Is it okay to use horse shampoo and conditioner

Perhaps I'm just being too literal when I read "horse shampoo".  However, if you're talking about the shampoo you buy in a feed store for a horse, I have some second-hand experience with that.

Horses have sensitive skin, so horse shampoo is really gentle.  We used it on our long-haired dog who had skin problems and she looked great after a shampoo and her normally coarse and dry fur felt soft.

Don't know how that translates to humans since hair and fur are different.  And maybe we're talking different products anyway.

I vaguely recall that the Mane 'n' Tail products had lots of PEG's (polyethelene glycols)... even more vaguely recall that they are reputed to help increase the hair's growth rate (but don't take my word for it, it's merely what I only faintly remember).

Regardless, I agree with AmandaPanda -- if it works well for your hair, by all means use it!

Never heard of Cabellina, but if these products work for your hair, then by all means use them.