Comparative preventive efficacy of ProHeart® 12, Heartgard® Plus and Interceptor® Plus against a macrocyclic lactone-resistant strain (JYD-34) of heartworm (Dirofilaria immitis) in dogs

Table 3 Study 1: Efficacy of ProHeart 12 compared to Heartgard^® Plus or Interceptor^® Plus against the JYD-34 heartworm strain: Day −30 inoculation, adult heartworm AG and MF results

Treatment	Dosage	Days of treatment	Number of infected dogs^{a, b}	No. dogs positive for adult heartworm AG^c		No. dogs positive for MF
Treatment	Dosage	Days of treatment	Number of infected dogs^{a, b}	Day 151 (181 days PI)	Day 178 (208 days PI)	Day 151 (181 days PI)	Day 178 (208 days PI)
Negative control	NA	0	6 of 6	6 of 6	6 of 6	4 of 6	6 of 6
ProHeart 12	0.5 mg/kg moxidectin^d	0	0 of 5	0 of 5	0 of 5	0 of 5	0 of 5
Heartgard Plus	Min. of 6 µg/kg ivermectin^e	0, 30, 60, 90, 120, 150	6 of 6	5 of 6^f	6 of 6^g	5 of 6	6 of 6
Interceptor Plus	Min. of 0.5 mg/kg milbemycin oxime^h	0, 30, 60, 90, 120, 150	6 of 6	6 of 6	6 of 6	6 of 6	6 of 6

^aEach dog was inoculated with 50 D. immitis third-stage larvae (JYD-34 strain) on day −30
^bAll dogs were necropsied for recovery of adult D. immitis on day 185 (215 days PI; 35 days after the last treatment with Heartgard^® Plus and Interceptor^® Plus)
^cDiroCHEK
^dProHeart 12 (moxidectin extended-release injectable suspension) administered according to commercial label directions which resulted in a point administration of 0.5 mg/kg of moxidectin to each dog. One dog in the ProHeart 12 group was euthanized on day 90 due to an abnormal health event unrelated to drug treatment
^eHeartgard Plus (ivermectin + pyrantel) administered according to commercial label directions which resulted in administration of from 6.6 to 11.2 µg/kg of ivermectin
^fTwo of six dogs positive only after heat treatment; positive on both DiroCHEK and Snap4DX Plus
^gTwo of six dogs positive only after heat treatment; positive on both DiroCHEK and Snap4DX Plus
^hInterceptor Plus (milbemycin oxime + praziquantel) administered according to commercial label directions which resulted in administration of from 0.52 to 1.0 mg/kg milbemycin oxime

ISSN: 1756-3305