Damage vs Security Deposit

[Joshua Kaster]

How do you landlords explain the difference between billing for tenant damage mid-lease and security deposit? Are there any laws or statements added to lease to clarify the difference? 

When billing a tenant to repair her ESA's damage to apartment about 2 months into lease, she expected it to come from her security deposit and then be no longer responsible. I was surprised by this interpretation and politley explained that she would be billed in full for all costs to restore apartment to previous condition and the security deposit was different. It is held for when lease ended to make apartment ready after move out and to lessen risks from tenants refusing to pay for rent or damages before legal action is taken. I've been renting for 6 years before landlording and never had this concept challenged. Wanted a sanity check, but couldn't find a satisfying answer online. It's difficult to research because so many articles are written on similar topics.

Backstory: Tenant's ESA dog cause moderate damage to a rented basment apartment in an attempt to escape. Chewed/clawed up trim, entryway door jam, door knob, and a ventless gas fireplace. Luckily it's mostly cosmetic damage and dog has had no serious problem afterwards. She's since paid for all the damage without complaint, but want to sharpend my understanding and potentially next year's lease if needed.