💊 Macrolide Antibiotic

Azithromycin for Dogs Dosage Calculator

Weight-based azithromycin dosing for dogs by indication — respiratory infections, skin/soft tissue, tick-borne disease — with tablet and suspension breakdowns.

🐶 Introduction

Azithromycin (Zithromax®) is a semi-synthetic macrolide antibiotic derived from erythromycin. It inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit and is effective against a broad spectrum of gram-positive bacteria, some gram-negative organisms, and atypical pathogens including Mycoplasma, Chlamydia, and Bordetella.

A key pharmacokinetic advantage of azithromycin is its extensive tissue distribution and intracellular accumulation, with tissue concentrations 10–100× plasma levels and an exceptionally long elimination half-life (~68 hours in dogs). This allows once-daily or every-other-day dosing with shorter treatment courses than many other antibiotics.

Note: Azithromycin is used off-label in dogs; it is not FDA-approved for veterinary use. Always use under veterinary prescription.

📚 Indication-Specific Dosing

Respiratory Infections (Kennel Cough, Pneumonia)

5–10 mg/kg PO q24h for 3–5 days. Effective against Bordetella bronchiseptica, Mycoplasma cynos.

Skin & Soft Tissue Infections

10 mg/kg PO q24h for 3 days, then 5 mg/kg PO q24h for 7–14 days. Alternative: pulse dosing every 48–72 hours.

Tick-Borne Diseases (Babesia, Haemobartonella)

10 mg/kg PO q24h for 10 days. Often combined with atovaquone for Babesia gibsoni.

Toxoplasmosis (adjunctive)

10 mg/kg PO q24h for 4 weeks.

Available Formulations

  • 250 mg tablets, 500 mg tablets (Z-Pak)
  • 200 mg/5 mL (40 mg/mL) oral suspension — ideal for small dogs
  • Note: 600 mg/15 mL suspension has different concentration — verify carefully

📋 How to Use

  1. Enter your dog’s weight in kg or lb.
  2. Select the indication to load the correct dose rate.
  3. Choose the formulation available.
  4. Click Calculate to view daily dose in mg, tablets or mL, and course duration.
  5. Azithromycin may be given with or without food; giving with food reduces nausea.

💊 Azithromycin Dose Calculator





⚠️

Drug interactions: Azithromycin inhibits CYP3A4 and can raise plasma levels of cyclosporine, digoxin, and warfarin. It may prolong the QT interval — caution in dogs with cardiac arrhythmias. GI side effects (vomiting, diarrhoea) are the most common adverse effects.

📖 References & Methodology

  1. Plumb DC. Plumb’s Veterinary Drug Handbook, 9th ed. Wiley-Blackwell, 2018. Azithromycin entry.
  2. Papich MG. Saunders Handbook of Veterinary Drugs, 4th ed. Elsevier, 2016.
  3. Lappin MR, et al. Antimicrobial use guidelines for treatment of respiratory tract disease in dogs and cats. J Vet Intern Med. 2017;31(2):279-294.
  4. Birkenheuer AJ, et al. Efficacy of combined atovaquone and azithromycin for the treatment of Babesia gibsoni. J Vet Intern Med. 2004;18(4):494-498.