Pet ‘Kisses’: Health Hazard or Health Benefit?

Parasites:

Pets are hosts for many parasitic worms and single celled parasites. Human infection from these parasites can result in intestinal disease, skin problems, blindness, and brain disorders. Pets may live with these parasites in their intestines with no signs of illness. But eggs passed in the pet’s feces can infect humans. Like bacteria, the major route of infection to humans is fecal-oral. Pets that have licked their anus can potentially pass the parasite eggs to humans during facial licking. With the exception of two single celled parasites, Giardia and Cryptosporidia, this type of infection is not likely. Most parasite eggs are not infective directly from the anus. They must undergo a period of maturation in the feces or contaminated environment in order to infect humans. Transmission to humans would require dogs licking human faces after mouthing or eating feces that was one to 21 days old, depending on the parasite. Because cats are not feces eaters (coprophagic), humans are unlikely to become infected by parasites from their cats. Giardia and Cryptosporidia are immediately infective so potentially could be transmitted by a lick.

The Benefits of Pet Saliva

The belief in the curative power of a dog’s lick dates back to ancient Egypt and has persisted through time. In modern France a medical saying translates to “A Dog’s Tongue is a doctor’s tongue.” Recent research has identified products in saliva that indeed aid in healing.

• Researchers in the Netherlands identified a chemical in pet saliva called histatins. Histatins speed wound healing by promoting the spread and migration of new skin cells.
• Dr. Nigel Benjamin of the London School of medicine has shown that when saliva contacts skin it creates nitric oxide. Nitric oxide inhibits bacterial growth and protects wounds from infection.
• Researchers at the University of Florida isolated a protein in saliva called Nerve Growth Factor that halves the time for wound healing.

Prudent Precautions with Pet Saliva

The risk of bacterial or parasitic infection from pet licks are the greatest for very young children, the aged, and immunosuppressed individuals on chemotherapy or inflicted with AIDS. Individuals with healthy immune systems are unlikely to become infected. Despite the relatively low risk of infection from pet licks, some sensible precautions by pet owners are in order. The Companion Animal Parasite Council recommends:

• Regular deworming programs
• Annual pet fecal examinations with appropriate anti-parasite treatment
• Treatment to control fleas and ticks
• Daily disposal of pet feces and compliance with pooper-scooper laws
• Covering children’s sandboxes when not in use
• Feeding cooked, canned, or dry dog or cat food
• Washing or cooking vegetables for human consumption
• Adequate hand washing after exposure to feces or fecal contamination.