Garlic For Treating Internal Parasites

link to MOFGA article

*First it is important to be sure the anemia that you witness in a lamb or sheep's eyelid is due to parasites. I have had a case in a lamb where anemia was due to white muscle disease which is easily corrected with a treatment of selenium (BO-SE).

*If the problem is parasites, the key to the effectiveness of using garlic seems to be catching the infection at an early stage. This can be achieved most accurately through fecal counts. But is easier using the FAMACHA© System.

* More work needs to be done on the optimum garlic dosage.

* More work needs to be done on the natural immunity some sheep seem to have to the parasites and genetic selection for this trait.

*One treatment has been effective for coccidia infections, more treatments are often necessary for Barber Pole Worms (H. Contortous).

*Garlic Barrier Concentrate comes in a one gallon jug from Garlic Research Labs. Inc.


This is a system that uses a visual observation of the redness of the interior of the eyelid using a specially developed eye color chart to determine the degree of infection due to Haemonchus Contortus.


Haemonchus Contortus - Simplified Life Cycle (H. Contortus, Strongylid Nematode) The Barber pole worm


I have spent considerable time researching Haemonchus Contortus and a “google” search brings up 1,680,000 references which is up about a million in the last 10 months. Needless to say there are contradictions in the data, and the workings of this parasite are still not completely understood. What follows is a short summary compiled from my research. I apologize for not keeping better track of all of my sources.

Eggs are shed by mature fourth stage H. Contortus attached to and feeding on blood of the sheep's stomach wall. One H. contortus morula stage female may pass as many as 10,000 eggs per day under favorable conditions, so one sheep can pass as many as 30,000,000 eggs per day. These eggs travel in the feces onto the pasture or into the bedding where they somehow are able to survive in hypobiosis (an arrested state similar to hibernation) for over a year. This means that one winter may not be enough to completely clean a pasture depending on your climate.Eggs

Warm, wet conditions and contact with soil are necessary for the eggs to hatch into larvae. If the weather is too hot, dry, or variable, the eggs will hatch quickly and the larvae will die. If the weather is too cold the eggs will not hatch. First stage Larvae(L1) develop from eggs in manure in 4-6 days of damp 75-85 degree weather and hatch to feed on microorganisms in the feces.

H. Contortus Eggs can vary in size. After a molt, second stage larvae (L2) also feed on microorganisms but they must have contact with soil as well as favorable conditions. This is good news because it means that the parasites cannot become infective in the barn where the lambs and sheep live on a bedding pack that insulates the larvae from the soil. I expect that composting the bedding pack effectively eliminates the parasites from the manure, making it safe to spread back on the pasture or fields.

The average length of the second stage (L2) is about 21 days. They then become third stage larvae (L3) that are active and infective. Research has shown that L3 larvae can survive over 15 years of being frozen in liquid nitrogen, however those conditions do not exist outside a laboratory and the larvae rarely survive more that a week in the field. Moisture and warmth are necessary for the infective third stage larvae to move from the manure and soil onto the grass, where they are consumed by the sheep eating the grass. When conditions are dry, the larvae are unable to migrate up the grass and will die. They also do not survive long in strong sunlight or high heat.

H.Contorus Life Cycle

Chart from Texas Ag Extension Service Texas A&M University L-5095

Variable weather has a large influence on the survival and development of the parasite on pasture. Short pasture conditions may lead to more severe internal parasite infestations because more infective larvae are normally found on the lower parts of the plants near the soil surface where the moisture is retained. L3 larvae do not survive in hay and the stubble exposes them to the sun and dries out effectively decreasing the parasite population. Sheep are short grazers, they eat the grass to the ground. Sheep could be confined until the dew or rain has evaporated before they are allowed to graze to help minimize infection. Thousands of parasites may infect a sheep with low resistance. Sheep with high resistance do not carry high populations of H. Contortus. Some sheep have resilience to H.Contortus, this means that they are able to thrive while carrying a high infection of the parasites. I have found that older sheep are less effected by H. Contortus.

Ingested larvae in the third stage (L3) lodge in the stomach glands until external conditions are favorably warm and wet are favorable and they molt again into fourth(L4) stage adults and attach to the wall of the abomasum where they suck blood to nourish the development of their eggs. When conditions are not favorable the L4 stage H. Contortus are able to survive in hypobiosis (an inhibited state) without taxing the sheep or shedding eggs. This is important because the sheep do not exhibit any indication of infection while they may be carrying a large population of parasites. There is some speculation that hypobiotic parasites are not affected by treatments. L4 stage parasites can suck more blood than the sheep can replace resulting in severe anemia. This anemia may develop quickly and cause acute symptoms and death before the animals can be treated. When conditions are favorable more and more stomach worms reach the adult stages and there is an enormous increase in egg shedding, pasture contamination, and anemia. One of my big questions is "what are the favorable conditions?" I have found that ewes with other stress ie. foot problems, triplets, etc. tend to have lower resistance to parasites.

The cycle repeats.

The variability of the length of the parasite's life cycle, and its optimal conditions are the most challenging aspects of understanding and overcoming the Haemonchus Contortus.