Older cat attacking younger cat due to smell?

I am hoping someone can help me. I have 7 indoor cats. Three from one litter who are around 9 years and 4 from another litter who are about 1-2 years. For the most part they all get along great, but the older male has a huge problem with one of the younger females and it has always been this way.

He goes after her and can't seem to even stand the smell of her. For example I was petting her tonight and he came sniffing around. He came up to smell her and as soon as he did he attacked her. None of the other cats have a problem with her and he really doesn't even have a problem with any other cats. He tended not to like it when I was fostering or when one of my TNR cats run in but he only hisses and never full out attacks like this.

She is a heavy cat who doesn't clean herself well so I don't know if it is that possibly or if she has something else that the vet didn't find in the past.

I figure I will take her to the vet if I need to get a full work up to see if something is off but I hate to spend the money on potentially nothing if I can help it.

Yes, smell can cause the behavior you described. It is normal for the alpha cat (this case, your older boy) to handle what I call the "misfit" in the group. Even after the visit to the vet, you may try investing on a Feliway difuser.

Originally Posted by brennok

She is a heavy cat who doesn't clean herself well

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Maybe you should put her on a diet? It'd be like solving two problems with one stone!

Originally Posted by howtoholdacat

Maybe you should put her on a diet? It'd be like solving two problems with one stone!

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I have been trying but with 7 cats it is tough to monitor food especially since I am gone 10-12 hours a day.

If they were spayed or nutered, It might help.

All of them are fixed and have been for a while. In fact the one didn't start putting on the weight until after she was fixed.