Prophylactic use of decoquinate for infections with Cryptosporidium parvum in experimentally challenged neonatal calves.
OBJECTIVE
To evaluate the effect of daily oral administration of decoquinate to neonatal calves experimentally challenged with various numbers of Cryptosporidium parvum oocysts.


METHODS
Clinical trial.


METHODS
75 calves.


METHODS
Calves were purchased from a commercial dairy during a 5-week period. Calves were housed in individual hutches and fed milk replacer with or without decoquinate (2 mg/kg [0.9 mg/lb per day]). Calves were randomly assigned to treatment and 1 of 5 challenge groups (0, 50, 100, 1000, or 10,000 C. parvum oocysts in 60 mL of saline [0.9% NaCl] solution administered p.o. on the day after arrival). Calves were maintained in the study for as long as 28 days. Calves were clinically assessed for diarrhea and dehydration. Fecal samples were submitted for oocyst enumeration 3 times each week.


RESULTS
Treatment did not affect number of days to first watery feces (diarrhea), number of days to first oocyst shedding, or duration of diarrhea or oocyst shedding. Duration of oocyst shedding was significantly associated with challenge dose of oocysts administered to calves and number of days to first oocyst shedding. Duration of diarrhea and number of days to first oocyst shedding were significantly associated with week of arrival and number of days to first watery diarrhea.


CONCLUSIONS
Daily treatment with decoquinate at the dosage used in this study did not affect oocyst shedding or clinical signs associated with cryptosporidiosis. However, there was an indication that if the number of oocysts calves received could be reduced, then the duration of oocyst shedding and, hence, environmental loading of C. parvum oocysts could be reduced.
D000284:Administration, Oral; D000818:Animals; D000831:Animals, Newborn; D002417:Cattle; D002418:Cattle Diseases / Q000517:prevention & control*; D003049:Coccidiostats / Q000008:administration & dosage*; D003457:Cryptosporidiosis / Q000517:prevention & control / Q000662:veterinary*; D016785:Cryptosporidium parvum / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D003667:Decoquinate / Q000008:administration & dosage*; D005243:Feces / Q000469:parasitology; D010270:Parasite Egg Count / Q000662:veterinary; D011897:Random Allocation
D003049:Coccidiostats; D003667:Decoquinate