Levamisole for Goat: 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.

Levamisole is a dewormer used against certain nematodes, which are parasitic roundworms. In goats, it is most often discussed for stomach and intestinal worms and sometimes lungworms, depending on the parasite involved and whether that parasite is still susceptible on your farm. It belongs to the imidazothiazole class of anthelmintics and works by causing paralysis of susceptible worms so they can be expelled.

In the U.S., levamisole products are commonly labeled for sheep or cattle, not goats. That means use in goats is often extra-label and should happen only under a valid veterinarian-client-patient relationship. Cornell's goat dewormer guidance specifically notes that, with limited exceptions for other drugs, dewormer use in goats is commonly extra-label and should be directed by your vet. Because goats metabolize many dewormers differently than sheep, dosing errors and underdosing are real concerns.

Levamisole can be very useful in the right situation, especially when your vet is trying to manage parasite resistance. But it has a narrower safety margin than many other dewormers. That is why accurate body weight, careful oral drenching technique, and a clear treatment plan matter so much.

Levamisole is used to treat susceptible gastrointestinal worms in goats. Depending on the herd and region, that may include parasites such as Haemonchus contortus (barber pole worm), Trichostrongylus, Cooperia, Nematodirus, Oesophagostomum, and sometimes lungworms. It is not a one-size-fits-all dewormer, and it does not treat every internal parasite problem.

The biggest reason your vet may choose levamisole is parasite resistance management. On many goat farms, some worm populations no longer respond well to commonly used dewormers. Cornell and other small-ruminant parasite programs emphasize that treatment decisions should be based on herd history, fecal testing, and whether a drug still works on that farm. In other words, the best dewormer is the one that is still effective for your goats.

Levamisole is not usually something to give on a routine calendar without testing. A more thoughtful plan may include fecal egg counts, FAMACHA scoring where appropriate, body condition monitoring, and selective treatment of goats that truly need it. That approach can help preserve drug effectiveness and reduce unnecessary medication use.

See your vet before dosing levamisole. In goats, commonly cited guidance for oral drench use is 12 mg/kg by mouth once when using levamisole soluble drench products such as Prohibit-type formulations. Cornell's goat dewormer chart lists this 12 mg/kg oral dose and notes that a 52 g packet dissolved in 1 quart of water yields a solution of about 49.6 mg/mL. For kids, Cornell notes it can be safer to dilute the solution further so the dose volume is larger and small measuring errors matter less.

Because levamisole has a narrow safety margin, goats should be weighed as accurately as possible. Estimating by eye can lead to overdosing or underdosing. Oral drenching is generally preferred over injectable or pour-on use for goats in parasite-control programs, because oral dosing is the route most commonly recommended in goat parasite guidance and helps avoid some resistance-related problems seen with other routes.

Your vet may also discuss withdrawal times if your goats produce milk or are intended for meat. Cornell's current goat chart lists a 4-day meat withdrawal and 3-day milk withdrawal for the 12 mg/kg oral levamisole dose, while older extension materials may list different intervals. Withdrawal recommendations can change with formulation, dose, and new FARAD guidance, so always confirm the exact withdrawal plan with your vet before treatment.

Do not redose, combine products, or adjust the concentration on your own. If a goat is thin, weak, dehydrated, pregnant, very young, or already ill, your vet may want a different plan or closer monitoring.

Levamisole side effects in goats are usually related to its cholinergic activity. Mild signs can include salivation, frothing, muscle quivering, restlessness, or temporary ataxia. Cornell goat parasite materials specifically note that some goats may show frothing and muscle quivering even at normal doses, which can be alarming for pet parents.

More serious toxicity signs can include marked drooling, tremors, weakness, stumbling, urination, defecation, collapse, and trouble breathing. Merck Veterinary Manual notes that levamisole toxicity is more likely when the normal therapeutic dose is exceeded, and severe poisoning can lead to respiratory failure. That is why this medication needs careful measuring and veterinary oversight.

See your vet immediately if your goat develops breathing changes, repeated collapse, severe tremors, profound weakness, or worsening neurologic signs after dosing. Also call promptly if the goat was accidentally overdosed, if multiple dewormers were given together, or if a debilitated goat was treated and now seems worse.

Levamisole should be used carefully with other medications or chemicals that can increase cholinergic effects. Merck Veterinary Manual warns that toxicity can increase when levamisole is used at the same time as organophosphates and other cholinergic drugs. In practical terms, that means your vet should know about any recent insecticide, lice treatment, fly control product, or other dewormer your goat has received.

This matters because some parasite-control and pesticide products can overlap in how they affect the nervous system. When those effects stack, a goat may be more likely to show salivation, tremors, weakness, or collapse. If your goat has recently been exposed to a farm chemical, dip, spray, pour-on, or another dewormer, tell your vet before levamisole is given.

Levamisole should also be used cautiously in severely debilitated animals. Product information for Prohibit advises consulting your vet before use in severely debilitated animals, and that is especially important in goats that are anemic, dehydrated, underweight, or already struggling with heavy parasite burdens.