# Sulfadimethoxine: veterinary dose and monograph

> Sulfadimethoxine is a veterinary antibiotic. Long-acting sulfonamide — bacteriostatic. Indications include canine / feline coccidiosis (Isospora / Cystoisospora); susceptible bacterial UTI; bovine respiratory disease / foot rot. This monograph lists 16 reference doses for dogs, cats, cattle, horses, rabbits and ferrets and 8 more species, each with route, frequency and source, plus meat and milk withdrawal periods for food animals.

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

## At a glance

- **Drug class:** Antibiotic
- **Also known as:** Albon, Bactrovet, Di-Methox
- **Species with doses:** Dogs, Cats, Cattle, Horses, Rabbits, Ferrets, Guinea pigs, Reptiles, Camelids, Chinchillas, Hamsters, Rats, Mice and Gerbils
- **General dose range:** 25–55 mg/kg PO q24h — check the species tables for the indication
- **Routes:** PO, IV
- **Last reviewed:** 1 October 2026

## Indications

- Canine / feline coccidiosis (Isospora / Cystoisospora)
- Susceptible bacterial UTI
- Bovine respiratory disease / foot rot
- Equine protozoal myeloencephalitis (EPM) — with pyrimethamine
- Avian coccidiosis

## Sulfadimethoxine 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

*Sulfadimethoxine doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Coccidiosis (label) | 55 mg/kg | PO | Day 1 loading | — |
| Coccidiosis maintenance (Day 2+) | 27.5 mg/kg | PO | q24h | 9 days (up to 14 days) |

- Coccidiosis (label): Plumb’s p.1092: coccidiosis 55 mg/kg PO on day 1, then 27.5 mg/kg once daily for 9 days (Matz); label for infections 55 mg/kg then 27.5 mg/kg q24h. Papich 5e: 55 mg/kg loading then 27.5 mg/kg q12h. Monitor Schirmer tear tests on longer courses (KCS).
- Coccidiosis maintenance (Day 2+): Plumb’s p.1092: 27.5 mg/kg PO once daily for 9 days after the 55 mg/kg loading dose (Matz); alternatively 50 mg/kg once daily for 10–14 days eliminates oocyst shedding in most dogs and cats (Marks); puppies 2–6 weeks 50 mg/kg day 1 then 25 mg/kg daily (Macintire). Papich 5e: 27.5 mg/kg q12h.

### Cats

*Sulfadimethoxine doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Coccidiosis | 50–55 mg/kg | PO | Day 1 loading | — |
| Coccidiosis maintenance (Day 2+) | 25–27.5 mg/kg | PO | q24h | 10–14 days |

- Coccidiosis: Plumb’s p.1092: label 55 mg/kg PO (or IV/SC) initially then 27.5 mg/kg once daily; coccidiosis 50 mg/kg once daily for 10–14 days (Marks). Papich 5e: 55 mg/kg loading then 27.5 mg/kg q12h. Ensure hydration; monitor CBC on longer courses.
- Coccidiosis maintenance (Day 2+): Plumb’s p.1092 (label): 27.5 mg/kg once daily after the loading dose; or continue 50 mg/kg once daily for 10–14 days (Marks). Papich 5e: 27.5 mg/kg q12h.

### Cattle

*Sulfadimethoxine doses for cattle*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| BRD / foot rot (label) | 55 mg/kg | IV | Day 1 loading | — | Withdrawal NOT established — treat as extra-label |

- BRD / foot rot (label): Papich 5e and Plumb’s p.1092 (Albon label): 55 mg/kg IV or PO initially, then 27.5 mg/kg q24h for up to 5 days; sustained-release bolus 137.5 mg/kg PO every 4 days; 110 mg/kg PO or IV q24h (Upson; Burrows). Withdrawals differ between injectable, oral and bolus products — follow the product label.

### Horses

*Sulfadimethoxine doses for horses*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Susceptible infection (label) | 27.5–55 mg/kg | PO | q24h (55 mg/kg on day 1) | — |

- Susceptible infection (label): Plumb’s p.1092 (Albon label): 55 mg/kg IV or PO initially, then 27.5 mg/kg q24h IV; Upson 1988: 55 mg/kg PO or IV q12h. (EPM regimens in the references use sulfadiazine or sulfamethoxazole with pyrimethamine, not sulfadimethoxine.)

### Buffalo

No buffalo-specific doses are on file, so buffalo are dosed as cattle.

*Sulfadimethoxine doses for buffalo*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| BRD / foot rot (label) | 55 mg/kg | IV | Day 1 loading | — | Withdrawal NOT established — treat as extra-label |

- BRD / foot rot (label): Papich 5e and Plumb’s p.1092 (Albon label): 55 mg/kg IV or PO initially, then 27.5 mg/kg q24h for up to 5 days; sustained-release bolus 137.5 mg/kg PO every 4 days; 110 mg/kg PO or IV q24h (Upson; Burrows). Withdrawals differ between injectable, oral and bolus products — follow the product label.

### Birds

*Sulfadimethoxine doses for birds*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| No reference dose for this species | Not established in Papich 5e or Plumb’s 10e — do not extrapolate from another species | — | — | — |

- No reference dose for this species: The previous 25–50 mg/kg PO bird row had no source; neither Papich 5e nor Plumb’s gives an avian sulfadimethoxine dose. Poultry products are dosed per their water/feed label.

### Rabbits

*Sulfadimethoxine doses for rabbits*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Susceptible infection / coccidiosis | 10–25 mg/kg | PO | q12–24h | — |

- Susceptible infection / coccidiosis: Plumb's p.1092: rabbits 10–15 mg/kg PO q12h (Ivey & Morrisey 2000); coccidiosis 25 mg/kg PO once daily (Burke 1999). Sulfonamides are safe in rabbits (unlike penicillins/macrolides).

### Ferrets

*Sulfadimethoxine doses for ferrets*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Coccidiosis | 25 mg/kg | PO | q24h | 14 days |

- Coccidiosis: Plumb's p.1092 (Williams 2000; Johnson 2006): 25 mg/kg PO/SC/IM once daily; coccidiosis 25 mg/kg PO q24h ×14 days.

### Guinea pigs

*Sulfadimethoxine doses for guinea pigs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Coccidiosis | 25–50 mg/kg | PO | q24h | 10–20 days |

- Coccidiosis: Plumb's p.1092 (Adamcak & Otten 2000): Mice/Rats/Gerbils/Hamsters/Guinea pigs/Chinchillas coccidiostat 50 mg/kg PO once, then 25 mg/kg PO q24h ×10–20 days (or 75 mg/kg PO ×7–14 days).

### Reptiles

*Sulfadimethoxine doses for reptiles*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Coccidia | 45–90 mg/kg | PO | Day 1 loading | 90 mg/kg day 1, then 45 mg/kg ×5 days |

- Coccidia: Plumb's p.1092 (Lewbart 2001): 90 mg/kg PO day 1, then 45 mg/kg PO on 5 successive days; may also give IM/IV. Maintain hydration.

### Camelids

*Sulfadimethoxine doses for camelids*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Coccidiosis (Eimeria) | 15–110 mg/kg | PO | q12–24h | — |

- Coccidiosis (Eimeria): Plumb's p.1092: 15 mg/kg PO q12h ×5 days (Walker 2009); or 110 mg/kg PO q24h for Eimeria in clinically affected animals. Monitor for polioencephalomalacia.

### Chinchillas

*Sulfadimethoxine doses for chinchillas*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Coccidiosis | 25–50 mg/kg | PO | q24h | 10–20 days |

- Coccidiosis: Plumb's p.1092: 50 mg/kg PO once then 25 mg/kg PO q24h.

### Hamsters

*Sulfadimethoxine doses for hamsters*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Coccidiosis | 25–50 mg/kg | PO | q24h | 10–20 days |

- Coccidiosis: Plumb's p.1092: 50 mg/kg PO once then 25 mg/kg PO q24h.

### Rats

*Sulfadimethoxine doses for rats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Coccidiosis | 25–50 mg/kg | PO | q24h | 10–20 days |

- Coccidiosis: Plumb's p.1092: 50 mg/kg PO once then 25 mg/kg PO q24h.

### Mice

*Sulfadimethoxine doses for mice*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Coccidiosis | 25–50 mg/kg | PO | q24h | 10–20 days |

- Coccidiosis: Plumb's p.1092: 50 mg/kg PO once then 25 mg/kg PO q24h.

### Gerbils

*Sulfadimethoxine doses for gerbils*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Coccidiosis | 25–50 mg/kg | PO | q24h | 10–20 days |

- Coccidiosis: Plumb's p.1092: 50 mg/kg PO once then 25 mg/kg PO q24h.

## Contraindications

Hypersensitivity to sulfonamides. Severe hepatic/renal impairment. Dehydration. Cats more susceptible to sulfonamide toxicity. Dobermans/Rottweilers predisposed to polyarthropathy. Pregnancy (teratogenic). Not for use with methenamine.

## Species-specific warnings

> **Caution:** Dogs: KCS (potentially permanent) and polyarthropathy. Schirmer test at baseline + 1–2 weeks. AVOID in Doberman Pinschers. Adequate hydration to prevent crystalluria.

> **Caution:** Cats: More sensitive to sulfa effects — neurological signs at high doses. Use lower end of range.

> **Caution:** Rabbits: One of FEW antibiotics SAFE orally in rabbits at 50 mg/kg PO q24h × 5 d. Useful for coccidiosis.

> **Caution:** Cattle: Approved for cattle coccidiosis and respiratory. Strict withdrawal: 5–10 d meat / 60 h milk.

> **Caution:** Horses: TMS (with trimethoprim) is widely used in horses. Plain sulfa less common.

> **Caution:** Birds: Poultry coccidiosis: 0.05% in drinking water × 6 days. Egg withdrawal periods vary by jurisdiction.

## Adverse effects

- Crystalluria (ensure hydration)
- Keratoconjunctivitis sicca / KCS (dogs — may be irreversible)
- Hepatotoxicity
- Haemolytic anaemia, thrombocytopenia, leukopenia
- Polyarthritis / skin eruptions (Dobermans, Rottweilers predisposed)
- Hypothyroidism (chronic use)

## Drug interactions

- Trimethoprim: SYNERGISTIC — sequential block of folate pathway = bactericidal (TMS combinations)
- NSAIDs: increased sulfonamide blood levels (displaced from protein binding)
- Anticonvulsants (phenobarbital, phenytoin): may displace sulfa from binding sites
- Warfarin: potentiates anticoagulation (sulfa displaces from protein binding)
- Methotrexate, methenamine: increased crystalluria risk
- Antacids: reduce sulfa absorption — separate by 2 h
- Sulfonamide cross-allergy: avoid in patients with known sulfa hypersensitivity (KCS, polyarthropathy, skin reactions)

## Pregnancy and lactation

Crosses placenta. Last-trimester use can displace bilirubin from albumin → fetal kernicterus risk. Use with caution and avoid near term. Excreted in milk in low amounts. Generally avoided in pregnant breeding stock when alternatives exist.

## Monitoring

- Schirmer tear test BASELINE + at 1–2 weeks for dogs on TMS — KCS is the most insidious adverse effect
- Urinalysis: check pH, crystals, casts — alkalinise if acidic
- CBC every 2 weeks on prolonged courses — thrombocytopenia, neutropenia
- Thyroid function (T4) — sulfa-induced hypothyroidism on chronic use
- Joint pain / lameness — discontinue immediately if observed (polyarthropathy)
- Withdrawal periods: cattle 5–10 d slaughter / 60 h milk; poultry 10 d
- Adequate hydration to prevent crystalluria

## Toxicity and overdose

KERATOCONJUNCTIVITIS SICCA (KCS) in dogs — dose-dependent and idiosyncratic; can be permanent. POLYARTHROPATHY (immune-mediated) especially in Doberman Pinschers. Hepatotoxicity, hypothyroidism, blood dyscrasia (thrombocytopenia, neutropenia), CRYSTALLURIA in acidic urine → renal tubular damage. Sulfa hypersensitivity — fever, dermatitis, vasculitis, Stevens-Johnson syndrome. Cats: more sensitive — keratoconjunctivitis, neurological signs.

Management: Discontinue. ALKALINISE URINE (sodium bicarbonate 1 mEq/kg IV q4–6h) to prevent crystalluria — target urine pH >7.5. Aggressive IV fluid diuresis. KCS: SCHIRMER TEAR TEST baseline + at 1–2 weeks of therapy; treat with cyclosporine ophthalmic drops + tear replacement, KCS may be permanent. Polyarthropathy: discontinue, NSAID/steroid for inflammation. Anaphylaxis: standard protocol.

## Clinical pearls

- Coccidiosis (calves, lambs, kids, kits, poultry): 55 mg/kg PO day 1, then 27.5 mg/kg PO q24h × 5–14 days
- Coccidiosis (dogs, cats): 55 mg/kg PO day 1, then 27.5 mg/kg PO q24h × 14–21 days
- Rabbits coccidiosis: 50 mg/kg PO q24h × 5 days (one of the few antibiotics safe orally in rabbits)
- Cattle / sheep / goat respiratory: 55 mg/kg PO/IV day 1, then 27.5 mg/kg q24h × 4 days
- Trimethoprim-sulfa combination (TMS, Tribrissen, Septra): synergistic bactericidal for UTI, soft tissue, prostatitis
- NEVER in dehydrated patients — crystalluria → AKI risk
- Schirmer tear test at baseline + 1–2 weeks in dogs — KCS develops insidiously
- AVOID in Doberman Pinschers — polyarthropathy risk
- Strict withdrawal periods in food animals — verify per jurisdiction

## Mechanism of action

Long-acting sulfonamide antibiotic. Competitive inhibitor of para-aminobenzoic acid (PABA) in bacterial folate synthesis — blocks dihydropteroate synthase, preventing dihydrofolate formation. Bacteriostatic. Spectrum: many Gram-positive cocci, Gram-negative aerobes, Eimeria (coccidia — the primary indication in cattle, sheep, poultry, rabbits). Long half-life allows single daily dosing. Combination with trimethoprim (potentiated sulfa) gives synergistic bactericidal activity via sequential block of folate pathway.

## Formulations and products

- Albon oral suspension 50 mg/mL
- Albon tablet 125 mg
- Albon tablet 250 mg
- Albon tablet 500 mg
- Albon injection 400 mg/mL

## Storage

Tablets / boluses: 15–30 °C, dry, protected from light. Oral suspension: 15–25 °C, shake well. Injection: 15–25 °C, protect from light. Some sulfonamides crystallise on cooling — warm before injection.

## 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 antibiotics

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- [Sulfadiazine](https://vetmasterji.com/drugs/sulfadiazine)
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## Frequently asked questions

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

Reference doses for Sulfadimethoxine in dogs: 55 mg/kg PO Day 1 loading (Coccidiosis (label)); 27.5 mg/kg PO q24h for 9 days (up to 14 days) (Coccidiosis maintenance (Day 2+)). Confirm against the label and the patient before use.

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

Reference doses for Sulfadimethoxine in cats: 50–55 mg/kg PO Day 1 loading (Coccidiosis); 25–27.5 mg/kg PO q24h for 10–14 days (Coccidiosis maintenance (Day 2+)). Confirm against the label and the patient before use.

### What is the dose of Sulfadimethoxine for cattle?

Reference doses for Sulfadimethoxine in cattle: 55 mg/kg IV Day 1 loading (BRD / foot rot (label)). Confirm against the label and the patient before use.

### What is the withdrawal period for Sulfadimethoxine?

Cattle, IV (BRD / foot rot (label)): Withdrawal NOT established — treat as extra-label. Follow the product label and national regulations where they differ.

### When should Sulfadimethoxine not be used?

Hypersensitivity to sulfonamides. Severe hepatic/renal impairment. Dehydration. Cats more susceptible to sulfonamide toxicity. Dobermans/Rottweilers predisposed to polyarthropathy. Pregnancy (teratogenic). Not for use with methenamine.

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

Crystalluria (ensure hydration); Keratoconjunctivitis sicca / KCS (dogs — may be irreversible); Hepatotoxicity; Haemolytic anaemia, thrombocytopenia, leukopenia; Polyarthritis / skin eruptions (Dobermans, Rottweilers predisposed); Hypothyroidism (chronic use).

## Sources

- Plumb's Veterinary Drug Handbook
- 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.