LambVirus1This is kitchen lamb, he has broken out with some kind of mouth papules after belatedly rejoining the herd. About half of the lambs already got this and got over it, the other half were unaffected. I’m pretty sure I saw it last year too. I’ve been wondering what this is, but so far haven’t found a definitive answer. Anyone know?

I think the best guess is soremouth (ovine ecthyma), but I’m not convinced that’s what it is.

Soremouth Symptoms

In reading about soremouth, it sounds like usually the manifestation is fairly severe, such that the lambs don’t want to, or can’t, nurse because the sores are so painful. Most example pictures I see show very large, blackish scabs. And supposedly you often see a reciprocal infection on the ewe’s udder. But it also sounds like there are many strains of soremouth. In my herd, the lambs get small, light-colored scabs, and they don’t seem to  be bothered by it. It runs its course within a week or so, and I see no udder problems on any of the ewes. It’s mostly just unsightly.

On Sheep 201, a website administered by small ruminant expert Susan Schoenian, there is a photo of a lamb with a similar infection, and the caption says “not soremouth.” But it doesn’t say what it is. I’ve emailed her to ask if she could elaborate on it.  I get frustrated at times by the lack of diagnosis information available for sheep raisers. My books often lack detail, or even mention, of diseases like this. Even Paula Simmons fails me here, in her book Raising Sheep the Modern Way, I can find no mention of soremouth. And I usually find everything in that book!

LambVirus3Treatment/Prevention

If it is soremouth, treatment is deemed “not rewarding.” I could vaccinate the ewes for it in the future, and then in theory, their lambs would then have enough immunity to not break out in sores. But in reading about the vaccine, it sounds like it has a lot of con’s, and not many pro’s. It sounds like maternal immunity passage from the vaccine has low effectiveness. And the vaccine’s immunity duration isn’t good either, it needs to be repeated at least annually. The vaccine is a modified live version in paste form, and it’s not very attenuated; so sheep treated with it will break out with sores in the treatment area. Thus it’s not recommended to vaccinate if you aren’t already sure you have the disease in your herd, because the vaccine will effectively introduce it. And apparently the human administrator can also break out in sores, if the vaccine paste is mishandled! For herds where the soremouth was so bad as to be causing significant weight loss or death in lambs, maybe the vaccine would be worth considering. But otherwise it doesn’t seem like the risk, expense and labor are justified.

I’m Going to Ride it Out

LambVirus2Some people practice segregation, to try to curtail the spread of the virus. But this is not convenient for me, it would be labor-intensive to inspect often for infection, catch the affected lambs and their ewes, and sort them into different holding areas for several weeks. And supposedly soremouth is very transmissible and survives a long time on surfaces, equipment, and in the environment. So I imagine once you’ve got it, all of your lambs will likely be exposed, despite best efforts to avoid that. I think since this is merely a temporary cosmetic affectation to my lambs, then it’s better to just let it run its course every year. Perhaps eventually the herd will develop immunity.

LambVirus4Zoonosis

The only other consideration is that soremouth is a zoonotic disease, called orf when humans get it. Though it sounds like human transmission is fairly rare and usually minor, sometimes the sores can be serious. For farms that leverage agritourism and let farm visitors cuddle lambs, it would be wise to schedule these activities well before the lambs are old enough to be showing symptoms of soremouth. And that probably works out, because about the time they are old enough to be pathogenic, they are losing their cuteness anyway.

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