"mempunyai" means have, Its more suitable with that context rather than "ada" because "ada" means like "there is" . Last but not least, animals are counted by "ekor" - 'tails', so that the classifier "ekor" usually used for animal. Ex: if you have one cat, you can said "seekor kucing" but if you have two cat, you said "dua ekor kucing" I hope it will help you. Have a nice day. Cheers..

seekor means -> "an" or "a" but seekor can only be use for "an animal" like an elephant -> seekor gajah.

"Ada" could be translated into "there is" or "exist". In your case, you need to use "punya" that means "have".