Veterinarians are just starting to employ a procedure that might offer the most consistent treatment yet for this puzzling condition.

Dana Sendro had big plans for Tex when she purchased him. He was supposed to give her daughter a shot at being competitive in the hunters. But Tex went from promising prospect to horse with an uncertain future in an instant after undergoing an X-ray for a mysterious bump.

Patricia Doyle, DVM, M.S., Dipl. ACVS of Mid-Atlantic Equine Medical Center in Ringoes, N.J., performed the examination.

“Dr. Doyle came back and said, ‘I don’t think the bump is from this, but during the X-ray, I found that he has kissing spine from T13 to L3,’ ” Sendro recalled.

The bump turned out to be a hema­toma, which Doyle drained, and it never returned. However, the 6-year-old geld­ing’s misbehavior issues didn’t go away with the hematoma.

“He is still very spooky and unpre­dictable,” said Sendro, Franklin, N.J. “He can go around on a loose rein and then all of a sudden just takes off. He can make this grimace where he shows his teeth like he is in pain. It could be the baby in him, but when he takes off like that it’s scary.”

Tex is currently in training with Liz Perry-Merbler, and Sendro is evalu­ating her options. She put in the hours researching kissing spine and learned about a promising new surgery called interspinous ligament desmotomy, which is now at the top of her list for treatment.

“It’s hard to sort through all of this and know where to start, especially with limited funds,” said Sendro. “I want to have a plan, rather than randomly throw lots of money into therapies, with the final outcome being that surgery is the best option. Bone scans will probably tell a lot about if the back is inflamed, but they are really costly. I would rather save up for this new ISLD surgery, since it sounds so promising and makes the most sense to me. This way I know the pain is gone and we can assess from there, but we are committed to him, whatever the outcome.”

A Common Problem

Tex is experiencing a problem that affects many horses. While kissing spine is simple to identify, that’s the only easy part. Figuring out how to treat it, repair it or live with it can be a major challenge.

Known clinically as overriding dorsal spinous processes, kissing spine most commonly affects the vertebrae in the mid and caudal thoracic area of a horse’s spine (T13-T18), where the saddle is placed. It can occur closer to the horse’s rump, but much more rarely. On a healthy spine, the dorsal spinous processes, the vertical part of the verte­bral body, are evenly spaced without touching each other. In kissing spine, the dorsal spinous processes impinge or come in contact with the spinous processes directly in front or behind, or cross each other rather than remaining in a straight line, upright, with the appropriate amount of spacing between them.

For some horses, the presence of kissing spine on radiographs is associ­ated with pain and behavior issues such as bucking, rearing, irritation during saddling, and back and hind end sore­ness. But one of the mysteries of the condition is that some horses clearly show developed kissing spine on radio­graph and exhibit no signs in their performance.

In 2011 at the American Association of Equine Practitioners Convention, Tracy Turner, DVM, MS, Dipl. ACVS, of Anoka Equine Services in Elk River, Minn., presented his study on lameness, kissing spine and back pain. He evalu­ated 212 horses from early 2004 to the end of January 2011 and determined that while kissing spine does contribute to back pain, it can be tough to pinpoint whether kissing spine is the cause of a horse’s back pain.

“My research suggests that about 40 percent of horses have this condition,” he said. “Certainly 40 percent of all horses do not have back pain. Kissing spine would appear to be a conforma­tion anomaly that predisposes to back pain. The difficult part is determining the horses that have pain as a result of kissing spines, but less than 5 percent of lameness issues are related to kissing spines.”

Turner found that Thoroughbreds were the most likely breed to have kissing spine—41 percent of his cases were Thoroughbreds, followed by Quarter Horses (26 percent), and warm­bloods (23 percent).

“I think kissing spines are in a horse’s genes,” said Turner. “I believe it develops sometime between when a horse is a weanling until they become 2 years of age. I have taken a signifi­cant number of back films in neonates and have not seen any cases of kissing spine. However, we have many horses that come in for pre-training screening [at 2-4 years old], and we have radio­graphed the backs of these horses and found kissing spines with no clinical signs [40 percent].”

A Simple Surgical Approach

Treatment options abound for horses that do have hampered performance ability due to kissing spine. Steroid injections, mesotherapy, shockwave therapy, acupuncture, chiropractic treat­ment, TILDREN, massage and physical therapy alone or in combination have been used to relieve the pain.

However, not all horses respond to these therapies, and, until recently, the only surgical option was quite involved and didn’t yield consistent positive results. This invasive procedure required incisions and often the use of a bone saw.

But Richard Coomer, MA, VetMB, CertES, Dipl. ECVS, MRCVS, of Cotts Equine Hospital in Narbeth, England, published a study in 2012 about a new surgical technique. The study, “A controlled study evaluating a novel surgical treatment for kissing spines in standing sedated horses,” came out in the June edition of Veterinary Surgery and showcases a new approach to kissing spine surgery.

“I began this work in 2009 in New South Wales,” Coomer said. “It devel­oped out of necessity really, as in this part of the horse world many are not insured, and there is not a lot of money to spend on treatments. I got the idea from a conversation I had with some colleagues in France who were working on endoscopic techniques to aid with kissing spine.”

The veterinarians noticed that simply cutting the interspinous ligament seemed to make the horses more comfortable as opposed to removing the bone.

“In theory, you could cut the ligament with a pair of scissors and still receive the benefit,” said Coomer.

His study included 37 horses he surgically treated with his method, which involves transecting the liga­ment through a 1-centimeter “keyhole” incision along the side of the affected vertebra or vertebrae while the horse is standing but sedated. There was also a control group of 38 horses treated with cortisone injections in the appropriate locations.

Both groups of horses were stall rested for 24 hours then handwalked twice a day for 30 minutes for three weeks before being turned out in a paddock. Eighty-nine percent of the medically treated horses recovered successfully in comparison to 95 percent of the surgical group. Nineteen cases experienced recurring back pain, and all of those were from the control group.

And the real shocker was that when Coomer took radiographs of 19 of the surgically treated horses, there was marked improvement in the spacing between vertebrae, apparently reversing the “kissing” syndrome.

“It’s cutting in the actual impinging area that’s the most important, and I know it’s the hardest thing to do because they usually are so close together,” Coomer said. “It’s conceptually very straightforward, but as a lot of surgeons have found, when you actually get down to it, it’s not as easy as it sounds. I prob­ably took 30 or 40 horses before I was able to cope with the right interspinous ligaments. The interesting thing is my success rate had no real change from the improvement of me handling the learning curve that went with the procedure. Early on we only received horses with very severe cases, like seven, eight or nine spaces that had really sore backs and chronically bad feet, and even when I felt I didn’t do a particularly good job, the results were encouraging, so we persisted.”

Coomer noted that surgery led to an immediate improvement in back pain. “A lot of horses become much more relaxed overnight,” he said.

Despite the encouraging results, Coomer said a horse’s rehabilitation after the surgery is just as integral to its healing.

“I say it’s 50 percent surgical and 50 percent aftercare,” he said. “This surgery focuses on rehabilitation, and if you don’t do the aftercare you won’t see the results. You have to allow the horse to start using his back again normally to rebuild his core strength and to be comfortable.”

More Than A Cure

While relief from the pain of kissing spine is a huge accomplishment, Coomer believes his new technique is just one step along the way of dealing with the condition.

“I hope down the line people will speculate on how these horses are performing after the surgery and look more at the possible genesis of kissing spine and why it really happens,” he said. “There are a lot of proposed mechanisms, but I think undiag­nosed lameness goes hand-in-hand with back pain. A large proportion of horses have back pain and then overuse their legs because they don’t use their backs. Then it accelerates the wear and tear on their legs. Many horses don’t have much core strength, so they would be prone to developing a back problem, and I think kissing spine is most likely a symptom of their chronically malfunctioning back.”

Another veterinary surgeon, Tim Lynch, DVM, Dipl., ACVS, ACVSMR, of the Peterson & Smith Equine Hospital in Ocala, Fla., took note of Coomer’s study and the high success rate for ISLD. Lynch has performed his version of the procedure on five horses since the winter months and feels it possesses great potential, but he hasn’t completed enough cases to pass judgment.

“It’s not a very pretty surgery, or what I would call glamorous,” he said. “It involves a lot of grinding around between the interspinous liga­ments, but it’s a very small incision. I followed the rehab protocol in the paper, and two horses are doing really well while the other three are still recuperating, so I haven’t done enough to make heads or tails of it, but it is very interesting.”

Like Turner, Lynch’s practice performs radiographs on a variety of young horses in training, and he’s always astonished by which horses present symptoms of kissing spines, while others seem to be impervious to the condition.

“We see a lot of horses that are back sore, so we bone scan them, and they have uptake in the dorsal spinal process, which is probably kissing spine, and they still perform very well,” he said. “Then there are the ones you can’t even get a saddle on, that buck and rear and are quite dangerous.”

Pre-purchase examination bone scans on young Thoroughbreds reveal kissing spine on a regular basis, but it’s difficult for veterinarians to predict whether the mechanical impinge­ment will ever lead to back pain and lameness.

“I’m always surprised by how young they are; they show no signs of clinical lameness, and they already having kissing spine,” Lynch said. “Is it because of the breed or confor­mation of the horse? It’s odd and frustrating for veterinarians because it’s all over the map.”

Lynch started performing the proce­dure because he found that many of the traditional medical therapies used to treat kissing spine led to disap­pointing results.

“It’s also very difficult for us as the veterinarians to determine which horse requires what kind of treat­ment,” he said. “I’m not saying this surgery could be a cure-all, but maybe we can discover which horses benefit from surgery versus medical therapy.”

Because the recovery rate in Coomer’s published paper is so good, it’s tempting to conclude that this surgery will be the right choice for every horse diagnosed with kissing spine. But it will take many more surgeries before veterinarians can determine the cases where the risk and expense of surgery will most likely yield a positive outcome.

“We are trying to weed our way through to identify if a horse has over­riding kissing spine do you leave it alone or cut it?” said Lynch. “You just try to include your odds, and we’ll see how this surgical procedure truly does work.”

If you enjoyed this article and would like to read more like it, consider subscribing. “New Surgery May Be The Key To Kissing Spine” ran in the Sept. 9, 2013 issue.