I think there is, but exactly how many that is depends on how much time and space you have to give to pigs. If you haven't got enough time to not only clean feed and water them, but to spend time with them every day and notice when there are any changes in their daily behaviour or feeding, then you have too many. Too many people have loads stacked up in cages/ hutches, and all they have time to do is take care of their basic needs.
The exception is of course rescues, who take pigs from bad situations with a view to finding them a lovely new home. They often have more than a person would have as pets, but their reasons for doing so are completely different.
But I don't understand people who have dozens of pigs as pets, and are happy with just taking very basic care of them and having the odd time where they'll give out cuddles etc. To me having pigs is about making them part of my home and life, and enjoying interacting with them and seeing them respond to the time and attention they get.
The most I've had is six, and I think four would be my limit at the moment.
