Longwood, Fla. -- A Longwood veterinarian has been successful with a treatment to counteract the poison that some believe is making pets sick.

It all started with a patient.

Tara Jenner’s dog, Holly, got sick earlier this month.

Vets at Longwood Veterinary Clinic determined Holly had kidney problems, and discovered she’d been eating some of the food, now recalled by Menu Foods.

The New York state food lab claims aminopterin is the contaminant that’s making animals sick.

Aminopterin is a former cancer drug, once used in the United States, until it was banned. It is now used as a rat poison in other countries, like China.

Jenner’s brother is a research scientist, and knew aminopterin’s history.

He told Tara about another drug, Leucovorin, which was used in the U.S. when aminopterin was used as a cancer drug, to counter-act the negative effects of it.

So Tara told Dr. Shellie Campbell, a veterinarian with Longwood Veterinary Clinic.

Campbell researched it and they decided to give it a try on the dog, Holly.

"Leucovorin is an activated B-vitamin and is able to get past the toxin to help the cells start functioning again," said Dr. Campbell.

After two days of the Leucovorin treatment, Holly's kidneys were back to normal.

The vets at Longwood Veterinary Clinic are cautious about saying this treatment is the magic bullet that could save all animals that got sick.

In fact, they believe Leucovorin is too strong for cats to handle.

However, for dogs, they say it's at least worth talking to your vet about.