SouthWest Equine Medical and Surgical Center Raising the Standard of Equine Veterinary Healthcare in Arizona

Featured Case of the Month - "SamIam"
Signalment:
5-year-old Warmblood gelding

History:
"Sam" was referred to Southwest Equine Medical & Surgical Center after being treated for the previous 10 months for ongoing hindlimb lameness. Prior to visiting Southwest Equine Medical & Surgical Center, "Sam" had been treated for recurrent upward fixation of patella (locked knee). With "Sam's" condition continuing to deteriorate, it was suggested that he receive a full neurologic examination at SWEMSC.

Physical Examination:
At presentation, "Sam" was given a thorough physical examination that revealed him to be bright, alert, and responsive. All "Sam's" vital parameters (heart rate, respiratory rate, and temperature) were within normal limits. His hydration tests (skin turgor, jugular distension, mucous membranes) indicated he was not dehydrated, gastrointestinal sounds were present in all four quadrants, and his heart and lungs were unremarkable upon auscultation. Marked wear was noticed on the dorsal (front portion) hoof wall of both hind feet.

Ancillary Diagnostics:
Neurologic Examination: Neurologic examination of "Sam" began with examination of his cranial nerves and then proceeded to more in depth test.

No cranial nerve deficits noted.

Marked wear on dorsal hoof wall of both hind limbs.

Proprioceptive deficits were noted on both forelimbs and hindlimbs (most notably on hindlimbs). This was decided to be the cause of the dorsal hoof wear in the hindlimbs.

Ataxia (incoordination) was noted, which seemed to be worse in the hind limbs

Hypermetria (exaggerated steps) present in hindlimbs, and had trouble pivoting
Due to the nature of the clinical signs, the following ailments were added to a Differential list for possible causes of "Sam's" current condition
Cervical Vertebral Malformation a.k.a. Wobbler's (CVM)

Equine Protozoal Myeloencephalitis (EPM)

West Nile Virus

Eastern/Western/or Venezuelan Encephalitis

Equine degenerative myeloencephalopathy (EDM)

Equine herpes virus (neurologic form rhinopneumonitis)

Though the above diseases are differentials for the condition of this horse, certain clinical signs along with the history and signalment helped in moving two of the conditions to the top of our differential list. These two conditions were Cervical Vertebral Malformation (static or dynamic) and Equine Protozoal Myeloencephalitis.

In order to further rule out the possible causes of "Sam's" condition, it was elected to perform survey radiographs (rule out CVM or trauma) and also perform a lumbosacral tap in order to have his cerebrospinal fluid analyzed for any abnormalities (help rule out EPM).

Survey Radiographs of the cervical spinal column were obtained and did not show any substantial lesion (fracture or static malformation).

Lumbosacral spinal tap was performed so that cerebrospinal fluid could be analyzed for any abnormalities and so that Western Blot test could be performed to determine if Equine Protozoal Myeloencephalitis was the culprit behind Sam's aliment. The picture below is borrowed form Equine Internal Medicine by Reed and Bayly and demonstrates how the procedure is done.

The results of the CSF tap came back negative for EPM and the survey radiographs were also negative for an obvious static lesion. It was then elected to perform a myelogram on "Sam" in order to fully rule out any compression to the spinal column. By performing a myelogram, clinicians are better able to visualize lesions that would not normally be seen on standard radiographs (dynamic lesions).

Myelogram was performed with "Sam" under general anesthesia

Results of the myelogram showed "Sam" to have a dynamic lesion that was compressing his spinal cord at the level of C4 -C5. The term dynamic indicates the lesion is only present when the spinal column is in a flexed position.

Therapy:
With the results indicating "Sam" to have a dynamic lesion at the level of C4-C5 (cervical vertebrae number 4 and 5) and the owners wishing to have a normal, athletic career the treatment options available were quite limited. Since "Sam's" condition had continued to deteriorate over the past 10 months, it was likely that conservative management of his condition would not elicit ideal results. Therefore it was elected to contact specialists in the area of spinal stabilization. "Sam's" owners contacted surgeons at The Ohio State University that were noted for their experience and expertise in this particular discipline and the case was thoroughly discussed. The surgeons at OSU interpreted "Sam's" myelogram and concluded that he would be a candidate for surgical intervention. The surgical procedure that would be performed is called Vertebral Interbody Fusion (vertebral stabilization). In brevity, this procedure required "Sam" to be placed under general anesthesia, and have surgeons remove much of the bony prominences on the ventral aspect of C4 and C5, remove the articular cartilage from between the vertebral bodies, and place a stainless basket between the two vertebrae in order to facilitate vertebral fusion, thus eliminating the dynamic component and spinal compression of this ailment.
Owners were made aware of the intricacies of the above procedure and the substantial risks involved in such a procedure. After this discussion, both owners felt that this option would allow "Sam" to have the best opportunity to have a normal life. Therefore, surgeons at SWEMSC contacted the surgeons at The Ohio State University and arrangements were made for them to fly to Arizona to perform the above surgery.

Recovery:
"Sam" recovered from anesthesia with little difficulty and progressed ideally post-surgery. "Sam" was maintained on a very strict antibiotic and anti-inflammatory regimen, and monitoring schedule for the duration of his stay at the hospital. After a 10 day stay at SWEMSC, "Sam" was released with detailed instruction of his required care that included such necessities as being confined to stall rest for 30 days and then returning to the hospital after that time period for follow-up radiographs. We are happy to report that "Sam" has progressed ideally since surgery and owners report that he is much more coordinated on his hind limbs and does not act near as "clumsy" as he was pre-surgery.

Horse Owner Education:
It is important for horse owners to understand that horses that suffer from Cervical Vertebral Malformation (a.k.a. Wobblers Syndrome) not only pose a danger to themselves, but also to people that handle and take care of them due to their incoordination. With this said, even though this condition is very serious there are options available for owners and their horses. In "Sam's" case he fit certain requirements that made him an ideal candidate for this surgery. These requirements included the duration of his clinical signs (ideally more acute the signs the better), his compression being dynamic rather than static, and the fact that "Sam" did not posses any osteochondrosis that would further complicate the procedure. Furthermore, there were some other very important non-surgical variables that led to the ideal outcome in "Sam's" case. Some of these variables include the temperament of the horse (very fractious horses do not make ideal patients) and none more important than owner compliance. In "Sam's" case, his owners were very dedicated to helping "Sam" in any way possible and were more than willing to aid in "Sam's " treatment and recovery in any matter that was asked of them.

It is our hope here at SWEMSC that by sharing "Sam's" case, horse owners will not only be able to spot such abnormalities sooner, but also be aware that there are options available to them in treating this condition.