Efficacy of four commercially available heartworm preventive products against the JYD-34 laboratory strain of Dirofilaria immitis

Table 5 Efficacy and summary statistics

Treatment group	N	No. of positive dogs	Geometric mean no. of worms^c	Percent efficacy ^d	Treated vs Non-treated P-value (Z-value)
Ivermectin/ Pyrantel ^a (Group 1)	8	8	13.1	29.0	0.069 (-1.96)
Milbemycin Oxime/ Spinosad^a (Group 2)	8	8	8.8	52.2	0.020 (-2.59)
Selamectin^a (Group 3)	8	8	13.1	28.8	0.046 (-2.18)
Imidacloprid/ Moxidectin^b (Group 4)	8	0	0.0	100.0	0.003 (-3.55)
Non-treated Control (Group 5)	8	8	18.4	NA	NA

^aAdministered as three treatments on SD 0, 31 and 60
^bAdministered once on SD 0
^cNumber of positive dogs/Number of dogs in treatment group × 100
^dGeometric mean number of worms (non-treated)-geometric mean number of worms (treated)/geometric mean number of worms (non-treated) × 100