Experience, parasites, and the drive to fight and live

Porter died in his favorite spot in the paddock. A bucket of water and a handful of raspberry leaves (highly nutritious and a great favorite among sheep) were in front of him, untouched. A good friend and I were recently talking about Porter’s death. I have been shepherding for sixteen years, and she has had her flock for about four. As we discussed the reasons for his death and the treatment I had used in an attempt to save him, she said that she found his death very disturbing. She had thought that, with experience, these types of things wouldn’t happen anymore — that experience would bring the ability to “catch” anemia or a heavy parasite load before it led to death. In one way she is right, but in another way not.

In the very early days of flock management, we have never seen what a sheep looks like carrying a heavy parasite load. It’s easy to miss the few warning signs and to lose a flock member due to our ignorance. Every new shepherd, no matter how vigilant, will make mistakes — and the flock pays for those mistakes. As we gain experience and confidence, our flock benefits. We begin to keep a mental catalog (and often a notebook) of possible illnesses and injuries, comparing each sheep in the flock to what we have seen before. As the years add up, we become much better at diagnosing and treating the common and sometimes even the unusual.

Yet as we change and become better at what we do, our flock is also changing. Each fall, we put together breeding groups with particular goals in mind for the coming lambs. We select for particular traits — and in this flock, parasite resistance or resilience is on that list. In fact, even though we’ve had an ideal year for internal parasites to flourish, I still have a number of lambs who have never had any dewormer in the five or so months of their lifespans. This signals our success in resistance- and resilience-building in our flock.

You will notice that I use both resistance and resilience when I speak of this trait. The reason is simple: I don’t know whether these lambs are resistant (somehow able to flush the internal parasites through their systems) or resilient (somehow able to function normally despite harboring a heavy load of internal parasites). All I know is that when I check for signs of internal parasites, they appear to be healthy and fine.

When it comes down to it, all sheep have internal parasites. I always tell new shepherds that our goal should be to breed for the strongest sheep and the weakest internal parasites. The sheep will always have some parasites, but we hope to keep the quantity at a low enough level so the sheep can thrive.

We use a variety of indicators to tell whether a lamb has too many parasites. Every time we move the sheep, we watch to see which are at the end of the group. Internal parasites can cause anemia, and sheep with low iron levels will move more slowly and be less eager to move longer distances. If we see sheep lagging, we catch them and pull down their lower eyelids. The inside of the lower lid (the tissues that normally lie against the eyeball) should be a nice pink. Anemia covers a spectrum, and we’ve seen the internal eyelid color range from the ideal pink to ghastly white. I allow for a bit of variation in the level of pink, but increasing paleness is an indicator that they likely need a dose of dewormer. But anemia is only one sign of internal parasites, and not all parasites cause anemia.

As I check on the flock each day, I’m also assessing their digestion, since parasites attack the digestive tract. As the parasites build in number, the normally pelleted droppings become softer and, eventually, liquid. As I walk among our sheep, I look for manure puddles or wet and manure-covered tail stubs and back legs. It’s amazing how quickly a dose of dewormer can correct this problem — usually only a day or two before a return to normal pellets. (Anemia, of course, takes much longer to respond, since the body must make more red blood cells to replace those lost to the parasites.)

The problem with breeding for better resistance or resilience is that we also create flock members who may carry heavy parasite loads without issue — at least for a while. They seem to be able to handle that load as long as everything is well balanced, including good pasture and a stress-free life among their flockmates. Yet it doesn’t take much to upset the scales and tip these sheep into a parasite crisis. Stress is the enemy, and it can come from a variety of places. Porter, escaping into another field, separated himself from the rest of the flock. With the added stress of separation from his friends, Porter’s resistance dropped (or his resilience flagged) and he succumbed to the onslaught of the parasites. My quick recognition of the problem, prompt deworming and high-nutrition diet weren’t enough to save him.

As I mentioned in my previous post about Porter, the sheep’s will to fight and live has a lot to do with their survival. On the same day we treated Porter, Romney ewe lamb Pegeen was also discovered to be severely anemic. This little ewe lamb had obviously been hit hard in the previous few days, and the inside of her eyelids was deathly white — much worse than Porter’s. When I felt along her spine, I could feel every bone. Pegeen, however, was and is a fighter. She struggled with us as we dosed her with dewormer — which worried us, since we knew she had so little energy for such a fight. Yet after only an hour of resting in the shade (during which I worried that the struggle had utterly exhausted her), this little gal was up and eating with her friends — she knew that she had to eat to live. Pegeen is now on the road to recovery. She is a fighter, and she’s not willing to just lie down and die! This little gal will be joining our flock.

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