NEW YORK >> It’s a trick-or-treating tradition: Dump the night’s candy haul onto the living room floor to pick out the gems, or do some horse trading with siblings or friends.

The excitement — and sugar rush — may leave humans unaware that all that candy might just be lethal for their hovering pet dogs and cats, however.

Those four-legged family members can’t metabolize candy like humans, said Leasa Greer, manager of nutrition and regulatory affairs for Solid Gold, a line of natural, health-focused foods and treats for dogs and cats. Generally, pet owners likely know what their animals should and shouldn’t eat, but they may not know why, she said.

Chocolate, for instance, contains caffeine and a compound called theobromine, which can be toxic in certain doses to both dogs and cats, Greer said. Cats can’t taste sweet so aren’t necessarily as drawn to chocolate as dogs, she noted. Theobromine is more concentrated in darker chocolates so that type is particularly perilous, Greer said.

Symptoms of chocolate upset include digestive upset (vomiting, diarrhea), restlessness, hyperactivity and trembling, she said.

Then there’s xylitol, a sugar substitute found in some sugarless gums and candies. It can cause hypoglycemia, seizures and even liver failure in dogs, Greer said. Symptoms of xylitol poisoning can include vomiting, weakness and lack of coordination.

“It is important to keep Halloween candy secured in a location above the animal’s reach. Containers with a secure lid will also prevent any possible encounters and reduce the smell. Many animals are attracted to the novel scent of the candy,” said Brian Ogle, an assistant professor of anthrozoology at Beacon College in Leesburg, Fla.

“Beyond candy, one other major threat to animals is the ingestion of glow sticks. Cats especially love to chew on these objects. The chemicals in these toys can cause severe drooling, mouth irritation and can be quite painful to animals,” he added.