CASE STUDY 24/10/1999 - Head Shaker

By Ian Bidstrup, BVSc (Hons), MACVSc (Equine Medicine), CertVetChiro. (AVCA), CertVetAcup (IVAS)

"Moxie", grey 16 year-old hack.

USE: Hacking.

HISTORY: Acquired early June 1999. Previously was used as a show jumper. Tosses head when being bridled with an up and down, "almost spastic jerky movement", which carries onto lowering of the head and snorting and violently shaking the whole head and neck. Follows behaviour by extending the neck and poll and flaring the lips in stallion like behaviour. Yawns frequently and "mouths" (chews without food present in it's mouth). Walks along with head down rubbing nostrils on the ground. Sometimes lies down and seems to be grinding head and neck into the ground. Behaviour intermittent. Worse in afternoons.

Visit 1 - 13/7/99

EXAMINATION:

Walk and trot - no obvious problems.

Muscle palpation - moderately tender around left temporo-mandibular joint. Very tense and tender over the muscles of the thorax behind the elbow and the triceps muscles. A twitch reaction was very easy to elicit in these muscles, even after gentle stroking to desensitise the region. There was also sensitivity of the intercostal muscles extending up the fourth and fifth intercostal spaces. There were muscle knots or trigger points present in the trapezius muscle opposite the dorsal spinous process of the 4th and 5th thoracic vertebrae. Minor tension was found in the muscles surrounding the atlas and similarly the middle and superficial gluteal muscles.

Dental exam - The main problem noted was the presence of a mild point, medial side of the last molar on the left.

Motion palpation - The motion of the atlas against the axis was mildly restricted in rotation on the right and left sides. The motion of the sacro-iliac joints was mildly restricted in a dorsal to ventral direction. The motion of the 4th and 5th thoracic vertebrae were moderately restricted in left and right rotation.

TREATMENT:

Chiropractic - the segments showing restricted motion were adjusted. The sacro-iliac joints were adjusted, using a toggle thrust on each tuber coxae, 60 degrees off the body line in a dorsal to ventral direction. The atlas was adjusted on each side using a rotary thrust to the skull, with the occipital condyles of the occiput engaged in the atlas ring, causing the atlas to rotate dorsal to ventral through a short range of movement with the rotary motion of the skull. The 4th and 5th thoracic vertebrae were adjusted using a toggle recoil thrust. The segmental contact point was the dorsal spinous process immediately under the tip. The line of correction was lateral to medial and slight dorsal to ventral.

Acupuncture - acupuncture points Spleen 21a, Bladder 12', 12'', Small Intestine 12, Large intestine 16 and Lung 11 and 7 were needled using simple needling for 15 minutes.

POST TREATMENT ADVICE:

To revisit in 1-2 weeks. I was uncertain that we had gotten to the bottom of the problem in the poll region. There was certainly a major change in the horse's demeanor once the thoracic vertebrae were adjusted.

TREATMENT OUTCOME:

31/7/99 - a very excited owner reported that the horse had been "cured" and that apart from 2 days soon after treatment the horse had been normal. As the owner was going away for a month the treatment was not followed up.

Early October 1999 the owner reported that the condition had returned by early September. She was going to get a second opinion from the local vet as she had trouble fitting a visit in to me during the week.

DISCUSSION:

Mair 99(2) lists the possible causes of head shaking to include ear mite infestation, otitis media/interna, traumatic cranial neuropathy and cervical injuries, guttural pouch mycosis, vasomotor rhinitis, allergic rhinitis, osteoma of the paranasal sinuses, stereotypic behaviour, partial asphyxia, optic trigeminal summation (Phototic head shaking) and trigeminal or infra-orbital neuritis. Treatment using infra-orbital neurectomy, cortico-steroids, anti-histamines, cyproheptadine, and muzzles and other physical means have had mixed success, with relief most often temporary.

From a chiropractic and acupuncture point of view other causes include occipito-axial joint dysfunction, atlanto-axial joint dysfunction and temporo-mandibular joint dysfunction. With classic cases of headshaking chiropractic alone does not often give satisfactory results(1). Dr Kerry Ridgeway, DVM, California(4) reports good results from the combination of chiropractic and acupuncture. Head shaking is common in horses that present for problems in the poll area, including problems putting on bridles, evasion of palpation of the poll area, difficulty turning the head to one side or being above or below the bit. In most cases that I see, the problem of head shaking is almost incidental - seen by the owners more as an individual behavioural trait and unchangeable. The significant fact is that in at least 50% of these more subtle cases the head shaking resolves once the poll dysfunction is ameliorated. I usually use a combination of acupuncture and chiropractic to treat these cases, though good results with normal poll problems are usually seen with chiropractic alone. This was the first classic case of headshaking that I have seen with the full range of symptoms from head shaking/tossing to rubbing its nose along the ground. Though the treatment only lasted a few weeks the results were dramatic.

It was not until this case that I suspected that other parts of the body than the upper neck and head may be directly involved. In this case the dysfunction of the joints of the poll were mild while the dysfunction of the upper thoracic area was certainly dramatic and it would be expected that the overall effect of this dysfunction could extend to the sympathetic nerve trunk at the base of the neck. Dysfunction of this trunk may in turn affect the upper cervical ganglia and sympathetics of the face. A wild extrapolation or a real possibility?!? Further cases may clarify this issue. My treatment of the intervertebral and costo-vertebral dysfunction of the wither area certainly was not as extensive in previous headshaker cases.


References:

1) RMIT University Master of Chiropractic (Animal Chiropractic) course lectures 1998/99 Head Lecturer Dr. Michael Gleason, D.C.

2) T.S. Mair; Assessment of bilateral infra-orbital nerve blockade and bilateral infra-orbital neurectomy in the investigation and treatment of idiopathic headshaking. EVJ 1999 31(3) 262-264

3) J.G. Lane The idiopathic headshaking syndrome Proceedings of the 15th Bain Fallon Memorial Lectures 1993. P265-268.

4) Dr. Kerry Ridgeway, DVM, California, USA. Equine practitioner specialising in acupuncture and chiropractic. Communication via Dr. Michael Gleason, D.C., Head lecturer, RMIT University Animal Chiropractic Group.

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