Canine patient emits toxic gas, sending veterinary staff to hospital

A dog thought to have ingested a toxic chemical created a dangerous situation at the Vail Valley Animal Hospital in Edwards, Colo., Dec. 7, sending an emergency room doctor and three technicians to the hospital. The Eagle River Fire Protection District suspects the dog ate zinc phosphide, commonly used as a rodenticide. When the dog vomited up the chemical, it created toxic gas and caused respiratory distress to those attending to the animal. Tests are still pending to definitively identify the toxin.

When ingested, zinc phosphide forms a poisonous gas when it comes in contact with water. “When the dog vomited, this released the gas as the pesticide had mixed with the contents in the dog’s stomach,” says a statement from the Eagle River Fire Protection District.

Eagle River Fire personnel working with Vail Valley hospital staff during the incident established an effective way to remove the dog from the contaminated area and was taken outside. Equipment was also removed from the clinic so a veterinarian could continue to treat the dog, but the dog did not survive.

According to the Centers for Disease Control and Prevention (CDC), the suspected expelled gas--phosphine gas--is colorless, flammable and explosive at ambient temperature and carries the odor of garlic or decaying fish. Inhalation of high concentrations can be deadly--it “inhibits oxidative phosphorylation and causes lipid peroxidation damage to cells and tissues,” says a release by the CDC. “Damage to the pulmonary, nervous, hepatic, renal and cardiovascular systems can occur.”

Nonfatal inhalation of the gas usually resolves within 30 days and rarely causes longterm disabilities, according to the CDC. In humans, symptoms include diaphragm pain, nausea, vomiting, excitement and a smell of phosphorus on the breath. Exposure to high concentrations can cause weakness, bronchitis, pulmonary edema, shortness of breath, convulsions and even death. The Vail Valley staff suffered from respiratory distress, including tightening of the chest, burning of the throat and difficulty breathing.

The CDC regards phosphine gas exposure at veterinary clinics as an occupational risk, but it is not common. The CDC’s National Institute for Occupational Safety and Health (NIOSH) received only four reports of phosphine gas poisonings from 2006 to 2011. The reports were from veterinary clinics in Michigan, Iowa and Washington.

Managing the risk of phosphine gas poisoning:

In response to the Michigan phosphine gas poison reports of 2006 and 2008, the Michigan Department of Community Health provided the American Veterinary Medical Association (AVMA) with information to alert veterinarians to the risk of occupational phosphine gas poisoning. In order to avoid human exposures while providing treatment to pets that have ingested zinc phosphide, veterinary teams should follow these guidelines:

• Determine whether the ingested product contains zinc phosphide, which is used to kill rats, mice, moles and gophers. It is available as a dark-gray powder or grain-based pellet bait. Trade names include Arrex, Commando, Dexol, Kilrat, GophaRid, Phosvin, Ridall, Ratol and Sweeney’s Poison Peanuts. The chemical has an odor of fish, garlic or acetylene.

• Have the dog vomit outside of the building, where there is plenty of ventilation and the area can be hosed down with water.

• Have all clinic personnel stand upwind of the animal.

• Do not lower the head down to the animal since phosphine gas is heavier then air and will be more highly concentrated closer to the ground.

• After vomiting is induced, take the animal upwind of the vomit.

• Flush the area with copious amounts of water while standing upwind. Vomitus can be washed down a storm sewer or off a hard surface onto grass--there will be adequate ventilation outdoors to prevent the phosphine from reaching harmful levels. Make sure the vomited matter is diluted enough that it does not attract other animals. Note that phosphine will be released from the product by water, making any remaining pellets nonhazardous.

• If the dog vomits in the exam room, remove personnel and animals from the area and ventilate. Most local fire departments can measure the level of phosphine in the air and determine when the area is safe to reenter.

• Have team members seek medical attention if they experience symptoms upon exposure to phosphine gas.