Kissing Spine in Horses Explained: Tips and Advice

Kissing spine in horses — clinically known as overriding or impinging dorsal spinous processes (ODSP/IDSP) — is the single most common cause of back pain in ridden horses, according to the MSD Veterinary Manual. It happens when the bony tips of two or more vertebrae along the horse’s back come too close together, touch, or overlap. Despite how alarming the diagnosis sounds, the modern picture is encouraging: the majority of correctly managed horses return to ridden work, and many compete successfully at high levels after surgery and rehabilitation.

This guide explains what kissing spine actually is, the symptoms to watch for, the UK diagnostic and treatment options available in 2026, and what realistic recovery looks like — including the surgical procedures (interspinous ligament desmotomy and dorsal spinous process resection) used in current British equine practice.

What Is Kissing Spine in Horses?

Each vertebra along a horse’s back has a tall bony projection on top called a dorsal spinous process. In a normal back, these processes sit comfortably apart with a layer of soft tissue (the interspinous ligament) cushioning the gap. In kissing spine, the gap narrows or disappears, and the processes touch, pinch or override one another.

The condition is most common in the saddle region — typically the thoracic vertebrae T13 to T18, where the saddle and rider’s weight load the back most heavily. Some horses develop changes in the lumbar vertebrae as well. A 2019 study at the Royal Veterinary College found radiographic kissing spine in approximately 40% of clinically “normal” sport horses examined — meaning many horses have the bony changes without showing pain. This is critical: the diagnosis is clinical, not just radiographic.

How Kissing Spine Affects the Horse

When the spinous processes contact each other under load, several things happen:

• Direct bone-on-bone friction creates inflammation
• The interspinous ligament becomes pinched and inflamed
• Nerve roots and surrounding soft tissue can be compressed
• The horse begins to brace and hollow the back to avoid the pain
• Hindlimb engagement deteriorates because the back can no longer flex correctly
• Compensatory tension develops in the neck, shoulders and hindquarters

The condition is graded radiographically (Denoix grades 1–4) based on the severity of changes — narrowing, sclerosis, lysis, and remodelling. Higher grades correlate weakly with pain levels, but not perfectly: some grade 4 horses are sound, while some grade 1 horses are visibly uncomfortable. Because the bony picture and the pain picture don’t always match, kissing spine sits alongside conditions like sacroiliac joint disease as a back problem that demands careful clinical interpretation rather than X-rays alone.

Causes of Kissing Spine in Horses

There’s no single cause. Most cases are multifactorial, combining genetic predisposition, conformation, training history and management.

1. Conformation and Genetics

Horses with long backs, weak top-lines or short loins may be more prone to develop the condition, simply because the geometry of the spine makes contact between processes more likely under load. Thoroughbreds are over-represented in published case series, and Warmbloods, Arabians and certain Quarter Horse lines also appear with above-average frequency. There’s growing evidence of a genetic component, though it’s not fully mapped.

2. Training and Saddle Fit

This is the most preventable cause. Three patterns recur in clinical histories:

• Working horses long and low without sufficient core engagement, hollowing the back over time
• Saddle fit that compresses the wither or loin region, transmitting concentrated load onto a small area of the spine
• Heavy or unbalanced riders who cannot maintain a centred seat

Modern UK saddle fitters increasingly view annual saddle checks as a clinical, not cosmetic, requirement.

3. Injury or Compensation

Kissing spine sometimes develops secondary to another problem — most commonly hindlimb lameness. A horse that’s sore behind shifts weight forward and braces the back, loading the spinous processes abnormally. The same applies to lower-limb pain such as coffin joint problems, which subtly alter how the horse carries itself. Treating the back without addressing the primary lameness rarely resolves the issue. This is why a thorough lameness work-up is essential before back-focused treatment.

4. Premature Work in Young Horses

Backing horses too young, or asking high-impact work (jumping, fast canter work) before the skeleton has matured, increases lifetime risk. Most international guidelines now recommend ridden work from age 3.5–4 years with light loads, and serious athletic work from age 5+.

Signs and Symptoms of Kissing Spine

The classic kissing spine horse doesn’t suddenly fall lame. Symptoms creep in, often dismissed as schooling problems or attitude. Recognising the early signs of kissing spine in horses is the single most useful thing an owner can do, because the earlier the condition is investigated, the better the outcome.

Behavioural Changes

• Reluctance to be groomed or saddled along the back
• Girthiness — pinning ears, biting, swishing the tail when the girth is tightened or the horse is tacked up
• Refusing to stand still at the mounting block
• Bucking on transitions, particularly upward into canter
• Rearing, planting or napping under saddle (see our napping guide for related behaviours)
• Sudden personality change in a previously willing horse

Performance Issues

• Loss of impulsion and back “swing”
• Difficulty with collected work, self-carriage or lateral movements
• Hollow outline; reluctance to come onto the bit
• Refusing fences or stopping at jumps the horse previously enjoyed
• One-sided stiffness
• Disunited canter, particularly behind

Physical Clues

• Sensitivity to pressure along the back
• Visible muscle wastage along the topline
• Asymmetric muscle development
• The horse drops the back away when palpated firmly along the spinal processes
• Cold-back behaviour at the start of work

Diagnosing Kissing Spine

Diagnosis requires a combination of clinical examination, imaging and — critically — confirming that the imaging findings explain the clinical signs.

Veterinary Examination

Your vet will start with:

• A full lameness examination at walk and trot, in straight lines and on circles
• Back palpation to localise pain
• Flexion tests on all four limbs
• Watching the horse ridden (where safe and possible)
• Neurological assessment to rule out other causes of poor performance, such as vertebral subluxation

X-Rays

Lateral radiographs of the thoracic and lumbar spine are the standard first imaging modality. Your vet will look for:

• Narrowed spaces between adjacent spinous processes
• Sclerosis (whitening) of opposing bone surfaces
• Lysis (erosion) of bone
• New bone formation
• Cyst-like changes within affected vertebrae

Ultrasound and Scintigraphy

Ultrasound assesses the surrounding soft tissue, including the supraspinous and interspinous ligaments. Bone scintigraphy (gamma scan) detects active bone remodelling and is particularly useful when X-rays show changes but the clinical picture is unclear — a hot spot on scan confirms the lesion is active.

Diagnostic Local Anaesthetic

The single most decisive test in many cases. Your vet injects local anaesthetic into the suspected interspinous spaces. If the horse demonstrably improves under saddle within 30 minutes, the diagnosis is confirmed and the surgical or medical target is identified. This step is what separates an incidental radiographic finding from a true clinical kissing spine.

Treatment Options for Kissing Spine in Horses

Treatment in the UK follows a tiered approach, starting conservative and escalating only if needed. Up to 70–80% of horses respond to conservative management alone.

Tier 1: Conservative Management

The foundation of any kissing spine treatment plan:

• Saddle re-fit by a Society of Master Saddlers qualified fitter
• Targeted physiotherapy — pole work, hill work, in-hand long-and-low stretching, sternal lifts
• NSAIDs for short-term pain relief during rehabilitation (phenylbutazone, meloxicam, firocoxib)
• Anti-inflammatory medication alongside structured rehab
• Mesotherapy — multiple shallow injections of corticosteroid and local anaesthetic into the back muscles
• Shockwave therapy — extracorporeal shockwave can reduce pain and stimulate bone remodelling
• Acupuncture and chiropractic as adjuncts when delivered by suitably qualified practitioners

Tier 2: Medical Injections

Image-guided injections of corticosteroid into the affected interspinous spaces. The procedure is typically done under standing sedation. Many horses respond well, often allowing them to stay in work while the rehabilitation programme strengthens the topline. Effects last 6–12 months on average and the procedure can be repeated.

Tier 3: Surgery

Reserved for horses that fail conservative care, or those with severe radiographic and clinical changes. Two procedures dominate UK practice in 2026.

Interspinous Ligament Desmotomy (ISLD)

The current first-line surgical option. Pioneered by UK surgeons in the 2010s, ISLD is performed under standing sedation through small skin incisions. The supraspinous and interspinous ligaments between affected vertebrae are cut, releasing the tension that pulls the bony processes together. Recovery is faster than traditional bone resection — most horses return to ridden work within 3–4 months.

Key facts:

• Procedure time: 30–60 minutes
• Standing sedation, no general anaesthetic
• Two-week rest, then a structured rehabilitation programme
• Reported success rates of 75–90% in published UK case series

Dorsal Spinous Process Resection

The traditional “bone-removal” surgery — the top portion of the affected spinous processes is surgically removed, eliminating the bone-on-bone contact. Done under general anaesthesia or standing sedation depending on case. More invasive than ISLD, with longer recovery, but indicated for severe cases where ligament desmotomy alone is unlikely to resolve the problem.

How Much Does Kissing Spine Surgery Cost in the UK?

As of 2026, ISLD surgery typically costs £2,500–£4,500 in the UK including standing sedation, surgery and follow-up. Dorsal spinous process resection runs £4,500–£7,500 depending on the number of processes operated on and whether general anaesthesia is required. Most equine insurance policies cover the surgery and post-operative care if the policy was in force before symptoms began — always read the fine print, as “back pain” is sometimes specifically excluded.

Rehabilitation After Treatment

Surgery doesn’t fix kissing spine on its own — rehabilitation does. A typical post-surgical programme runs 3–6 months and progresses through:

1. Weeks 1–2: box rest with controlled in-hand walking
2. Weeks 2–8: progressive walking, then trotting in straight lines
3. Weeks 8–16: lunging, schooling on big circles, pole work, hill work
4. Months 4–6: ridden work with focus on long-and-low engagement, gradually reintroducing collected work and jumping

Working with an ACPAT-registered veterinary physiotherapist is strongly recommended throughout.

Prevention and Long-Term Management

For all horses — even those without diagnosis — these practices reduce risk:

• Annual professional saddle checks
• Build core strength gradually before asking for collection
• Plenty of long-and-low work in warm-up
• Pole work and hill work as core fitness, not as “extras”
• Avoid forcing a young or unfit horse into an outline
• Manage rider weight and balance honestly
• Keep regular veterinary, dental and farrier appointments
• Investigate behaviour changes early rather than dismissing them as attitude

Prognosis

The picture for kissing spine horses has shifted dramatically in the last 15 years. Published outcomes for the major treatment options:

• Conservative management: 70–80% improvement, particularly when caught early
• Medical injection alone: similar success rates short-term, with many horses requiring repeated treatment
• ISLD surgery: 75–90% return to former ridden work in published UK series
• Dorsal spinous process resection: 70–85% return to former work, longer recovery

Famous British competition horses including event and showjumping internationals have returned to top-level work after kissing spine surgery. As Horse & Hound notes in its owner guidance, diagnosis is not a career end — and in many horses, the diagnosis prompts management changes that improve overall welfare and longevity.

When to Call the Vet

Get a veterinary back exam booked if:

• Your horse becomes girthy or sensitive to grooming
• Performance has dropped without obvious cause
• Bucking, rearing or napping has appeared in a previously willing horse
• You see visible muscle loss along the topline
• The saddle no longer seems to fit despite no obvious weight changes
• A previous lameness has resolved but performance hasn’t improved

For broader guidance on routine equine health and welfare, the British Horse Society is a reliable starting point for owners.

Frequently Asked Questions

Can a horse recover from kissing spine?

Yes — most do. Conservative management resolves clinical signs in 70–80% of cases, and surgery has a similar or better success rate for those that need it. Recovery requires time, structured rehabilitation and management changes, but a kissing spine diagnosis is rarely a career-ending one.

What are the first signs of kissing spine in horses?

Earliest signs are usually behavioural: girthiness, pinning ears at the saddle, sensitivity to grooming the back, reluctance to stand at the mounting block, and a gradual loss of forward energy. These often appear months before any obvious performance problem.

How is kissing spine fixed in a horse?

Treatment is tiered. Most horses start with saddle re-fit, physiotherapy, and anti-inflammatory medication. If those don’t resolve the problem, image-guided corticosteroid injections often help. For non-responsive or severe cases, surgical options include interspinous ligament desmotomy (ISLD) — the modern UK first choice — and dorsal spinous process resection for more severe cases.

At what age does a horse develop kissing spine?

The condition can appear at any age but is most commonly diagnosed in horses between 6 and 12 years old, often after 2–4 years of ridden work. Early-onset cases in 4–5 year olds suggest a strong conformational or genetic component. The radiographic changes can develop earlier, even in unbroken horses.

How much does kissing spine surgery cost in the UK?

As of 2026, ISLD surgery typically costs £2,500–£4,500 in the UK including standing sedation, surgery and follow-up. Dorsal spinous process resection runs £4,500–£7,500 depending on the number of processes operated on and whether general anaesthesia is required. Most equine insurance policies cover the surgery and post-operative care if the policy was in force before symptoms began — read the fine print, as “back pain” is sometimes specifically excluded.

Can a horse with kissing spine still jump?

Yes. Many international showjumpers and event horses have returned to top-level competition after kissing spine treatment. The key is rehabilitation that genuinely strengthens the back and topline rather than rushing back to jumping work.

Is kissing spine hereditary?

There is growing evidence of genetic predisposition, particularly in Thoroughbred and Warmblood lines. The exact genetic basis hasn’t been fully mapped, but breeding from horses with confirmed clinical kissing spine should be considered carefully alongside the rest of the horse’s breeding profile.

For more on equine health, browse our horse care advice and related guides to sacroiliac joint disease and vertebral subluxation.