What is Sulfasalazine used for?

Sulfasalazine is indicated for: colitis, Inflammatory bowel disease.

Which species have cited Sulfasalazine dosing data?

Sulfasalazine dosing in the ExoticRx formulary covers 3 species: Cat (Domestic), Dog (Domestic), Ferret.

Is Sulfasalazine a controlled substance?

Sulfasalazine is not federally scheduled in the US. Controlled-drug status differs by country — verify your local rules.

Sulfasalazine

US brand names:Azulfidine

Also known as: Sulphasalazine

Calculate dosage

Sourced from published veterinary references. Awaiting credentialed clinical reviewer — our editorial process.

Sulfasalazine is dosed at 62.5–125 mg/animal PO q8-24h in ferrets, per Hedley J. Small Animal Formulary-Part B: Exotic Pets, 10th ed., British Small Animal Veterinary Association, Gloucester, UK; 2020. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.959 — Carpenter's Exotic Animal Formulary 6th ed, Table 11.10 (Miscellaneous Agents Used in Ferrets.a). The copy held is an ebook conversion with no printed page numbers, so the table — not the page — is the citable location. — SOURCE EDITION: Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929. Verify against current literature before clinical use.

Drug Class

Gastrointestinal

Routes

Indications

colitisInflammatory bowel disease

Mechanism of Action

Cleaved by colonic bacteria to 5-aminosalicylic acid (mesalamine) and sulfapyridine. 5-ASA acts locally to reduce colonic inflammation.

Side effects & warnings

Used for colitis in dogs. KCS (dry eye) risk — monitor Schirmer tear test. Cats: salicylate sensitivity. Folate supplementation recommended. GI upset.

Species with Sulfasalazine dosing data (5 dose rules)

Cat (Domestic)Dog (Domestic)Ferret

Species references:All Cat (Domestic) drugs All Dog (Domestic) drugs All Ferret drugs

Evidence levels across 5 dose rules

Strong×2Moderate×1Weak×2

Each ExoticRx dose rule is graded by the strength of its primary evidence — see the editorial process.

Backed by 4 published sources

· Hedley J. Small Animal Formulary-Part B: Exotic Pets, 10th ed., British Small Animal Veterinary Association, Gloucester, UK; 2020. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.959 — Carpenter's Exotic Animal Formulary 6th ed, Table 11.10 (Miscellaneous Agents Used in Ferrets.a). The copy held is an ebook conversion with no printed page numbers, so the table — not the page — is the citable location. — SOURCE EDITION: Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929
· Neiger R, Salavati S. Chapter 53: Motility disorders of the alimentary tract. In: Bruyette DS, ed. Clinical Small Animal Internal Medicine. John Wiley & Sons, Inc.; 2020:563-582. doi:10.1002/9781119501237.ch53; Hall EJ. Chapter 277: Diseases of the large intestine. In: Ettinger SJ, Feldman EC, Côté E, eds. Vol 2. Elsevier Health Sciences; 2017:1565-1592. — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.1230 (2026-08-01). — Plumb's 10th ed (held) printed p.1203, Sulfasalazine monograph spanning p.1202-1203; 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, — CEILING: BSAVA Small Animal Formulary, Sulfasalazine, corpus p.404 (printed p.389) — "Dogs: All uses: 15-30 mg/kg p.o. q8-12h, maximum 6 g/day"; and Plumb's, printed p.1230, DOGS/Inflammatory large bowel disease — "not to exceed a total daily dose of 6 g". max_dose_mg is set to 2000 so that the fastest permitted interval (q8h) cannot exceed 6 g/day.

Sample dosing (2 of 5 cited rules)

A dog/cat sample is shown here. Cited dosing for all 3 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
Dog (Domestic)	PO	15–30 mg/kg	q8-12h (max 6 g total daily dose)	Strong	Plumb's Veterinary Drug Handbook, 10th ed (2023, held copy; the original seed cited the 9th, which was never consulted), p.1230 (Sulfasalazine, Dosages, DOGS); corroborated by BSAVA Small Animal Formulary 10th Ed Part A p.388 'Dogs: All uses: 15-30 mg/kg p.o. q8-12h, maximum 6 g/day' — Plumb's 10th ed (held) printed p.1203, Sulfasalazine monograph spanning p.1202-1203; page located 2026-08-05 from the book's own running heads, and carries this exact dose under the matching species heading. — 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 — CEILING: BSAVA Small Animal Formulary, Sulfasalazine, corpus p.404 (printed p.389) — "Dogs: All uses: 15-30 mg/kg p.o. q8-12h, maximum 6 g/day"; and Plumb's, printed p.1230, DOGS/Inflammatory large bowel disease — "Initial dosages range from 15 - 30 mg/kg PO every 8 to 12 hours, not to exceed a total daily dose of 6 g". max_dose_mg is 2000 so that the fastest permitted interval (q8h) cannot exceed 6 g/day.
Dog (Domestic)

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