34th Annual Scientific Meeting proceedings

The possibility of using the Cloward technique for the treatment of equine cervical malformation (wobblers) was first introduced by George Bagby MD over drinks at the Frontier Lounge, Las Vegas Nevada in February 1977 while attending an Orthopedic Surgery seminar as guests of Dr. Bagby.  Drs. Pam Wagner and Marc Ratzlaff were interested in developing a MarMor  implant for the treatment of degenerative joint disease in racing thoroughbreds. George had developed a cooperative program with the medical community in Spokane Washington and the College of Veterinary Medicine, Washington State University in Pullman, Washington. George drew out the design of the Cloward technique on a cocktail napkin for the use in fusing cervical vertebrae in humans. Within a week we did our first case!  Since that time we have done over 1200 clinical cases with 87% of patients improving 1/5 grades and over 54% improving TWO grades or more.

The procedure has evolved from a single level using a 16 mm autologous bone dowel to a 25 mm bone dowel, bovine xenografts, stainless steel baskets (Bagby basket , fully and partially threaded stainless steel Seattle Slew implants and now we use titanium.

The accuracy of the diagnosis improved as we developed with myelograms initially using an oil base contrast agents  to metrizamide and now to Iohexol . We also started the use of CT to evaluate the degree of lateral compression.  Initially this was limited to the anterior cervical vertebra, but stimulated by the work of  Mads Kristofferson at Evidensia in Sweden, using a large bore CT unit can result in diagnostic images including C7/T1 in a horse weighing greater than 600kg. Now there are over 15 units world wide capable of doing Caudal Cervical CT/Myelogtsms.

Other projects have included the role of genetics and diet, effects of stem cells into the spinal cord, use of force plates for objective assessment of response to treatment , EEG evaluation and on board sensors.

1.  Treating the cause of inflammation or compression of the spinal cord can result in some amazing improvement if the patient is kept alive and given a chance.
2. The successful treatment of spinal cord pathology is based on the same philosophy I use to approach all my cases:  Develop an aggressive plan for a complete diagnosis with appropriate treatment ASAP (as soon as possible).
3. Myelograms and Computed Tomography (including C7/T1) CAN BE PERFORMED efficiently in private practice (up to 600 Kgs and more).  Even a negative myelogram   is worth the time and effort for the client and patient.
4. Even Grade 4/5  patients can stand after a CT/Myelogram although may require a sling assistance.
5. Excellent quality cervical radiographs can be obtained in a field situation concurrently with the initial neurological exam and blood samples sent for Herpes and EPM assessment.  Not only do the radiographs enhance the bottom line of the practice, but clients appreciate the complete prompt service.
6. Wobbler Syndrome is NOT limited to young horses.  Many middle aged  and older horses having poor performance issues can have mild compression and finally reach a point of no longer wanting to do their jobs or becoming acutely ataxic especially following chiropractic treatments.
7. Patients with subtle signs (and mild compression changes) can show a number of changes in behavior that do not respond to a longer whip, more leg and spurs, more bits and changes in saddle.  These include refusal to enter the show ring or racetrack, wheeling and bolting, flagging of tail, bucking, heavy on fore hand, head shaking, refusing to back (in a straight line), pacing.  When presented with patients like this it is worthwhile to do neck flexions, placement tests, backing and going up and down hill with head both normal and elevated.  IF no obvious ataxia, and no history of stumbling, then observe them under tack.  They can make a good rider look bad with excessive hip movements (saddle up and down), cross cantering, and inability to maintain a canter in a small circle for more than one complete round.
8. Whenever possible a neurological evaluation should also have a complete lameness exam AT THE SAME TIME since the same pathogenesis resulting in  cervical developmental problems  can also cause problems in many other joints especially the stifles, hocks and fetlocks. When a source of lameness/ gait symmetry is not obvious THINK NEURO!
9. Many horses with recurring suspensory ligament problems (especially hind legs) have neurological deficits related to the cervical region.  Nuclear scintigraphy often shows multiple sites of isotope uptake in the feet since they are hitting the ground unevenly and with more force than a normal horse. Horses can have both appendicular and skeletal pathology at the same time.
10. Horses with myelopathy and a foot bruise or abscess will appear lamer than a normal horse with the same condition.  Many post operative horses that are lame or uncomfortable 6 to 8 weeks after surgery often have foot abscesses that have matured with the stress and the stall confinement.
11. Patients can start showing improvement within 2 weeks of fusion depending on the type of lesion.  Rehabilitation can be initiated within 30 days when an EXPERIENCED TEAM is involved with a compliant patient.  Our own horse HUGO TEE started race training at 60 days post op and won his first start at Santa Anita at Day 180.
12. Clinical Signs can be slow to improve and the entire team (owners, trainers and veterinarians) have to be resigned to being patient.  Many horses require 18 to 24 months to get as good as they are going to get.
13. Physical Therapy in the Rehab Period is very important and usually the more MONITORED exercise the better.
14. The key to successful outcomes and professional enrichment is developing a TEAM approach of surgeons, anesthesia, technicians, recovery room assistants and grooms    who are positive using the aggressive approach and have experience with anticipated and unusual post operative developments.
15. Young foals can – and should – have cord compression treated early in life.  They DO NOT have to wait until they are weaned or yearlings to undergo successful surgery.  Horses can have both EPM and cord compression at the same time – and need to be treated at the same time – DO NOT treat EPM for 3 to 6 months, and then go to surgery and expect  the best result.

Surgical Tips

1. Endoscopic exam to make sure patient is not a roarer before surgery. If they have left sided recurrent laryngeal neuropathy then use a left sided approach. Always have a tracheostomy pack immediately available.
2. Video tape a neuro exam before surgery. Review the images and lab before going to surgery.
3. Place preoperative markers on same side as the cassette will be placed as parallax especially on a smaller horse can be confusing. Always state  OUTLOUD that proper level is being done when viewing intraoperative images!
4. BEFORE Closing always inspect the site for sponges etc and state OUTLOUD “I Don’t See any Frigging sponges!
5. Do not retract the front legs too forcefully. Release pressure when beginning initial closure to reduce myopathy/neuropathies.
6. Place urinary catheter prior to moving patient to recovery. Safer floor and quieter recovery.
7. Hand recover on a large soft pad with head and tail ropes and experienced team.
8. Grade 4/5 patients over 2 years should be conditioned to a sling before surgery.
9. Be Patient! especially if anesthesia has over sedated post operatively.
10. Leave an endotracheal tube in place as long as possible especially on caudal cases.
11. If traveling to an outside hospital take a Hudson Brace JUST IN CASE. Spend time with the technician/nurse in charge of surgery going over procedure and answering any concerns.

References

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• Cloward RB. Vertebral body fusion for ruptured cervical discs. Am J Surg 1959;98:722-7.
• Adrian M, Grant B, Ratzlaff M, et al. Electrogoniometric analysis of equine metacarpophalangeal joint lameness. Am J Vet Res 1977;38(4):431-5.
• Wagner PC, Grant BD, Bagby GW, et al. Surgical stabilization of the equine cervical spine. Vet Surg 1979;8:7-12.
• Wagner PC, Grant BD, Bagby GW, et al. Evaluation of cervical spinal fusion as a treatment in the equine wobbler syndrome. Vet Surg 1979;8:84-8.
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• Grant BD, Barbee DD, Wagner PC et al. Long term results of surgery for equine cervical vertebral malformation. Proc Am Assoc Equine Pract 1985; 31: 91–96.
• Bramlage LR. Arthrodesis of the metacarpophalangeal joint-results in 43 horses. Vet Surg 1985; 14:49.
• Moore BR, Reed SM, Robertson JT. Surgical treatment of cervical stenotic myelopathy in horses: 73 cases (1983–1992). J Am Vet Med Assoc 1993; 203: 108–112.
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• Trostle SS, Grant BD, Bagby GW et al. Clinical results of kerf cylinder (Seattle Slew Implant) to reduce implant migration and fracture in horses undergoing surgical interbody fusion. Vet Surg 2003; 32: 499.
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• Grant BD, Schutte AC, Bagby GW. Surgical treatment of developmental diseases of the spinal column. In: Equine Surgery, 3^rd ed. Auer JA, Stick JA (eds) Saunders Elsevier 2006; 544–565.
• Francois I, Lepage OM, Carpenter E, Grant BD et al. Mesenchymal stem cell transplantation into the spinal cord of healthy adult horses undergoing cervical anterior interbody fusion. Vet Surg.2021;50(5) :1107-1116 doi:10.1111/vsu.13611
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