Thiamine (Vitamin B1): veterinary dose and monograph

At a glance

Drug class

Veterinary drug

Also known as

Thiamine HCl, Vitamin B1, Aneurine, Thiamin

Species with doses

Dogs, Cats, Cattle, Horses, Goats, Sheep, Pigs and Camelids

General dose range

10–20 mg/kg IM q6–12h (polioencephalomalacia) — check the species tables for the indication

Routes

IM, SC, PO

Last reviewed

1 October 2026

Indications

• Polioencephalomalacia / cerebrocortical necrosis (cattle, sheep, goats, camelids)
• Thiamine deficiency in cats and dogs (raw fish, sulfite-preserved or thiaminase diets)
• Adjunct in lead poisoning (ruminants) and ethylene glycol toxicosis
• Prophylaxis during prolonged amprolium treatment (camelids)

Thiamine (Vitamin B1) 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

• Thiamine deficiency: Papich 5e: 12.5–50 mg/dog/day IM or SC; 10–100 mg/dog/day PO. Plumb’s p.1108: 5–50 mg IM, SC or IV (Phillips); 2 mg/kg PO once daily (Davis); 100–250 mg SC twice daily until signs regress (Hoskins); ethylene glycol adjunct 100 mg/day PO.

Cats

• Thiamine deficiency (neurological signs): Plumb’s p.1109: 10–20 mg/kg IM or SC two to three times daily until signs abate, then 10 mg/kg PO daily for 21 days (Morgan); 10–20 mg/kg IM for several days (Abramson); 100–250 mg per cat twice daily. Papich 5e gives lower maintenance doses: 12.5–25 mg per cat per day IM/SC, or 5–30 mg per cat per day PO (max 50 mg).
• Maintenance / hepatic lipidosis support: Papich 5e. Plumb’s p.1109 (Center 2005): hepatic lipidosis with ventroflexion — 100 mg thiamine in 1 L crystalloid with other B vitamins; check potassium, phosphate and magnesium.

Cattle

• Polioencephalomalacia: Plumb’s p.1108: 10 mg/kg IV initially, then 10 mg/kg IM twice daily for 2–3 days — if no improvement in 4 days consider salvage (Dill); 10–20 mg/kg IM or SC three times daily, diluted in isotonic fluid if given IV (Walz); 10 mg/kg up to four times daily, first dose slow IV (Cebra) — severe cases may also need dexamethasone 1–2 mg/kg and mannitol 1 g/kg. Papich 5e (deficiency, per animal): cattle 125–250 mg/day IM. No withdrawal is specified in either reference.
• Lead poisoning (adjunct with Ca-EDTA): Plumb’s p.1108 (Brattan & Kowalczyk 1989): 2 mg/kg IM at the same time as Ca-EDTA, total daily dose 8 mg/kg.

Horses

• Thiamine deficiency: Plumb’s p.1109: 0.5–5 mg/kg IV, IM or PO (Robinson); 100–1000 mg per horse IM, SC or IV by formulation (Phillips). Papich 5e: 125–250 mg per horse per day IM; foals 37.5–65 mg/day. Perinatal asphyxia (foals): 1 g in 1 L fluids IV once daily (Slovis).

Goats

• Polioencephalomalacia: Plumb’s p.1109 (sheep & goats, Dill 1986): 10 mg/kg IV initially, then 10 mg/kg IM twice daily for 2–3 days.

Sheep

• Polioencephalomalacia: Plumb’s p.1109 (sheep & goats, Dill 1986): 10 mg/kg IV initially, then 10 mg/kg IM twice daily for 2–3 days; consider salvage if no improvement within 4 days. Papich 5e: sheep 65–125 mg/day IM, lambs 12.5–25 mg/day IM (deficiency).

Pigs

• Thiamine deficiency: Papich 5e: sheep and pigs 65–125 mg/day IM. Plumb’s p.1109: 5–100 mg IM, SC or IV depending on formulation (Phillips).

Buffalo

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

• Polioencephalomalacia: Plumb’s p.1108: 10 mg/kg IV initially, then 10 mg/kg IM twice daily for 2–3 days — if no improvement in 4 days consider salvage (Dill); 10–20 mg/kg IM or SC three times daily, diluted in isotonic fluid if given IV (Walz); 10 mg/kg up to four times daily, first dose slow IV (Cebra) — severe cases may also need dexamethasone 1–2 mg/kg and mannitol 1 g/kg. Papich 5e (deficiency, per animal): cattle 125–250 mg/day IM. No withdrawal is specified in either reference.
• Lead poisoning (adjunct with Ca-EDTA): Plumb’s p.1108 (Brattan & Kowalczyk 1989): 2 mg/kg IM at the same time as Ca-EDTA, total daily dose 8 mg/kg.

Camelids

• Prophylaxis during amprolium > 5 days: Plumb’s p.1109 (Cebra 2007): 10 mg/kg SC once daily after the 5th day of amprolium treatment for Eimeria macusaniensis.

Contraindications

Known hypersensitivity. Give IV doses slowly and diluted — rapid IV thiamine has caused anaphylactoid reactions and collapse; IM or SC is preferred for repeat doses.

Adverse effects

• Anaphylactoid reactions after rapid IV injection (rare)
• Injection-site pain

Monitoring

• Neurological response within 24–48 h (PEM)
• Serum electrolytes in cats with hepatic lipidosis

Clinical pearls

• Treat suspected PEM immediately — response within hours supports the diagnosis; poor response after 4 days carries a grave prognosis
• B-complex injections do not contain enough thiamine for PEM
• Cats fed raw fish or sulfite-preserved food present with ventroflexion, mydriasis and seizures — thiamine responsive

Formulations and products

• Thiamine HCl injection 100 mg/mL
• Thiamine HCl tablet 100 mg

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.

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• Tranexamic Acid
• Trilostane

Frequently asked questions