Clinical Features of Primary Neck Problems in Horses

It has become easier in recent years to acquire X-rays of the neck in the field due to the advances in X-ray equipment. This has led to an increasing diagnosis of so-called neck problems. This is in part through lack of appreciation that a large proportion of mature, comfortable horses have X-ray abnormalities of the neck vertebrae that are clinically silent. Moreover, there are clinical problems that can masquerade as possibly being related to the neck. But, in fact, they reflect an unrelated problem.

For example, a horse might be unwilling to turn to the right and appear to have a stiff neck. However, the primary problem is right hindlimb lameness. Using appropriate nerve blocks in the limb, the horse turns easily, despite the presence of X-ray abnormalities of several neck vertebrae.

It is therefore of critical importance to be aware of key clinical features that might reflect a primary neck problem.

Warmblood Study of Necks

Researchers conducted a recent study of Warmblood horses in the U.S. and UK. Horses with neck pain or stiffness or forelimb lameness attributable to the neck were studied. The study also included horses with incoordination and weakness consistent with compression of the spinal cord in the neck region. Extensive, systematic, standardised clinical assessments were performed.

The results from these ‘case horses’ were compared with control horses. These animals were either working comfortably and undergoing pre-purchase examinations, or they had another problem such as lameness that was abolished by nerve blocks of the affected limb.

Two experienced equine veterinarians performed the clinical evaluations of all horses.

Findings of the Study

Focal muscle atrophy (wastage) in the caudal (lower) half of the neck was only seen in cases and not control horses (see above image).

Patchy sweating, focal areas of reduced reaction to touch, or areas that were hyperreactive to touch were also only observed in cases.

Only cases showed a pain response to firm pressure applied over the caudal cervical articular process joints and transverse processes. The horse moved away when pressure was applied and altered its facial expression.

neck flexion test — Restricted lateral neck flexion. The horse is tilting its head as it tries to reach the food bowl. It could not reach farther back. The horse persistently placed the right forelimb in front of the left as it tried to bend to the right. The horse had neck-related forelimb lameness. Courtesy Dr. Sue Dyson

This sideways flexion of the neck was restricted in a higher proportion of the cases compared with controls.

In no case was hindlimb lameness attributable to neck problems. Hindlimb incoordination and weakness was not observed in control horses. However, it was identified in 40% of case horses.

Cases were more likely to have a low head and neck carriage when moving in hand, on the lunge, and when ridden compared with control horses.

Restricted range of motion of the neck when turning in small circles, on the lunge, and ridden was more prevalent in cases compared with control horses.

Cases were more likely to show tilting of the head and neck during exercise than control horses.

head and neck tilt — Tilting of the head and neck with the nose to the right in left canter. The horse, a showjumper, had a neck-related left forelimb lameness. The head tilt was consistently worse in canter than trot, especially on the left rein. Courtesy Dr. Sue Dyson

Limb Signs in the Study

Hopping-type forelimb lameness was only observed in cases. Cases were more likely to show forelimb stumbling than control horses. Deterioration in forelimb lameness after diagnostic anaesthesia (nerve blocks) occurred in cases and not control horses.

neck pain and stubling — A Highland pony stumbling on the left forelimb. The pony shook the head after stumbling and tilted the nose to the right, with the left eye tightly closed, reflecting neck pain. This was associated with degeneration of intervertebral discs at the cervicothoracic junction. Courtesy Dr. Sue Dyson

In no case was hindlimb lameness attributable to neck problems. Hindlimb incoordination and weakness was not observed in control horses. However, it was identified in 40% of case horses.

Conclusions

It was concluded that systematic comprehensive clinical evaluation should enable clinical differentiation between horses with caudal cervical lesions and horses with other causes of gait abnormalities.

Correct diagnosis is essential for the development of appropriate treatment and management strategies.