Amprolium
Amprolium is an orally administered anticoccidial that acts as a structural analogue of thiamine, or vitamin B1. It is used to control or treat susceptible coccidial infections in livestock and poultry, with additional extralabel uses in small animals and other selected species.
Its activity depends on coccidial species and stage, and it should not be treated as a general treatment for all protozoal diarrhea. The antagonism of thiamine that gives it anticoccidial activity also explains why excessive or prolonged exposure can cause thiamine deficiency in the host.
Group
Thiamine-antagonist anticoccidial
Mechanism of Action
Amprolium competes with thiamine uptake and utilization in susceptible coccidia. Thiamine is required for enzymes involved in carbohydrate metabolism, so limiting its availability interferes with energy-producing pathways and normal parasite development within intestinal cells.
Its principal effects are associated with early intracellular developmental stages, reducing successful multiplication and subsequent intestinal injury. Sensitivity differs among Eimeria species, explaining why a regimen effective against one coccidium does not establish equal control of every species or mixed infection.
At appropriate exposure the parasite is more sensitive than the host, but that selectivity is incomplete. High or prolonged dosing can also impair host thiamine status. Conversely, excess available thiamine can antagonize the intended anticoccidial effect, reflecting competition at the same nutritional pathway.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Coccidiosis | Reference only | PO | Up to 7 days; Add 1.25 g of 20% powder to daily feed, or 30 mL of 9.6% solution to 3.8 L drinking water for 7 days. These are feed/water regimens, not a universal per-animal absorbed dose. | |
| Small-puppy coccidiosis | 100 mg/animal | PO | Every 24 h | Up to 12 days; Expected adult weight below 10 kg. 7–12 days using 20% powder. The wording does not unambiguously distinguish active-drug mass from powder mass; do not convert until that basis is clarified. |
| Large-puppy coccidiosis | 200 mg/animal | PO | Every 24 h | Up to 12 days; Expected adult weight above 10 kg. 7–12 days using 20% powder. The wording does not unambiguously distinguish active-drug mass from powder mass; do not convert until that basis is clarified. |
| Coccidiosis – powder with food | 250–300 mg/animal | PO | Every 24 h | Up to 12 days; Pups or bitches; listed range is 250–300 mg total daily. 7–12 days using 20% powder. The wording does not unambiguously distinguish active-drug mass from powder mass; do not convert until that basis is clarified. |
| Coccidiosis – lower water inclusion | Reference only | PO | Up to 10 days; 22.5 mL of 9.6% solution per gallon as the only drinking water for no more than 10 days; ensure intake and hydration. A separate course uses 30 mL/gallon for 7–10 days. | |
| Coccidiosis prophylaxis – drinking water | Reference only | PO | 0.075% drinking-water solution; intake determines exposure. | |
| Coccidiosis – sulfadimethoxine combination | 150 mg/kg | PO | Up to 14 days; Combined with sulfadimethoxine 25 mg/kg for 14 days; the canine listing omits route/frequency. Do not infer the complete feline schedule. |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Coccidiosis | Reference only | PO | Up to 7 days; Add 1.25 g of 20% powder to daily feed, or 30 mL of 9.6% solution to 3.8 L drinking water for 7 days. These are feed/water regimens, not a universal per-animal absorbed dose. | |
| Cystoisospora infection | 60–100 mg/animal | PO | Every 24 h | Up to 7 days |
| Coccidiosis – high-dose food course | 300–400 mg/kg | PO | Every 24 h | Up to 5 days; Administer in food; high exposure warrants close neurological monitoring. |
| Coccidiosis – alternative food course | 110–220 mg/kg | PO | Every 24 h | Up to 12 days; 7–12 days in food. |
| Coccidiosis – sulfadimethoxine combination | 150 mg/kg | PO | Every 24 h | Up to 14 days; With sulfadimethoxine 25 mg/kg PO daily; monitor for thiamine-deficiency signs. |
| Coccidiosis – water course | Reference only | PO | Up to 10 days; 7.5 mL of 9.6% solution per gallon drinking water daily for 10 days; actual exposure depends on intake. |
Cattle
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Coccidiosis prevention | 5 mg/kg | PO | Every 24 h | Up to 21 days; Do not use in: Calves intended for veal; Calves; oral/feed administration. |
| Coccidiosis treatment | 10 mg/kg | PO | Every 24 h | Up to 5 days; Do not use in: Calves intended for veal; Calves. |
Ferret
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Coccidiosis | 19 mg/kg | PO | Every 24 h |
Rabbit
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Coccidiosis | 13.7142857143 mg/kg | PO | Every 24 h | Up to 5 days; Converted from 1 mL of 96 mg/mL solution per 7 kg; use exact product concentration. |
| Coccidiosis – water course | Reference only | PO | Up to 10 days; 0.5 mL of 9.6% solution per 500 mL water for 10 days. |
Pigs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Coccidiosis | 25–65 mg/kg | PO | Every 12–24 h | Up to 4 days; 3–4 days. |
| Coccidiosis – feed or water alternative | 100 mg/kg | PO | Every 24 h | Total daily exposure supplied in food or water; ensure actual intake. |
Sheep
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Lamb coccidiosis | 55 mg/kg | PO | Every 24 h | Up to 19 days; Distinct prolonged lamb regimen; monitor neurological signs, as it exceeds the usual short-course duration. |
Camelid
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Eimeria macusaniensis infection | 10 mg/kg | PO | Every 24 h | Up to 5 days |
| Eimeria macusaniensis – prolonged alternative | 10 mg/kg | PO | Every 24 h | Up to 15 days; 10–15 days using 1.5% oral solution. Thiamine 10 mg/kg SC once every 5 days is described during this course. |
Bird
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Coccidiosis – water treatment | Reference only | PO | Up to 5 days; 2 mL of 9.6% solution per gallon water for 5 days or longer; intake-dependent. Steam-clean cages and address reinfection. Resistance has been reported in toucans and mynahs. |
Indications
- Treatment and control of susceptible coccidiosis in calves and cattle, including susceptible Eimeria bovis and Eimeria zuernii infections.
- Coccidiosis in sheep and goats using the relevant species-specific regimen; flock or herd hygiene and exposure control remain necessary to limit reinfection.
- Treatment or prevention of susceptible poultry and other avian coccidiosis, recognizing variable activity among Eimeria species.
- Extralabel coccidiosis treatment in puppies and other supported small-animal settings; feline feed/water treatment has also been described. The presence of diarrhea alone is not sufficient evidence of susceptible coccidiosis.
Contraindications
- Do not administer to debilitated animals.
- Do not use the described cattle product in calves intended for veal.
- Puppy courses should not exceed 12 days unless a distinct specialist protocol is deliberately selected.
Interactions
- High supplemental thiamine can reduce anticoccidial efficacy; toxicity treatment is a separate situation.
Adverse effects
- High doses may produce neurological signs of thiamine deficiency.
- Rare depression, anorexia, diarrhea or neurological disturbance.
Toxicity
Prolonged excessive dosing can cause thiamine-deficiency neurological disease and impaired erythropoiesis. Stop amprolium and give parenteral thiamine; a reported canine treatment amount is 1–10 mg/day IM or IV.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Amprolium 9.6% oral solution | Oral Liquid | 96 mg / mL | PO |
| Amprolium 20% powder | Powder | 200 mg / g | PO |
Monitoring and Administration
Water and feed mixtures depend on actual intake and must not be converted into a guessed mg/kg exposure.
Store tightly closed and protected from light at room temperature. The soluble powder packet size alone does not establish active concentration.
A rodent/chinchilla passage describes parenteral divided daily amounts, but no sterile injectable amprolium preparation is established. Do not inject oral solution or powder; these incomplete injection entries are excluded from calculation.