This seems reasonable. I don't think I owe them an apology for yelling, since they were completely inconsiderate to begin with, but I would apologize just to make things right.
BTW I did look up the laws for the City of Dallas, and there is a 4 cat/dog limit for duplex's (for example: you are allowed no more than 4 dogs, or 2 dogs + 2 cats, 3 cats+ 1 dog, etc)
They are WAY past that limit. They have at least 5 dogs, probably more, and they have a cat, that sleeps in my vegetable garden (which I don't mind too much, because it doesn't disturb my plants and it keeps other pests away)
Good call looking that up.. IF they're unreasonable when you talk to them just say something like "I'd hate to have to get the authorities involved, especially since you have more pets than the city allows in your building". I'm sure they'll be cool about it though.