It's a well-known fact that rodenticide is highly toxic to people and pets as well as rodents, but it turns out that the vomit of dogs that have ingested the poison is hazardous, too. From 2006 to 2011, eight known cases of phosphine gas poisoning were reported in veterinary hospital staff members, according to a recent report from the U.S. Centers for Disease Control and Prevention (CDC).

The staff members are thought to have inhaled the gas after rodenticide-poisoned dogs vomited in their hospitals. Zinc phosphide, a rodenticide commonly used for home and commercial use, produces phosphine, a toxic gas, when it comes into contact with stomach acid or water.

The CDC's National Institute for Occupational Safety and Health received reports of the phosphine poisoning at four different veterinary hospitals: two in Michigan, one in Iowa and one in Washington state. All of the reported victims were exposed to phosphine gas after treating dogs that ingested zinc phosphide.

So just how worried should veterinary staff be about phosphine gas exposure? Very worried, says Justine Lee, DVM, associate director of veterinary services at Pet Poison Helpline (PPH). And clinical staff members aren't the only ones who should take the risks of phosphine gas exposure seriously. "It's a huge public health risk, and veterinarians are liable when we tell pet owners to induce vomiting at home without warning them of the risk of the gas poisoning them due to secondary exposure," Lee says.

Veterinarians need to train their staff members—most importantly receptionists and technicians—about how the poison works before they give recommendations to pet owners, she says. In the case of zinc phosphide poisoning, it's recommended to give an antacid, not food, since food (for example, milk or toast) tends to increase gastric acid production, which in turn can increase phosphine gas production. Additionally, if the dog vomits in the car en route to the veterinary hospital, owners should be warned to ventilate the car by safely opening windows.

Once the pet is on site at the veterinary hospital, team members should carefully take a patient history to determine the type of poison the pet ingested, Lee says. Many veterinarians assume that all rat poisons are vitamin K1-dependent types and can accidentally poison themselves and their staffs when they induce emesis, as evidenced by the cases reported to the CDC, Lee says.

Pet Poison Helpline wants to remind veterinary teams that the diagnosis of zinc phosphide rodenticide toxicity is based on history, the presence of the rodenticide in the environment and correct identification of the active ingredient. Phosphine gas has often been characterized as smelling like rotten garlic, eggs or fish, but even though this odor may be helpful in diagnosing zinc phosphide poisoning, veterinarians should not rely on the presence of odor alone, PPH says.

In the event that the animal vomits at the hospital or vomiting is induced, the American Veterinary Medical Association (AVMA) advises staff to remain upwind and above animal level to reduce their contact to the toxic gas, as the gas is heavier than air and will sink toward the ground. If the animal vomits in an enclosed area, such as an examination room, the area should be evacuated and the local fire department notified. If practical, windows and doors should be opened and a fan placed at ground level to evacuate the gas away from people and other animals.

Veterinary employees or pet owners who are exposed to vomit or gastric contents containing phosphine gas should seek immediate medical attention if symptoms of poisoning are present, the AVMA says.