There was also lots of mold, and the house smelled of urine.

I keep imagining that the cabinets will be chewed or the carpet will wreak of urine.

I'm assuming it's urine and you're probably gonna have to tear something out, clean the area, and replace it.

The previous owner had cats and there is a strong urine odor coming through the floors by the kitchen.

Many hours and costs to mitigate for urine in basement concrete floor.

The deferred maintenance was significant- 3/4 of the roof needed replaced, the hallways were incredibly dirty, 3 vacant units that needed complete rehab, residents had anything from holes in their ceiling to faucets shut off because they were leaking so badly, landscaping overgrown and/or dead, and the entire building smelled like cigarettes and urine.

The roof was leaking, the entire building smelled like cigarettes and urine, residents' maintenance requests were ignored, 3 units were vacant, and residents weren't always paying rent.

It could have a pet urine odor, mold or musty smell. 

We used Killz to paint the floor under the carpet after a tenant snuck a dog in that urinated everywhere and it seemed to help.

While we do have in our contract that 1 pet under 25 lbs is allowed, we are concerned about cats on our property, as when they urinate in hidden corners, it may not be visible right away but could stink up the house later, requiring extensive restorations.