ExoticRx · exoticrx.com/drugs/pyrimethamine
US brand names:Daraprim
Pyrimethamine is dosed at 0.5 mg/kg PO q12h in african grey parrots, per 159. Formulary. In: Chitty J, Lierz M, Chitty J, Lierz M, eds. BSAVA Manual of Raptors, Pigeons and Passerine Birds; British Small Animal Veterinary Association, Gloucester, UK; 2008:384-390. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.441 — Carpenter's Exotic Animal Formulary 6th ed, Table 5.4 (Antiparasitic Agents Used in Birds). The copy held is an ebook conversion with no printed page numbers, so the table — not the page — is the citable location. — SOURCE EDITION: BSAVA Small Animal Formulary, Part A — Canine and Feline — ISBN 9781910443705, https://openlibrary.org/isbn/9781910443705; Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929. Verify against current literature before clinical use.
Inhibits dihydrofolate reductase in protozoa, blocking folic acid synthesis required for DNA replication. Synergistic with sulfonamides.
Bone marrow suppression possible — monitor CBC. Supplement with folinic acid (leucovorin). Teratogenic. Do not use in pregnant animals.
Species references:All African Grey Parrot drugsAll Amazon Parrot drugsAll Cat (Domestic) drugsAll Dog (Domestic) drugs
Each ExoticRx dose rule is graded by the strength of its primary evidence — see the editorial process.
A dog/cat sample is shown here. Cited dosing for all 4 species — reptiles, birds, pocket pets, livestock, and equine — is free on the per-species pages above. Pro adds the weight-based calculator for every species.
| Species | Route | Dose | Frequency | Evidence | Source |
|---|---|---|---|---|---|
| Cat (Domestic) | PO | 0.25–0.5 mg/kg | q12h | Moderate | Foster SF, Martin P. Lower respiratory tract infections in cats: Reaching beyond empirical therapy. J Feline Med Surg. 2011;13:313-332. doi:10.1016/j.jfms.2011.06.001 — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.1127 (2026-08-01). — Plumb's 10th ed (held) printed p.1100, Pyrimethamine monograph spanning p.1099-1100; page located 2026-08-05 from the book's own running heads, and carries this exact dose under the matching species heading. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207 |
| Dog (Domestic) | PO | 0.25–1 mg/kg | q24h; 0.25-0.5 mg/kg may be given q12h | Weak |
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View PlansSource citations and evidence levels available on the live page. Reference only — verify against current literature before clinical use.
| Plumb's Veterinary Drug Handbook, 10th ed., printed p.1100 (corpus PDF p.1127), Dosages > DOGS; corroborated by BSAVA Small Animal Formulary 10th ed., Pyrimethamine, printed p.354 (corpus PDF p.370) - 'Dogs, Cats: Toxoplasmosis/neosporosis: 1 mg/kg p.o. q24h or divided q12h for 4 weeks, alongside sulphonamides' — SOURCE EDITION: BSAVA Small Animal Formulary, Part A — Canine and Feline — ISBN 9781910443705, https://openlibrary.org/isbn/9781910443705; Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207 |