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 2 species: Cat (Domestic), Dog (Domestic).

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 15–30 mg/kg PO q8-12h (max 6 g total daily dose) in dogs, per Plumb's Veterinary Drug Handbook, 9th Ed, 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'. 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 (4 dose rules)

Cat (Domestic)Dog (Domestic)

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

Evidence levels across 4 dose rules

Strong×2Moderate×1Weak×1

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

Backed by 3 published sources

· 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 Veterinary Drug Handbook, 9th Ed, 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'
· Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.1230 (2026-08-01).

Sample dosing (2 of 4 cited rules)

A dog/cat sample is shown here. Cited dosing for all 2 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, 9th Ed, 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'
Dog (Domestic)	PO	10–30 mg/kg	q8-12h	Strong	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).

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