Side effects of Zithromax?

Hello,

Has anyone heard of side effects from Zithromax being used for a feline
respiratory infection? One of our cats at the sanctuary where I volunteer
was prescribed this medication by the vet. Within a day she developed
seizures and unfortunately, lived only couple of days. The vet did not
speculate on what caused the seizures (e.g., whether it could have been
related to the medication, or whether something else entirely different
happened, like a brain tumor or something toxic).

I plan to seek another opinion, but wanted to see whether anyone had heard
of such side effects.

Thanks much,
Dave