# Sulfasalazine: veterinary dose and monograph

> Sulfasalazine is a veterinary gastrointestinal drug. Sulfapyridine–5-aminosalicylic acid prodrug split by colonic bacteria; the 5-ASA acts locally in the colon. Indications include chronic colitis / large-bowel IBD (dogs, cats, ferrets); cutaneous vasculitis (dogs). This monograph lists 4 reference doses for dogs, cats and ferrets, each with route, frequency and source.

Source: https://vetmasterji.com/drugs/sulfasalazine · Last reviewed: 2026-10-01

## At a glance

- **Drug class:** Gastrointestinal
- **Also known as:** Salazopyrin, Azulfidine, Sulphasalazine
- **Species with doses:** Dogs, Cats and Ferrets
- **General dose range:** 10–30 mg/kg PO q8–12h — check the species tables for the indication
- **Routes:** PO
- **Last reviewed:** 1 October 2026

## Indications

- Chronic colitis / large-bowel IBD (dogs, cats, ferrets)
- Cutaneous vasculitis (dogs)

## Sulfasalazine 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

*Sulfasalazine doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Colitis / large-bowel IBD | 10–30 mg/kg | PO | q8–12h, then taper | — |
| Cutaneous vasculitis (adjunct) | 20–40 mg/kg | PO | q8h | — |

- Colitis / large-bowel IBD: Papich 5e: 10–30 mg/kg q8–12h PO. Plumb’s p.1095: 20–40 mg/kg q8h for 3 weeks, then q12h for 3 weeks, then 10–20 mg/kg q12h for 3 weeks (Marks); 20–50 mg/kg (max 1 g per dose) q8h, usually starting at 20–30 mg/kg, tapering at 2–4-week intervals (Leib); 10–25 mg/kg q8h for 4–6 weeks (Washabau). Check Schirmer tear tests before and during treatment.
- Cutaneous vasculitis (adjunct): Plumb’s p.1095: 20–40 mg/kg PO q8h (Hillier; Griffin); 25 mg/kg three times daily (Bloom). Monitor tear production and CBC.

### Cats

*Sulfasalazine doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Colitis (short course, caution) | 10–20 mg/kg | PO | q12–24h | maximum 10 days |

- Colitis (short course, caution): Plumb’s p.1095: 10–20 mg/kg PO once daily, tapered (Jergens & Willard; Moore; Marks); 10–20 mg/kg q8–24h for no more than 10 days (Dimski; Krecic). Papich 5e: 20 mg/kg q12h PO. Cats are sensitive to salicylates.

### Ferrets

*Sulfasalazine doses for ferrets*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Colitis | 10–20 mg/kg | PO | q8–12h | — |

- Colitis: Plumb’s p.1095: 10–20 mg/kg PO two to three times daily (Williams); 25 mg per ferret twice daily (Weiss).

## Contraindications

Sulfonamide or salicylate hypersensitivity; pre-existing KCS; hepatic disease or blood dyscrasias. Cats are salicylate-sensitive — short courses at low doses only.

## Adverse effects

- Keratoconjunctivitis sicca (dogs)
- Vomiting, anorexia
- Cholestatic jaundice, haemolytic anaemia, leukopenia (rare)
- Allergic dermatitis

## Monitoring

- Schirmer tear test before and periodically during treatment
- CBC and liver values on long courses

## Formulations and products

- 500 mg tablet (plain or enteric-coated)

## Before you use this dose

> **Caution:** 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

- [Ranitidine](https://vetmasterji.com/drugs/ranitidine)
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- [Sucralfate](https://vetmasterji.com/drugs/sucralfate)
- [Tylosin](https://vetmasterji.com/drugs/tylosin)
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## Frequently asked questions

### What is the dose of Sulfasalazine for dogs?

Reference doses for Sulfasalazine in dogs: 10–30 mg/kg PO q8–12h, then taper (Colitis / large-bowel IBD); 20–40 mg/kg PO q8h (Cutaneous vasculitis (adjunct)). Confirm against the label and the patient before use.

### What is the dose of Sulfasalazine for cats?

Reference doses for Sulfasalazine in cats: 10–20 mg/kg PO q12–24h for maximum 10 days (Colitis (short course, caution)). Confirm against the label and the patient before use.

### What is the dose of Sulfasalazine for ferrets?

Reference doses for Sulfasalazine in ferrets: 10–20 mg/kg PO q8–12h (Colitis). Confirm against the label and the patient before use.

### When should Sulfasalazine not be used?

Sulfonamide or salicylate hypersensitivity; pre-existing KCS; hepatic disease or blood dyscrasias. Cats are salicylate-sensitive — short courses at low doses only.

### What are the side effects of Sulfasalazine in animals?

Keratoconjunctivitis sicca (dogs); Vomiting, anorexia; Cholestatic jaundice, haemolytic anaemia, leukopenia (rare); Allergic dermatitis.

## Sources

- Plumb's Veterinary Drug Handbook
- Papich 5e — Sulfasalazine
- Papich, Papich Handbook of Veterinary Drugs, 5th edition

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VetMasterJi is a clinical decision-support and education platform for veterinary professionals and students. It does not provide veterinary advice, diagnosis or treatment for specific animals. All drug doses, calculators and differentials are references that must be independently verified before clinical use; the attending registered veterinarian remains solely responsible for every clinical decision.