Morantel Tartrate for Ox: Uses, Dosing & 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.

Morantel tartrate is an oral dewormer used in cattle to treat certain gastrointestinal roundworms. It belongs to the tetrahydropyrimidine class of antiparasitic drugs. In cattle, it is mainly used against worms living in the abomasum and intestines rather than parasites outside the gut.

Morantel is poorly absorbed from the digestive tract in cattle, which is part of how it works. Most of the drug stays in the gut, where it acts on susceptible worms, and much of it is then passed in the manure. Because of that limited absorption, it is not considered a broad systemic parasite medication and does not provide the same coverage as some injectable or pour-on dewormers.

In the U.S., morantel tartrate has been marketed in cattle as medicated feed and in some sustained-release intraruminal devices. Product choice matters. Feed products and sustained-release products are used differently, have different withdrawal periods, and are not interchangeable. Your vet can help match the product to your herd goals, season, and parasite risks.

Morantel tartrate is used in cattle for the removal and control of mature gastrointestinal nematode infections. FDA labeling for medicated feed includes stomach worms such as Haemonchus spp., Ostertagia spp., and Trichostrongylus spp., small-intestinal worms such as Cooperia spp., Trichostrongylus spp., and Nematodirus spp., and the large-intestinal worm Oesophagostomum radiatum.

That means it is aimed at adult worm stages in the digestive tract. It is not the right fit for every parasite problem. Merck notes that because morantel is negligibly absorbed in cattle, it does not provide meaningful systemic activity against lungworms or arrested tissue larvae. If your ox has poor weight gain, rough hair coat, diarrhea, bottle jaw, or a high fecal egg count, your vet may consider morantel as one option among several deworming strategies.

In some grazing systems, sustained-release morantel products have also been used to reduce pasture contamination over part of the grazing season. That approach can be useful in selected groups, but resistance patterns, age, body weight, and local parasite pressure all matter. Your vet may recommend fecal testing before and after treatment to confirm that the chosen dewormer is still working on your farm.

Morantel tartrate dosing in cattle depends on the formulation. For Rumatel 88 medicated feed, the FDA freedom-of-information summary states the feed should deliver 0.44 grams morantel tartrate per 100 lb body weight, which is about 4.85 mg/kg, given orally in feed as a single treatment. Accurate body weight matters, because underdosing can reduce effectiveness and may contribute to parasite resistance.

Some cattle products have used sustained-release intraruminal devices rather than feed. In FDA approval documents for Paratect-type devices, the targeted sustained dosage was about 90 mg morantel base per head per day for roughly 90 days, with a minimum body weight restriction of 200 lb for administration. These products are managed very differently from feed medications, so your vet should confirm whether a product is still available, appropriate, and labeled for your class of cattle.

For food animals, dosing is only part of the safety picture. Withdrawal times matter. FDA documents for one sustained-release cattle product established a 102-day slaughter withdrawal, while the Rumatel 88 goat/cattle feed approval documents show different withdrawal information depending on species and product context. Because medicated feed must be used exactly as labeled and extra-label use of medicated feed is prohibited in the U.S., your vet and feed mill should verify the current label, class of cattle, and withdrawal instructions before treatment.

Morantel tartrate is generally considered well tolerated in cattle when used according to label directions. FDA safety summaries for cattle sustained-release products reported no adverse reactions observed in studied calves at dosing or on follow-up examinations, and no treatment-related lesions were identified in those studies.

Even so, any dewormer can cause problems if the wrong product is used, the dose is inaccurate, or the animal is already stressed or ill. Pet parents and livestock caretakers should watch for reduced appetite, loose manure, unusual lethargy, poor rumen fill, or a drop in feed intake after treatment. With intraruminal devices, your vet may also want you to watch for dosing injury, regurgitation, or failure of proper administration.

Call your vet promptly if an ox seems weak, stops eating, develops severe diarrhea, shows choking or swallowing trouble after administration, or if multiple animals react after the same batch of feed. In herd situations, a treatment failure can look like a side effect at first, so follow-up fecal testing and a review of feed mixing, body weights, and parasite resistance may be needed.

Published cattle-specific interaction data for morantel tartrate are limited, and there are no widely cited routine drug interactions that pet parents can safely manage on their own. The bigger practical concern is using morantel alongside other parasite-control products without a clear herd plan. Combining dewormers may be appropriate in some situations, but it should be based on your vet's guidance, fecal testing, and residue considerations.

Because morantel in cattle is often used as a medicated feed, there is an important regulatory point: extra-label use of medicated feed is prohibited in the U.S. That means changing the dose, duration, species/class, or mixing directions outside the approved label is not allowed. This is especially important in food animals because incorrect use can lead to illegal tissue or milk residues.

Tell your vet about all products your ox is receiving, including other dewormers, medicated feeds, ionophores, coccidiostats, mineral supplements, and any recent injections. Your vet can then check for compatibility, withdrawal timing, and whether a different parasite-control option would make more sense for your operation.