Quoting from the Hogwarts letter Harry receives in the first HP book:
students may bring an owl OR a cat OR a toad.
The word "may" suggests that students can also choose not to bring a pet/familiar at all, or to bring one that's not an owl, cat, or toad. Hermione and Scabbers, in the first two books, show that both of these conclusions are indeed the case.
What about the word "OR"? Grammatically this suggests that students may not bring more than one familiar (or if you want to be pedantic, not more than one of the three specified: it doesn't say anything about bringing both an owl and a rat). Is there such a rule at Hogwarts?
- Does Hogwarts allow students to bring more than one pet?
If there's no canon answer to that question, then
- Do we know of any instances of a student bringing more than one pet?