• Prescribed for: Bacterial Infections
  • Species: Dogs, Cats, and Horses (Foals)
  • Therapeutic Class: Semi-synthetic Macrolide Antibiotic

Basic Information:

Azithromycin is a semi-synthetic macrolide antibiotic derived from erythromycin, widely used in veterinary medicine for its efficacy against bacterial infections. Compared to erythromycin, azithromycin exhibits a longer half-life and better absorption, making it a preferred choice in treating dogs, cats, and horses. Its mechanism of action involves inhibiting protein synthesis in susceptible bacteria, rendering it bacteriostatic.

Veterinary Medicine Uses:

Azithromycin finds application in treating a diverse array of bacterial infections in dogs, cats, and horses, including streptococci, staphylococci, Chlamydia, haemophilus spp, mycoplasma spp, and borrelia burgdorferi, among others. It is commonly utilized in the management of dermatological infections, urogenital infections, respiratory tract infections, and otitis media in animals. Notably, azithromycin has demonstrated effectiveness against specific conditions such as Babesia Gibsoni in dogs, Bartonella in cats, and Rhodococcus equi infection in foals.

Potential Side-Effects:

Gastrointestinal issues like abdominal discomfort, vomiting, and diarrhea are among the most common side effects associated with azithromycin administration. Rare but severe side-effects may include cardiac arrhythmia, ventricular tachycardia, and renal function issues, necessitating careful monitoring during treatment.

Drug Interactions:

Azithromycin can interact with various medications, including ergotamine, dihydroergotamine, triazolam, pimozide, cisapride, and other macrolide antibiotics. Concurrent use with rifampin is common, although caution is advised with oral antacids and drugs metabolized by cytochrome P450.


Gastrointestinal side effects are frequently encountered, particularly in foals, necessitating vigilant monitoring and dose adjustments as needed. Notably, hyperthermia, potentially fatal, has been reported in foals receiving azithromycin, warranting limited turnout time and aggressive cooling measures if necessary.