Billing tenant for damages prior to move-out

[Michael Braun]

Hey all, first time landlord with ~3 months experience here.

I brought a tenant in 3 months ago with an insurance company paying the rent (tenant's house is being repaired after a fire). For this post, the long story short is that no cats were on the application but lo and behold, there are 4 cats in the house during my first inspection. Along with a kiddy-pool sized litterbox in one corner of a room, cat urine and feces in the OTHER corner of the room on the carpet (newly installed by the seller when I bought), and a smell that made my eyes water walking in the front door.

The lease has a clause for Tenant-Caused Damages resulting from tenant negligence. We also received a $2400 security deposit. I don't want to wait to fix this, because the urine could seep into the subfloor and legally speaking I need to mitigate my damages. So instead of waiting for the problem to compound until the lease is over, the plan is to replace the carpet immediately rather than try to muck with cat urine and get it 80% clean with various other solutions. I intend on sending the tenant a bill for the exact repair cost as "additional rent" (per the lease) instead of evicting in the winter and deducting from the security deposit. This would be from the same carpet company I used when I fixed up the house, so not trying to gouge them or anything.

I'm looking for some guidance in this situation, pitfalls I could run into, or just straight up illegality. I'm confident a judge would see the picture evidence I have and go "damn!", but I don't want to unknowingly do something against landlord-tenant law (Baltimore City, Maryland) to make the judge say "damn!" even louder. I can't find any law about tenant-responsible repair costs during occupancy, only situations on withholding from the security deposit after move-out. Any and all advice is welcome and appreciated!