USDA’s National Animal Health Monitoring System collected data on swine health and management practices, representing more than 90 percent of the U.S. pig inventory. The data showed that 69.7 percent of sites used some type of deworming program for internal parasites.

Sows and gilts were the most common group to be dewormed, occurring on 83 percent of sites with breeding females. Contrary to the belief that boars are often excluded from parasite treatment, the study indicated that boars were dewormed on 76.8 percent of sites housing boars.

Producers reported roundworms present on 19.6 percent of sites with grow/finish pigs, 18 percent of sites with nursery-age pigs. Roundworms accounted for 21.2 percent of sites reporting worms.

Most operations – 76.8 percent – where market hogs had some outside activity reported routine deworming protocols. Only 44.6 percent of sites with indoor facilities made deworming routine.

Roundworms were a reported problem in weaned pigs on more operations in the western United States than any other region.

More operators (23.9 percent) of “small” sites considered roundworms a problem, compared with only 10 percent of “medium” and 12 percent of “large” operators. Sixty two percent of the “small” sites dewormed weaned pigs, 27 percent of “medium” and 8 percent of “large” sites. Some type of dewormer was given to grow/finish pigs on 54.4 percent of sites.

The most common internal-parasite treatment for grow/finish pigs was through feed, followed by injection and then water. Fendbendazole was the most common dewormer given to grow/finish pigs in feed. Ivermectin was the most common injectable product used, and levamisole was the most common water dewormer.