Safer Sheep Shearing

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Country Vet

Keeping a healthier flock

By Andrea Looney, DVM.

Many of our sheep develop abscesses after shearing. What's the cause of this and how do we deal with the abscesses?

-Lisa Capriano
Burns, OR

Dear Lisa:

Virtually every sheep and goat producer faces the age-old problem of recurring abscesses in the flock. Most of these abscesses can be attributed to the bacteria Corynebacterium ovis and the disease called caseous lymphadenitis, or CLA. While many shepherds view the disease as a harmless problem, CLA can cost sheep and goat producers a lot of money in terms of decreased reproduction and production efficiency, as well as the cost of labor and drugs to treat affected animals.

The disease seems to be more common in western and south-central United States, where sheep are more likely to graze year-round in an environment conducive to skin abrasions. Sheep can actually contract the bacteria through ingestion, inhalation, or penetration through intact skin. However, most do become infected via contact between infectious exudate and skin wounds. Contact with infected feeders, bedding, or equipment can spread the disease. Your sheep probably become infected at shearing time, when minor skin nicks and abrasions routinely occur. Once the clippers become infected, disinfection is difficult, and since the abscesses are not always so visible, spread from one clipped ewe to the next unclipped one is very likely.

So how do we treat these abscesses? For the simple once-a-year abscess, the treatment is easy. Isolate the animal first, as an abscess that is broken contaminates the environment with thousands of potential abscess-forming organisms. Trim the hair around the abscess and hot pack for three to four days. If the lump fails to come to a head and break, lance it (make an incision at the bottom) with a clean blade and continue to hot pack. Consult your veterinarian for appropriate antibiotics.

If the abscesses are a herd problem, draining many abscesses and administering systemic antibiotics may simply result in temporary improvement. The bacteria produces thick-walled abscesses and the capsule serves to keep the bacteria in and the antibiotics out, even if the abscesses are drained and flushed. Infections are likely to recur once treatment is discontinued. Long-term antibiotics may be economically impractical. Segregation of ewes with abscesses is of paramount importance until the abscess is opened and no longer draining.

In herd problems, it is extremely important to sanitize shears, combs, cards, and dipping vats, along with knives and emasculators. You can use quaternary ammonium compounds, chlorhexidine, hypochlorite solutions, iodines, and phenolic solutions on equipment once you remove organic material with hot water and a detergent. You should remove dirt from floors, walls, and walkways, and clean them with steam and detergent as well.

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