CBS Local — The holiday season is here and veterinarians are warning pet owners that all the extra candy laying around this time of year can be fatal for their dogs and cats.

Writing in the journal Veterinary Record, Vets say Christmas and Easter are the most dangerous times of the year for pets to fall ill from eating chocolate. Their study found hundreds of cases of dogs suffering from chocolate poisoning after stealing candy, eating out of open chocolate boxes, or even drinking unguarded cups of hot cocoa.

“The take home message is firstly to make sure that people recognize that chocolate is a potential problem and to be vigilant with their chocolate gifts over the holiday period,” Dr. Philip Jones said, via the BBC. Jones warns pet owners, “if their dog does get access… contact their veterinary surgeon.” The veterinary lecturer at the University of Liverpool added that owners should have an estimate of how much chocolate their pet has eaten when contacting their vet.

The study, which focused on canine medical records over the last five years, found that chocolate poisoning was four times more likely on Christmas than on a non-holiday. Eating chocolate can reportedly result in diarrhea, seizures, and even death for both dogs and cats.