Haemonchus contortus (Barber Pole Worm) Infestation in Goats

UNP-0078, December 2006, Maria Lenira Leite-Browning, DVM, Extension Animal Scientist, Alabama A&M University

Gastrointestinal nematodes, commonly known as worms, present the greatest danger to the goat industry in the Southeastern region of the United States. Haemonchus contortus, commonly referred to as the barber pole worm, is a clinical problem for goats. Anemia, low packed cell volume (PCV), diarrhea, dehydration, peripheral, and internal fluid accumulation are common signs of barber pole worm infestation. Infested goats have lower growth rates, markedly reduced reproductive performance, and have higher rates of illness and death. Consequently, H. contortus may account for greatly reduced profits in a goat operation.

In the Southeast region, there are a number of factors that contribute to barber pole worm infestation in goats:

• Environment with high temperatures, humidity, and rainfall
• Genetic make-up of goats makes them highly susceptible
• Resistance to anthelmintics as a result of excessive usage
• Frequent anthelmintic treatments per year without a positive fecal sample exam
• Many goat producers overstock their pastures and maintain as many as 40 goats per acre
• Few anthelmintics drugs are approved by the Food and Drug Administration for goat use.

About Barber Pole Worms

Haemonchus contortus is cylindrically shaped, tapered at both ends, and has a complete digestive system. This worm is a worldwide threat, but is more prevalent in sub-temperate and temperate regions under warm and wet conditions, such as in the Southeastern United States.

Morphology

• Adults (20-30 mm); Eggs are thin-shelled, 24 cell
• Adult H. contortus live in the abomasum (true stomach) of goats.

Adult H. contortus recovered after necropsy.

Life Cycle

Goats are born without H. contortus; however, they become infested with the worm when they start grazing. The L3, or infecting larvae, are eaten by the goats during grazing. The L3 larvae then burrow into the internal layer of the goat's abomasums (true stomach) where they develop to a L4, or pre­adult larvae. The L4 molts into L5, the adult form.

Adult male and female worms live in the abomasum of goats, where they feed on blood. The worms mate and produce eggs. Adult females deposit from 5,000 to 10,000 eggs per day, which are passed through goat feces to the pasture. Eggs are hatched either in soil or water. When the soil is warm and moist, eggs will hatch into L1 larvae (first stage juveniles). The L1 larvae then develop through stages L2 and L3. Large numbers of juvenile parasite worm (L3) may accumulate on heavily grazed pastures.

Damage Caused by Barber Pole Worm

After a goat has ingested L3 larvae, the worm will burrow into the mucosal (internal layer) of the stomach, nourishing on the red blood cells of the goats, which can be life-threatening to the goat. An infected goat can bleed to death within hours.

Stomach after necropsy. [Diffused hemorrhagic areas of the mucosa (internal layer) of the stomach]

Signs of the barber pole worm infestation in goats:

• Diarrhea
• Dehydration
• Unthrift appearance, rough hair coat, depresssed, low energy, lethargic, and uncoordinated
• Significantly reduced growth and reproductive performance
• Fluid accumulation in sub-mandibular tissues (bottle jaw), abdomen, thoracic cavity, and gut wall
• Blood loss, white mucous membranes, anemia/PCV

Signs of peripheral and submandibular (bottle jaw) edema		Extreme dehydration, near death
Note: Larva is a juvenile form, the newly hatched, or earliest stage worm that undergoes metamorphosis, differing markedly in form and appearance from the adult. Anthel-mintics are widely used to battle worms and worm eggs.
		Blood loss, anemia, white musous membranes

Controlling Barber Pole Worm

Scientists have been researching ways to manage this parasitic worm and minimize cost production in herds. Management practices must be based upon breaking or interrupting the life cycle of the worm by:

• Use of chemical anthelmintics commercially available
• mproved herd and pasture management practices
• Use of plants with anthelmintic properties

Use of Commercial Anthelmintics

Anthelmintics (chemicals/drugs) are widely used to battle barber pole worms. However, only two anthelmin-tics are approved by the Food and Drug Administration (FDA) to treat goats: Morantel tartrate and Fenbendazole. Producers have reported that the drugs have shown little effectiveness in the control of the barber pole parasite in goat herds because of the worm's resistance.

Use of others anthelmintics is called extra-label use because they are not approved by the FDA for use on goats unless used under veterinarian guidance.

Improved Herd, Pasture and Management Practices

Here are some ways to control barber pole worms:

Feeding Practices

• Keep stocking rates low.
• Provide clean water and minerals.
• Use gravel or concrete in the feedlot area to break the worm life cycle and to prevent re-infestation.
• Provide high-quality hay for goats raised in areas where forage is not available year-round or when the pasture conditions are poor. Hay should be kept off of the ground to avoid contamination by feces.

Dry lot to interrupt worm life cycle.

Pasture Maintenance

• Incorporate browse plant species when possible. Goats love to browse and prefer shrubs and forages to grass. If goats consume forages at least 6 inches tall, infestation from barber pole worms is reduced.
• Try a mixed species grazing program using cattle and goats.
• When possible, use the pasture for hay cutting after grazing. This will help to break the worm life cycle and prevent re-infestation. Direct sunlight during the summer months or during freezes in the winter will also help decrease the population of larvae that remain in the soil.
• When possible, alternate the pasture with a short cycle crop, such as culture alfalfa. This management practice will help to break the worm's life cycle, and decrease larvae population in the pasture and prevent re-infestation.
• Use clean feeders and continue to practice good hygiene in the pens and pasture.

Goats are browsers, introduce shrubs and forbes in your pasture.

Doe Treatment

• Provide good nutritional management. Well-nourished animals are better able to respond to H. contortus infestation. Does with good nutrition at late pregnancy have an increased immune response to parasites.
• Deworm the doe soon after she has kidded. The pregnancy hormone progesterone and the lactate hormone prolactin have been shown to reduce the ability of does to fight worm infestation. Progesterone suppresses the doe's immune system. Does that are lactating and raising kids are more susceptible to worms. Monitor the herd closely from kidding to weaning.
• Goat genetics are an important component that will determine an animal's ability to resist H. contortus infestation. Resistance can be measured by fecal egg counts (FEC). The resistance to worm infestation is heritable. The doe's ability to withstand infestation is defined as resilience and is measured by blood hematocrit or packed cell volume (PCV). Resilience is less heritable than resistance.

FAMACHA System as a Management Tool to Control Barber Pole Worms in Goats

The FAMACHA system was developed by South African scientists and veterinarians. It is a low-cost tool that can greatly influence management practices in goats. The FAMACHA system monitors clinical anemia (reduction of red blood cells, packed cell volume) by examining the color of the goat's lower eyelids and comparing it to a color-coded chart. Variation in eyelid color from pale to red indicates the degree of anemia. Based on this chart, only goats with anemia should be treated. This practice will prevent the overuse of anthelmintics and consequently minimize chances of parasite resistance to anthelmintics. The test has an effectiveness of 90 percent compared to the 20-30 percent effectiveness of overused anthelmintics.

Goat producers should check 10 percent of the total animals in the herd as frequently as every other week using the FAMACHA chart. A fecal exam should accompany FAMACHA examination.

FAMACHA also provides producers with a tool for genetic selection. Using FAMACHA, producers can identify animals that are more susceptible to hosting the worm and can cull these goats from the herd. In turn, producers will be able to identify animals with high resistance and resilience, which seem to be inherited traits in goats.

Use of Plants with Anthelmintic Properties

Researchers are exploring the use of plants to control barber pole worm. Forages, such as clover, vetches, chicory, and sericea lespedeza, contain condensed tannins. Condensed tannins reduce the number of stomach worms and egg production. Feeding sericea lespedeza hay to goats can reduce fecal eggs counts by 80 percent and create a higher packed cell volume.

References

Browning, R. Jr., et al. (August 2006). Evaluation of three meat goat breeds for doe fitness and reproductive performance in the southeastern United States. IN 8th World Congress on Genetics Applied to Livestock Production, Belo Horizonte, MG, Brazil.

Fleming, S. A., et al. (2006). Consensus Statement on: Anthelmintic resistance of gastrointestinal parasites in small ruminants. Journal of Veterinary Internal Medicine, 20, 435­444.

Kaplan, R. M., et al. (2004). Validation of the FAMACHA© eye color chart for detecting clinical anemia in sheep and goats on farms in the southern United States. Veterinary Parasitology, 123, 105-120.

Shaik, S. A., et al. (2006). Sericea lespedeza hay as a natural deworming agent against gastrointestinal nematode infection in goats. (2006). Veterinary Parasitology, 139 (1-3), 150-7.

Van Wyk, Jan A. & Bath, Gareth F. (2002). The FAMACHA© system for managing haemonchosis in sheep and goats by clinically identifying individual animals for treatment. Veterinary Research, 33, 509-529.

For more information, contact your county Extension office. Visit http://www.aces.edu/counties or look in your telephone directory under your county's name to find contact information. Issued in furtherance of Cooperative Extension work in agriculture and home economics, Acts of May 8 and June 30, 1914, and other related acts, in cooperation with the U.S. Department of Agriculture. The Alabama Cooperative Extension System (Alabama A&M University and Auburn University) offers educational programs, materials, and equal opportunity employment to all people without regard to race, color, national origin, religion, sex, age, veteran status, or disability.