Equine Health: Kissing Spine in Horses – The Basics

Now before we start let’s cover some of the fancy lingo!

Dorsal Spinous Process (DSP):

Dorsal = Near the top or upper surface of an animal (Think of those sinister shark fins, which are called the Dorsal fin i.e the fin at the top of the shark!)

Spinous Process = Bony protrusion on a vertebra (see images)

Therefore, DSP translates to the TOP MOST BONEY PROTRUSION OF THE VEREBRA. You can feel the top of these just under the skin along a horses back (especially in a thoroughbred!).

Bone Density: In simple terms how porous the bone is i.e proportion of holes or gaps in the structure.

• Higher bone density - Less porous = stronger. Less susceptible to damage.

• Lower bone density – More porous = weaker. More susceptible to damage.

The former and latter are very much like comparing a Nestle Yorkie bar to a Cadbury Crunchie Bar – Which is easier to eat?

Remodeling: Is the process of removing a damaged structure and rebuilding it stronger.

️What should the perfect spine look like?

Good degree of space between each DSP allowing for full spinal range of movement. Healthy bone density with no abnormal signs of remodeling. Refer to image below:

What happens in Kissing spine?

Usually presents as one or both when in multiple places of the examples discussed:

• NO SPACE between the neighboring DSP’s (far to intimate to be just neighbors!). With no space they are already overriding when the spine is at rest, when we then factor in movement the two DSPs will “rub” together causing damage to the bone.
  

• CLOSE but not touching DSPs at rest (Not quite there yet but eyeing each other up! Scandal!), in this case they are fairly unproblematic at rest but may come into contact continuously or intermittently in movement.

• In the below image you can see darker patches depicted, this is where changes in bone density may be seen due to remodeling, on Xray this will be seen as whiter patches (increased density), or darker patches (lower density) depending on the severity and stage of remodeling the bone is in. Sometimes trauma to the bone is too frequent and severe for the bone to repair and the remodeling gets out of hand.

But not all Kissing Spine Cases are significant!?

This is very true and can be slightly complicated to grasp and is a hot discussion topic especially when it’s been found on a sales vetting in a horse that has truly never shown any signs of ill health or poor performance (doh!!)

So let's break it down simple...ishhh?

Below are two case examples with confirmed Kissing Spine, 1) is likely significant as there are indicators of pain and impairment of structures. 2) is likely less significant as there are no indicators that the Kissing Spine diagnosis is causing pain or impairment to the horses day to day life and ridden demands.

1) Likely Significant: Horse DISPLAYING PAIN under saddle (i.e ears pinned, nostrils flared, wild eye), BUCKS AND BRONKS when ridden, STRUGGLES TO DEVELOP ITS TOPLINE.

2) Likely insignificant: HORSE HAPPILY PERFORMS AND PROGRESSES through its training, SOUND, NO apparent SIGNS OF PAIN, WELL-MUSCLED and balanced.

Now to complicate it further Case 2) could present like Case 1) later in its career if it sustains an injury or for example develops arthritis in a limb that puts additional/abnormal strain on the spine and aggravates the previously non-problematic area of Kissing Spine.

Or

After stepping up a level or two in training complexity or competition, this is because its previous training and exercise routine did not put any additional strain on the Kissing Spine site but the new training/competition demands do. In this case if the horse steps back or plateaus at its prior training level the Kissing Spine diagnosis is likely to become non-problematic again.

The above is just a dip of the hoof into the water of variables that impact how relevant a Kissing Spines diagnosis is and there are many other variables such as, age, injuries, breed, conformation, discipline, strength and condition and how severe/damaged the DSP’s are ect that can be factored in. Happy to cover this in future posts but this is already a long one! – just comment below if you want more information.

Is Kissing Spine a primary or secondary diagnosis?

It can be both! But more and more research and findings in clinical practice are finding its often secondary to an underlying issue and that Kissing Spine is highly prevalent and non-significant in a large portion of the horse population.

Look out for future posts on Kissing Spine treatment and rehab!