In a world where we deal with big-picture items that affect swine health, nutrition, welfare and other areas, we sometimes forget about the basics that need to be attended to every day.

One of those potentially forgotten areas is parasite control. Parasites in swine are often silent thieves with no obvious signs of health effect or financial loss. But parasites can also be not-so-silent thieves.

Case Study No. 1

We were called to a farm where finishing pigs were experiencing diarrhea problems. Pigs were finished outside.

This group of pigs had been placed for about a month. The majority showed signs of diarrhea. Many had blood in the feces. Approximately 10% of the group were showing signs of slow growth. The list of health issues that we ruled out included ileitis, swine dysentery and whipworms.

On postmortem examination, there were no respiratory lesions and no evidence of liver scars, and the intestines looked normal except for the colon and cecum, which were lined with what looked like “hair.” This hair was actually attached whipworms.

The group was dewormed with a parasiticide that controlled whipworms. The pigs responded well and had no subsequent concerns.

Case Study No. 2

We were called to a 600-head finishing farm with a history of skin lesions in pigs about 40 days after purchase. About 30% of the group showed some skin thickening in the shoulder area and crusting around and in the ears. The pigs were very restless. At any one time, about 5% of the group could be seen scratching on the gating or with their hind legs.

Skin scraping for mange was not attempted due to the difficulty in getting a positive result in spite of positive signs of skin lesions. The group was fed a mange control product for seven days. The skin lesions resolved nicely.

Case Study No. 3

We were called to a 600-head, farrow-to-finish farm with a history of chronic respiratory disease in finishing pigs.

Postmortem examinations were done on two finishing pigs. Both livers in these pigs were nearly white with ascarid (roundworms) migration liver scars.

The normal life cycle of ascarids involves the eggs being eaten, then burrowing through the liver and the lungs. The pig then coughs them up, only to be swallowed and grown into egg-laying adult worms.

This farm was already deworming sows and pigs — but it was not being done at the correct times. Their process was to deworm sows twice per year as an entire herd program and deworm pigs in the nursery.

Since an ascarid can go from an egg that is eaten to an egg-laying adult worm in 6-8 weeks, the farm needed to adjust the timing of the deworming program.

We have changed to deworming sows as they enter the farrowing crate. Feces are scraped behind the sows for 48 hours after the dewormer is administered. The theory here is to provide “clean” pigs going into the nursery. Before the worm eggs can become egg-laying adults, the pigs are weaned and have moved into the nursery.

Since most of the modern nurseries have raised flooring, the amount of fecal-oral contamination is limited and so is the exposure to worms. Therefore, the pigs entering and leaving the nursery should have very few, if any, worms.

In the new program, no nursery deworming is done. From the postmortems that were conducted, it was known that the finishers were contaminated with ascarid eggs.

We chose to begin with a two-step deworming program in the finisher. Forty days after the pigs are placed in the finisher, the first deworming is done. This allows the pigs to go around like little vacuum cleaners picking up ascarid eggs.

The process of deworming kills the adult worms before they are old enough to lay eggs. The groups were all dewormed a second time in 40 days to again decrease the numbers of eggs in the environment. This was done for two turns of the finisher. The second round of deworming was phased out in the third turn of pigs.

We continue to monitor this farm intermittently with fecal examinations. The fecal exams have been negative to date. At a cost of slightly more money per head, this farm has gone from terrible to good internal parasite control.


The industry has excellent deworming and mange control products that will effectively control internal and external parasites. Contact your veterinarian for assistance in choosing the correct product and the strategic time for its use.