# Thiamine (Vitamin B1): veterinary dose and monograph

> Thiamine (Vitamin B1) is a veterinary drug. Water-soluble B vitamin (cofactor for pyruvate and α-ketoglutarate dehydrogenase and transketolase). Indications include 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. This monograph lists 10 reference doses for dogs, cats, cattle, horses, goats and sheep and 2 more species, each with route, frequency and source, plus meat and milk withdrawal periods for food animals.

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

## 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 (Vitamin B1) doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Thiamine deficiency | 12.5–50 mg per dog IM or SC daily (or 10–100 mg PO daily) | IM | q24h | — |

- 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 (Vitamin B1) doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Thiamine deficiency (neurological signs) | 10–20 mg/kg | IM | q8–12h until signs abate, then 10 mg/kg PO q24h for 21 days | — |
| Maintenance / hepatic lipidosis support | 5–30 mg per cat PO daily (max 50 mg), or 12.5–25 mg IM/SC daily | PO | q24h | — |

- 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

*Thiamine (Vitamin B1) doses for cattle*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Polioencephalomalacia | 10–20 mg/kg | IM | q6–12h (first dose slow IV, diluted) | 2–3 days or until signs resolve | Withdrawal NOT established — treat as extra-label |
| Lead poisoning (adjunct with Ca-EDTA) | 2 mg/kg | IM | q6h (8 mg/kg/day) alongside Ca-EDTA | — | Withdrawal NOT established — treat as extra-label |

- 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 (Vitamin B1) doses for horses*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Thiamine deficiency | 0.5–5 mg/kg | IM | q24h | — |

- 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

*Thiamine (Vitamin B1) doses for goats*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Polioencephalomalacia | 10 mg/kg | IM | first dose IV, then IM q12h | 2–3 days | Withdrawal NOT established — treat as extra-label |

- 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

*Thiamine (Vitamin B1) doses for sheep*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Polioencephalomalacia | 10 mg/kg | IM | first dose IV, then IM q12h | 2–3 days | Withdrawal NOT established — treat as extra-label |

- 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 (Vitamin B1) doses for pigs*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Thiamine deficiency | 65–125 mg per pig IM daily (5–100 mg by size) | IM | q24h | — | Withdrawal NOT established — treat as extra-label |

- 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.

*Thiamine (Vitamin B1) doses for buffalo*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Polioencephalomalacia | 10–20 mg/kg | IM | q6–12h (first dose slow IV, diluted) | 2–3 days or until signs resolve | Withdrawal NOT established — treat as extra-label |
| Lead poisoning (adjunct with Ca-EDTA) | 2 mg/kg | IM | q6h (8 mg/kg/day) alongside Ca-EDTA | — | Withdrawal NOT established — treat as extra-label |

- 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

*Thiamine (Vitamin B1) doses for camelids*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Prophylaxis during amprolium > 5 days | 10 mg/kg | SC | q24h from day 5 of amprolium | — |

- 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

> **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.

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## Frequently asked questions

### What is the dose of Thiamine (Vitamin B1) for dogs?

Reference doses for Thiamine (Vitamin B1) in dogs: 12.5–50 mg per dog IM or SC daily (or 10–100 mg PO daily) IM q24h (Thiamine deficiency). Confirm against the label and the patient before use.

### What is the dose of Thiamine (Vitamin B1) for cats?

Reference doses for Thiamine (Vitamin B1) in cats: 10–20 mg/kg IM q8–12h until signs abate, then 10 mg/kg PO q24h for 21 days (Thiamine deficiency (neurological signs)); 5–30 mg per cat PO daily (max 50 mg), or 12.5–25 mg IM/SC daily PO q24h (Maintenance / hepatic lipidosis support). Confirm against the label and the patient before use.

### What is the dose of Thiamine (Vitamin B1) for cattle?

Reference doses for Thiamine (Vitamin B1) in cattle: 10–20 mg/kg IM q6–12h (first dose slow IV, diluted) for 2–3 days or until signs resolve (Polioencephalomalacia); 2 mg/kg IM q6h (8 mg/kg/day) alongside Ca-EDTA (Lead poisoning (adjunct with Ca-EDTA)). Confirm against the label and the patient before use.

### What is the withdrawal period for Thiamine (Vitamin B1)?

Cattle, IM (Polioencephalomalacia): Withdrawal NOT established — treat as extra-label; Cattle, IM (Lead poisoning (adjunct with Ca-EDTA)): Withdrawal NOT established — treat as extra-label; Goats, IM (Polioencephalomalacia): Withdrawal NOT established — treat as extra-label; Sheep, IM (Polioencephalomalacia): Withdrawal NOT established — treat as extra-label; Pigs, IM (Thiamine deficiency): Withdrawal NOT established — treat as extra-label. Follow the product label and national regulations where they differ.

### When should Thiamine (Vitamin B1) not be used?

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.

### What are the side effects of Thiamine (Vitamin B1) in animals?

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

## Sources

- Plumb's Veterinary Drug Handbook
- Papich 5e — Thiamine Hydrochloride
- 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.