Lasalocid for Ox: Uses, Benefits & 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.

Lasalocid is an ionophore feed medication used in cattle. In the US, it is approved as a medicated feed additive, not as a tablet or injection. Common cattle products include Bovatec and some generic or combination medicated feeds. Your vet may talk about it as a tool for coccidiosis control and for improving how efficiently cattle use feed.

Ionophores work by changing ion movement across cell membranes. In practical terms, that means lasalocid can help suppress certain coccidia parasites and can also shift rumen fermentation in ways that support feed efficiency. It is used only in labeled feed forms and labeled cattle classes, because medicated feeds in major food animals must be used according to approved labeling.

For pet parents and producers, the key point is safety: lasalocid is helpful when it is mixed correctly and fed exactly as directed, but overdoses and feed-mixing mistakes can be dangerous. It is also highly toxic to horses and other equines, so cross-contamination and accidental access are serious concerns.

Lasalocid is most often used in cattle to control coccidiosis, especially infections caused by Eimeria bovis and Eimeria zuernii. These parasites can cause diarrhea, straining, dehydration, poor growth, and setbacks in young calves or stressed groups. In calves, lasalocid may be included in milk replacer or starter feed when your vet and feed team are building a prevention plan.

It is also labeled in certain beef cattle and replacement heifer programs to support improved feed efficiency and, in some situations, increased rate of weight gain. That does not mean every animal needs it. The best fit depends on age, weight, production stage, housing, parasite pressure, and whether the goal is prevention, performance support, or both.

Lasalocid is not a broad treatment for every cause of diarrhea or poor growth. If an ox has blood in the stool, fever, severe dehydration, weakness, or sudden drop in feed intake, your vet may need to rule out other problems such as salmonellosis, respiratory disease, ration issues, or toxicities before deciding whether a lasalocid-containing feed is appropriate.

Lasalocid dosing in cattle is based on the approved feed label, the cattle class, and the feeding system. For pasture cattle and replacement heifers, labeled use commonly provides 60 to 300 mg per head per day for gain and feed efficiency. For coccidiosis control in cattle up to 800 lb, approved labeling commonly targets 1 mg per 2.2 lb body weight per day, with a maximum of 360 mg per head per day, usually fed continuously for 28 days. In medicated milk replacer, FDA references list lasalocid at 1 mg per 2.2 lb body weight per day.

Merck also notes that lasalocid has been effective for prevention of experimental coccidiosis at about 0.75 to 3 mg/kg, and calf starter programs may use labeled feed concentrations rather than a hand-measured oral dose. That is why this medication should not be measured out casually at home. The actual amount each animal receives depends on feed concentration, expected intake, body weight, and whether the ration is hand-fed, mixed, or free-choice.

Because lasalocid is a medicated feed, extra-label use in cattle is generally prohibited in the US. Your vet and feed mill should match the product, concentration, and feeding directions to the exact cattle group. If intake is inconsistent, the ration changes, or animals are sorting feed, the delivered dose may drift away from the target range.

A practical cost range for lasalocid-containing cattle feed programs is often about $0.05 to $0.25 per head per day, depending on formulation, inclusion rate, and local feed costs. Custom mixing, veterinary oversight, and combination medicated feeds can raise the total herd cost.

When fed correctly to the right cattle class, lasalocid is usually well tolerated. Problems are more likely with overdose, mixing errors, accidental access to concentrated product, or use in the wrong species. Signs of ionophore toxicity can include reduced appetite, lethargy, weakness, diarrhea, stiffness, trouble walking, rapid breathing, collapse, or sudden death. Muscle and heart damage are the biggest concerns.

In cattle, severe overdoses may cause skeletal muscle necrosis or heart injury. Merck notes that toxic feed concentrations have been fatal in cattle, and newborn calves given excessive repeated doses have developed muscle necrosis. Even if an animal survives the first day or two, weakness and poor performance can continue because damaged muscle takes time to heal.

See your vet immediately if an ox on lasalocid stops eating, becomes weak, seems painful when moving, breathes hard, or if you suspect a feed-mixing mistake. Also call your vet right away if horses or donkeys may have accessed the feed, because equine exposure can be fatal. Keep feed tags, batch information, and a sample of the ration if toxicity is suspected.

The most important interaction concern with lasalocid is other ionophores or drugs that can increase ionophore toxicity risk. Feed formulation errors, accidental double-medication, or combining products without veterinary review can raise the chance of muscle and heart injury. Your vet should know about all medicated feeds, top-dresses, mineral products, and recent treatments before lasalocid is started.

Merck notes that ionophore toxicity risk can increase when ionophores are given with certain antimicrobials, including tiamulin, erythromycin, or chloramphenicol. Not every one of these combinations is common in cattle practice, but they matter because they can lower the margin of safety. Combination feeds that include lasalocid with other approved drugs, such as chlortetracycline or melengestrol acetate in specific cattle classes, must still be used exactly according to label.

There is also a practical interaction issue with species exposure rather than a classic drug-drug interaction: lasalocid-containing feeds must be stored and handled so horses and other equines cannot access them. If your ox is receiving any other medication, supplement, or medicated ration change, ask your vet and feed supplier to confirm the full program is compatible before feeding continues.