Shortly after moving in, I learned that they had a pet policy that required the pet to be less than 50lbs.

Do you typically have them pay a pet deposit again upon renewal?

Anything from a contractor or agent or some parents use combo boxes for kids or pet sitters

pets ok in the buildings ?

Thanks Rehab and Parrot for your advice.

We allowed 1 pet in the beginning... she brought in 3.

You as an investor ...What interview questions would u ask a real estate agent to determine if you want to work with them  and make part of your team, you want someone that will not be telling you here is nice countertop which is of no value  to u as investor ...... you only want to hear  things of value investors want to hear about on any rental property u are considering and not trivial things like here is a nice SEPEARATE door entry for your pet 😀 

A tenant asked if they could adopt a pet; when I replied with the information regarding deposit and pet rent, I never heard back until I followed up today (3 weeks later), making sure they saw my email, and reminding them that having an unauthorized pet would be a violation of their lease agreement.

They moved early so I've been trying to re-lease and refund them part of their lease if we get a new tenant before year end - just to help with the baby expenses.Also, I don't allow pets - bad experiences with another rental in the past. 

You can get disposable litter boxes to make life easier.General cat care: https://www.aspca.org/pet-care/cat-care/general-cat-careGood Luck!