This is how conspiracy theories get started—in the vacuum of verifiable causes. I know because recently I created my own conspiracy. Three weeks ago, three perfectly healthy ewes simply laid down and died within a few hours of each other. The circumstances were similar and puzzling: sudden death with no sign of stuggle or evidence of disease or pregnancy. Only two sheep have died here in the past 12 months, making this a clear case of something—but what?
During lambing, sheep in distress are a part of the job: lambs badly presented, twins tangled up in the uterus, lambs too big to be born without human assistance, uterine prolapse, fatal magnesium and calcium deficiencies. None of these have happened during this lambing, a small miracle for which I am endlessly grateful.
Instead, three perfectly healthy sheep laid down and died. The only disease factor I could come up with was clearly wrong: a massive bacterial infection of the gut commonly known as “pulpy kidney” because one of the symptoms is deterioration of the tissue in the kidneys. The bacterium is Clostridium, commonly found in the gut of healthy sheep, and it simply goes out of control, causing death within a few hours. All of my sheep were vaccinated for pulpy kidney as lambs, and given a booster 6 weeks before this lambing, making it a most unlikely cause. As far as I know, I’ve never lost an adult sheep to pulpy kidney.
I toyed with the idea of a nutritional deficiency, but had to let that idea go since the sheep with the greatest nutritional challenge—the new mamas—were thriving, as were their babies.
And so the conspiracy theory began. The cause of last resort in my lexicon is snakebite. It’s actually quite hard for a snake to get a good bite through long wool, so they’d have to hit on the face. And three in the space of 36 hours? There was a storm the night before I found the first dead ewe. Could all three have been struck by lightning? Or a combination of snakebite and lighting strike? Or do thunderstorms make snakes go mad and rampage around biting anything they encounter? Less than satisfactory, but all I could come up with.
Until I thought of gunshot wounds—did I have a poacher on the place Friday night, during the storm, who for unfathomable reasons shot three ewes and then left them behind?
I swear to you that all of these ideas found a place in my fertile brain as I struggled desperately to make sense of these completely unexpected losses.
And then a few days ago, a fourth ewe died with the same (lack of) symptoms. This time I was ready. Karen and I took tissue and gut content samples and collected feces to check for any sort of intestinal parasite. When we got to the kidney sample, it was suspiciously squishy. Karen, the vet and I are all reasonably sure the deaths were due to pulpy kidney, though I have yet to get the official results from the post mortem. Worm counts were zero on both classes of worms, leading the pathologist to comment, "Parasites are unlikely to have contributed to mortality." (I've actually never seen a zero worm count before, by the way.)
With my conspiracy theory thrown out, I’ve been considering what may have triggered an outbreak of pulpy kidney at this particular juncture. Pulpy kidney most often occurs in “fat” sheep, not poor sheep. All of my sheep have been in good condition for months, but the pregnant and lactating ewes would be working harder to support themselves and their lambs than would “dry” sheep like the ones that died. So that fits the verifiable evidence.
Of the major vaccines, pulpy kidney has the highest failure level. To counter this, a regime of three years of boosters is recommended after the first two courses as lambs. In the past, I did annual vaccinations at shearing time, just before October lambing, to give the new lambs a boost of immunity from their mamas. Since I didn't lamb over the past three years, and therefore didn't vaccinate, my 3 year-olds did not get the additional annual boosters they should have. Three of the four sheep who died were 3-year-olds. So that fits the verifiable evidence, too.
Could another factor be a relative lack of plant dietary diversity—because I’ve been unable to shepherd for six weeks—making it harder for the ewes at risk to self-medicate and stave off the Clostridium outbreak in their tummies? I will probably never know, but I immediately let the flock move into the best fresh paddock I have that has lots of “weeds”. Fingers crossed this will prevent any more deaths and preclude me invoking "alternative facts" in the future. And this lot of lambs will certainly get their 3 annual boosters!