I would not worry about a cat peeing on the plant.
However, some cats do enjoy eating the plant.
More than a few times I had a cat of mine top a plant and also attempt to eat the entire plant.
Some cats love marijuana plants. It has already been pointed out that it is best to keep them out of the grow area.
Watch the cats, they are very fast and it does not take them long to get into an area that they want to be in.
Interesting to note there is a strain of marijuana called "Cat piss"