Animal-Derived Pet Treats Can Be Dangerous to Owners

By Carol Johnson

Salmonella bacteria were first discovered in 1885, and since then parents everywhere have been cautioning their children to wash their hands after playing with turtles or frogs. But contact with reptiles is just one of the ways salmonella can be caught; most human salmonella infections are acquired by handling or consuming contaminated food products, particularly foods made from animals. More than a million people are infected with salmonella each year in the U.S. and Canada.

Poultry and raw eggs are the most frequent causes of foodborne salmonella illnesses, as well as other types of food that has been cooked or frozen and not eaten right away. In March, the New York Times reported that the U.S. government had said that 16.3% of all chickens are contaminated with salmonella. Although salmonella contamination of eggs is much less common than it used to be, thanks to improvements in hygiene measures and the vaccination of laying hens, there are many different strains of salmonella that can cause severe diseases in animals and humans. One of those strains causes typhoid fever. A salmonella infection can cause serious illness in very young children, older adults, and people with compromised immune systems or chronic diseases.

Salmonella-infected animals usually shed the organisms in their feces. Most pet owners know that animals can carry harmful bacteria, and they should wash their hands before eating, particularly if they’ve just scooped the cat box or cleaned up an accident on the carpet. But one source of salmonella infections has gone relatively unreported, although every pet owner in the world should be made aware of it.

In recent years, more and more types of animal-derived pet treats have become available for purchase at pet stores. Pet owners have eagerly bought treats such as pig ears, dehydrated hooves, and rawhide treats, to have something different and long-lasting to give their pets. But unfortunately, animal-derived treats such as these have been confirmed in recent years as being the sources of outbreaks of salmonella infections in local populations.

In February 2005, a 26-year old man in Alberta went to the doctor with diarrhea and fever, and cultures were taken. The man had fed his dog beef pet treats a few days before the onset of his illness, but the dog was asymptomatic. A week later, a woman in British Columbia also came down with diarrhea illness after feeding her dog salmon pet treats a few days earlier. The dog also had diarrhea. A few weeks later an 81-year old woman in British Columbia became ill and was hospitalized with diarrhea, fever, and vomiting after feeding beef pet treats to her dog. In all three cases the treats were packaged by the same manufacturing plant in Washington.

During 2004-2005, there were nine culture-confirmed outbreaks of salmonella poisoning directly attributed to contaminated pet treats of beef and seafood origin in western Canada and the state of Washington. Because laboratory-confirmed cases of salmonella represent such a small proportion of cases in local communities, and many people may have dismissed the symptoms as stomach flu or food poisoning, this outbreak may have actually involved hundreds of infections. And the number of culture-confirmed outbreaks from contaminated pet treats is steadily growing, with product recalls necessitated in Washington, Calgary, Alberta, and Texas.

In Canada, pet treats are not regulated, but the Animal Health Act has resulted in companies being encouraged to recall products that are found to be at risk for carrying salmonella bacteria. In the United States, pet treats are regulated by the Food and Drug Administration. FDA administrators have encouraged manufacturers to take voluntary steps to ensure the absence of salmonellae in pet treats. In addition, the American Pet Products Manufacturers Association published Guidelines for the Manufacturing of Natural Part Treats for Pets to educate its members about contamination risks.

Detecting and controlling the transmission of salmonella organisms through pet treats is challenging for several reasons. The dehydration process used to produce such treats might not be effective at killing the bacteria, and pets consuming the treats may carry the bacteria without showing symptoms. In 2004, the FDA initiated nationwide testing of pet treats for salmonella, and the results have shown that the prevalence of the bacteria in pet treats has not decreased. Therefore, pet treat manufacturers, retailers, health-care providers, public health authorities, veterinarians, and consumers should be made aware of the potential for animal-derived pet treats to cause salmonella infection in humans.

For pet owners, the easiest way to prevent salmonella infection is to simply wash your hands before eating, if you have been handling your pet or giving it animal-derived pet treats. Although giving your dog a tasty rawhide bone might keep him busy for a couple of hours, it might end up keeping you in the bathroom for a couple of days.