From Dog

Amprolium (1-(4-amino-2-propyl-5-pyrimidinemethyl)-2-methyl-pyridinium chloride hydrochloride) is a coccidiostat used for treatment of coccidiosis in dogs, effective against a small range of protozoa, particularly Eimeria spp and Isospora ohioensis[1].

It is similar in action to other coccidiostats such as toltrazuril.

Amprolium is an analog of thiamine that acts via competitive inhibition or thiamine transporter enzymes intracellularly. It is excreted via the kidneys and should be used with caution in dogs with renal disease[2].

This drug is not effective against Neospora caninum[3] and can cause signs of thiamine deficiency in dogs when used for long periods (for 4 - 6 weeks).

Amprolium normally has a wide safety margin in dogs[4] but neurological disease has been reported, paticularly a chronic degenerative neuropathy characterized by weakness and ataxia[5].

Recommended dose rate in dogs is 60 - 100 mg/kg orally given once daily for 5 days.


  1. Olson ME (1985) Coccidiosis Caused by Isospora ohioensis-like Organisms in Three Dogs. Can Vet J 26(3):112-114
  2. Beyer KH & Gelarden RT (1975) Functional characteristics of the renal tubular secretion of amprolium, a quaternary organic base. J Pharmacol Exp Ther 195(2):194-200
  3. Lindsay DS et al (1994) Examination of the activities of 43 chemotherapeutic agents against Neospora caninum tachyzoites in cultured cells. Am J Vet Res 55(7):976-081
  4. Plumb DC (2002) Appendices. In: Plumb DC ed. Veterinary Drug Handbook, 4th pocket ed. Iowa State Univ Pr. pp:806–807
  5. Hazlett MJ et al (2005) A degenerative encephalomyelopathy in 7 Kuvasz puppies. Can Vet J 46(5):429-432