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 Neck Muscle Bracing: How Horses Cope with Forelimb Pain

 

 

Forelimb lameness is common enough that most horse owners can recognize the signs and symptoms. What often goes unnoticed is the compensation occurring in the neck muscles of the horse. Neck muscle bracing is how horses change the loading over the front end to mitigate pain sensations coming from the forelegs. During this time the neck muscles can become overtaxed, painful and stiff. This neck muscle pain must be addressed at the same time as the forelimb lameness, and perhaps for a long time after it’s been resolved. The relationship between the neck and the forelegs may seem complex, but I’ll do my best to breakdown this compensation pattern.

 

How Does Bracing the Neck Help the Horse?

Most horses will have a forelimb lameness at some point in their life. Horses who are lame in either front leg develop the classic “head bob” in conjunction. This distinctive gait feature with the head and neck swinging upward while the painful leg is on the ground, is relieving the horse’s discomfort. The equine head and neck weigh a few hundred pounds and swinging these structures up as the painful leg lands, reduces the load on that limb.

This compensation brings the horse some immediate relief. It’s a strategy that works well so long as the lameness is short lived, as with a hoof abscess or stone bruise. However, horses diagnosed with chronic conditions such as navicular disease, ringbone, or arthritis of the forelegs will end up over using their neck muscles to subtly reduce the pressure placed over the forelimbs. This is particularly common in bilateral lameness cases, (where both front legs are affected). Horses with bilateral forelimb pain can mask the lameness well because both sides of the neck will brace to create equal stride length of the forelimbs.

Many horses can “disguise” an underlying lameness this way for years until finally the pathology in the feet or legs becomes too much. Some horses will have acutely painful necks and may develop neck arthritis in extreme cases. Because the compensation of the neck is a protective response, it can become a more permanent movement pattern. Therefore, neck muscle bracing can continue after the horse is no longer acutely lame, causing pain and performance problems.  

 

Quick Anatomy Lesson

According to authors of Activate Your Horse’s Core, Hillary Clayton and Narelle Stubbs, the equine neck is a complex structure and it houses the most mobile vertebrae in the spinal column. Despite being highly mobile, the neck can be a stabilizing structure as it has robust muscle attachments to the body trunk and forelimbs. There are many complex muscle groups and structures in the horses’ neck. Many of these muscle groups contribute to help the horse, but Let’s look at just two muscles that are frequently sore and over used in the lame horse.

The muscle called brachiocephalicus runs from the base of the horse’s skull at the occipital bone, and attaches to the humerus; a large bone in the forearm just below the shoulder. The muscle called omotransversarius runs from the wing of the first neck vertebrae called the atlas, to the spine and body of the scapula. The function of these muscles under normal movement is to advance the limb forward by extending the shoulder.

In a painful forelimb, brachiocephalicus and omotransversarius can be used to brace the base of the neck and by pulling the forelimb upward, thus limiting the full range of motion of the limb. This can help the horse continue to move forward while reducing his pain and pressure through the forelimbs.

 

Above : Brachiocephalicus is the mucle on the lower portion of the neck and connects to the foreleg. Omotransversarius is the muscle that lies closer to the mane, and connects to the spine of the scaplula.



Test Rounding Response


Here’s a simple test you can do on your own horse at home. This test is a fun way to get to know your horse’s anatomy, but it will not replace an exam by a veterinarian. It could help you detect an issue and reach out for further help and diagnostics.

I learned this simple technique from Arlene White who is a human and animal physical therapist at the Animal Rehab Institute in Florida. If you are on the left side of the horse, use your left hand to gently but firmly hold the brachiocephalicus muscle and apply gentle pressure. Try to make your hand feel gentle but firm while slowly squeezing. Horses with a healthy brachiocephalicus and omotransversarius will round their neck up in an arched shape when these muscles are gently squeezed. This creates the motion we often refer to as “rounding” when we are riding. If a horse has healthy, non-painful muscles he will round away when a small amount of pressure is applied.

A horse with painful muscles at the base of the neck will lift his head, step backwards and invert his neck. Some horses may pin their ears or try to bite. Always be aware of your own safety and have a handler help you if necessary.

 Above: Here the horse shows a healthy rounding response when brachiocephalicus is squeezed.


Above: the horse has been coaxed with a treat into a position that would display a painful response to this test.  

 

Which Horses are at Risk?

Horses with a history of long term bilateral hoof pathology such as navicular or laminitis should have their necks looked at by a veterinarian. Horses with a club foot or high heel/low heel syndrome could also be coping with neck muscle bracing and imbalances due to the discrepancy in their forelimbs. Horses with short term lameness in one front limb (as with an abcess or stone bruise) are less likely to have continued compensation, however checking their necks is always a good idea.

 

Signs and Solutions

If your horse has a history of chronic painful conditions in the forelegs, have a veterinarian do a thorough examination of your horse’s neck. Bracing of the neck muscles maybe a continued part of how these horses move and alleviate stresses to the front legs. This can be subtle to see, but a horse who is compensating this way will have a hard time rounding the neck when ridden, and may feel very heavy or stiff the bridle. I’ve known horses who were thought to be “hard mouthed”, however upon examination by a vet there was an underlying neck issue likely caused by prolonged compensatory bracing. These horses will often struggle to build a healthy topline and will look “ewe necked”.

Horses with over used neck muscles can benefit greatly from massage, stretching and mobilization exercises. Pain relief can be achieved if the muscles can relax and move normally. Horses with acute pain are sometimes treated by the veterinarian with shockwave and injection therapies. Often a further inspection of the forelimb pain source will be required, which may mean the original lameness isn’t as well controlled as previously believed.

Sorting the issues out can take some time and a good team of professionals including your vet, farrier, bodyworker, chiropractor and massage therapist.  Horses make tremendous progress and even fully recover their neck movement with the right help.  Your horse may become a light, willing partner with a little attention paid to his neck.

 

References

  1. Activate Your Horse’s Core by Hillary M. Clayton and Narelle C. Stubbs. 2008 Sport Horse Publishing
  2. Atlas of Equine Anatomy by Chris Pasquini, DVM,MS,  1991 Sudz Publishing