Tilmicosin for Ox: Uses, Dosing & Major Safety Warnings

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 cattle under your vet's direction. In the U.S., the best-known injectable product is Micotil 300, which contains 300 mg/mL of tilmicosin as tilmicosin phosphate. It is labeled for subcutaneous use in cattle only, not for intravenous or intramuscular injection.

This medication is mainly used in beef cattle and certain nonlactating dairy cattle for respiratory disease. It concentrates well in lung tissue, which is one reason your vet may consider it when an ox has signs consistent with bovine respiratory disease (BRD).

Tilmicosin also carries one of the most serious handler warnings in food-animal medicine. Accidental human injection has been associated with fatalities. Because of that, handling, storage, and administration matter as much as the dose itself. Your vet may recommend a different antibiotic if safe handling on your farm is a concern.

In cattle, tilmicosin is labeled for the treatment of BRD associated with susceptible bacteria including Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni. It is also labeled for the control of respiratory disease in cattle at high risk of developing BRD, such as newly arrived, stressed, or commingled animals when your vet believes metaphylaxis is appropriate.

Your vet may consider tilmicosin when an ox has fever, depression, reduced appetite, nasal discharge, cough, or increased breathing effort and the herd history supports bacterial pneumonia. It is not a good fit for every respiratory case. Viral disease, advanced lung damage, dehydration, or mixed infections may change the treatment plan.

Because antimicrobial stewardship matters, your vet may choose tilmicosin only when the likely bacteria, handling conditions, withdrawal needs, and human safety risks all line up. Other labeled BRD drugs may be safer or more practical in some operations.

Tilmicosin should be dosed only by your vet or exactly as your vet instructs. For cattle, the labeled injectable dose is 10 mg/kg subcutaneously once, which equals 1 mL per 30 kg body weight or about 1.5 mL per 100 lb. Some current product training materials also describe a labeled cattle dose range of 10 to 20 mg/kg SC once for specific use patterns, but your vet should decide whether the lower or higher labeled dose is appropriate for the situation.

Do not give tilmicosin intravenously or intramuscularly. IV use in cattle has caused deaths, and IM injection can cause significant local tissue injury. The product should be given subcutaneously only, and no more than 10 mL should be placed in one injection site.

Food-animal details matter too. Current U.S. labeling states a 42-day preslaughter withdrawal time after the last treatment. The product should not be used in female dairy cattle 20 months of age or older, because a milk withdrawal time has not been established. If your ox is part of a breeding, dairy, or show program, ask your vet to confirm that the planned use fits all label and residue requirements.

Common cattle side effects are usually related to the injection site. Your ox may develop pain, swelling, or inflammation where the medication was given. Some animals can also show reduced feed intake, reduced water intake, lameness, or temporary depression after treatment.

More serious reactions are less common but important. Tilmicosin is known for cardiac toxicity, including tachycardia and decreased heart contractility. Cattle have died after intravenous injection, which is why route errors are emergencies. Product materials also list collapse and anaphylaxis or anaphylactoid reactions among reported adverse events.

See your vet immediately if your ox seems weak, collapses, has marked swelling, labored breathing, severe depression, or worsening respiratory signs after treatment. Also seek urgent medical help right away for any accidental human exposure, especially injection, eye exposure, or significant skin or oral exposure.

Tilmicosin is a macrolide antibiotic, so your vet will usually think carefully before combining it with other antimicrobials that may overlap in activity or stewardship concerns. In feedlot and hospital-pen medicine, treatment timing matters. Regulatory guidance for tilmicosin medicated feed notes that feed use should not occur concurrent with or following an injectable macrolide, and should not occur within 3 days after a nonmacrolide injectable BRD therapy. That does not automatically apply to every injectable case, but it shows why your vet needs a full medication history.

Because tilmicosin can affect the heart, your vet may also avoid combining it with drugs or situations that could increase cardiovascular risk. If your ox has already received another BRD antibiotic, anti-inflammatory medication, sedative, or electrolyte therapy, tell your vet before treatment.

Never mix tilmicosin into a do-it-yourself protocol. The safest approach is to give your vet a complete list of all recent injections, feed medications, supplements, and withdrawal constraints so they can choose the most practical option.