Cyfluthrin for Ox: Fly and Tick Control Uses & Side Effects

This information is for educational purposes only. Never give your pet any medication without your veterinarian's guidance. Dosing, frequency, and safety depend on your pet's specific health profile.

Cyfluthrin is a synthetic pyrethroid insecticide used on cattle to help control external parasites. In US cattle products, it is most commonly found as beta-cyfluthrin in insecticide ear tags rather than as an oral medication or injectable drug. This means it works on the skin surface and hair coat, where it helps kill or repel certain flies and ticks.

For oxen and other cattle, cyfluthrin products are used as part of a herd parasite-control plan. Merck Veterinary Manual lists cyfluthrin and beta-cyfluthrin among pyrethroids used in cattle, with cyfluthrin used for flies and lice and beta-cyfluthrin used in ear tags for flies and ticks. Because these are food animals, your vet should guide product choice, timing, and label compliance.

Cyfluthrin is not a treatment for every skin problem. If your ox has hair loss, crusting, wounds, weight loss, fever, or heavy parasite burdens despite treatment, your vet may want to check for lice, mange, pinkeye risk, wounds, nutrition issues, or resistance to the insecticide being used.

In cattle, beta-cyfluthrin ear tags are labeled to control horn flies, face flies, Gulf Coast ticks, and spinose ear ticks. These pests do more than irritate cattle. Heavy fly pressure can reduce comfort, grazing time, and weight gain, while ticks can contribute to skin irritation and disease transmission risk.

One current US label for CyLence Ultra states it is for beef and dairy cattle, including lactating cattle, and can provide control for up to five months when used as directed. For many farms, that makes it a seasonal fly-control option rather than a year-round product.

Your vet may also discuss cyfluthrin as one part of a broader integrated pest management plan. That can include manure management, premise sprays, pasture rotation, fly traps, and rotating insecticide classes when resistance is a concern. If flies remain heavy after correct tag placement, your vet may suspect resistance or a mismatch between the product and the parasites on your farm.

Cyfluthrin dosing in oxen depends on the exact product and label, not the animal's weight alone. For the current US beta-cyfluthrin ear tag label, all mature animals in the herd should be tagged. The label states one tag per animal may be used for horn fly control, while one tag in each ear, or two tags per animal, is used for optimum control of face flies, horn flies, Gulf Coast ticks, and spinose ear ticks.

The same label says calves younger than 3 months should not be tagged because ear damage may occur. Tags should be applied with the labeled applicator, and they should be removed at the end of fly season or before slaughter. Because these are food animals, do not change the number of tags, placement, species, or timing unless your vet confirms the product labeling allows it.

Cost range varies by herd size and supplier, but a 20-count box commonly runs about $63 to $90 in the US in 2026. In practical terms, that is often about $3 to $9 per head for the tags themselves, depending on whether one or two tags are used and whether you are buying in volume. Labor, chute time, and applicator costs are separate.

You can ask your vet which approach fits your goals best: a conservative seasonal plan for lighter fly pressure, a standard whole-herd tagging plan, or a more advanced integrated program if your cattle have persistent fly problems or suspected pyrethroid resistance.

Most cattle tolerate label-directed pyrethroid products well, but side effects can happen. The most common concerns are local skin or ear irritation, head shaking, rubbing, or inflammation around the tag site. Young calves are at higher risk of ear injury if tagged too early, which is why current labels say not to use these tags in calves under 3 months old.

If an ox is overexposed, chews a tag, or is treated with the wrong product, pyrethroid toxicity can affect the nervous system. Merck notes that signs can include excessive drooling, mild tremors, incoordination, excitability, or depression. More severe poisoning can cause marked tremors, seizures, and breathing trouble.

See your vet immediately if your ox develops neurologic signs, collapses, has trouble breathing, or shows severe irritation after exposure. Also call your vet if the ears become swollen, infected, torn, or if parasite control fails despite correct use. That may point to resistance, reinfestation pressure, or another skin problem that needs a different plan.

Cyfluthrin is a topical insecticide, so classic drug interactions are less common than with oral medicines. Still, interactions and additive toxicity can matter. Merck notes that piperonyl butoxide, a common synergist included in some pyrethroid products, slows breakdown of the insecticide and can increase toxicity risk. Some products containing beta-cyfluthrin already include piperonyl butoxide, so it is important not to layer multiple insecticide products without your vet's guidance.

Merck also notes that cimetidine and chloramphenicol can have a similar potentiating effect on pesticide metabolism. In food animals, chloramphenicol use is prohibited, but the broader point still matters: your vet should know about every medication, pesticide, pour-on, spray, ear tag, and feed-through product being used on the farm.

Extra caution is also wise when combining pyrethroids with other insecticides, especially organophosphates, or when treating debilitated animals. If your ox is sick, underweight, dehydrated, or has skin damage, ask your vet whether the planned parasite-control product is still appropriate and how to monitor for adverse effects.