Tilmicosin for Sheep: Uses, Safety Warnings & 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.

Tilmicosin is a prescription macrolide antibiotic used in sheep for certain bacterial respiratory infections. In the U.S., injectable tilmicosin is labeled for ovine respiratory disease associated with Mannheimia haemolytica. It is commonly recognized under the brand name Micotil 300 and is given by subcutaneous injection under your vet's direction.

This drug is notable for two reasons. First, it concentrates well in lung tissue, which is one reason vets may consider it for pneumonia cases. Second, it carries serious human safety risks. Accidental exposure in people can cause severe heart effects and has been associated with death. Because of that, the FDA-approved labeling now emphasizes use of the product's safety shroud, quick-connect system, and tube-fed safety syringe.

Tilmicosin is not a routine at-home medication for most pet parents. It is a livestock antibiotic that should only be handled by trained adults following label directions and your vet's instructions. It is also a food-animal drug, so meat withdrawal times and treatment records matter.

In sheep, tilmicosin is used for bacterial pneumonia, especially cases of ovine respiratory disease linked to Mannheimia haemolytica. Your vet may consider it when sheep show signs such as fever, depression, separation from the flock, reduced appetite, fast breathing, coughing, or nasal discharge. Respiratory outbreaks are often influenced by stressors like transport, crowding, poor ventilation, commingling, or concurrent disease.

Tilmicosin is not a broad answer for every coughing or weak sheep. Pneumonia in sheep can have different causes, including viruses, parasites, aspiration, or other bacteria. That is why your vet may pair treatment decisions with an exam, temperature checks, flock history, and sometimes necropsy, culture, or other diagnostics.

Your vet may also build a wider care plan around the antibiotic. Depending on the case, that can include anti-inflammatory medication, improved ventilation, reducing stress, separating affected animals, and reviewing nutrition and biosecurity. The best option depends on the age of the sheep, severity of illness, handling safety, and food-safety considerations.

Tilmicosin dosing in sheep should come only from your vet. The FDA approval documents for Micotil 300 list the labeled sheep dose as a single subcutaneous injection of 10 mg/kg, which equals 1 mL per 30 kg body weight or about 1.5 mL per 100 lb. It should be given subcutaneously, not into a vein. Intravenous injection in cattle or sheep is fatal, according to the labeling.

There are important limits on who should receive it. The labeling states do not use in lambs under 15 kg body weight. It is also not for species other than cattle and sheep, and exposure has been reported as fatal in several non-target species. Because this is a food-animal medication, your vet also needs to account for the labeled 28-day meat withdrawal period after a single labeled sheep dose.

Do not guess the dose, split doses on your own, or substitute equipment. The FDA labeling specifically requires the product's approved safety system rather than standard single-use or powered syringes. If a sheep is not improving, gets worse, or more animals become sick, contact your vet promptly instead of redosing without guidance.

In sheep, tilmicosin can cause pain or swelling at the injection site. Macrolide antibiotics as a group may also be associated with local tissue irritation after injection. Some sheep with pneumonia may still look dull, breathe hard, or eat poorly for a period after treatment because the underlying disease can take time to improve.

A major concern with tilmicosin is its potential for cardiac toxicity. Macrolide references note that tilmicosin is characterized by tachycardia and decreased contractility, and this risk is especially important in accidental overdosing, wrong-route administration, or exposure in non-target species. If a treated sheep collapses, becomes profoundly weak, or shows sudden worsening, see your vet immediately.

The most urgent safety issue is actually human exposure. Accidental injection, skin, eye, or oral exposure requires immediate medical care. The FDA states there is no antidote and that human exposure can cause severe heart effects and death. If anyone is exposed while handling the drug, stop and seek emergency medical help right away.

Tilmicosin belongs to the macrolide antibiotic family, so your vet will think about interactions that matter for that class. Merck notes that macrolides probably should not be used with chloramphenicol or lincosamides because these drugs may compete for the same bacterial ribosome binding site. In practice, that can make combination therapy less logical unless your vet has a specific reason.

Macrolide injections may also be incompatible with many other pharmaceutical preparations, so they should not be mixed casually in the same syringe or treatment setup. If your sheep is receiving other medications, supplements, or supportive care, tell your vet exactly what has already been given and when.

Because sheep are food animals, interaction planning is not only about safety. It is also about withdrawal times, residue avoidance, and legal use. If your vet is considering extra-label combinations or use in lactating animals, they may need to consult residue guidance resources and set a different withdrawal plan.