Avoiding Footrot-By Carol Gomes October 2000-2011-Manage the biosecurity
of your flock.
Contagious footrot is caused by two anaerobic (without oxygen) bacteria. The bacteria Fusobacterium necrophorum is commonly found in soil, manure, etc. and colonizes the soft tissue between the toes of sheep. This is followed by penetration of the skin by a second bacteria Bacterioido nodosus. Both bacteria have to be present with certain enviromental conditions to cause contagious footrot. There are different strains of B. nodosus, some being more infectious and/or more severe. Scald is a less severe form of footrot and happens with just Fusobacterium necrophorum present which is commonly found in soil, sheep manure and is also housed in the sheep's gut. Some sheep seem more prone to footrot and scald. Depending on the sheep's immune system, their immune response to bacterial infections like footrot and scald can vary.
The B. nodosus organism has to be brought in on the property (Fusobacterium n. is already on the property in soil/sheep's gut/manure). Bringing in footrot infected sheep is a good way to spread footrot into your herd and onto your property. Carrier sheep may not show signs of footrot at the time of purchase. When conditions are right, carrier sheep can have an outbreak of the disease. As soon as it becomes infectious again in the sheep, it is easily spread to other sheep and onto the property. Especially if your sheep are in mud where the bacteria can thrive in an anaerobic (without oxygen) state. Some articles I have read say the bacteria can live inside the hoof for up to 2 years in carrier sheep. Because sheep have different immune responses, not all sheep will be affected the same.
Environmental conditions conducive to outbreaks of footrot are warmth, moisture and an anaerobic (without oxygen) state. Spring and fall in Oregon are the best times for footrot outbreaks with warmer moist conditions. Keeping sheep in dryer conditions will also help prevent spread and outbreaks since footrot thrives in an anaerobic state in mud and manure.
We don't trim our sheep's hooves. A minuscule cut into the integral wall of the hoof opens it up to bacterial infections. Our sheep's hooves break off naturally with no trims. Over time a line will form where the hoof breaks off. Mother nature does an excellent job while we also selectively breed for good feet with compact hooves that maintain well on their own.
To avoid footrot/scald, quarantine all new animals, no exceptions. Make sure
your quarantine is long enough to include proper environmental conditions
that are conducive to a footrot outbreak. Footrot is caused by the introduction
of sheep into a flock carrying the disease, by carrier sheep that don't display
the disease at time of sale but have a relapse when added to a clean herd
they infect during their outbreak or by contaminated premises. Shepherds who
track in manure housing footrot also expose their sheep to footrot. Since
the B. Nodosus organism will live in soil for only 14 days, there are some
arguments to whether it lives longer, the major means of contamination is
by sheep to sheep contact. Footrot bacteria can live in cracks, crevices,
etc. of sheep's hooves for an extended period of time (I have read up to 2
years inside the hoof) therefore sheep can serve as a carrier of footrot without
showing symptoms. This makes it even more difficult to avoid footrot or eradicate
article states B. nodosus can persist up to 3 years in chronically infected
Not all shepherds agree with me on scald. In 20 years of raising sheep, we have never had a case of scald or footrot. So I believe there is some relationship between scald and footrot. In Oregon, I'm told by sheep breeders scald is just a mild infection between the sheep's toes and a plugged oil gland that starts the infection. But you have to realize I was told many versions of this story by many breeders years ago who diagnosed their foot problems as scald. Most had some form of infection in the hoof that required treatment. They told me it was due to the wet warmer weather. Sounds like footrot to me. Here's why. Our Dorsets would go down to a pond to drink in the lower pasture during spring and fall months with warmer very wet weather. Conditions are ideal for footrot related infections during this time. None of our sheep have ever had any foot infections or issues what so ever. Since there are about 20 strains of B. Nodosus (I read that on several reputable sites) and the severity varies in the different strains, I have to believe that scald is a milder form of footrot. We bought a footrot free herd back in 1989 to start our foundation Dorset herd. We closed our herd 2 years later once we found out we couldn't trust what different breeders were telling us and how to bring in new rams and avoid footrot. All of those breeders I contacted to bring in a new ram had footrot or scald. To positively avoid footrot, we closed our herd. We have avoided footrot and scald for 25 years now.
UPDATED NOVEMBER 2010
Some sheep breeders insist that contagious footrot lives in the soil and is unavoidable since sheep have roamed the Willamette Valley for decades. Every single article, every bit of research, every person who I ask that has had it and eradicated it, all agree on this one point: Contagious footrot has to be brought in. Scald, a non contagious form of footrot, comes from the Fuso.bacterium which lives in the soil. Sheep ingest it while grazing, it's housed in the sheep's gut, then passes back out again only to start the cycle all over again. Since the scald bacteria lives in the soil and is always present, sheep prone to scald may get it. Both bacterias, B. nodosus, which doesn't live in the soil that long, and Fuso. bacterium, which lives in the soil, have to be present for contagious footrot. If you break the cycle, you can eradicate contagious footrot.
Article Written by Carol Gomes/Updated January 7, 2014