Understanding the Equine Neck With Dr. Richard Wheeler

In the past, when a horse’s gait has felt off or lacking in its usual impulsion, it was often assumed to be an issue of lameness. Now however, thanks to the improved diagnostics readily available at the Palm Beach Equine Clinic veterinarians are able to more accurately pinpoint the problem area. Perhaps surprisingly, it’s not always in the legs or hooves. With increasing frequency, the horse’s neck is being diagnosed as the root of the issue.

The Anatomy of the Equine Neck and What Can Go Wrong

In order to understand the problems that can arise in association with the horse’s neck, it’s important to first understand the anatomy.

The neck is composed of seven cervical vertebrae running from the head to the thorax, named C1 through C7, and each articulating with each other. The primary purposes of the neck are to move the head and to protect and transport the spinal cord and nerves, which run through the middle of the vertebrae.

Such a major role as the protection of the nerves and spinal cord can also come with some major risks and complications, with clinical signs of these problems generally presenting themselves either neurologically, as neck pain, or as lameness in the front legs. These more specific symptoms may include:

• Ataxia or clumsiness – Ataxia is defined as the “lack of control of bodily movements”. In the case of an ataxic horse, you may begin to notice staggering, sudden loss of balance, or even an inability to remain upright. Ataxia is generally an indicator of a neurological condition or damage to the spinal cord itself, caused by either developmental issues, trauma, or an infectious disease such as equine protozoal myeloencephalitis (EPM). Such neurological cases can often be the most debilitating.
• Lameness – You can think of the spinal cord and the nerves in the neck like an interstate, with the spinal cord itself acting as the major highway. As you are “driving” along the interstate, every so often there are little exits, which is where the other nerves come out. Should there be any impingement on the interstate or spinal cord itself, you’re likely looking at more severe complications – much like an accident on the highway. Should there be impingement on the nerves coming off of the spinal cord, it will more likely present itself like an accident a little way off an exit – not affecting the interstate itself, but possibly causing problems that spread elsewhere. That is where we see lameness issues arise.

This can be more difficult to pin down, but can often be due to pressure on the smaller nerves that pass through the openings in the vertebrae and supply the front legs. Arthritis of the articular facet joints of the vertebrae is another common reason for lameness, as anytime these joints become arthritic or inflamed, it can easily translate to the forelimbs.

• Neck Pain – This will often go hand-in-hand with lameness, as factors such as arthritis of the articular facet joints can lead to both symptoms. Other possible reasons for neck pain include trauma or inflammatory diseases.

Diagnosing the Problem

Neck problems, particularly those related to lameness, are generally diagnosed through a process of exclusion, first performing nerve blocks to or ruling out lower regions of the horse’s body. Palpation of the neck, testing of the neck’s movement, and full neurological exams may also be performed in addition to a full lameness exam, depending on the horse’s symptoms.

As an example, if arthritic factors are suspected, nuclear scintigraphy can be used to look for areas of increased bone turnover. On the resulting bone scan, veterinarians are looking for areas where there is an increased calcium uptake because the bone is actively remodeling. These areas will appear darker on the scan and are generally a good indicator of a boney injury or arthritis, with the darker “hot spots” often appearing above the articular facet joints.

Also new and groundbreaking for the diagnosis of equine neck problems is the use of a Computerized Tomography or CT scan, with the ability to scan a standing horse with light sedation on the near horizon which will be available at the clinic this upcoming winter season.

Treatment