Morantel Tartrate for Cow: 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 nematodes, or roundworms. It belongs to the tetrahydropyrimidine class of antiparasitic drugs. In the U.S., it is marketed in medicated feed form for cattle, commonly under the brand name Rumatel 88.

This medication works mainly inside the gut. Morantel is poorly absorbed in cattle, so most of the drug stays in the digestive tract where the worms are. That makes it useful for stomach and intestinal worm control, but it also means it is not a broad-spectrum choice for every parasite problem.

For cattle, morantel is labeled for the removal and control of mature gastrointestinal worm infections. It is not a one-size-fits-all dewormer, and parasite resistance can reduce how well it works on some farms. Your vet may recommend fecal testing, herd history review, and a broader parasite-control plan before choosing it.

Morantel tartrate is used in cows for the removal and control of mature stomach and intestinal roundworms. Label indications include stomach worms such as Haemonchus spp., Ostertagia spp., and Trichostrongylus spp., plus intestinal worms such as Cooperia spp., Nematodirus spp., Trichostrongylus spp., and Oesophagostomum radiatum.

It is best thought of as a GI worm dewormer, not a catch-all parasite product. Merck Veterinary Manual lists morantel as active against abomasal and intestinal nematodes in cattle, but not cestodes. Because it has minimal systemic absorption, it is also not relied on for lungworms or tissue-arrested larvae.

Your vet may consider morantel when a herd needs a labeled oral option for susceptible gut worms, especially when milk-withdrawal concerns matter. It can be a practical tool in some dairy and beef settings, but the right choice depends on local resistance patterns, production stage, and whether the goal is treatment, monitoring, or a larger herd parasite program.

Morantel tartrate dosing in cattle should follow the product label and your vet's instructions. For the currently marketed U.S. medicated-feed label, the ration is fed as a single therapeutic treatment at 0.44 grams of morantel tartrate per 100 pounds of body weight, which is about 9.7 mg/kg. The medicated feed should be consumed within 6 hours.

Accurate body weight matters. The label specifically warns not to underdose, because incomplete dosing can lead to poor parasite control and may encourage parasite resistance. Cattle are often grouped by size so each animal has a better chance of receiving the intended amount.

Withdrawal timing is also important in food animals. The current cattle label states do not treat cattle within 14 days of slaughter. It also states no milk discard is required following use in dairy cattle when used according to label directions. If a cow is sick, severely debilitated, pregnant, lactating, or receiving other medications, your vet should confirm whether morantel is an appropriate fit.

Morantel tartrate is generally considered to have a wide safety margin in cattle when used correctly, and adverse effects are uncommon at labeled doses. Still, any dewormer can cause problems if the wrong animals are treated, the dose is inaccurate, or the product is mixed incorrectly.

Possible concerns include reduced appetite, loose manure, poor feed intake, or lack of expected response after treatment. In many real-world cases, the bigger issue is not a dramatic side effect but treatment failure, often related to underdosing, poor feed consumption, or parasite resistance.

Call your vet promptly if you notice marked weakness, severe diarrhea, breathing changes, tremors, collapse, or if multiple cattle seem affected after treatment. The label also advises caution in severely debilitated animals. If a cow looks significantly ill before or after deworming, your vet may want to rule out heavy parasite burden, dehydration, another disease process, or a medication error.

Morantel tartrate should not be treated as interchangeable with every other dewormer or feed additive. The current U.S. label specifically says do not mix it in feeds containing bentonite. That matters because feed ingredients can change how evenly the medication is delivered and how reliably cattle consume the full dose.

Pharmacology references also advise extra caution when morantel is used alongside organophosphate compounds or other drugs with similar cholinergic effects. These combinations may increase the risk of adverse reactions, especially if dosing or timing is not carefully managed.

Because cattle are food animals, interaction questions are not only about safety. They are also about residue avoidance, withdrawal times, and legal use. If your herd is receiving other dewormers, insecticides, medicated feeds, or extra-label treatments, ask your vet to review the full treatment plan before morantel is used.