Cold weather may lead to chewing, sucking louse infestations in cattle

As colder weather continues throughout Wyoming, environments ideal for lice infestations prevail.

University of Nebraska-Lincoln Extension Educator Dave Boxler explained that controlling chewing and sucking louse species is important for both production and animal longevity.

Impacts

“Symptoms of cattle lice are rough haircoats, rubbing and scratching, hair on fences, hair loss, scaly skin and raw skin,” said Boxler.

However, he noted that other conditions can mimic a lice infestation such as natural shedding, poor nutrition and mineral deficiency, as well as other diseases.

It is known that lice infestations can impact weight gain, reduce milk production, cause blood loss and can ultimately result in animal mortality.

Boxler commented that several studies done in the past have indicated that lice infestations have a large impact on cattle production.

“Drummond in 1981 indicated that all four species of lice in the United States cause losses exceeding $126 million per year,” he said.

A 1992 study in Nebraska found that having an infestation of greater than 10 lice per square inch impacted weight gains of calves by 0.21 pounds per day.

Boxler continued, “Kunz in 1994 stated that losses of 0.70 pounds per head in average daily gain by heavily infested feeder cattle have been reported, but well-nourished cattle with light to moderate louse infestations suffered little or no loss.”

Factors

According to Boxler, multiple factors can increase lice populations on cattle.

“Some of these factors include colder temperatures, longer hair coats, drier skin, animal crowding, animals in poor condition and poor nutrition and chronic carriers, as well as applying control treatments too early,” he explained.

Alternatively, there are other considerations that may decrease lice populations.

Boxler noted, “There are factors that can decrease lice populations, such as warmer temperatures and sunlight, shorter hair coats, animal grooming and an increase in oil from the skin.”

Chewing

The primary louse species of concern are the chewing louse and three sucking lice species.

The chewing louse is commonly referred to as the little red chewing louse, said Boxler.

“It is rather small, only one to two millimeters in length, reddish-brown in color and feeds on skin scales, scruff and hair,” he continued.

The average lifecycle from egg to egg of female for the little red chewing louse is 28 to 29 days.

Boxler noted, “This louse species can reproduce asexually, or without mating, which can account for the large increase in louse populations during the winter.”

This louse species is usually located on the rump, back, side, shoulder, chest and sides of the neck of infested animals.

Sucking

“The short-nosed cattle louse is the largest sucking species, ranging from three to five millimeters in length,” said Boxler, noting that the lifecycle egg to egg of female is approximately 28 days.

Heavy infestations may cause the animals to look greasy, be anemic and can result in weight loss.

Boxler continued, “This louse can be found on the withers, top of the neck, poll, tail head and perineum.”

The long-nosed cattle louse averages 2.5 millimeters in length and has a characteristic long head.

“This is one of the most frequently found louse species on cattle,” he said.

The average lifecycle is approximately 25 days from egg to egg of female and is found on the topline, withers, top of the neck, dewlap, sides, belly and perineum.

The third type is the little blue louse, which is the smallest of the sucking louse at one to two millimeters in length.

“This species will normally occur in dense patches with adults, nymphs and eggs on heavily infested cattle,” continued Boxler. “The lifecycle egg to egg of female usually takes about 21 to 22 days.”

The little blue louse typically prefers the upper shoulder, neck, head and dewlap areas.

Checking

“To confirm the presence of cattle lice, producers should restrain animals in a chute and use a two-handed hair parting technique to locate and identify lice populations,” explained Boxler.

While there are numerous sites that can be used to locate lice, Boxler recommended producers focus on the muzzle, shoulder and topline of the animal.

Other tools may be beneficial for locating lice populations on cattle, such as a magnifying glass or a high-intensity light.

The number of lice found per square inch can be used to characterize the grade of infestation.

“Lice infestations ranging from one to five per square inch is considered a light infestation, six to 10 is a moderate population and more than 10 lice per square inch would be considered a very heavy population,” Boxler concluded.

Emilee Gibb is editor of Wyoming Livestock Roundup and can be reached at emilee@wylr.net.