Ceftiofur for Horses: 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.

Ceftiofur is a prescription injectable antibiotic in the third-generation cephalosporin family. In horses, your vet may use it as ceftiofur sodium or ceftiofur crystalline free acid, depending on the infection, how often treatment is practical, and whether your horse needs a shorter-acting or longer-acting option.

This medication works by interfering with bacterial cell wall formation. That means it is used for bacterial infections, not viral illness. In equine medicine, ceftiofur is especially associated with respiratory infections, but your vet may also consider it for other susceptible bacterial infections when culture results, exam findings, and the horse's overall condition support that choice.

For many pet parents, one practical difference is the formulation. Ceftiofur sodium is shorter acting and may need more frequent dosing. Ceftiofur crystalline free acid is a sustained-release form that is often given less often, which can be helpful when daily injections are difficult or stressful.

Because ceftiofur is an injectable prescription drug, it should only be used exactly as your vet directs. Route matters. Product labels and client education materials warn that accidental intravenous administration of crystalline free acid formulations can be dangerous, so this is not a medication to improvise with at home.

In the United States, ceftiofur is FDA-approved in horses for lower respiratory tract infections caused by susceptible strains of Streptococcus equi subsp. zooepidemicus, often written as S. zooepidemicus. This bacterium is a common cause of equine bacterial respiratory disease, especially when horses develop fever, nasal discharge, cough, or abnormal lung sounds.

Your vet may also use ceftiofur in other situations when a bacterial infection is suspected or confirmed and the likely organisms are expected to respond. In practice, that can include some pneumonia cases, selected soft tissue infections, and certain foal infections, but the exact choice depends on exam findings, culture and sensitivity testing, age, hydration status, and whether your horse can tolerate repeated injections.

Ceftiofur is not the right fit for every infection. Some bacteria are naturally less susceptible, and resistance patterns can vary by farm, hospital, and region. That is why your vet may recommend a culture and sensitivity test before starting treatment or if a horse is not improving as expected.

If your horse has severe breathing trouble, high fever, depression, or rapid worsening, antibiotics are only one part of care. Horses with serious respiratory disease may also need airway support, anti-inflammatory medication, fluids, isolation, and close monitoring.

Ceftiofur dosing in horses depends on the formulation, the horse's weight, the infection being treated, and whether the patient is an adult horse or foal. A commonly referenced equine dosing range for ceftiofur sodium is 2.2 to 4.4 mg/kg IV or IM every 12 to 24 hours. Merck also lists foal dosing at 10 mg/kg IM or IV every 6 to 12 hours in some situations. These are veterinary dosing references, not a substitute for an individualized treatment plan.

For ceftiofur crystalline free acid (Excede) in horses, the labeled regimen for respiratory infection is 6.6 mg/kg intramuscularly, with two injections given 4 days apart. This long-acting option is designed to maintain therapeutic concentrations for several days, which can reduce handling and repeated needle sticks in some horses.

Your vet will calculate the exact volume based on body weight and the product concentration. They may also adjust the plan if your horse is a foal, is dehydrated, has kidney concerns, is receiving other medications, or has a condition that changes how aggressively the infection needs to be treated.

Do not change the dose, route, or schedule on your own. Do not stop early because your horse looks better after a day or two. Stopping too soon or underdosing can increase the risk of treatment failure and bacterial resistance.

Many horses tolerate ceftiofur reasonably well, but side effects can happen. The most common concerns are injection-site pain, swelling, firmness, sensitivity, or edema. With cephalosporin antibiotics as a group, some horses may also develop decreased appetite, loose manure, diarrhea, or general digestive upset.

More serious reactions are less common but matter. Horses can have allergic or hypersensitivity reactions, including hives, facial swelling, rash, fever, or breathing changes. If your horse seems suddenly distressed after an injection, contact your vet right away. Product information for crystalline free acid formulations also warns that adverse reactions may require prolonged care because the drug remains in the body longer.

As with other antibiotics, ceftiofur can disrupt normal gut bacteria. In adult horses, any antibiotic-associated diarrhea deserves attention because horses are sensitive to intestinal imbalance. Call your vet promptly if you notice significant diarrhea, worsening depression, colic signs, or refusal to eat.

Use extra caution in horses with kidney disease or dehydration, especially if they are also receiving other drugs that can stress the kidneys. If your horse is on a longer course or is medically fragile, your vet may recommend monitoring hydration, appetite, manure output, and sometimes bloodwork.

Ceftiofur does not have a long list of dramatic day-to-day interactions, but it still deserves a full medication review before treatment starts. Tell your vet about all prescription drugs, supplements, joint products, ulcer medications, and injectable therapies your horse is receiving.

The biggest practical concern is combined kidney stress. Ceftiofur and other cephalosporins have some nephrotoxic potential, even though serious kidney injury is uncommon at standard doses. Risk may be higher when ceftiofur is used alongside aminoglycosides such as amikacin or gentamicin, or with other potentially nephrotoxic drugs like amphotericin B, furosemide, and sometimes NSAIDs in a dehydrated or compromised horse.

There are also known in vitro incompatibilities with some cephalosporin preparations, which is one reason your vet may avoid mixing injectable drugs in the same syringe unless compatibility is well established. If your horse is hospitalized, the care team will usually manage this automatically.

Finally, horses with a history of allergy to cephalosporins or penicillin-type antibiotics need special caution because cross-reactivity can occur. If your horse has ever had hives, facial swelling, collapse, or another suspected antibiotic reaction, make sure your vet knows before the first dose.