Preventive efficacy of oral moxidectin at various doses and dosage regimens against macrocyclic lactone-resistant heartworm (Dirofilaria immitis) strains in dogs

Table 1 Study 1 design and efficacy of oral moxidectin against Dirofilaria immitis (JYD-34)

Group^a (n = 8)	Treatment^b,c	Dosage (µg/kg)	Days of treatment	No. of dogs with worms	Adult D. immitis worm counts^d
Group^a (n = 8)	Treatment^b,c	Dosage (µg/kg)	Days of treatment	No. of dogs with worms	Individual worm counts	Geometric mean^e	% reduction
T01	Placebo	na	0, 30, 60	8 of 8	29, 32, 33, 35, 36, 39, 43, 43	35.9^g	–
T02^f	Moxidectin	3	0	8 of 8	20, 25, 27, 29, 30, 32, 35, 39	29.1^h	19.0
T03	Moxidectin	6	0	8 of 8	19, 21, 24, 25, 26, 28, 35, 43	26.8^h	25.5
T04	Moxidectin	12	0	8 of 8	17, 20, 20, 23, 23, 26, 33, 35	24.0^h,i	33.3
T05	Moxidectin	24	0	8 of 8	7, 13, 16, 16, 19, 20, 24, 29	16.8ⁱ	53.2
T06^f	Moxidectin	3	0, 30, 60	8 of 8	7, 13, 18, 21, 25, 27, 29, 36	20.0^h,i	44.4

^aAll dogs were inoculated with 50 D. immitis L3 (JYD-34 strain) at Day -30
^bTo maintain masking, dogs in T02, T03, T04 and T05 were administered an empty hydroxypropyl methycellulose (HPMC) capsule on Days 30 and 60
^cMoxidectin administered as HPMC capsules filled with the appropriate amount of hand-pulverized ProHeart^® tablets to deliver the correct dose
^dAll dogs were necropsied for recovery and enumeration of adult heartworms on Day 122 (140 days post-inoculation)
^eMeans with different superscript letters (g–i) are significantly different (2.51 ≤ t_df ≤ 5.28, P ≤ 0.0342, where 4.65 ≤ df ≤ 8.61)
^fConducted as part of this study but first reported in McTier et al. [32]
Abbreviation: na, not applicable

ISSN: 1756-3305