Foot rot can affect a goat or sheep’s weight gain, reproductive rate and milk and wool production. Consequently, it reduces the animal’s value to you or a prospective buyer. You can prevent foot rot from entering your herd, but if it does show itself, it is possible to manage and eradicate it.
For foot rot to occur, two anaerobic bacteria must interact: Fusobacterium necrophorum and Dichelobacter nodosus. F. necrophorum is a typical inhabitant of a ruminant’s digestive tract. When it meets up with D. nodosus and enters the hoof, an enzyme is produced that digests the hoof’s soft tissues. Left unchecked, the horn will separate from the flesh of the foot. There are several strains of D. nodosus that vary with respect to their virulence. Those with low virulence affect only the skin between the toes, while highly virulent strains quickly undermine and separate the horn from the foot.
Reddish and moist skin between the toes is an early sign of infection. If left alone, it will spread to the heel or center of the toe and produce a strong odor. Once the rot has encompassed the entire sole, you may see a swollen hoof, pus and spreading toes, and the animal may exhibit a fever and loss of appetite. This can be quite painful, and an animal that limps, eats while kneeling or seems unwilling to walk is a signal to you that foot rot may have made its way onto your farm. Not all lame animals have foot rot, though. A foreign object lodged between the toes, corns, abscesses or laminitis can also cause lameness. When in doubt, call your veterinarian.
|PHOTO COURTESY OF LEE KRETSCHMAR/STOCK.XCHNG.
If your animal does have foot rot, separate it from the rest of the herd and move it to a clean pen. Then trim, trim, trim the animal’s hooves. Remove all affected tissue to the point of separation. Because the bacterium does not survive in the presence of oxygen, you want to expose the infected area to air, which also encourages it to drain and dry out. Once you’ve finished trimming, spray with a 10 percent solution of zinc sulfate, copper sulfate or formalin. Then, return the animal to its clean, dry pen and keep it there for 24 hours. Before you put your trimming tools away, clean them with a 10 percent bleach solution. The last thing you want to do is help spread the disease by trimming a healthy animal’s clean hoof with infected tools.
After the initial 24-hour period, turn the animal out to clean, dry pasture and treat it daily with footbaths comprised of 10 percent zinc sulfate or copper sulfate solutions. Be warned: copper sulfate is toxic if the animal drinks from the bath. It will also stain wool and corrode metal. Recommended soak times range from a few minutes to one hour. You can either fill a cup with the solution and hold the foot in it, or you can build a structure to contain the animal as it stands in the bath. Base your technique on the number of infected hooves and the animal’s temperament and tolerance levels. And, make sure you maintain a quality footbath solution over time; when it’s compromised by debris and manure or diluted with rainwater, change it. Antibiotics can be used to treat severe cases, but they can be expensive. Consult your veterinarian if you’re interested in going this route.
D. nodosus can persist in the hoof and your pasture’s soil for up to three weeks. If after several weeks there is no response to treatment, the animal should be culled. Otherwise, you will have a carrier on your hands, and it only takes one carrier to support bacteria and spread infection.
There are a few ways D. nodosus can make it onto your farm. One way is to introduce it to your herd by purchasing an infected animal. The bacteria enter the soil via infected hooves and are picked up by hooves of uninfected animals. Before you purchase an animal, inspect its hooves thoroughly and ask about its ancestor’s hoof health, as hoof problems can be heritable. Be aware of the animals it’s been penned with. Even if those hooves don’t appear to be infected, if it is penned with infected animals, those seemingly healthy hooves could be harboring the bacteria. When you bring a new animal home, trim and treat its feet, isolate it from the rest of the herd and monitor its hooves for the next 30 days.
You can also introduce foot rot to your farm by transporting animals in contaminated trucks and trailers. Before transporting in someone else’s equipment, make sure you clean it thoroughly. Goats and sheep can also be exposed to foot rot at fairgrounds and show rings. Show animals should be quarantined and monitored for 30 days before being returned to the herd. The bacteria can also be spread via your boots, so it’s not a bad idea to disinfect your boots after visiting other farms or going to shows. Large goat and sheep farms often ask that you wear rubber boots that can be disinfected or you use a pair of disposable boots while visiting.
There are a number of preventative measures you can take. You should minimize muddy and wet conditions, as they not only allow the bacteria to persist in the environment, they also soften and moisten the hoof, predisposing it to dermatitis and injury. Also, routinely check and trim feet, as this improves your chances of detecting it in the early stage and helps to reduce hoof stress and prevent injury. Injuries are gateways for foot rot. Also, overgrown hooves tend to curl under towards the sole, creating an area the bacteria will thrive in. After trimming, spray any of the three solutions mentioned earlier. Place a footbath near food and water, at gates or regular travel lanes so animals are forced to walk through it. Maintain adequate mineral levels in the diet; animals deficient in zinc, copper and selenium will have poor hoof structure and be more susceptible to D. nodosus. There is a foot rot vaccine for sheep that is consider-ed effective when combined with other preventative measures; it is not approved for use in goats.
The author, a brand new contributor to Farming, is a biologist who lives and farms in Vermont’s Northeast Kingdom.