Five Ways to Ensure Your Pour-On De-wormer Pays Off

Boehringer Ingelheim

Implementing a strategic deworming program can enhance cow comfort, reproductive efficiencies and productivity. In fact, a single application of a quality pour-on dewormer can increase milk production by over three pounds per cow, per day.1

“Cows need a deworming program that keeps them comfortable and allows them to perform their best,” said Hector Quiroz, Lone Pine Dairy, Kuna, Idaho.



To maximize the return on investment for your pour-on dewormer, Quiroz and Stephen Foulke, DVM, Boehringer Ingelheim, offered some advice:

Know the signs of mange and lice

“Tail head mange and lice are extremely irritating to cattle and can impact behavior patterns that are linked to potential milk production,” said Dr. Foulke. “Rubbing, itching and restlessness associated with external parasites often results in reduced feed intake and resting time.”

Mange mites are considered the most concerning of late fall and winter parasites in most dairy herds. It only takes a small number of mites to create widespread lesions and animal discomfort. Clinical signs of mange include hair loss, crusty and wrinkled skin near the tail head, areas immediately adjacent to the tail head and just above the rear udder and medial thigh.

Lice are another common parasite and breaking their life cycle can be a challenge. Clinical signs of lice include rough hair coats, patchy spots and hair loss from itching. However, once producers see symptoms of hair loss, the population and number of eggs present on the cow’s haircoat have skyrocketed.

Stay one step ahead of parasite populations

Only deworming cattle after clinical signs of parasites are detected can be a costly practice. “If you are seeing signs of lice or mange, cow comfort has already been affected,” said Quiroz. “We try to stay ahead of the parasites as much as possible to limit their burden on productivity.”

In general, producers are encouraged to consider deworming during each of the following:

  • Spring –knock down flies and internal parasites going into summer
  • Fall – control external parasites that become more active in the winter months
  • Freshening –enable your cows to get the most from their nutrition and maximize production
  • New herd additions –dry cows, first-calf heifers, bulls and purchased animals should be dewormed 14 days prior to entry into the adult herd to prevent re-infestation of lice and mange if incoming animals are harboring these parasites

“Application timing is going to depend on where a herd is located. Consulting a veterinarian who is familiar with the area is a great way to determine the most effective time to apply a pour-on dewormer,” added Dr. Foulke.

“We apply a high-quality pour-on dewormer to our herd right before it starts to warm up,” said Quiroz. “We’ve found that the best timing for the first application is when the cows are switching from their winter to summer coats.”

Choose a quality product

Dr. Foulke encourages producers to choose a pour-on dewormer with zero meat and zero milk withhold.

“When producers are treating for lice and mange, it’s important to treat the whole herd at once, so there aren’t any animals harboring parasites that will re-infect the herd as soon as treatment wears off,” explained Dr. Foulke. “If you choose a product that can be used on the whole herd, you don’t have to dump milk or worry about what milk can or can’t go in the tank.”

Quiroz also mentioned the benefit of purchasing a dewormer that provides a product-satisfaction guarantee. “We’ve never had any problems with the pour-on we’re currently using, but it’s nice to have that assurance.”

Read and follow label directions

Adherence to label directions can significantly impact the effectiveness of the dewormer. When using a pour-on dewormer, carefully apply the product along the topline in a narrow strip from tailhead to withers. This will reduce product runoff and maximize efficacy.



Administering the correct dose is another important practice. Although convenient, dosing to the average weight of the herd will under- or overdose many cows. Underdosing will diminish effectiveness of the dewormer and contribute to parasite resistance, while overdosing wastes product and money. Using a scale, weight tape or a cull weight slip to determine cow weight will increase dosing accuracy along with product efficacy.

Consult your veterinarian

Parasite populations, product selection, timing of application and adherence to label directions are all factors that influence the potential return on investment for your pour-on dewormer. Your local veterinarian is your best cattle parasite resource and can help develop a deworming program to maximize cow comfort and performance on your operation.


Watson CL, Forbes AB. An outbreak of sarcoptic mange in dairy cows. UK Vet Livestock. 2000;5:48-50.

This article has been supplied by Boehringer Ingelheim, is the second largest animal health business in the world, with net sales of almost $4.7 billion (3.9 billion euros) worldwide in 2018, about 10,000 employees and a presence in more than 150 markets.


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