Combating Sheep Flock Parasites – Part 1, by Mike V.

My mother went back to school to be a social worker, and she did a project which was quite interesting. She taped (remember cassette tapes?) one of our dinner conversations and then played it back to us when her project was over. I do not remember what her point was but I do remember that three planes flew over the house and two trains went by and none of us skipped a beat with the conversation. We lived in the flight path of one of the largest airports in the world and the train tracks were right next door. I guess it is mandatory for the train to toot the horn one long, two short, and one long as it passes the crossing. It was difficult researching the Doppler effect of sound in the encyclopedia especially when you have never heard of the Doppler Effect. It dawned on me that we just tuned the DC-10 out as if it was background noise. To determine why the train made that weird sound as it passed required a trip to the library which was about 20 blocks away with about 15 trees and a whole lot of concrete.

You can’t grow much on concrete except in the cracks. When the land is made of that material you are pretty sure that food comes from the store along with all of the things which make up dinner. Meat comes from behind the glass; milk comes from the carton, vegetables in the bins with the little misters. Who knew someone had to grow all these things in order to eat. In order to be able to grow something, anything, we were going to have to change the substrate we lived on.

We have replaced the concrete with actual dirt and grass over the ensuing decades. It took a while to get to this point but like everything else in life, you can’t take the steps forward without the steps before. Let us begin with the sheep. We have been raising them for the past 6 years because we like lamb. Most of you already know that there are certain requirements that are necessary to raise livestock such as acquiring good animals. Or you could do what we did. Just get a couple from the lady down the road and see what happens. Grass and water, what else do you need? Yeah, the fencing so you do not have to chase them.

The side benefit of poor fencing is learning how to lasso and knowing that you are in shape enough to jog around until they get tired so that you can catch them. There is one other problem that small ruminants have that is the topic of this post. Haemonchus Contortus, the dreaded barber pole worm. It is nasty and difficult to control.

Our problems began soon after we received our ewes. Did I mention that we had a llama? Well, the llama got sick and of course no veterinarian around here knows anything about llamas. A long search on the internet yielded multiple possible causes for his symptoms but the common thread in all of the articles was worms. The vet will do a stool test for 15 dollars to tell you that the animal has worms. If you ask what kind of worms you get no definitive answer and if you ask to see the slide they say no. That is 15 dollars not so well spent.

In any event, Haemonchus is a nematode that in its larval form will infect the animal after ingestion. The life cycle is simple in that an egg will be deposited in the stool and within a few days will hatch and the larval form will climb the first few inches of grass and be eaten. The larvae will develop into an adult worm and will reside the animal’s abomasal mucosa (the fourth stomach in sheep) and will feed on blood. They are tiny vampires and cause anemia and edema (bottle jaw) due to severe blood/protein loss. Adult worms can lay thousands of egg per day which are then released back into the environment to complete the cycle. The eggs hatch in warm moist weather and but there are some studies that suggest an encapsulated egg can survive for extended periods in poor conditions. Hot dry weather and cold will kill the eggs. Another unique way Haemonchus has adapted is that the worm stage can undergo hypobiosis which is a dormant state in the animal’s abomasal.

The worms in this state do not feed and do not lay eggs. This typically occurs during the winter when eggs are less likely to survive. The worms will come out of this state if the animal becomes stressed such as with pregnancy, lambing and lactating. Once your animals are infected it is all about control of disease.
One of the easiest ways to look after your sheep is to do what is called FAMACHA scoring. This is a way of grading anemia in ruminants and also modified ruminants such as camelids. The grading is from 1-5 with five being a nice red color and one being a pale pink and profoundly anemic. The link above gives a great description as well as pictures to match eye mucous membranes to the grade of anemia. It is relatively simple to do the grading by applying a little pressure under the eye to fold the lower lid down to observe the mucosa.

Alternatively, you can visualize the animal’s oral mucous membranes with similar results. With all things animal-related, the first few times kind of upsets them, but they will get used to manipulation over time. I did not say they would like it, just not go bonkers crazy when you poke around their eyes. With large flocks you would probably need notes and tags to keep track of individual sheep but with a small flock you can pretty much remember what each animal looks like and can tell if there is a change.

In our small flock, each animal’s baseline is different. Some may have a baseline at four or some at three. It is important to know your animal’s baseline in order to determine if any changes occur and if those changes warrant treatment. The worm problem can never be eradicated so when to treat becomes the primary issue.
If I look at an animal and think that something is not quite right, something is not quite right. That little thought in the back of your head that says, “that looks weird”, “she looks a little different today” is your brain telling you something is off and do not ignore it. Sheep are just looking for a way to die and go from looking ok to moribund very quickly. Are they more anemic than the last time you checked? If the score is the same do not just stop there. Remember you thought something was wrong so you can perform another relatively simple test to gather some more information. The animal will likely need a fecal egg count which is called the modified McMaster test. You can either bring the stool pellets to the vet for them to charge you a pretty penny for each test or learn to do it yourself.

This is a really easy test to perform by yourself as long as you have the equipment. There is some investment up front but at 10-15 dollars per test at the veterinarian’s office it will take no time at all to recoup your investment. The most significant cost is the microscope. It does not have to be a pathologist grade scope, just a monocular medium magnification. They sell for 80-120 dollars and will last forever if you take care of it. 50cc plastic test tubes sell in packs of significant quantity but are reasonably cheap. I have been using the same 4 tubes for the past 5 years. Just clean them after each test. Little plastic pipettes which hold about a cc also come in quantity packs but again, I just keep reusing the same ones after cleaning.

The McMaster slides can be purchased separately or as part of a kit which contains the test tubes as well as the pipettes. My 4 slides were about 40 dollars 5 years ago and I am sure that they are more expensive now as with everything else. A small scale which can weigh at the gram level is also needed and is also pretty inexpensive. You are not measuring out drugs, just weighing feces, so any cheap thing will do. To strain the stool slurry you can pick up one of those small strainers that you put into the sink so that your wife’s hair does not clog the drain. They work great for both purposes but it would be best not to multipurpose that piece of equipment. Lastly, you will need the flotation fluid.

You can make this at home with Epsom salt and water mixed to the right concentration. The easiest recipe is take a quart of warm water and add Epsom salt slowly while mixing until some of the salt crystals will no longer dissolve. You will then have a saturated solution with a specific gravity of somewhere above 1.25 which is appropriate for the test. You could also just buy a gallon of Fecamed which is a sodium nitrate solution with a specific gravity of 1.25. It will last you years and costs about 15 dollars.

(To be concluded tomorrow, in Part 2.)