Carruthers: Concur.

If I'd been licked my a giraffe ('70s childhood) I would have scrubbed myself until my skin nearly came off. Eurgh! Gross!
Although to be fair it would more likely be Mum cleaning me up with spit and a tissue, which was equally squirmy because that was for babies.

Licked by a tiger cub however, I'd be with Packham all the way.

I think you've hit the nail on the head there Dani. It's common knowledge that overcrowding, be it animal or human, brings with it the danger of all manner of infections. Unfortunately, what you or I call overcrowding, the agricultural fraternity calls 'intensive farming' and the whole thing descends into a pharmaceutical arms race.
The only people to benefit, and the livestock certainly doesn't, are the likes of Bayer, Roche, Pfizer et al.