Today we are going to talk about back pain in horses.  Back pain is a difficult diagnosis in horses as the signs are vague and horses that appear sensitive to palpation or pressure over the back may not necessarily be painful in this area.  The diagnosis can be aided by nuclear scintigraphy to pinpoint areas of inflammation.  Many times back pain is actually secondary to other problems such as hock pain that is causing the horse to travel incorrectly and creating stress on the back.  Also, back pain can be caused by external factors such as a poor fitting saddle. 

Treatment of back pain requires treatment of any underlying problems as well as rest and anti-inflammatories.  A common treatment used by many veterinarians for horses with suspected back pain is interspinous injections of various substances between the spinous processes of the vertebrae directly in the back.  A recent study was published concerning the ability to actually inject the interspinous area.  The interspinous ligament that is supposedly injected is actually only 1.5 mm thick. In comparison, to show how small this ligament is, the diameter of the 21 gauge needle used to attempt the injections is almost 1 mm in diameter, and this 21 gauge needle is usually smaller than the normal needle routinely used for vaccination.  Consequently, it is not surprising that 90% of the injections attempted by four different veterinarians did not enter the interspinous ligament, but actually ended up in the muscles on each side of the spine.  There are no reports of efficacy of supposed interspinous injections in horses.  It is possible that the local injection of medication in the muscle may be helpful with back pain, but this study indicates the medication is not deposited in the interspinous ligament, and injection of the same substances in any muscle may be just as effective.