Tetanic torticollar spasms (TT) refers to a neurologic disorder observ
ed in a line of Medium White turkeys. The condition is characterized b
y the dorsomesial extension of the neck and head such that the head re
sts on the back with the beak directed upwards. The spasms vary in dur
ation from 1 to 5 s to longer than 1 min followed by the resumption of
normal posture. The spasms appear to be spontaneous but can be induce
d by sudden loud noises and eating and drinking. When expressed in pou
lts at hatching the condition is usually lethal due to starvation and
dehydration. Typically, TT is expressed during the first 7 days postha
tching but can be as late as 18 wk of age. Breeding tests indicate tha
t TT is the expression of a sex-linked recessive gene with incomplete
penetrance, 86%. Microscopic examination of the otoconia in the inner
ears and histologic examination of the cerebellum and brainstem of TT
turkeys have not revealed any abnormality. The gene symbol tt is propo
sed.