Flashing third eyelids and other involuntary facial movements in tetanus in four dogs

Abstract

This study describes four dogs with tetanus that presented with ‘flashing third eyelids’ and other involuntary facial movements. Flashing of the third eyelids reflects the intermittent involuntary bilateral eyeball retraction accompanied by passive movements of the nictitating membranes. Four dogs presented with ‘flashing third eyelids’ either as a sole sign or accompanied by other signs of focal tetanus such as trismus, risus sardonicus and erected pinnae. The combined movements of the eyeballs and nictitating membranes were more prominent while moving the head horizontally, that is, during performance of the vestibulo‐ocular reflex. Along with retraction of the eyeballs, all dogs had accompanying asynchronous blinking and medial eyebrow movements because of retractor bulbi, orbicularis oculi and levator anguli oculi medialis muscle fasciculations, respectively. Intermittent involuntary bilateral eyeball retraction accompanied by passive movements of the nictitating membranes, blinking and medial eyebrow movements can be an early sign of focal tetanus, usually grade I.