Famotidine: veterinary dose and monograph

At a glance

Drug class

Gastrointestinal

Also known as

Pepcid, Famotid

Species with doses

Dogs, Cats, Cattle, Horses, Rabbits, Ferrets, Hedgehogs and Primates

General dose range

0.5–1 mg/kg PO q12–24h — check the species tables for the indication

Routes

PO, IV, SC

Last reviewed

1 October 2026

Indications

• Gastritis and gastric / duodenal ulceration
• Reflux oesophagitis
• Acid suppression in mast-cell tumour / uraemic gastropathy
• Stress-ulcer prophylaxis in critical patients

Famotidine 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

• Acid suppression / ulcer: Papich 5e: 0.5 mg/kg q12h PO, IV, SC or IM; 1 mg/kg q12h for more reliable acid suppression; CRI 1 mg/kg IV load then 8 mg/kg/day. Plumb’s p.502: 0.5 mg/kg q12–24h (Matz); oesophagitis 0.5–1 mg/kg PO q12h; CKD 0.5 mg/kg once daily (Polzin 2005).

Cats

• Acid suppression / uraemic gastritis: Papich 5e: 0.2 mg/kg q24h up to 0.25 mg/kg q12h IM, SC, PO or IV (IV slowly over 5 min). Plumb’s p.502: 0.2 mg/kg q24h (Marks 2008); 0.5 mg/kg q12–24h; CKD 0.5–1 mg/kg PO q12–24h (Zoran; Wolf). Plumb’s warns about IV use in cats (haemolysis) — give slowly or use another route.

Cattle

• Abomasal ulceration (calves, extra-label): Papich 5e: cattle 0.4 mg/kg IV q6h. Oral efficacy in ruminating cattle is limited. Extra-label — obtain a FARAD withdrawal.

Horses

• Gastric ulceration (adjunct): Papich 5e: 0.2–0.4 mg/kg IV q6h. Plumb’s p.502 (Duran & Ravis 1993): 0.23 mg/kg IV q8h or 0.35 mg/kg IV q12h. ARCI Class 5.
• Gastric ulceration (oral): Papich 5e: 1–2 mg/kg q6–8h PO. Plumb’s p.502 (Duran & Ravis 1993): 1.88 mg/kg PO q8h or 2.8 mg/kg PO q12h. Omeprazole is more effective for EGUS.

Buffalo

No buffalo-specific doses are on file, so buffalo are dosed as cattle.

• Abomasal ulceration (calves, extra-label): Papich 5e: cattle 0.4 mg/kg IV q6h. Oral efficacy in ruminating cattle is limited. Extra-label — obtain a FARAD withdrawal.

Rabbits

• Stress-ulcer prophylaxis (critically ill): Plumb's p.503 (Johnston 2006): rabbits 1 mg/kg IV once daily once the critically ill animal has stabilised.

Ferrets

• Stress ulcer / Helicobacter adjunct: Plumb's p.503 (Williams 2000; Fisher 2005): 0.25–0.5 mg/kg PO or IV once daily; part of Helicobacter mustelae therapy.

Hedgehogs

• Gastric ulcer prevention / treatment: Carpenter Exotic Animal Formulary 6th ed, Table 8-7 (p.519): hedgehogs 1 mg/kg SC q24h.

Primates

• Gastric / duodenal ulcer, oesophagitis: Carpenter Exotic Animal Formulary 6th ed, Table 13-7 (p.707): 0.5–0.8 mg/kg PO q24h; more potent than cimetidine but poorer oral bioavailability (~37%).

Contraindications

Significant renal impairment (reduce dose / frequency — renal elimination). Known hypersensitivity.

Adverse effects

• Generally very well tolerated
• Rare: inappetence; intravascular haemolysis reported in cats with rapid IV — give slow / diluted

Drug interactions

• Azole antifungals (ketoconazole, itraconazole, fluconazole): by RAISING gastric pH famotidine reduces their absorption — if both are needed, give the azole one hour BEFORE famotidine
• Cefpodoxime, cefuroxime: absorption may be decreased; giving with food may alleviate this
• Oral iron salts: absorption decreased — give iron at least one hour before famotidine
• Famotidine causes markedly fewer interactions than cimetidine, which inhibits hepatic P450 — this is the main reason to prefer it

Toxicity and overdose

Plumb's p.502: a very wide margin of safety. The minimum acute lethal dose in dogs is reported as >2 g/kg orally and about 300 mg/kg intravenously. IV doses of 5–200 mg/kg in dogs produced vomiting, restlessness, mucous membrane pallor and redness of the mouth and ears; higher doses caused hypotension, tachycardia and collapse. Because of that margin most overdoses need only monitoring; consider gut-emptying protocols for a massive oral overdose and give supportive therapy where warranted.

Clinical pearls

• Plumb's p.502 records two studies worth knowing: famotidine did NOT improve Helicobacter eradication when added to triple antibiotic therapy in dogs (Leib et al. 2007), and omeprazole was SUPERIOR to famotidine for preventing exercise-induced gastritis in racing sled dogs (Williamson et al. 2010)
• For true ulcer healing or severe oesophagitis a proton-pump inhibitor (omeprazole / pantoprazole) is superior — use H2 blockers for milder acid control
• Tolerance to the acid-suppressing effect can develop over ~2 weeks of continuous use
• Dilute and give slowly IV in cats — rapid injection has caused intravascular haemolysis

Mechanism of action

Plumb's p.502: H2-receptor antagonist. At the H2 receptors of gastric parietal cells famotidine COMPETITIVELY inhibits histamine, reducing acid output both basally and when stimulated by food, pentagastrin, histamine or insulin. By cutting the volume of gastric juice it also reduces pepsin secretion. Note what it does NOT do: gastric emptying time, pancreatic and biliary secretion, and lower oesophageal pressure are unaltered — so it is an acid reducer, not a prokinetic. Incompletely absorbed orally with only minimal first-pass metabolism (human bioavailability 40–50%); only 15–20% protein bound; in rats it does not cross the blood-brain barrier or placenta but IS distributed into milk. Compared with cimetidine it has fewer drug interactions and its activity may persist longer.

Formulations and products

• Famotidine 10 mg tablet
• Famotidine 20 mg tablet
• Famotidine 10 mg/mL injection

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 gastrointestinal drugs

• Bismuth Subsalicylate
• Capromorelin
• Cimetidine
• Cisapride
• Hyoscine Butylbromide (N-Butylscopolammonium)
• Lactulose
• Loperamide
• Metoclopramide

Frequently asked questions