Effects of the paralysis tick, Ixodes holocyclus, on the electrocardiogram of the Spectacled Flying Fox, Pteropus conspicillatus.
OBJECTIVE
To evaluate cardiac electrical function in the Spectacled Flying Fox (bat) infested with Ixodes holocyclus.


METHODS
Prospective clinical investigation of bats treated for naturally occurring tick toxicity.


METHODS
ECGs were performed on bats with tick toxicity (n = 33), bats that recovered slowly (n = 5) and normally (n = 5) following treatment for tick toxicity, and on normal bats with no history of tick toxicity (n = 9).


RESULTS
Bats with tick toxicity had significantly prolonged corrected QT intervals, bradycardia and rhythm disturbances which included sinus bradydysrhythmia, atrial standstill, ventricular premature complexes, and idioventricular bradydysrhythmia.


CONCLUSIONS
The QT prolongation observed on ECG traces of bats with tick toxicity reflected delayed ventricular repolarisation and predisposed to polymorphic ventricular tachycardia and sudden cardiac death in response to sympathetic stimulation. The inability to document ventricular tachycardia in bats shortly before death from tick toxicity may be explained by a lack of sympathetic responsiveness attributable to the unique parasympathetic innervation of the bat heart, or hypothermia-induced catecholamine receptor down-regulation. Bradycardia and rhythm disturbances may be attributable to hypothermia.
Campbell
F E
FE
School of Veterinary Science, The University of Queensland, Queensland 4072.
Atwell
R B
RB
Smart
L
L
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000150:complications / Q000503:physiopathology / Q000662:veterinary*; D002685:Chiroptera; D016757:Death, Sudden, Cardiac / Q000209:etiology / Q000662:veterinary; D004562:Electrocardiography / Q000662:veterinary; D018884:Ixodes; D012720:Severity of Illness Index; D013985:Tick Paralysis / Q000150:complications / Q000503:physiopathology / Q000662:veterinary*