Development of Experimental Cystoisospora canis Infection Models in Beagle Puppies and Efficacy Evaluation of 5 % Ponazuril (Toltrazuril sulfone) Oral Suspension

Abstract

In a pilot study, three pairs of Beagle puppies were inoculated with 2.5, 3.75 or 5 x 10 4 sporulated oocysts of Cystoisospora canis. All exhibited patent infections within ten days post-inoculation. In an efficacy study, 33 puppies were given 5 x 10 4 oocysts of C. canis and randomly allocated to receive 20, 30, 40, or 50 mg/kg ponazuril on day 0, or 30 mg/kg ponazuril or placebo on days 0 and 7. Clinical health observations and oocyst excretion were monitored daily post treatment. All dosages decreased oocyst counts > 97 % (P < 0.05) by day 4. In an attempt to prolong patency, 42 puppies were inoculated with 1 x 10 4 oocysts on days -10, -8 and -6. Puppies were allocated to receive 30 or 50 mg/kg ponazuril on day 0, or 30 mg/kg ponazuril or placebo on days 0 and 7. All dosages decreased oocyst counts (P < 0.05) by day 2. Analyses indicated that greater oocyst count reduction was achieved by higher dosages of ponazuril and by a second dose on day 7. The frequency of abnormal clinical signs did not differ significantly between treatment groups in either study, and no adverse effects were associated with any dosages of ponazuril.

Experimentally Induced ClinicalCystoisospora canisCoccidiosis in Dogs with Prior Natural PatentCystoisospora ohioensis–like orC. canisInfections

“…Buehl et al (2006) reported that 2 3 10 4 oocysts of C. canis obtained from dogs in Austria were pathogenic for 3-wk-old beagle puppies. Results of the present study support those of Buehl et al (2006), Mitchell et al (2007), and Reinemeyer et al (2007) and confirm that C. canis is a primary pathogen in young dogs.…”

“…Oral inoculation of 5 3 10 4 oocysts of our isolate of C. canis used in the present study from Brazil caused similar clinical signs and prepatent and patent periods in 6-wk-old recipients, as did inoculation of 5 3 10 4 oocysts of an isolate of C. canis obtained from dogs from Virginia Reinemeyer et al, 2007) in 6-wk-old pups. An isolate of C. canis from Illinois was not pathogenic for 6-wk-old pups inoculated with 1 3 10 5 sporulated oocysts (Lepp and Todd, 1974).…”

“…We previously demonstrated that oocysts of C. canis isolated from pitbull puppies from Virginia are pathogenic for young beagle dogs and that this isolate could be used to demonstrate drug effacacy in experimentally infected beagles (Reinemeyer et al, 2007). Unfortunately, this line of C. canis was lost due to a normal decline in infectivity with oocyst age.…”

Sarcocystis sp. encephalomyelitis in a cat

“…To the authors' knowledge there is no published data regarding treatment of S. neurona in cats; ponazuril therapy was initiated given its effectiveness against S. neurona in horses (5–10 mg/kg for 28 days) 31 and its use in dogs and cats for the treatment of other protozoal infections 16,32–34 . The recommended anticoccidial dose in cats is 7.5–15 mg/kg 16 and doses >30 mg/kg and up to 50 mg/kg have been demonstrated to have better efficacy and equal safety margins in a group of research Beagles 34 . Based on these findings, a loading dose of 50 mg/kg was administered for 4 days and the lower dose was administered at discharge.…”