Hi Megan. Great question and one we see in similar situations all the time, especially with dogs that have spent their lives on hard floors. From Sadie’s perspective, you’ve suddenly put a soft, absorbent patch of grass-like material in the house. 😊 The fact she’s only doing it at night and is still toileting outside during the day is an important clue. A few thoughts: 1. Make sure the smell is completely gone. Even if you can’t smell it, Sadie almost certainly can. Ordinary carpet cleaners often don’t remove the urine proteins that tell a dog “this is the toilet.” - Use an enzymatic pet urine cleaner (not just a deodoriser). - Saturate the affected area enough to reach as deep as the urine did. - Let it air dry naturally according to the instructions. - Avoid ammonia-based cleaners—they can actually smell like urine to dogs. 2. Remove the temptation for a couple of weeks. If possible, roll the rug up and put it away while you break the habit. Every time she pees there, she’s reinforcing that it’s an acceptable toilet spot. If you can’t remove it: - Block access to that area overnight with a baby gate or furniture. - Or keep her sleeping somewhere she can’t access the rug. 3. Restrict her overnight. Even well-trained adult dogs sometimes benefit from a smaller sleeping area when a new habit develops. If she’s happily crate-trained or sleeps in a smaller room, that can help because dogs are generally reluctant to toilet where they sleep. 4. Consider one last toilet trip later. If 9 pm is quite a while before everyone goes to bed, try another quick “go wees” right before lights out. Some dogs simply need that final opportunity. 5. Rule out a medical issue if it continues. Because this is a sudden change in a dog who has been reliably toilet trained for two years, it’s worth considering a vet check if it persists after you’ve cleaned the rug thoroughly. A urinary tract infection, bladder irritation or increased urine production can sometimes first show up as nighttime accidents.