Amprolium
Amprolium hydrochloride
Also known as: Amprovine · Corid · Coxoid · Coxiprol · Nemapro · Harkers Pigeon Coccidiosis Treatment · Amprolium hydrochloride · Amprocidi
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Coccidiosis (Small Pups < 10 kg adult weight) | 100 mg (total dose) | PO | q24h | 7-12 days | 🌎 NA |
| Coccidiosis (Large Pups > 10 kg adult weight) | 200 mg (total dose) | PO | q24h | 7-12 days | 🌎 NA |
| Coccidiosis (Pups or bitches, in food) | 250-300 mg total dose | PO | q24h | 7-12 days | 🌎 NA |
| Coccidiosis (Pups or bitches, in water) | 30 mL of the 9.6% solution in one gallon of water | PO | ad libitum | 7-10 days | 🌎 NA |
| Prophylaxis | 0.075% solution as drinking water | PO | ad libitum | — | 🌎 NA |
| Coccidiosis (Combination therapy) | 150 mg/kg of amprolium and 25 mg/kg of sulfadimethoxine | PO | q24h | 14 days | 🌎 NA |
| Control of coccidiosis | 1.5 tablespoonsful (22.5 mL) of the 9.6% solution per one gallon of water | PO | ad libitum | Not to exceed 10 days | 🌎 NA |
| Coccidiosis | 200-300 mg/dog | PO | q24h | 7-12 days | 🌍 EU |
| Coccidiosis | 60-100 mg/dog | PO | q24h | 7-12 days | 🌍 EU |
| Coccidiosis | 200 mg/dog | PO | q24h | 7-12 days | 🌍 EU |
- Coccidiosis (Small Pups < 10 kg adult weight): Using the 20% powder in a gelatin capsule
- Coccidiosis (Large Pups > 10 kg adult weight): Using the 20% powder in a gelatin capsule
- Coccidiosis (Pups or bitches, in food): Using the 20% powder on food
- Coccidiosis (Pups or bitches, in water): No other water provided
- Control of coccidiosis: Sole drinking water source. Monitor water consumption; rarely some dogs may not drink due to bitter taste.
- Coccidiosis: Various doses are suggested.
- Coccidiosis: Dose for small puppies.
- Coccidiosis: Dose for larger puppies.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Cystoisospora spp. | 60-100 mg total dose | PO | q24h | 7 days | 🌎 NA |
| Coccidiosis (On food) | 300-400 mg/kg | PO | q24h | 5 days | 🌎 NA |
| Coccidiosis (On food) | 110-220 mg/kg | PO | q24h | 7-12 days | 🌎 NA |
| Coccidiosis (In water) | 1.5 teaspoonsful (7.5 mL) of the 9.6% solution in one gallon of water per day | PO | ad libitum | 10 days | 🌎 NA |
| Coccidiosis (Combination therapy) | 150 mg/kg amprolium with sulfadimethoxine (25 mg/kg) | PO | q24h | 14 days | 🌎 NA |
| Coccidiosis | 60-100 mg/cat | PO | q24h | 7 days | 🌍 EU |
| Coccidiosis | 110-220 mg/kg | PO | q24h | 7-12 days | 🌍 EU |
- Coccidiosis: Administer on food.
Small Mammals
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Coccidiosis (Rabbits) | 1 mL/7 kg BW (using 9.6% solution) | PO | q24h | 5 days | 🌎 NA |
| Coccidiosis (Rabbits, in drinking water) | 0.5 mL/500 mL | PO | ad libitum | 10 days | 🌎 NA |
| Coccidiosis (Gerbils, Mice, Rats, Hamsters) | 10-20 mg/kg total daily dose divided | SC/IM | q8-24h | — | 🌎 NA |
| Coccidiosis (Chinchillas) | 10-15 mg/kg per day divided | SC/IM/IV | q8-24h | — | 🌎 NA |
Ferrets
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Coccidiosis | 19 mg/kg | PO | q24h | — | 🌎 NA |
Birds
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Coccidiosis in pet birds | 2 mL (using the 9.6% solution)/gallon of water | PO | ad libitum | 5 days or longer | 🌎 NA |
- Coccidiosis in pet birds: Cages should be steam cleaned. Supplement diet with B vitamins. Some strains resistant in Toucans and Mynahs.
Cattle
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Coccidiosis Treatment | 10 mg/kg | PO | q24h | 5 days | 🌎 NA |
| Coccidiosis Prophylaxis | 5 mg/kg | PO | q24h | 21 days | 🌎 NA |
Swine
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Coccidiosis Treatment | 25-65 mg/kg | PO | q12-24h | 3-4 days | 🌎 NA |
| Coccidiosis Treatment | 100 mg/kg/day in food or water | PO | q24h | — | 🌎 NA |
Sheep
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Coccidiosis (Lambs) | 55 mg/kg daily | PO | q24h | 19 days | 🌎 NA |
| Eimeria macusaniensis (Camelids - New World) | 10 mg/kg | PO | q24h | 5 days | 🌎 NA |
| Eimeria macusaniensis (Camelids - New World) | 10 mg/kg as a 1.5% solution | PO | q24h | 10-15 days | 🌎 NA |
- Eimeria macusaniensis (Camelids - New World): Dosed for camelids
- Eimeria macusaniensis (Camelids - New World): Give thiamine at 10 mg/kg SC once daily every 5 days during treatment. Dosed for camelids.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Amprolium is a widely used anticoccidial agent, structurally analogous to thiamine (Vitamin B1). While FDA-approved primarily for poultry and cattle to treat and prevent Eimeria infections, it is frequently used off-label in companion animals, small mammals, and exotics to treat coccidiosis (e.g., Cystoisospora spp. in dogs and cats).
Clinical Pearls:
- Because it acts as a thiamine competitive inhibitor, its safety margin is generally wide for short courses, but prolonged use can precipitate thiamine deficiency (polioencephalomalacia in ruminants or neurologic signs in small animals).
- Treatment courses typically should not exceed 12-14 days.
- The liquid formulation is notoriously bitter; when administered via drinking water, patients must be monitored closely to ensure adequate hydration.
Mechanism of action
Amprolium is a thiamine (Vitamin B1) analog. It competitively inhibits the active transport and utilization of thiamine by the parasite.
- Mechanism: Amprolium → blocks thiamine uptake → disrupts carbohydrate metabolism in the parasite (specifically inhibiting thiamine pyrophosphate (TPP)-dependent enzymes) → parasite death.
- It primarily targets the first-generation schizont in the cells of the intestinal wall, preventing differentiation into merozoites. It may also suppress the sexual stages and sporulation of oocysts.
- Because the host's thiamine transport mechanisms have a lower affinity for amprolium than the parasite's, toxicity to the host is minimized during short-term therapy.
Safety & warnings
Contraindications
- Prolonged use (>12-14 days) especially in puppies
- Concurrent high-dose thiamine supplementation (reduces efficacy)
Adverse effects
- Neurologic disturbances (rare, dose-related)
- Depression
- Anorexia
- Diarrhea
- Thiamine deficiency (polioencephalomalacia) with prolonged high doses
Precautions
Not recommended to be used for more than 12 days in puppies. Prolonged high dosages can cause thiamine deficiency in the host. The undiluted liquid or pastes are reportedly unpalatable, which may lead to decreased water or food intake if mixed.
Drug interactions
Exogenously administered thiamine in high doses may reverse or reduce the anticoccidial efficacy of amprolium.
Exogenously administered thiamine may reduce the efficacy of amprolium.
Monitoring
- Clinical efficacy (resolution of diarrhea, negative fecal floats)
- Hydration status (especially if administered in drinking water)
- Neurologic signs (ataxia, depression) indicating potential thiamine deficiency
Overdose
Amprolium has induced polioencephalomalacia (PEM) in sheep when administered at 880 mg/kg PO for 4-6 weeks and at 1 gram/kg for 3-5 weeks. Erythrocyte production also ceased in lambs receiving these high dosages.
In dogs, overdoses of amprolium will produce neurologic clinical signs.
Treatment:
- Discontinue amprolium therapy immediately.
- Administer parenteral thiamine (1-10 mg/day IM or IV).
Available products
Formulations
- 9.6% (96 mg/mL) Oral Solution
- 20% Soluble Powder
- Medicated feeds
Veterinary
- Amprolium 9.6% (96 mg/mL) Oral Solution (Amprovine, Corid)
- Amprolium 20% Soluble Powder (Corid)
- Medicated feeds and feed additives
Regulatory status
Available as AVM-GSL (Authorised Veterinary Medicine - General Sales List) in some regions.
Marketed as AVM-GSL for pigeons; used off-label in dogs and cats.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Unless otherwise instructed by the manufacturer, amprolium products should be stored at room temperature (15-30°C).
Client information
Important: This medication is used to treat coccidia, a common intestinal parasite. It is often mixed into your pet's food or water.
- Taste & Hydration: The liquid form of this medication can be very bitter. If you are instructed to add it to your pet's drinking water, monitor them closely to ensure they are actually drinking it. If they refuse the water, contact your veterinarian immediately to prevent dangerous dehydration.
- Dietary Supplements: Do not give your pet extra Vitamin B supplements (specifically thiamine) while they are on this medication unless explicitly directed by your veterinarian, as it can stop the drug from working.
- Side Effects: Watch for loss of appetite, diarrhea, or unusual neurologic signs (such as stumbling, extreme lethargy, or weakness). Contact your vet if these occur.
- Hygiene: Coccidia is spread through feces. Clean litter boxes, cages, and yards frequently to prevent your pet from reinfecting themselves.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.