HOUSTON -- A Texas sheriff said Saturday that he could not arrest and charge a veterinarian shown in a Facebook post bragging about killing a cat with a bow and arrow unless an investigation determines the picture of the dead cat is genuine.

Austin County Sheriff Jack Brandes said he was disturbed by the image that shows Kristen Lindsey holding up what she described as a dead feral tom cat. He has assigned two deputies and an investigator to the case.

"I've had people calling me from all over the country expressing their concern," Brandes said, speaking from a pasture while inspecting his cattle. "I just want everybody to know several things. We can't arrest and charge someone like that based on a picture on the internet. We have to make sure that is true and correct.

"Anybody can take a computer and alter a photograph."

The operators of the clinic where Lindsey worked in Brenham, about 100 miles northwest of Houston, said Friday she was fired after they learned of the posting earlier in the week, which has since been removed, along with her Facebook account. The posting prompted hundreds of phone calls also to the Washington Animal Clinic.

"We are absolutely appalled, shocked, upset, and disgusted by the conduct," the clinic posted on its website. "We do not allow such conduct and we condemn it in the strongest possible manner."

Bruce Buenger told Bryan-College Station television station KBTX (http://bit.ly/1CWummO ), which first reported the story, his clinic's goal was to "try to fix our black eye and hope that people are reasonable and understand that those actions don't anyway portray what we're for here."

"We put our heart and soul into this place," he said.

A sign outside the clinic that lists its vets had her name covered with tape.

No telephone listing for Lindsey could be determined Saturday and she could not be reached for comment.

The sheriff said his office had reached out to her.

"She didn't want to talk to us at this time," he said. "She said she was going to come in with her attorney. Hopefully early next week, we get something cracking. Hopefully this girl comes in. She may. She may not."

The incident is believed to have taken place in his county, which is adjacent to Washington County, which includes Brenham. The results of the investigation would be turned over to the county district attorney, who could present the evidence to a grand jury or issue a warrant.

Depending on the nature of the charge, animal cruelty can be a misdemeanour or a state jail felony in Texas.

Brandes said while Lindsey's posting described the animal as a feral cat, he was aware of some reports that it was a lost domestic cat.

"We haven't determined that 100 per cent at this time," he said.

The Texas State Board of Veterinary Medical Examiners lists Lindsey as holding a valid license since June 2012 and with no disciplinary actions.

"All these people are jumping up and down, they want action," Brandes said. "The wheels of justice turn slow. You want to be sure once you accuse and arrest someone."