Pain Management Case of the Month: Q

A 15-year-old dressage Morgan gelding with no significant medical history  presented with progressive ataxia.

Management of Chronic Pain in a 15-Year-Old Morgan Gelding

by Lindsay RD Benson, DVM, CVA, CVPP

D-CS-Q1.pngSignalment and History

Q, a 15-year-old dressage Morgan gelding, presented with progressive ataxia in the previous month. He had not had any significant medical history prior. His owners were willing to do anything necessary to improve mobility to have Q back to eventing.

Physical Examination and Diagnostics

Physical exam revealed a grade 3/5 ataxia and paresis in all four limbs, which was more severe in hind limbs. He was resistant to backing up and had a hypermetric gait. Q weighed 435 kg, with body condition 5/9. Pain  was noted on palpation at C2–C5 with decreased range of motion with lateral flexion of the neck, left greater than the right. Neurologic examination revealed intact
cranial nerves, tail, and normal anal tone. Muscle atrophy of the left pectoral and triceps muscles was present. There was hypertonicity of the neck muscles, withers, and lumbar muscles. He was
noted to cross his hind limbs, indicating a decreased central proprioception and knuckled intermittently. His Colorado State University (CSU) comfort score was 3/4.

Cervical neck radiographs and myelogram diagnosed cervical vertebral malformation, “wobblers syndrome,” spinal cord compressive lesion at C7–T1 with hypoplasia of C6 transverse process. He had a moderate articular facet joint osteoarthritis at C4–C5, C5–C6, and C6–C7. Cytologic analysis of cerebrospinal fluid was unremarkable. Q underwent a Bagby Basket implant for cervical  stabilization at vertebrae C6–C7. Goals of treatment postoperatively were to maintain pain and rehabilitate to move into dressage.

Treatment and Outcome

A multimodal treatment plan including analgesics, nutraceuticals, acupuncture, massage, physical therapy, laser therapy, and mesotherapy was developed knowing that the recovery  postoperatively would be lengthy. Q recovered uneventfully from the procedure, with a CSU comfort score of 1.5/4. He maintained postoperatively on phenylbutazone and started on vitamin E supplementation. Seven days postoperatively, Q was noted to be quite stiff and reluctant to move, have an elevated heart rate 80 beats per minute, and have prominent muscle fasciculation in his neck, chest, and cranial thorax; his CSU comfort score was 3/4.

Q was given adjunctive pain management with the addition of butorphanol constant rate infusion, which reduced his CSU comfort score to 1/4. Q was maintained in the Anderson Horse Recover Sling System for 4 weeks postoperatively until the implant was determined to be stable with adequate remodeling of cervical vertebrae at the surgical site. During these weeks, Q was given daily  physical therapy exercises in the sling and supervised periods without the sling support to encourage coordination, maintain muscle tone, and regain muscle strength. He also received massage therapy sessions by an equine massage therapist.

Q was given acupuncture twice weekly to aid in his muscle stiffness and pain from his surgery and restriction of activity in the sling. A combination of dry needle, electroacupuncture, and aquapuncture were used in varying combinations of points focusing on cervical pain relief and ataxia. Adequan was administered at BL 23 (500 mg per horse IM q 4 d x 28 d, then monthly).

Once Q was stable enough to remain upright without the sling support, he was started on a daily rehabilitation program with the physical therapist. This consisted of hand walking, walking over curbs, walking up and down hills, backing, passive range of motion exercises, and carrot stretch exercises to encourage motion of the neck in all directions. Q made slow but steady progress with this program; however, he experienced short episodes of setbacks where he became stiffer and more reluctant to move, likely due to overexertion. Each time he responded well to a course of therapy with phenylbutazone, acupuncture, and massage.

Rehabilitation Program

D-CS-Q2.png

Cavaletti Work

Q was recommended to be worked twice a day using cavalettis at differing heights and spacing. He was worked for 20 minutes each time with a 5- to 10-minute warm-up and cool-down period of hand walking. These sessions were gradually increased to 40-minute sessions.

Warm-up was hand walking for 5–10 minutes on flat ground aiming for him to get less stiff and warmed up. At the end he was backed up for about 10 paces to work on  mangaging his stifles.

Morning cavalletti course consisted of 7 poles: 1 pole (single), then 10 feet, then 2 poles 2 feet apart (double) then 10 feet and a single and repeating that pattern.

  • Stage One: Poles are first placed on the ground.
  • Stage Two: increased to 4-inch height for 3 passes.
  • Stage Three: increased 4 more inches for 3 passes. Double poles increased another 4 inches for 3 additional passes.

Afternoon cavalletti course consisted of 7 poles: 1 pole (single), then 10 feet, then 2 poles 2 feet apart (double) then 10 feet and a single and repeating that pattern,  placed in an arch shape.

  • Stage One: Poles are first placed on the ground.
  • Stage Two: increased to 4-inch height for 3 passes.
  • Stage Three: increased 4 more inches for 3 passes. Double poles increased another 4 inches for 3 additional passes.
  • Cool-down: Walk on flat ground for 5–10 minutes to allow muscle to cool down. Application of hot pack over his neck and low back area for 5–10 minutes.

Q was transitioned to a maintenance pain plan prior to transport from the clinic to stable for continued recovery. A combination of continued anti-inflammatory and pain management therapy with gabapentin (5 mg/kg q 12 hours) and Firocoxib (0.1 mg/kg q 24 hours) along with a rehabilitation program focusing on cavaletti rails and stretches was  applied. His acupuncture and laser therapy targeted his neck, wither, back, and pelvis areas. A class 4 laser—set at post-op (neck), neck (cervical), and joint (neck)—was used.

Q had a severe setback: Upon the trailer ride from the hospital to the stable for continued rehabilitation and care, Q’s pain notably increased and his range of motion diminished; his CSU comfort scale was 3/4. All current therapies were adjusted, increasing electroacupuncture and laser therapy to twice weekly, increasing gabapentin (10 mg/kg q 8–12 hours), reducing height of daily  Cavaletti rails, and continuing Firocoxib (0.1 mg/ kg q 24 hours). Despite adjustments made to Q’s protocol, a decrease in pain score and improvement in range of motion was not achieved.

Transport to a hospital setting for more extensive care was not an  option due to risk of further injury, so a mesotherapy treatment at the stable was performed. Q was sedated for his treatment with Detomidine 0.015 mg/kg and Butorphanol 0.02 mg/ kg IV. Mesotherapy technique with a 5 linear multi-injector, 27 G x 4 mm needles were used with solution of bupivacaine (0.02 mg/kg of 0.5%), methylprednisolone (200 mg single dose), and 10 mL Sarapin diluted in lactated ringers solution to 120 mL volume. Two bilateral parallel rows, starting caudal to the withers along the two Chinese acupuncture bladder meridians (approximately 6 cm and 12 cm parallel off dorsal spine) and extending to pelvis, were injected to the size of 0.5 cm diameter blebs.

A single row, approximately 6 cm off dorsal spine, was injected cranial to the withers. The horse grimace scale (HGS) was used to record his pain, with a significant improvement in comfort level. His HGS prior  to treat was 15/16 and post treatment had improved to 4/16. The mesotherapy treatment was very successful at moving Q to a more comfortable overall state.

Unfortunately, after mesotherapy, Q became very averse to any acupuncture. He was moved to pasture and maintained well on a protocol including controlled exercise, gabapentin (5 mg/kg q 12–24 hours PRN), Adequan (500 mg IM q 2 months), and Platinum Performance Equine.

Clinical Outcome 

Q was eventually able to move to comfortable pasture life and short rides after 8 months of treatment. His CSU comfort score on average is 1/4. The original goal was to attempt to move Q back to his life prior to surgery, which included longer rides and dressage. This was not achieved, as it elicited too much pain and cervical stiffness after, but the ultimate goal of leading a life with well-managed pain was accomplished. Overall, Q was maintained long term on controlled exercise and supplementation of Platinum Performance Equine daily. On days that he is more active, including the rare short ride, his trainers evaluate his pain using changes to lateral neck flexion and length of his stride, as these have historically been key indicators of increased pain for him. If a change is noted, gabapentin (5 mg/kg q 12–24 hours PRN) is used. He has rarely needed more than that for comfort. Q will likely in the future need to reinstate his acupuncture treatments and addition of periodic NSAIDs as we continue to monitor cervical osteoarthritis and mobility with aging.

Horse Grimace Scale

The Horse Grimace Scale, developed by Dalla Costa et al. in 2014, shows images and explanations for each of the 6 facial action units (FAUs). Each FAU is scored according to whether it is not present (score of 0), moderately present (score of 1), and obviously present (score of 2).

Click here to view the Horse Grimace Scale

Conclusion

Wobblers syndrome, or cervical vertebral stenotic myelopathy, is one of the most common causes of neurologic disease noted in horses in practice. It is most commonly seen as narrowing or stenosis of the vertebral canal and compression of the spinal cord between C3–C7, and less often C1–T2. Q had surgical intervention to attempt to correct his stenosis because of his owner’s
desire to alleviate pain and attempt to move him back into dressage. His postoperative treatment plan goals were to alleviate pain during recovery while supporting joint health and muscle  strengthening by utilizing pharmaceutical therapy and integrative modalities.

Physical therapy is a large component in recovery as it can reduce postoperative scar tissue that can lead to limited range of motion. Greater focus on monitoring and treating central sensitization would  have been an area for improvement. An alternative CRI to butorphanol could have been considered to provide a greater level of analgesia; butorphanol is a mu opioid antagonist with low intrinsic activity and kappa opioid agonist, and it does not provide as much analgesia as morphine or methadone could as they are full mu opioid agonists.

Q had a large setback during transport between the hospital and the stable, which may have been caused by an exacerbation of chronic pain leading to neural sensitization and release of mediators both peripherally and centrally, causing activation of N-Methyl D-asparate (NMDA), resulting in central sensitization (hyperalgesia and allodynia). Addition of Amantadine (NMDA antagonist) early on in treatment could have been considered to potentially have avoided or lessened the painful setback he experienced. Q’s case is a review of how a multimodal pain approach and coordination between the surgical center and referral hospital as well as veterinarians in multiple skill modalities can work together to achieve a comfortable daily state. It demonstrated that even with all the efforts of a multimodal approach including pharmaceutical therapy, acupuncture, laser therapy, mesotherapy, physical therapy, and constant rate infusion, the initial goal in the end may not be met. As mentioned previously, Q was not able to return to dressage and long rides, but a comfortable quality of life was achieved.

Benson_Lindsay_bio.jpg
Lindsay RD Benson, DVM, CVA, CVPP, earned her DVM from Washington State University and is certified by the Chi Institute of Chinese Medicine as a Veterinary Acupuncturist.
She is a veterinarian at AAHA-accredited Associated Veterinary Medical Center in Walla Walla, Washington.

Discussion by Mike Petty, DVM, CCRT, CVPP, DAAPM

Outcome measure should be considered for every medical case that we encounter. In other words, what does the client want to see at the end of the treatment? For most things like ear  infections or diarrhea, the outcome is tacit and doesn’t need to be discussed. But for complex pain cases with a predisposing cause that cannot be fixed, this becomes more important: Do they want their arthritic dog to get to the point where he can use the stairs unassisted or do they want him to go on a three-mile walk? Oftentimes the success of a case hinges more on the client’s desire for their animal and the feasibility of attaining it and less on the degree of comfort you have provided their animal. The outcome measure becomes even more important in the
case of a performance animal like Q.

In the horse performance world, the animal is often looked at more like a commodity than a pet. It doesn’t mean that the owner doesn’t love their horse, but the expense and care of a horse that is in chronic pain might mean that the financial resources to get a “new” performance horse while caring for the retired horse just isn’t possible. Add to that the medical costs that didn’t return the horse to the desired function and it could mean the difference between retiring the horse and euthanasia. The treatment of Q and possible outcomes were discussed in this case, but it is important to put special emphasis on what will happen if the outcome measure isn’t met.

Michael C. Petty, DVM, CCRT, CVPP, DAAPM, is in private practice in Canton, Michigan. He is a frequent national and international lecturer on topics related to pain management. Petty offers commentary on each Pain Case of the Month (and occasionally writes one himself). He was also a member of the task force for the 2015 AAHA/AAFP Pain Management Guidelines for Dogs and Cats.

 

Photo credits: Photos courtesy of Lindsay RD Benson, DVM, CVA, CVPP

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