The disclosure relates to topical localized formulation for the treatment or prophylaxis of parasite infestation in animals by spot-on or pour-on administration, which comprises an effective amount of at least one isoxazoline compound of the Formula (I’) and a pharmaceutically or veterinary acceptable liquid carrier vehicle comprising N,N-diethyl-3-methylbenzamide as a solvent wherein the preferred veterinary acceptable liquid carrier further comprises a co-solvent of at least two of acetone, ethyl-L-lactate, dimethyl sulfoxide, dimethylacetamide and glycofurol. The most preferred isoxazoline compound disclosed is 4-[5-(3,5-dichlorophenyl)-5-trifluoromethyl-4,5-dihydroisoxazol-3-yl]-2-methyl-N-[(2,2,2-trifluoroethylcarbamoyl)-methyl]-benzamide.
