The Maui Humane Society says it is investigating three separate cases in which they believe dogs were poisoned.

KHON-TV reports that the suspected dog poisonings were in the Maui Uplands neighborhood.

Humane society officials say that a family noticed one of their dogs acting funny last weekend, so they took it to the veterinarian. It later died.

The family’s other dog began showing the same symptoms and also died.

The vet believes they suffered from antifreeze poisoning.

Maui Humane Society CEO Jerleen Bryant says she has received a report of another dog at the vet with similar symptoms. She says people found dog treats in their yards.

Symptoms of antifreeze poisoning in dogs include excessive thirst, urination, vomiting and lethargy.