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Parasite Problems Could Worsen After US Winter Warmth

11 February 2016

US - Recent mild weather has set the stage for what could be a significant infestation of potentially deadly parasites in sheep and goats this spring, a Purdue Extension expert has said.

Mark Kepler, Extension educator in Fulton County and a goat producer, said the barber pole worm, the most common internal parasite among small ruminants, lays its eggs around the time of lambing and kidding, typically in late winter and early spring.

Mr Kepler said the parasite eggs survive longer on warmer ground, increasing the chances they hatch and develop into worms to infest animals.

“At kidding and lambing time, the potential worm load is a lot greater,” Mr Kepler said. “It is a killer. The eggs are excreted and after hatching they climb up a blade of grass to be consumed, affecting the animal. In usual springtime conditions, the process proceeds quickly.”

Most lambs and kids are turned out to pasture when the weather warms.

“Come spring and warm temperatures, those worms are just itching to go find some young animal to prey upon,” Mr Kepler said. “Older animals are more immune, but still susceptible.”

If left untreated, worm infestations can cause anaemia by consuming the host’s blood and eventually damaging an animal’s vital organs, including the lungs, liver and stomach. Producers can use faecal testing to determine whether their herds have been infested.

But treating the parasites can be difficult.

“There is a lot of parasitic resistance to deworming medications,” Mr Kepler said. “Control of these worms is just not as simple as repeatedly giving the same drug over and over again.”

Mr Kepler offered these tips to avoid major worm problems in the spring:

  • Do not overuse deworming drugs. Overuse can lead to the parasites developing resistance to the drugs.
  • Use faecal samples to determine if the deworming medication is working.
  • Rotate pastures to reduce worm potential. Do not let animals graze pastures into the ground.
  • Cull members of the flock or herd that are genetically more susceptible to worms.

Although worms are less active in winter months, Mr Kepler said animals could be susceptible to external parasites such as mites in colder temperatures.

“There are several different types of mites that affect animals in different locations,” he said. “Goats can lose hair around their lower legs, eyes, muzzles or ears, and the skin will redden and become crusty.”

Mr Kepler said it is necessary to work with a veterinarian when treating goats or sheep for any major parasite issues.
“Effective parasite treatment takes management, knowledge and professional advice,” he said. “I really encourage people to speak with a veterinarian about treatment.”

More information on managing sheep and goat parasites is available at Purdue Extension’s sheep and goat website at

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