Headshaking

Veterinary advice should be sought before applying any treatment or vaccine.

Headshaking

Headshaking (HSK) is a spontaneously occurring disorder associated with the horse's trigeminal nerve. Affected horses demonstrate violent, uncontrollable, typically downward, jerks, shakes, or flicks of the head without any apparent physical cause. The behavior might occur continuously or intermittently, with some horses showing progressive severity. In severe instances, the headshaking can be so intense that it results in self-trauma to the horse in the form of abrasions on the muzzle and/or legs, or the animal being a danger to handle or ride.

59% of headshaking horses have exhibited clinical signs seasonally, starting in the spring and early summer and lasting until late summer or fall. Weather patterns, wind, rain, exercise, increased exercise intensity, sharp load sounds, and vibrations can also affect the onset of signs. Photic headshakers is a term used to describe horses which exhibit severe signs of HSK during bright sunny days. 52% of 109 headshakers (86% live in North America) have been thought to be photic headshakers, which is thought to be associated with varying levels of UV exposure.

Clinical signs
The most common types of headshaking behavior demonstrated by affected horses include:
  • Flipping or shaking of the head within a vertical plane
  • Behaving as if a fly flew up their nose
  • Rubbing their muzzle continuously
  • Snorting
  • Anxiousness
There have been some incidences of headshaking horses that spontaneously stopped (for a period of a couple weeks up to several years), following several years of headshaking behavior.

Symptoms

Shaking or flipping the head in a vertical plane
86%
Acting as if an insect flow up their nose
80%
Muzzle rubbing
72%
Snorting
63%
'Flips' upper lip
72%
Strikes at face with foot
53%
Anxious expression
61%
Rubs nose on ground
45%
Horizontal headshaking
21%
Sensitive muzzle
13%
Staring into space
11%
Submerges muzzle in water
3%

Diagnosis

  • History
  • Clinical signs
  • Physical exam
  • Necropsy

Treatment

TherapiesDetails
Avoidance of known triggersRide during the day as opposed to at night
Nose netsHalf or full nets can be used
Soft rope plaitsOr a similar device that attaches to the noseband or browband
Cyproheptadine0.3 mg/kg PO twice daily
CarbamazepineAdministered 2-8 mg/kg PO 2-4 times daily
Gabapentin5 -20 mg/kg administered PO once or twice daily
Fluphenazine50 mg administered IM every 1-4 months
Phenobarbitone3-6 mg/kg administered PO twice daily
Hydroxyzine0.8 mg/kg administered PO twice daily
Sodium cromoglycate eye drops1 drop per eye, administered four times a day; has been used successfully in 3 horses with seasonal headshaking.
Magnesium10-20 mg administered PO once daily
Chiropractic therapy
MelatoninHorses that received 15-18 mg orally once a day in the evening, reportly improved seasonal headshaking in 2 of 7 horses
Tinted goggles or contact lenses
Homeopathy
Acupuncture
SurgeryInfraorbital neurectomy/sclerosis or platinum coil implantation
Magnesium supplements10-20 g given orally, once a day showed some improvement by owners of affected headshaking horses

Prognosis

Guarded to poor for performance.

Scientific Research

General Overviews

Age Range

The majority of horses experience their first onset of HSK between 5-10 years of age.

Seasonality

WinterSpringSummerAutumn