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    Wormer- Costs and Effectiveness

    Wormer- costs and effectiveness
    by Martha McGrath

    Now that summer is here and all the ewes have lambed and are out on pasture, we have a bit of a respite from most shepherding chores. One of our important jobs, though, is keeping internal parasites under control. Most of you know that total elimination of internal parasites is not practical, or even desirable, but worms can cause a lot of damage to lambs if left unchecked.

    Deworming programs should be based on parasite life cycle, weather conditions, and individual farm management practices to reduce pasture contamination from parasite eggs and larva.

    In the past, it was believed that pasture rotation would reduce parasite problems. This may not be true. Rotating large numbers of ewes and lambs through small grazing paddocks often concentrates parasite larva into the same small area. Ten to twenty day pasture rotations may also parallel life cycles of parasites, returning the sheep to a paddock when the pasture contains large numbers of infective larva.

    Ideally, you should periodically take fecal samples to your vet to have them checked for type and number of worm eggs and the effectiveness of the anthelmintics used.

    I generally use a drench dewormer, crowding the sheep into a corner of the barn with a hog panel, and squirting it in the sheep's mouth. I purchased a drench nozzle tip (about $9.00) for my disposable automatic syringe (which I do not dispose of till it breaks!- costs about $13.00). I also purchase the largest quantity of wormer available to save money. I bought "Prohibit" levasole drench powder, did some math, and only mix up what I'll need for a worming.

    There was a wonderful series of articles in Shepherd Magazine by Joe Rook (Jan., Feb., Mar./94) about the cost of each dose of several wormers. The horse pastes were the most expensive, Tramisole/Levasole drench, still effective in most flocks, was one of the least- about $.45/dose for an adult sheep. Another good article on wormer dose costs is from Pipestone Vet.

    An approach that I don't think is really being taken advantage of by many breeders in this country is selecting rams on the basis of worm resistance.
    Sustainable Worm Control
    Genetics-breeding worm resistant sheep

    Wormer costs are important, but if the medicine is not effective, you are wasting your money. Susan Shoenian, the Maryland Extension agent who does the MD Small Ruminant Page, wrote an article in the Jan. 22, 2002 issue of the Delmarva Farmer about a Virginia Tech study of the effectiveness of "persistent activity" dewormers. Virginia Tech compared Ivomec drench, Quest, a paste dewormer for horses, and Cydectin, a pour-on for cattle. For three successive years, grazing lambs were treated with Quest and Cydectin, and compared to the control group treated with Ivomec at four-week intervals. Quest provided better parasite control than the Ivomec and did not need to be administered as frequently. Effective parasite control was obtained when Quest was administered at six to eight week intervals. Cydectin was not effective when used as a pour on, HOWEVER, it was the most effective dewormer in the study when given orally at eight-week intervals at a rate of 150% of the recommended cattle dose. Susan cautioned that the use of Quest and Cydectin were extra-label, and one should consult one's vet, and practice longer withdrawal times before slaughter or using milk from treated animals. We have been using Cydectin on our flock with good results. We squirt it in the mouth. It smells horrible, and takes the paint right off a disposable syringe! Many goat owners are also using Cydectin orally, but are being cautioned to NEVER use it as a pour-on, as neurological damage and death has been reported in goats treated this way.

    Someone wrote to me that she had used Quest on her horses one spring as per label directions, and one of her mares promptly aborted her foal. She has since spoken to a mirad of horse owners and veterinarians that say that quest has killed adult horses and foals. She has also spoken to 3 veterinarians who say they will not use Quest in their practice. As she stated "We know even less about Quest in sheep."

    Cydectin Concerns;
    I received a letter from a shepherd friend who stated that she dewormed with Cydectin five days before first lambs were born...barely alive or dead. They were BORN with cold mouths and could not regulate body temperature. Only eight of the first 24 born survived. She did not know if any of her ewes aborted. She underestimated the weight of the pregnant ewes and did not give them a full dose. Things improved after 10 days and are back to normal at this point. A friend of hers who also used Cydectin in late gestation lost 27 of 48 ewes in a three day period, about a week after using Cydectin. About six of her ewes aborted. She did not deworm the ewes in an adjoining lot and they were not affected. Neither people changed feed, vaccinations, locations, anything from other years, EXCEPT they used Cydectin in the last week of gestation. They have not totally ruled out a possible reaction between Cydectin and something else, but haven't found a common vector. Lab results from five ewes (different labs) show the ewes died from heart failure- enlarged hearts/fluid. Lab reports lambs show they had "subcutaneous edema on the ventral thorax." She wrote to an Extension agent who replied; "All I can say is that I talked to someone at either the Sheep Industry Board Meeting or on the breedersworld forum (can not remember who) that had experienced something similar. They were attempting to draw a connection between the previous use of pour on Cydectin/Moxidectin as an off labelled drench in sheep and goats followed by using the drench cydectin formulated for sheep and goats. The theory was that using the pour on was effective, but potentially changed the enzymes or function in the liver and possibly portions of the product did not metabolize and stayed stored in the liver tissue. Then when the switch was made to the drench the liver could not function as necessary and the metabolization of the new product combined with the stored material and the additional drain of filtering the lambs systems. This may have caused blood levels to be toxic or at levels that put the lambs at risk. I do not know if this was based on theory or sound research however it sounded like a possibility to me."

    More on Internal Parasites

    One of the biggest problems we have in raising healthy sheep is controlling internal parasites. More and more of our "wormers" (anthelmintics) are becoming ineffective in killing the worms. Since no new anthelmintics will likely be approved for sheep in the near future, we must learn about the life cycle of parasites, and use more effective ways to control them. There is new thinking in the best ways to control internal parasites in sheep. No longer are we being told to simply rotate pastures every 2 weeks, worm every animal in the flock, or use one wormer for a year. It is very difficult to know the best way to control internal parasites!

    Some of the new techniques that shepherds can use to more effectively control internal parasites are; strategic deworming, better nutrition, genetic selection of sheep for resistance to worm infection, fecal egg counting and FAMACHAŠ. Fecal egg counts can be used to determine the level of pasture contamination and the need for anthelmintic treatment. FAMACHA is a technique developed in South Africa in which a color eye chart depicting varying degrees of anemia is used to determine the need for anthelmintic treatment. Famacha
    Comparing the inner eyelid to the FAMACHA chart. Notice how pressing the thumb against the closed eye causes the lower membrane to protrude. This sheep did not need deworming.

    In a recent newsletter, Stan Potratz of Pipestone made these recommendations for controlling internal parasites in sheep and goats;

    If possible, graze ewes and their lambs on pastures that were not grazed by sheep or goats in the previous 12 months.

    Deworm the ewes just before they go out to grass. If they are grazing "dirty" pastures (had sheep/goats on it last year) continue to deworm them every 19 - 21 days (not 22) for the first 60 days of grass. (it takes 21 days for a larva that's been consumed by a sheep or goat to begin producing worm eggs)

    Deworm the lambs as soon as they are seriously grazing grass (5 weeks old?). Continue to deworm the lambs/kids until they can moved to "clean" feed (feedlot, hay field, etc.) or until they are 120 days old.

    Feed the ewes with high protein feed (e.g. soybean meal) prior to lambing. Experiments have shown that doing so results in ewes that are better able to mount an immune response to parasites, and reduces the quantity of worm eggs that will be shed by lactating ewes on pasture.

    Graze cattle or horses with sheep/goats. The internal parasites of the first two species don't affect the last two species, but sheep parasites do damage goats and vice versa.

    Don't graze the grass too short (less than 2 - 3 in.). A worm larvae (that hatches from eggs deposited in on the ground in sheep/goat manure) can only climb about 4 in. up a grass blade. So forage taller than 4 in. is relatively free of worm larvae.

    Do periodic fecal samples. The results allow you to determine if a anthelmintic is necessary and/or which parasites need to be treated.

    Some other recommendations to help to slow anthelmintic resistance are targeting anthelmintic treatments to the most susceptible animals in the herd- lambs, first time lambers and high producers, leaving some less susceptible animals untreated. Sheep which require frequent treatment may have low genetic resistance, and should probably be culled from the flock.

    Animals should not be underdosed. Sheep should be weighed to determine the proper dosage. When deworming a group of animals, the dose should be set for the heaviest animals in the group, not the average. Anthelmintics should be administered orally, over the tongue of the animal. Research has shown that benzimidazoles are more effective when the animals are fasted 12 to 24 hours before treatment or when two treatments are given 12 hours apart.

    Further reading on internal parasites;
    MD Small Ruminants/Parasites
    Internal Parasite Control Sheep 201...a beginner's guide
    Photo of sheep with "bottle jaw"
    Fighting and Winning the Parasite Battle in Sheep
    Controlling Internal Parasites in Sheep by Mike Neary, Extension Sheep Specialist, Purdue University
    Control of Internal Parasites in Sheep VA Tech
    The Internal Parasites That Affect Sheep and Goats This site has a table listing species, common names, life cycle information and clinical signs of parasites.
    Integrated Parasite Management (IPM) in Small Ruminants producers can no longer rely on anthelmintics alone to control parasites in their herds. A more integrated approach will be necessary.
    Managing Internal Parasitisum info on worms, worming, and FAMACHA
    Anthelmintics Used to Control Internal Parasites in Livestock
    Southern Consortium for Small Ruminant Parasite Control The mission of the SCSRPC is to develop and validate novel methods for sustainable control of gastrointestinal nematodes in small ruminants and to educate stakeholders in the small ruminant industry on methods and recommendations for gastrointestinal nematode control.
    How to to do home Fecal Testing
    McMaster counting slides/testing kits

    By Deborah Mumma
    Hearts of the Meadow Farm
    Tanner, WV

    Deb wrote the following article for the ACR Newsletter, issue #7, and gave me permission to re-print it here

    Just put the following in the "I learned something ELSE about sheep" column! I hope that you will learn how not to almost lose your new breeding ram or any of your other sheep-we almost did!

    Two weeks ago as we were putting the sheep in for the night, my husband returned from the ram barn to say that our new breeding ram was "down". The ram was neither interested in standing to join the others for grain or even be forced to get up and move. I thought that we were going to lose him! I called the vet and to make a long story short, we carried the ram to the car, carefully placed him on an old coverlet and headed for the vet's office.

    The ram had been wormed with Ivomec drench on August 8 and that evening was September 18. We thought that the ram couldn't be sick from worms to the point that he was in the weak condition that he showed. The vet suggested to worm him with Panacur, my husband thought that the ram needed an immediate medication, that the worming would take too long and not take effect in time.

    The ram was lifeless, had no desire to eat and had scours that were watery and somewhat "clear" in color, unlike the color of fecal matter. Once we got to the vet's and took the ram inside, the vet had no problem telling us that he had worms! I wanted a fecal sample taken and I wanted to find out the specific worms that were present and just how we were to take care of this problem that seems to be never-ending!

    The vet gave the ram 6cc of penicillin (he said that was only because his syringe didn't hold more ), we were instructed to give him a follow-up of 10cc of penicillin the next night and 5cc of penicillin for an additional four or five nights-we decided to stop on the third night with the follow-ups.

    The vet also gave a shot of Dexamethasone, this is a steroid-we were told that this was going to make him "feel better". We were instructed to give him an additional steroid shot for the next two nights. The dosage of this I am not sure of because the vet prepared the syringes for us to take home.

    The ram was also given Panacur. This is a worm medication that we buy form our vet, although you may be able to order from a catalog. The important information here is that our vet gives a dosage of 5cc per 100lbs. He wanted us to do the entire flock the following day ( we did ) and give a follow-up in TWO WEEKS of Panacur with the 5cc per 100lbs. for the ram and the remaining flock, we did this as well.

    The learning fact with this for us-our vet stated that Panacur is not a wormer that will kill the sheep if given in larger dosages, he actually recommended the follow-up with the ram to be 5-10cc's. Notice that you are able to give it again and not have to wait the usual 30 day period before a follow-up dosage!

    I thought that Panacur was a worm medication for tapeworms, like SafeGuard and did not need a follow-up dosage. I also thought that Ivomec, tramisole, and the similar wormers were for the "other" worms and needed a follow-up in 30 days to get the eggs of the worms-I found out that Panacur treats worms other then the tapeworm, in fact, the fecal sample that was taken from our ram didn't even show a tapeworm. Two types of worm eggs were found, one was the haemonchus contortus and the other was the nematodirus stathider.

    The haemonchus contortus is a common worm in sheep, a barberpole worm. I have done some research on this subject and found out that you can forget about the 30 day follow-up plan. These worms live in the abomasum and lay eggs in huge numbers that are then passed in the manure. Following passage onto the pasture in the manure, they must develop into infective larvae before they are capable of infecting the sheep. The period of time required for the hatching of the egg and development of the larvae is dependent on the weather conditions, but it may take as little as five days or as long as several months. Larvae develop and survive best under warm, wet conditions-our vet suggests a worming program of every 30 days with these conditions. When the larvae is eaten by the sheep, they must continue the development process before becoming adults and being able to lay eggs. This requires a very specific time period; about 14 days with this specific worm. This type of worm is also referred to as a blood sucker and they live in the stomach and the small intestine to be specific.

    The second worm egg that was found was not as common. I have not been able to find out a lot about it at this point in time. I have found that it is a thread-necked worm. The prepatent period is less than 27 days and it may also be found in the small intestine of the sheep.

    Our entire flock is now again in good health and all looks good for the breeding season! My husband and I have learned the importance of a regular worming program. Just another bit of information, if you have seen sections of tapeworms in droppings from your sheep and then saw a white, very thin and moving wormlike creature-----------it is not a worm, it is the egg-bag of the tapeworm and yes, it does move a bit! My husband thought that the worms were able to be seen by the naked eye, something else to learn-if your sheep droppings are "clean", don't assume that they are worm-free. I suggest taking fecal samples from several of your sheep and taking them to your vet's to be tested. It is simple and if you decide that you are really interested in keeping "on top" of this, invest in a microscope and a testing kit and take care of this yourself! If you want additional information, please type in: "internal parasites in sheep" on your internet service and read on!

    Jim and Martha McGrath
    HC 72 Box 14D
    Franklin, WV, 26807
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