Fig. 2
Cats positive for heartworm antibody were significantly older than the heartworm antibody-negative cats (mean ± standard deviation: 5.32 ± 4.37 vs 4.29 ± 3.63; χ2 test, P = 0.018). In addition, Dirofilaria immitis antibody-positivity was found in 31 of 1049 female cats and 46/1114 male cats (χ2 test, P = 0.074) (data not shown)