2.9 Investigation of Equine Back Problems

Question 1

What is the core tenet about equine back probelms and lameness?

Answer 1

• back pain does NOT cause lameness
• lameness can cause back pain

Question 2

What are the presenting signs of equine back pain?

Answer 2

poor performance, bucking, rearing, ‘cold back’, sensitivity when brushing

Question 3

How do you diagnose equine back problems?

Answer 3

(1) physical exam
- temperment/behavior: swishing tail, refusing to move
- conformation: short-backed horses = great risk of impinging spinous processes
- muscle symmetry
- osseous symmetry
- palpation

(2) dynamic assessment
- ‘disunited’ cantering can be associated with sacro-iliac dysfunction / back pain

(3) nuclear scintigraphy + radiography
- evidence of boney change/pathology + increased metabolic bone activity can demonstrate clinically relevant processes much better than one alone

(4) diagnostic analgesia
- inject 10mls mepivicaine abaxially and ride 15 minutes later
- significant improvement indicates clinical significance

other:
- evaluate track (saddle, saddle pads, restrain devices)
- is saddle too large for the ength of the horses back?

Question 4

What is the radiological grading system for equine spine pathology?

Answer 4

Question 5

What are some differentials for equine back pain?

Answer 5

lecturer was unclear, but I believe the most common are:
- impinging dorsal spinous processes (Kissing Spines)
- fractured dorsal spinous processes (DSPs) due to a fall or blunt trauma
- sacroiliac joint pain (syndrome)

(8) Many nerves along the sacrum. Importantly the nerve outflows occur at the locations marked in black. Any injury/OA/degeneration to these areas could cause impingement of the nerve. The joints are circled. (10) Much more difficult to treat than kissing spinous processes -> only 17% of horses returned to full work. But note, this may also be because sacroiliac joint pain is almost NEVER isolated. It is always secondary to another disease process causing unusual loading or gait (most commonly, a PSD - proximal suspensory ligament desmitis).

Question 6

How do you perform a SI block in the horse?

Answer 6

Right: This is a 3D view from underneath the spine. Note the needle placement (red dot, right). Left: view with spine in upright (normal) position. In both views, you can see two needles, one for each iliac wing.

Question 7

What are the surgical treatments for impinging spinous processes in the horse?

Answer 7

Two options for surgery:

1. Interspinous ligament desmotomy: cuts the ligament between the two spinous processes. Minimalluy invasive (keyhole surgery) with a 53% success rate. Low chance for complications. Not completely sure why this works, but thought to possibly be an incidental nervectomy, which would reduce pain.
2. Subtotal ostectomy: remove bone on spinous processes. 79% success rate, but greater risk of infection.

Question 8

How do you manage impinging dorsal spinous processes in the horse?

Answer 8

(1) ALWAYS start conservative:
- corticosteroids (injection)
- phenylbutazone (analgesic)
- NSAIDs
- ectracorporeal shockwave therapy
- box rest
- 6 weeks non-ridden exercise program

(2) surgery if necessary
- interspinous ligament desmotomy
- subtotal ostectomy