An injectable veterinary pharmaceutical composition comprising (a) microspheres comprising about 1% to about 40% w/w, based on the weight of the microspheres, of one or more physiologically active macrocyclic lactone(s), and about 60% to about 99% w/w, based on the weight of the microspheres, of polycaprolactone, and (b) particles of an isoxazoline compound of Formula wherein R 1 = halogen, CF 3, OCF 3, CN, n = integer from 0 to 3, preferably 1, 2 or 3, R 2 = C 1 -C 3 -haloalkyl, preferably CF 3 or CF 2 Cl, T = 5 to 12-membered mono or bicyclic ring system which is optionally substituted by one or more radicals Y, Y = methyl, halomethyl, halogen, CN, NO 2, NH 2 -C=S, or two adjacent radicals Y form together a chain, especially a three or four-membered chain; Q = X-NR 3 R 4 ora 5-membered N-heteroaryl ring which is optionally substituted by one or more radicals; X = CH 2, CH(CH 3), CH, CO, CS, R 3 = hydrogen, methyl, haloethyl, halopropyl, halobutyl, methoxymethyl, methoxyethyl, halomethoxymethyl, ethoxymethyl, haloethoxymethyl, propoxymethyl, ethylaminocarbonylmethyl, ethylaminocarbonylethyl, dimethoxyethyl, propynylaminocarbonylmethyl, N-phenyl-N-methyl-amino, haloethylaminocarbonylmethyl, haloethylaminocarbonylethyl, tetrahydrofuryl, methylaminocarbonylmethyl, (N,N-dimethylamino)-carbonylmethyl, propylaminocarbonylmethyl, cyclopropylaminocarbonylmethyl, propenylaminocarbonylmethyl, haloethylaminocarbonylcyclopropyl, wherein Z A = hydrogen, halogen, cyano, halomethyl (CF 3); R 4 = hydrogen, ethyl, methoxymethyl, halomethoxymethyl, ethoxymethyl, haloethoxymethyl, propoxymethyl, methylcarbonyl, ethylcarbonyl, propylcarbonyl, cyclopropylcarbonyl, methoxycarbonyl, methoxymethylcarbonyl, aminocarbonyl, ethylaminocarbonylmethyl, ethylaminocarbonylethyl, dimethoxyethyl, propynylaminocarbonylmethyl, haloethylaminocarbonylmethyl, cyanomethylaminocarbonylmethyl, or haloethylaminocarbonylethyl; or R 3 and R 4 together form a substituent selected from the group consisting of: and c) an aqueous carrier; wherein the microspheres (a) and the particles of compound (b) are suspended in the aqueous carrier (c). (a) microspheres comprising about 1% to about 40% w/w, based on the weight of the microspheres, of one or more physiologically active macrocyclic lactone(s), and about 60% to about 99% w/w, based on the weight of the microspheres, of polycaprolactone, and (b) particles of an isoxazoline compound of Formula wherein R 1 = halogen, CF 3, OCF 3, CN, n = integer from 0 to 3, preferably 1, 2 or 3, R 2 = C 1 -C 3 -haloalkyl, preferably CF 3 or CF 2 Cl, T = 5 to 12-membered mono or bicyclic ring system which is optionally substituted by one or more radicals Y, Y = methyl, halomethyl, halogen, CN, NO 2, NH 2 -C=S, or two adjacent radicals Y form together a chain, especially a three or four-membered chain; Q = X-NR 3 R 4 ora 5-membered N-heteroaryl ring which is optionally substituted by one or more radicals; X = CH 2, CH(CH 3), CH, CO, CS, R 3 = hydrogen, methyl, haloethyl, halopropyl, halobutyl, methoxymethyl, methoxyethyl, halomethoxymethyl, ethoxymethyl, haloethoxymethyl, propoxymethyl, ethylaminocarbonylmethyl, ethylaminocarbonylethyl, dimethoxyethyl, propynylaminocarbonylmethyl, N-phenyl-N-methyl-amino, haloethylaminocarbonylmethyl, haloethylaminocarbonylethyl, tetrahydrofuryl, methylaminocarbonylmethyl, (N,N-dimethylamino)-carbonylmethyl, propylaminocarbonylmethyl, cyclopropylaminocarbonylmethyl, propenylaminocarbonylmethyl, haloethylaminocarbonylcyclopropyl, wherein Z A = hydrogen, halogen, cyano, halomethyl (CF 3); R 4 = hydrogen, ethyl, methoxymethyl, halomethoxymethyl, ethoxymethyl, haloethoxymethyl, propoxymethyl, methylcarbonyl, ethylcarbonyl, propylcarbonyl, cyclopropylcarbonyl, methoxycarbonyl, methoxymethylcarbonyl, aminocarbonyl, ethylaminocarbonylmethyl, ethylaminocarbonylethyl, dimethoxyethyl, propynylaminocarbonylmethyl, haloethylaminocarbonylmethyl, cyanomethylaminocarbonylmethyl, or haloethylaminocarbonylethyl; or R 3 and R 4 together form a substituent selected from the group consisting of: and c) an aqueous carrier; wherein the microspheres (a) and the particles of compound (b) are suspended in the aqueous carrier (c).