Veterinary drug · Drug monograph

Ferrous Sulfate: veterinary dose and monograph

Ferrous Sulfate is a veterinary drug. Oral iron for confirmed iron-deficiency anaemia (usually chronic external blood loss) and to support erythropoietin therapy. Indications include iron-deficiency anaemia; iron support during erythropoietin therapy; haematinic (large animals). This monograph lists 6 reference doses for dogs, cats, cattle, horses, sheep and pigs, each with route, frequency and source, plus meat and milk withdrawal periods for food animals.

At a glance

Drug class: Veterinary drug
Also known as: Ferrous sulphate, Oral iron
Species with doses: Dogs, Cats, Cattle, Horses, Sheep and Pigs
Routes: PO
Last reviewed: 1 October 2026

Indications

Iron-deficiency anaemia
Iron support during erythropoietin therapy
Haematinic (large animals)

Ferrous Sulfate 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

Ferrous Sulfate doses for dogs
Indication	Dose	Route	Frequency	Duration
Iron-deficiency anaemia	100–300 mg per dog PO once daily	PO	q24h	—

Iron-deficiency anaemia: Papich 5e and Plumb’s p.519: 100–300 mg per dog per day (with a meal to reduce GI upset — absorption is better apart from food; Harvey).

Cats

Ferrous Sulfate doses for cats
Indication	Dose	Route	Frequency	Duration
Iron-deficiency anaemia / erythropoietin support	50–100 mg per cat PO once daily (5–50 mg; or 10 mg/kg)	PO	q24h	—

Iron-deficiency anaemia / erythropoietin support: Papich 5e: 50–100 mg per cat q24h. Plumb’s p.519: 50–100 mg per cat daily (Macintire; Vaden); 5–50 mg (DiBartola & Chew); 10 mg/kg (Macintire). Many cats do not tolerate oral iron — iron dextran 50 mg IM every 3–4 weeks is an alternative.

Cattle

Ferrous Sulfate doses for cattle
Indication	Dose	Route	Frequency	Duration	Withdrawal
Haematinic	8–15 g per animal PO daily for ≥2 weeks	PO	q24h	—	Withdrawal NOT established — treat as extra-label

Haematinic: Plumb’s p.519 (Adams 1988).

Horses

Ferrous Sulfate doses for horses
Indication	Dose	Route	Frequency	Duration
Haematinic	2–8 g per horse PO daily for ≥2 weeks	PO	q24h	—

Haematinic: Plumb’s p.519 (Adams 1988). True iron deficiency is rare in horses — confirm before supplementing.

Sheep

Ferrous Sulfate doses for sheep
Indication	Dose	Route	Frequency	Duration	Withdrawal
Haematinic	0.5–2 g per sheep PO daily for ≥2 weeks	PO	q24h	—	Withdrawal NOT established — treat as extra-label

Haematinic: Plumb’s p.519 (Adams 1988).

Pigs

Ferrous Sulfate doses for pigs
Indication	Dose	Route	Frequency	Duration	Withdrawal
Haematinic	0.5–2 g per pig PO daily for ≥2 weeks	PO	q24h	—	Withdrawal NOT established — treat as extra-label

Haematinic: Plumb’s p.519 (Adams 1988).

Buffalo

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

Ferrous Sulfate doses for buffalo
Indication	Dose	Route	Frequency	Duration	Withdrawal
Haematinic	8–15 g per animal PO daily for ≥2 weeks	PO	q24h	—	Withdrawal NOT established — treat as extra-label

Haematinic: Plumb’s p.519 (Adams 1988).

Contraindications

Haemolytic anaemia or iron overload; GI ulceration. Do not give with antacids, tetracyclines or fluoroquinolones (chelation).

Adverse effects

GI upset, nausea, dark stools
Constipation

Formulations and products

325 mg tablet (65 mg elemental iron)

Before you use this dose

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.

Frequently asked questions

What is the dose of Ferrous Sulfate for dogs?

Reference doses for Ferrous Sulfate in dogs: 100–300 mg per dog PO once daily PO q24h (Iron-deficiency anaemia). Confirm against the label and the patient before use.

What is the dose of Ferrous Sulfate for cats?

Reference doses for Ferrous Sulfate in cats: 50–100 mg per cat PO once daily (5–50 mg; or 10 mg/kg) PO q24h (Iron-deficiency anaemia / erythropoietin support). Confirm against the label and the patient before use.

What is the dose of Ferrous Sulfate for cattle?

Reference doses for Ferrous Sulfate in cattle: 8–15 g per animal PO daily for ≥2 weeks PO q24h (Haematinic). Confirm against the label and the patient before use.

What is the withdrawal period for Ferrous Sulfate?

Cattle, PO (Haematinic): Withdrawal NOT established — treat as extra-label; Sheep, PO (Haematinic): Withdrawal NOT established — treat as extra-label; Pigs, PO (Haematinic): Withdrawal NOT established — treat as extra-label. Follow the product label and national regulations where they differ.

When should Ferrous Sulfate not be used?