It’s a dog-gone mystery.

A package containing a canine’s head was lost in the mail — and Texas veterinarians are barking mad, according to a report Tuesday.

The dog noggin was supposed to be sent to a state lab in Austin and tested for rabies after the pooch bit a worker at Bright Star Veterinary Clinic in Sulphur Springs, according to KLTV.

The pooch owner agreed to euthanize the dog after the attack because its heath was already poor, the local station reported.

Noting that brain tissue is the best way to test for rabies, workers removed the canine’s head and stuffed it in a package, according to the station.

Workers at the animal clinic sent it via express mail through a local shipping company — but the lab never received the creepy package, according to the station.

Without the rabies diagnosis, vet techs were forced to rush to a hospital in Dallas and fork over cash for vaccines.

The cost to vaccinate workers who handled the doggy brains was about $80,000, the clinic’s office manager told the station.

Vets still have no clue where the package ended up.