If you read my very first post, Life with Horses, you’ll remember that Larry made a trip to the Ontario Veterinary College in August. My vet had recently taken radiographs (X-rays) that showed that Larry had kissing spine in a couple of spots, as well as arthritic changes in his neck. We decided to send him to the OVC for a more thorough neurological workup.

At the time, it seemed like the whole world knew about kissing spine except me. So let me tell you what I’ve come to understand of Larry’s condition.

Horses, humans – all vertebrates – have a spine that is made up of vertebrae which fit together in a flexible column. Each vertebra is a bony ring with an inner hole through which the spinal cord runs. Sticking out of the dorsal surface of each vertebra is a bony projection called a spinous process. In humans, the spinous processes are the knobs we can feel when we run a finger down the middle of our backs. Spinous processes are where muscles and ligaments attach to the spine.

The technical term for kissing spine is overriding dorsal spinous processes (ORDSP). In a normal horse’s back, the spinous processes can be close to each other, but shouldn’t touch. In the case of kissing spine, though, two or more of the processes are so close that they rub, or “kiss”. This causes irritation and pain, and may lead to bone cysts and arthritic changes.

Below is a radiograph of Larry’s spine. You can see the spots where his spinous processes are close enough to have caused irritation, which shows as white areas. The worst spot is T11-T12. (“T11” means Thoracic vertebra 11).  The muscles in this region tighten in an attempt to keep the spinous processes from rubbing together. Since I bought Larry three years ago, I’ve had on-and-off problems which can ultimately be traced to him protecting his back. It’s made his hocks and stifles sore. Injecting his hocks was helpful, but didn’t address the root cause.

What is the root cause? Simple answer: I don’t know. Several factors may have contributed.

As a race horse, Larry was asked to carry the weight of a rider when he was two years old – still a baby. His back wouldn’t have been very strong and his vertebrae wouldn’t have finished growing – a horse’s vertebrae don’t ossify till he’s 3 – 5 years old. The rider’s weight would have caused his spine to dip a little, and that would have brought his spinous processes closer together.

A poorly fitting saddle would also make Larry brace and hollow his back. When I bought him, I also had to buy a new saddle. He was hard to fit because his back is so short and the dip behind his withers is so pronounced. Even with a new saddle that was professionally fitted, it took over a year of fine-tuning till I was satisfied that it was fitting well enough not to be contributing to his discomfort.

The way he’s been ridden for several years could also have affected his spine as well as the arthritis in his neck. Too many of us don’t really know how to gymnastically develop a horse so he’s strong enough to carry our weight and perform the exercises involved even in low-level dressage. I’ll talk about my journey on this path in future posts.

In addition to kissing spine, Larry’s radiographs also showed some arthritis on the dorsal surfaces of his cervical vertebrae (i.e. in the neck) just in front of his withers. I know for a fact that this part of his neck used to be crunched together when I would try to ride him “in a frame”. This would have irritated the arthritis in this area. The reason I took him to the OVC was to obtain more detailed radiographs in order to determine if his spinal cord was affected. If arthritis had penetrated into the spinal cord channel, then roughened edges and constricted space would irritate the spinal cord. The first layer of spinal cord that would be affected is the part that innervates the hind end. This would cause Larry to become wobbly in his hind legs. If serious enough, it could cause him to fall.

Fortunately, the arthritis in his neck was determined not to have affected the spinal cord. This means I can continue to ride him, as long as I am “aware of his limitations”. In other words, I have to make sure his saddle fits him really well. It must position me in the right spot on his back. I have to ride him in a way that will strengthen his core in order to “counteract spinal dipping and keep the gaps between the processes open when carrying the rider“.

So I have an amazing opportunity to learn new skills that will make Larry comfortable and happy under saddle. . There is life after kissing spine and neck arthritis. I know it will be exciting. Stay tuned…