Atovaquone: veterinary dose and monograph

At a glance

Drug class

Antiparasitic

Also known as

Mepron, Wellvone, Atovaquone

Species with doses

Dogs and Cats

General dose range

13–15 mg/kg PO q8h with fatty food — check the species tables for the indication

Routes

PO

Last reviewed

1 October 2026

Indications

• Babesia gibsoni / B. conradae (dogs) — with azithromycin
• Cytauxzoon felis (cats) — with azithromycin (the standard, survival-improving protocol)
• Hepatozoon / certain other protozoal infections (adjunct)

Atovaquone dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

Dogs

• Babesia gibsoni (with azithromycin): Papich 5e: 13–15 mg/kg PO q8h for 10 days with azithromycin 10 mg/kg q24h. Plumb’s p.123 (Birkenheuer 2004): 13.3 mg/kg PO q8h + azithromycin 10 mg/kg once daily for 10 days. Give with a fatty meal (absorption).
• Pneumocystosis: Plumb’s p.123 (Greene 2006): 15 mg/kg PO once daily for 3 weeks, with food.

Cats

• Cytauxzoon felis (with azithromycin): Papich 5e and Plumb’s p.123 (Birkenheuer 2008): 15 mg/kg PO q8h with azithromycin 10 mg/kg PO q24h, with food, typically for 10 days; cases also received IV fluids and most received heparin.

Contraindications

Use as MONOTHERAPY (rapid resistance — always combine, e.g. with azithromycin). Administration on an empty stomach (treatment failure). Known hypersensitivity. Severe hepatic impairment (caution). Confirm the protozoal diagnosis (PCR).

Species-specific warnings

Cats: Cytauxzoonosis is often fatal — atovaquone + azithromycin (with food) plus aggressive supportive care (fluids, heparin, nursing) is the standard; start early.

Adverse effects

• Generally well tolerated
• GI upset (vomiting, diarrhoea)
• Treatment failure/relapse if under-absorbed (empty stomach) or used alone (resistance)
• Rare hepatic enzyme elevation

Drug interactions

• Fatty food: greatly INCREASES absorption (required for efficacy)
• Metoclopramide / rifampin: reduce atovaquone levels (avoid)
• Azithromycin: the standard synergistic partner
• Tetracyclines: may reduce levels

Pregnancy and lactation

Limited data; use only if the protozoal infection threatens the dam and no safer option exists.

Monitoring

• Parasitaemia / PCR response (Babesia, Cytauxzoon)
• Confirm dosing WITH FATTY FOOD (absorption) — the commonest cause of failure
• Liver enzymes; clinical/supportive parameters (Cytauxzoon is critical — intensive care)
• Relapse surveillance (small Babesia can recrudesce)

Toxicity and overdose

Well tolerated — overdose mainly causes GI upset and possible hepatic enzyme elevation. The clinically important "failure mode" is not toxicity but UNDER-ABSORPTION (empty stomach) or monotherapy resistance, leading to treatment failure/relapse of a serious infection.

Management: No specific antidote. Supportive care; monitor liver values. Effects are generally mild. Manage the underlying protozoal disease with appropriate supportive care.

Clinical pearls

• Always COMBINE (with azithromycin) and always give WITH A FATTY MEAL — these two rules make or break treatment of Babesia gibsoni and Cytauxzoon felis
• Atovaquone + azithromycin is the standard, survival-improving protocol for feline cytauxzoonosis (plus intensive supportive care)
• Monotherapy breeds resistance and relapse — never use it alone
• Treatment failure is usually under-absorption (empty stomach) — counsel owners carefully on feeding

Mechanism of action

Atovaquone is a ubiquinone (coenzyme Q) analogue that binds the cytochrome bc1 complex (complex III) of the protozoal mitochondrial electron-transport chain, collapsing the mitochondrial membrane potential and shutting down pyrimidine synthesis and ATP production — killing the parasite. Selectivity comes from much higher affinity for the protozoal than the mammalian complex. Combining with azithromycin (a different mechanism) improves efficacy and limits resistance.

Formulations and products

• Oral suspension 150 mg/mL (Mepron)
• Atovaquone + proguanil tablet (Malarone — human)
• Mepron — 150 mg/mL suspension, Oral suspension (human-label)
• Malarone (atovaquone + proguanil) — 250 mg atovaquone tablet (combination), Tablet (human-label)

Storage

Suspension: 15–30 °C, shake well; do not freeze. Tablets per label.

Before you use this dose

Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

Other antiparasitics

• Albendazole
• Allopurinol
• Amitraz
• Amprolium
• Buparvaquone
• Clorsulon
• Closantel
• Cypermethrin

Frequently asked questions