Footrot can be economic disaster for sheep producers
When sheep get that wet, smelly, rotten-looking open wound between their hooves it can make producers cringe. Especially if the culprit is footrot, which is currently considered one of the most serious issues facing the sheep industry, according to Michael Neary, who is a small ruminant extension specialist with Purdue University.
“Producers leave the sheep business because of footrot,” Neary said. “They just give up because it is so hard to treat. It is a costly disease to individual operations, as well as the industry as a whole.”
The disease, which is highly contagious, takes a lot of effort and management to eradicate, Neary said. However, with careful management, the disease is entirely preventable. “I tell producers to only buy or lease breeding stock from footrot-free operations. Some operations have had the disease for a long time, and think of it as part of the operation or no big deal.” Neary reminded producers there is no such thing as a little footrot. “You either have it or you don’t. There is no in-between.”
Footrot in sheep is caused by two anaerobic bacterias, and outbreaks are more likely to occur in extremely wet conditions, like many of the farm flock and western states have experienced this year. Neary said he doesn’t believe footrot bacteria can be spread through floodwater, but scientific research hasn’t confirmed that.
Before declaring the sheep have footrot, Neary encourages producers to evaluate the animals on an individual basis. “Just because a sheep or goat is limping doesn’t mean they have footrot. They may have an injury or something else. You need to inspect and treat them on a case by case basis,” he said.
Because the disease is contagious, Neary advised producers not to commingle sheep or share trailers. Show animals, as well as new breeding stock, should be quarantined from the rest of the flock for about 30 days, he said. “The problem is that bacteria gets in the cracks and crevices of the hoof, so the animal may not be symptomatic right away. Sometimes a 30-day quarantine may not be enough.”
With vaccinations unavailable in the U.S., producers are left with a few options to control the disease. Traditionally, producers would trim the hooves of infected sheep down to the quick to try and expose all of the hoof to air. However, based on more recent research, many animal health experts no longer recommend trimming the hooves, because it can allow the disease to spread easier to uninfected animals and it can increase healing time.
Foot baths with zinc sulfate, copper sulfate, or formaldehyde are also an option. “Foot baths are a good way to control footrot, but it doesn’t work as well to eradicate it,” Neary said. He also finds zinc sulfate works better than copper sulfate, but either are good drying agents.
In severe cases, the solution can’t penetrate deeply into the hoof. Neary recommends soaking the hooves by putting the sheep in a tub or container of some sort. “Soaking the hooves for at least 10 minutes two or three times a week can be more effective than running them through a foot bath,” he said, adding that producers need to put them in a dry area afterward.
Despite these traditional methods, Neary said producers may soon have access to an antibiotic that could help them eradicate footrot. “Gamithromycin (Zactran) is the newest and most exciting development in the sheep industry for control or eradication of footrot,” Neary said. “It has been on back order for a while now, but I am hoping it will be available to producers again soon.” Historically, the drug has been used as an antibiotic to treat cattle for respiratory disease. It is not approved in the U.S. for use in sheep without a veterinarian script, but it is approved in other countries as an effective treatment for footrot in sheep.
Research has shown the drug is so effective in treating footrot, producers don’t have to trim the hooves, separate the flock, or use foot baths and soaks. In fact, it is so effective, Neary worries producers will overuse it and it will become ineffective like many of the parasite control methods on the market today. “Producers need to use it as a complete eradication tool, not as a treatment. They should make a schedule and a plan. Once the footrot is gone, don’t reintroduce it to the flock,” he said.
Because the drug is expensive, he recommends using it when production numbers are at their lowest, like after weaning. Neary also expressed the importance of limiting antibiotic exposure. “Some veterinarians are reluctant to prescribe Zactran for sheep. But there is a lot of research that proves how effective it can be. I send veterinarians the URL so they can see the research for themselves,” he said.
No matter which method producers choose, Neary said infected animals should be monitored after treatment. In the case of eradication, if the animals don’t clear up, and it is a small flock, he recommends selling the animals. Producers should wait at least two to three weeks before purchasing a clean flock. “If that is not feasible, check the feet of every animal in the flock. Segregate the infected animals, and run the clean animals through a foot bath and put them in a clean area,” he said.
Once the flock is clean, Neary recommends stepping up the bio-security program to limit visitors, and require the ones who do visit to wear appropriate footwear. “There will always be some you can’t clear up,” he said. “Those animals are the carriers, and they are spreading footrot to the rest of the flock. They should be culled.” ❖
— Clark is a freelance livestock journalist from western Nebraska. She can be reached by email at firstname.lastname@example.org.
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