An 8-day-old newborn female twin Holstein calves with a history of weakness, anorexia, emaciation and convulsion were presented to Tabriz University Veterinary Teaching Hospital. On admission, the calves were febrile and recumbent. Physical examination revealed many ticks from the external body surface of the animals, right and left prescapular lymphadenopathy, severe opisthotonos, nystagmus, p...