High severity

Shivers

Shivers is a chronic neuromuscular condition, usually in the hind limbs — trembling or hyperflexion when backing, lifting a hind limb, or sometimes when asked to move off. It is not locked stifle (upward fixation of the patella), not stringhalt (exaggerated hind-limb flexion when walking forward), and not ordinary lameness. It is often worse when backing or picking up a hind foot; the horse may look normal at rest. The cause is not fully known. A photograph cannot diagnose shivers. A still cannot tell shivers from stringhalt, locked stifle, hitch, or ordinary hind-limb spasm — this is a movement problem, and a still photo is especially weak here. Diagnosis is a vet exam (walk/trot, backing, lifting a hind limb), not a photo. The gait scan is a first look at the movement to share with a vet, not a shivers test, and there is no shivers scanner.

Symptoms to watch for

Trembling or hyperflexion of a hind limb when backing — the movement is the clue, not a still photo

Trembling or hyperflexion when lifting a hind foot; often worse when picking up a hind foot — the act is a clue, not a diagnosis

Sometimes trembling or hyperflexion when asked to move off — a reason to book a vet, not a photo verdict

May look normal at rest; the first sign is often when backing or lifting a hind limb — that is a vet visit, not a photograph

A hind-limb spasm that can look like stringhalt, locked stifle, hitch, or ordinary hind-limb spasm — a still cannot tell them apart

A still photo is especially weak here: this is a movement problem — a reason to book a vet, not a photo verdict

Common causes

A chronic neuromuscular condition, usually in the hind limbs — the cause is not fully known; history and movement are clues, not a diagnosis
Not locked stifle (upward fixation of the patella — a hind limb that sticks in extension, then snaps forward), not stringhalt (exaggerated hind-limb flexion when walking forward), and not ordinary lameness
Often worse when backing or picking up a hind foot; the horse may look normal at rest — rest vs movement is a clue, not a photo verdict
A still cannot tell shivers from stringhalt, locked stifle, hitch, or ordinary hind-limb spasm — those need a vet

Prevention

Watch for trembling or hyperflexion when backing, lifting a hind foot, or moving off, and book a vet rather than waiting on a photo
Do not work through a new hind-limb tremble or hyperflexion hoping it will settle — that is a vet visit, not a photo
Do not treat a photo, a still of a hind limb, or a scan result as a diagnosis — a still is especially weak on a movement problem
Do not treat a photo, a backing hitch, or a scan result as a diagnosis
A gait clip can help you and the vet look at the movement — it does not confirm or rule out shivers, and it cannot tell shivers from stringhalt, locked stifle, hitch, or ordinary hind-limb spasm

What to do

1
Book a vet visit if a hind limb trembles or hyperflexes when backing, when you lift a hind foot, or when asked to move off. Diagnosis is a vet exam (walk/trot, backing, lifting a hind limb) — not a photograph.
2
Do not treat a still of a hind limb as a verdict. A still cannot tell shivers from stringhalt, locked stifle, hitch, or ordinary hind-limb spasm, and a still photo is especially weak here.
3
If you record a gait clip, film walk and trot, backing, and lifting a hind limb on a hard, level surface from the side — that is a video, not a still, and it is a first look to share, not a diagnosis.
4
Use a gait scan only as a first look at the movement to share, not as a shivers test. There is no shivers scanner.
5
If shivers 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 a hind limb trembles or hyperflexes when backing, when you lift a hind foot, or when asked to move off, or if the horse looks normal at rest but the hitch appears when you ask for those moves. Call sooner if the horse will not bear weight or is in obvious pain. A photograph cannot diagnose shivers. A still cannot tell shivers from stringhalt, locked stifle, hitch, or ordinary hind-limb spasm — a still photo is especially weak here. Diagnosis is a vet exam (walk/trot, backing, lifting a hind limb). The gait scan is a first look at the movement, not a shivers test, and there is no shivers scanner.

Get a first look at the movement

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

Scan the gait

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

Educational content only. Not a substitute for veterinary advice.