Enrofloxacin for Pigs: 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.

Enrofloxacin is a prescription fluoroquinolone antibiotic used in veterinary medicine to treat certain bacterial infections. In U.S. swine practice, the best-known injectable product is Baytril 100. It is labeled for specific uses in pigs, not as a general-purpose antibiotic for every cough, fever, or diarrhea case.

For pigs, enrofloxacin is important because it can reach good tissue levels and works against several bacteria involved in respiratory disease and some enteric disease situations. That said, it is also a drug class with major antimicrobial stewardship concerns. In food animals in the United States, extra-label use of fluoroquinolones is prohibited, so your vet has to stay within approved labeling and residue-avoidance rules.

This matters for pet parents with companion pigs and for people caring for production pigs. A medication that seems familiar from dogs or cats may follow very different legal and safety rules in swine. Your vet will consider the pig's age, intended use, body weight, clinical signs, and food-safety status before deciding whether enrofloxacin is an appropriate option.

In pigs, enrofloxacin is labeled primarily for swine respiratory disease (SRD) associated with susceptible bacteria including Actinobacillus pleuropneumoniae, Pasteurella multocida, Mycoplasma hyopneumoniae, Streptococcus suis, and Bordetella bronchiseptica. Your vet may consider it when pigs have fever, increased breathing effort, coughing, depression, or reduced feed intake and the herd pattern fits bacterial respiratory disease.

It is also labeled for control of colibacillosis in weaned pigs under specific conditions. On the product label, treatment is intended to begin within the first 60 days after weaning when clinical signs are present in at least 2% of the group. If pigs are not improving within about 48 hours, your vet may want to reassess the diagnosis, because viral disease, ventilation problems, parasites, or resistant bacteria can look similar.

Enrofloxacin does not treat viral infections, and it is not the right answer for every pig with diarrhea or pneumonia. In many cases, your vet may recommend diagnostics, supportive care, environmental changes, or a different antibiotic based on likely bacteria, withdrawal needs, and stewardship goals.

For U.S. swine labeling, enrofloxacin injectable solution is given as a single dose of 7.5 mg/kg body weight, which is approximately 3.4 mL per 100 lb of body weight. The label allows intramuscular or subcutaneous injection behind the ear, and the administered volume should not exceed 5 mL per injection site. In smaller pigs, the product may be diluted with sterile water according to label directions, and diluted solution should be used within the labeled time window.

Because pigs vary widely in size, accurate weighing matters. A small math error can become a meaningful overdose or underdose, especially in miniature pigs or young growing pigs. Your vet or veterinary team can show you how to calculate the exact volume, where to place the injection, and how to split the dose across sites if needed.

Do not change the dose, route, or schedule on your own. In food animals, using fluoroquinolones outside approved labeling is not allowed in the U.S. Your vet should also review withdrawal timing before treatment. For labeled Baytril 100 use in swine intended for food, pigs must not be slaughtered within 5 days of treatment. If your pig is a companion animal, tell your vet that clearly so the medical record reflects the pig's status.

Many pigs tolerate enrofloxacin reasonably well when it is used correctly, but side effects can happen. The most common concerns with this drug class are digestive upset such as reduced appetite, loose stool, or diarrhea. Injectable products can also cause a temporary local tissue reaction at the injection site, which matters in food animals because it may lead to trim loss at slaughter.

Less common but more serious reactions can include neurologic signs such as incoordination or seizures, especially in animals with underlying neurologic risk or after dosing errors. Fluoroquinolones are also used cautiously in young, rapidly growing animals because this drug class has been associated with joint cartilage damage in immature animals. If your pig seems stiff, lame, unusually reluctant to move, or suddenly less active after treatment, contact your vet promptly.

See your vet immediately if your pig has facial swelling, collapse, severe weakness, worsening breathing trouble, persistent vomiting, marked diarrhea, or no improvement after treatment. Those signs may mean the infection is progressing, the diagnosis needs to be revisited, or the medication is not the right fit.

Enrofloxacin can interact with other medications and supplements, so your vet should know everything your pig is receiving, including over-the-counter products, minerals, and medicated feeds. Fluoroquinolones can bind to multivalent cations such as magnesium, aluminum, zinc, calcium, and iron. In practical terms, that means products like antacids, sucralfate, zinc supplements, and some mineral-containing products can reduce absorption when enrofloxacin is given by mouth.

This drug class can also affect levels of theophylline and other methylxanthines, potentially increasing the risk of nervous system or heart-related side effects. Some references also advise caution with cyclosporine, certain other antibiotics, and medications that may lower the seizure threshold. If your pig has kidney disease, liver disease, dehydration, or a seizure history, your vet may want closer monitoring.

The safest approach is to avoid mixing medications unless your vet has reviewed the full plan. If your pig is on multiple treatments for pneumonia, pain, ulcers, or chronic disease, ask your vet to confirm the timing and compatibility of each one.