore, not a withers abscess, and not ordinary trauma swelling — a still cannot tell fistulous withers from those, and those need a vet

Prevention

Fit the saddle so it does not pinch, rub, or bruise the withers
Watch the withers for new swelling, heat, pain, or a draining tract and rest rather than riding through it
Protect the withers from trauma in work and in the stall
Do not treat a photo, a withers swell, or a scan result as a diagnosis
Skin photos can help you and the vet look at the withers skin and swelling — they do not confirm or rule out fistulous withers, and they cannot tell it from a saddle sore, withers abscess, trauma swelling, or poll evil

What to do

1
Book a vet visit if the withers are swollen, hot, painful, or draining. Diagnosis is a vet exam — not a photograph.
2
Stop riding through a painful or draining withers. Rest the horse and do not add a tighter saddle or extra work hoping the swell will go down.
3
Photograph the withers in good light, from the side and from above, and keep the photos on the horse's record so you and the vet can see change over time — a first look to share, not a diagnosis.
4
Use a skin scan only as a first look at the withers skin/swelling to share, not as a fistulous-withers test. There is no fistulous-withers scanner.
5
If fistulous withers (supraspinous bursitis) is confirmed, follow the plan your vet prescribes. Do not start a treatment protocol from a photo.
6
Keep the vet on the same page. Share what you see; do not treat a photo as a verdict.

When to call the vet

Pick up the phone if…

Schedule a vet visit if the withers are swollen, hot, painful, or draining, or if the swell appeared after a poorly fitting saddle or trauma. Call sooner if the horse is dull, off feed, in obvious pain, or if you are worried about Brucella — that is a vet call (zoonotic), not a photo diagnosis. A photograph cannot diagnose fistulous withers. A still cannot tell fistulous withers from a saddle sore, withers abscess, trauma swelling, or poll evil (poll is a different place). Diagnosis is a vet exam. The skin scan is a first look at the withers skin/swelling, not a fistulous-withers test, and there is no fistulous-withers scanner.

Get a first look at the withers skin

Scan the skin in HorseCare. 5 free scans this month, then Pro.

Scan the skin

5 free scans this month, then Pro. Scans run in the HorseCare app.

Educational content only. Not a substitute for veterinary advice.