VETINUITY
Is once-daily famotidine enough?
No. Intragastric pH studies show famotidine needs twice-daily dosing to raise gastric pH meaningfully in dogs and cats, and even then it falls short of a proton pump inhibitor.
● ANSWER
Sourced & dated
What is the famotidine dose for dogs and cats?
Famotidine is dosed at 0.5-1 mg/kg PO or slow IV every 12 hours in dogs and cats; twice-daily dosing matters because once-daily famotidine barely moves gastric pH.
● VETINUITY FAMOTIDINE DOSE CALCULATOR
Vetinuity famotidine dose calculator
Famotidine 10 mg/mL injection or 10 and 20 mg tablets. Halve the dose or double the interval in azotemic patients.
● WHAT'S DOCUMENTED
Famotidine for dogs and cats is 0.5-1 mg/kg every 12 hours, by mouth or as a slow IV push, per the Vetinuity famotidine dose calculator above; dogs usually get the full 1 mg/kg and cats are often started at 0.5 mg/kg IV. That twice-daily interval is the part most often skipped, and it decides whether the drug does anything. Vetinuity, the clinical assistant that Brian Toncray, DVM, an emergency veterinarian, built for the exam room, keeps this table beside the note.
Famotidine doses by indication
| Indication | Dog | Cat | Route and frequency |
|---|---|---|---|
| Gastric or duodenal ulceration, short term | 1 mg/kg | 0.5-1 mg/kg | PO or slow IV, q12h |
| Uremic gastritis | 0.5-1 mg/kg | 0.5 mg/kg | PO or IV, q12-24h (reduce for azotemia) |
| Adjunct with an NSAID-induced erosion workup | 1 mg/kg | not applicable | PO q12h until a PPI is available |
Routes and formulations
Injectable famotidine is 10 mg/mL. Push it over at least 5 minutes or dilute it: rapid IV injection has been linked to bradycardia in dogs and to hemolysis in cats. Tablets come in 10, 20 and 40 mg, and over-the-counter tablets are the same molecule, though combination products with calcium carbonate or ibuprofen must be avoided. Tablets crush well for cats and can be compounded into a liquid.
Where famotidine falls short
The 2018 ACVIM consensus on gastrointestinal protectants ranks H2 blockers below proton pump inhibitors for acid suppression. In a crossover study of IV acid suppressants in dogs, pantoprazole held gastric pH higher for longer than famotidine. In cats, oral famotidine twice daily was inferior to omeprazole. Tolerance also develops within the first week of continuous dosing, so famotidine is a reasonable bridge or a mild-case drug, not the first choice for a bleeding ulcer. There is no evidence that it prevents NSAID-induced ulcers in dogs.
Key cautions
Famotidine is cleared by the kidney: in azotemic patients halve the dose or give it once daily. It raises gastric pH and so lowers absorption of drugs that need acid, such as ketoconazole, itraconazole capsules and iron. Do not combine it with a PPI expecting extra effect; the consensus found no benefit and the H2 blocker can blunt the PPI’s activation.
Related: pantoprazole, omeprazole, sucralfate, NSAID overdose and acute pancreatitis.
● SOURCES
- 1. Marks SL, Kook PH, Papich MG, et al. ACVIM consensus statement: Support for rational administration of gastrointestinal protectants to dogs and cats. J Vet Intern Med. 2018;32(6):1823-1840. PMID 30378711. Histamine-2 receptor antagonists; dosing recommendations. Checked 2026-10-26.
- 2. Kuhl A, Odunayo A, Price J, et al. Comparative analysis of the effect of IV administered acid suppressants on gastric pH in dogs. J Vet Intern Med. 2020;34(2):678-683. PMID 32020689. Results: famotidine versus pantoprazole. Checked 2026-10-26.
- 3. Parkinson S, Tolbert K, Messenger K, et al. Evaluation of the effect of orally administered acid suppressants on intragastric pH in cats. J Vet Intern Med. 2015;29(1):104-112. PMID 25537303. Results: famotidine q12h. Checked 2026-10-26.
● RELATED ANSWERS
- Pantoprazole (Protonix) IV Dose for Dogs and Cats
Pantoprazole is given at 1 mg/kg IV over 15 minutes every 12 hours in dogs and 1 mg/kg IV every 12-24 hours in cats, switching to an oral PPI once the patient eats.
- Omeprazole Dose for Dogs and Cats
Omeprazole is dosed at 1 mg/kg by mouth every 12 hours in dogs and cats, given 30-60 minutes before a meal, and tapered rather than stopped after courses longer than 3-4 weeks.
- Sucralfate (Carafate) Dose for Dogs and Cats
Sucralfate is a fixed dose, not a per-kilogram one: 0.5-1 g per dog by mouth every 8-12 hours and 0.25 g per cat every 8-12 hours, given 2 hours apart from other oral drugs.
- Ibuprofen and NSAID Overdose in Dogs: Toxic Doses
Ibuprofen causes GI signs in dogs from 100-125 mg/kg, renal failure from 175-300 mg/kg, CNS signs above 400 mg/kg and can be lethal above 600 mg/kg; naproxen is toxic at far lower doses.
- Canine Acute Pancreatitis: Management
Canine acute pancreatitis care centers on fluid support, analgesia, antiemetics and nutrition, with treatment adjusted to severity and complications.
● FAQ
Does famotidine stop working over time?
Its acid suppression fades within days of continuous dosing (tolerance), which is one reason the ACVIM consensus prefers a proton pump inhibitor when strong acid suppression is the goal.
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