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Something was causing damage to Calvin's yard. His lawn was covered with unsightly fan-shaped mounds of soil, and many of his dahlia tubers, lily bulbs, and garden vegetables had been eaten or destroyed. Calvin found out that all of this damage was being caused by pocket gophers, a type of rodent that burrows through underground tunnels feeding on plant material.

Calvin bought some poison bait to get rid of the gophers. He read the product label first which said not to apply the product in his garden. He then identified which burrows should be treated, and carefully inserted the bait according to label directions. When he was finished, he covered the openings with loose sod and went into the garage to store the bait container where his kids and dog could not reach it.

Calvin came back outside about 10 minutes later and found that something had dug through the sod into the gopher tunnels after the bait... Then Calvin saw his dog "Buddy" looking very guilty with dirt on his nose. Calvin called the National Pesticide Information Center (NPIC) right away for more information.

Take Home Message

Calvin told the NPIC specialist that Buddy did not have any symptoms yet. The NPIC specialist explained that his gopher bait contains an active ingredient called zinc phosphide, which is often prepared with other ingredients, like common foods, dogs may like to eat. Therefore, covering the treated burrows with a heavier material, or containing the dog away from the treated areas may help restrict the dog's access to the bait.

The NPIC specialist explained that, when eaten, zinc phosphide reacts with water and acid in the stomach to produce phosphine gas. Signs of poisoning can include vomiting, loss of appetite, depression, deep or wheezy breathing, weakness, incoordination, convulsions, and possibly death. The amount of zinc phosphide it takes to make an animal sick varies greatly.

Calvin was told that signs of poisoning from eating zinc phosphide usually occur within 15 minutes to 4 hours of exposure. However, an animal with an empty stomach may develop symptoms later than an animal with a full stomach; in some cases an empty stomach can delay symptoms up to 12-18 hours after eating the bait.

Calvin also learned that some zinc phosphide products include ingredients that may help induce vomiting in order to limit phosphine gas production inside the stomach. In fact, zinc phosphide itself has a strong tendency to cause vomiting in animals that are capable of vomiting, including dogs.

The NPIC specialist directed Calvin to contact his veterinarian for treatment-related advice. Calvin was also given the telephone number for the 24-hour National Animal Poison Control Center (NAPCC): (888) 426-4435.