I’ve been treating one of my lambs, Eostre, for what appears to be a parasitic disease. It’s hard to tell exactly what she had but the symptoms were frequent coughing, some foaming at the mouth, tooth grinding, and difficulty eating and drinking. She could have had a respiratory infection, an object caught in her throat, or parasites of the respiratory tract, either bot fly larva or lung worms. Not having a bottomless well of resources I have had to do my own diagnosis.
After looking in Eostre’s mouth and seeing that nothing was stuck in her throat I decided that she had either a respiratory infection or parasites of the respiratory tract. I bought antibiotics and a worming drug called ivermectin. The antibiotics made no difference in her condition which was getting worse. Eostre was barely eating and drinking and I could see she was loosing weight. She moved slowly, her ears and eyes were droopy, and she lay down in the tall grass a lot.
I built a small pen for Eostre in the shed and put her inside with fresh bedding, a water pan, a grain pan, and a box of hay and grass. I then measured out a half a dose of ivermectin and mixed it into some grain with a little extra molasses. I did this every day for three days, skipped a day and repeated it for three more days. This seems to have worked and the coughing has almost stopped. Her appetite began to improve and I was able to get her to drink water. I knew she was getting better when she began to chew her cud again. She also stopped grinding her teeth. I continued to feed her what I had been feeding the sheep all summer which is grass with clover, trefoil, dandelions, daisies, goldenrod, stitchwort, and pigweed. I also gave her small handfuls of aspen leaves. To her water I added a packaged electrolyte powder that had vitamins and minerals.
Sheep can be parasitized by a variety of worms: flat worms, flukes, tapeworms, and all sorts of roundworms. There are also sheep bot flies, one possible cause of Eostre’s illness, which lay already hatched maggots on the noses of sheep. The maggots migrate into the sinuses where they develop and mature. Once mature the maggot crawls back out, drops to the ground and pupates to later become an adult fly. Bot fly maggots cause irritation of the sinuses. Sheep bot flies also infest cows, deer, and horses. They can infest humans, too. The distraction and irritation they produce can lead to the sheep stopping feeding with consequent malnutrition.
Eostre’s coughing could have been produced by lungworms, too. Her symptoms seem to point to that more than bot flies. Lungworms are nematodes (roundworms) and there are several genera and species. Supposedly, they are host specific so that those of sheep will not infect deer and vice versa.
It is possible Eostre contracted this parasite from pasture contaminated with egg-containing feces. So far none of the other sheep have shown any sign of lungworm infection. I am still trying to figure out how it got here in the first place but suspect that three sheep brought here for a short time last fall may have introduced it. I later found out none of them had been wormed before being brought here and two were from low-lying pastures where snails, an intermediate host for some species of lungworms, live. My pastures are well drained and dry and not connected to wetlands or low areas where snails live.
Parasite infestation can be minimized by rotating pastures, keeping pens clean, and hay and cut forage in mangers off the ground. One of my pasture projects this summer has been to divide the pasture into four paddocks. So far, I have two paddocks enclosed and am working on the others. By setting up my pasture into four paddocks on a three week rotation I can decrease the chances of fecal-oral transmission of parasite eggs. It will not be a 100% prevention but it will lessen the chances of parasite infection by allowing eggs and larva to dry out and die waiting for a host. Cleaning the sheep pen and keeping their forage in the mangers is practiced, too.
For parasites of the digestive tract it is possible to control them by adding plants like wormwood, fever-few, balsam fir, aspen, and willow to their diet. These plants contain compounds like thujone, terpenes, and tannins that interfere with the metabolism of parasites. Care must be taken to give wormwood and fever-few in small amounts as they are toxic to mammals, too. Plants with tannins should not be fed in large quantities as tannins are anti-nutrients that bind to proteins and make them indigestable. I have been feeding aspen and willow, which contain tannins, and balsam fir, a source of terpenes, to my sheep several times a month as a supplement to their grasses and was glad to learn about these potential benefits. However, these herbal treatments may not work well if the parasite load is very high. Treatment with a drug specifically for parasitic worms at once a year is a good practice.
Eostre is better than she was but still coughs occasionally. But she is stronger and is able to be with the flock again. I am hoping that when I treat the whole flock that she will be rid of this disease.