Shropshire sheep found

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Quarantined sheep that disappeared from an eastern Ontario farm earlier this year may have ended up on a Bruce County farm

Comments

I am the lawyer for Montana Jones. In preparing for Ms. Jones’ judicial review application, we consulted with several top experts on scrapie and related diseases. The opinion that was expressed to us is that eradication of scrapie is impossible, and that even scientists in the CFIA are aware of this. Apparently, nobody wants to jeopardize his/her job by going on record against official policy.

Studies in Iceland have shown that even after intensive cleansing of prion-infected farms, and even after farms were left depopulated of sheep for as long as 21 years, the prions persisted and were able to infect new sheep.

Some genotypes of sheep appear to be more susceptible to what is known as “classical” scrapie, while others appear to be more resistant. Farmers who consider scrapie to be of major concern can breed resistance into their flocks simply by selecting their breeding stock appropriately.

However, there are disadvantages to a regimented, draconian rule that all sheep of the most susceptible genotype must be killed if they have been exposed to scrapie.

Scrapie has a long incubation period—sometimes as long as 8 years. During that time, the sheep may show no symptoms whatsoever—which also means no loss of productivity. It makes no sense to insist that 3-year-old sheep be killed when they might not suffer from reduced productivity until the age of 8, and they would normally be culled from the flock at the age of 6 or 7 anyhow.

More importantly, however, emerging scientific evidence has shown that eradicating particular genotypes of sheep inadvertently predisposes the surviving sheep to other forms of scrapie.

The CFIA is well aware of this fact. In fact, one CFIA veterinarian co-authored the following in a published scientific study: “…selection for genotypes resistant to classical scrapie may result in greater susceptibility to other scrapie strains. In particular, genotypes with increased resistance to classical scrapie, including ARR/ARR, have been found to be susceptible to the recently identified atypical strain (originally termed Nor98) of scrapie. The potential for unintended selection of a new strain of scrapie should caution regulatory authorities against any PRNP selection strategy that takes a sheep population towards homogeneity.”

Yet this same veterinarian sat at Montana Jones’ kitchen table and told her that all of her sheep with genotype ARQ/ARQ would have to be slaughtered.

If a farmer who owns susceptible sheep wants to take the risk of his/her animals being less productive or dying at a younger age, surely that is the farmer’s own business and nobody else’s. After all, other farmers who wants to protect their own flocks against such risks can do so single-handedly by breeding the resistant genotype. It is not necessary for all shepherds to march in lock-step.

Industry groups might consider developing voluntary certification programs for farmers who want an assurance when they purchase livestock that the animals have been tested or genotyped. Farmers who choose not to breed resistant sheep would reduce the marketability of their animals—but that’s their choice, and they will reap the consequences, bad or good.

Might there be any good consequences to keeping scrapie-susceptible sheep? Yes, indeed. One study shows that the very genotype that the CFIA considers most susceptible to scrapie—the ARQ/ARQ genotype—actually produces the hardiest crop of lambs. These ARQ/ARQ sheep have “higher postnatal survival rates than sheep carrying the more scrapie-resistant alleles.” The study comments that “Lamb survival is of critical economic and welfare importance to sheep enterprises, where an average of 10% and up to 40% of the total lamb crop can be lost during the neonatal period under temperate climates…”

So it was not at all foolish for Montana Jones to want to keep her ARQ/ARQ sheep alive. She had observed the hardiness of these sheep herself. Her ewes were lambing well into old age, with twins being the norm. Even if the now-dead sheep ultimately prove to have scrapie—we are still awaiting test results—it’s worth considering whether there is something about Montana’s farm that kept her sheep apparently healthy and productive despite the prion infection.

There is still much that scientists don’t know about the field of “gene expression”. We do know, however, that being genetically predisposed to a disease such as diabetes is not an automatic life sentence for getting the disease. Humans can adjust their lifestyles to avoid getting diabetes even if they are genetically predisposed to it. Perhaps the living conditions of sheep can also be adjusted so that they remain healthy and productive despite a susceptibility to scrapie. Killing these sheep instead of studying them was a foolish, knee-jerk response to the problem.

Karen Selick

I read someone's comments regarding the Shropshire sheep (and Montana Jones) who indicated that the CFIA was and is trying to control Bio Diversity and that was a more likely reason for the cull. Is there any truth to this?

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