Parasites are a constant scourge for horses. These pests almost always cause problems — and sometimes in pretty devious ways.

Take the neck threadworm. It gets its name from adult worms that lurk under the skin along the top of a horse’s neck. But these particular worms aren’t the culprits when it comes to spreading the disease. Instead, that distinction belongs to their offspring that travel under the skin.

These youngsters tend to collect along a horse’s belly or chest where no-see-ums and black flies tend to feed. After finishing a ‘meal,’ the insects transport the tiny pests to other horses, and the cycle starts anew.

Young neck threadworms cause severe itching, and affected horses can rub themselves raw trying to scratch. Fortunately, treatment is usually effective. Signs of neck threadworms can mimic other diseases, so contact your veterinarian before doing anything else.