Dog arthritis causing missed toilet spots

An arthritic older dog repeatedly missing the tray edge is one of those situations where the cleaning problem and the underlying mobility problem are completely tangled together — because if the smell isn't fully gone, he'll keep going back to the same spots regardless of how well you manage his positioning. The only products that permanently eliminate pet odours are enzyme-based cleaners; anything else just masks the smell, which means he'll return to those patches again and again. So let me ask: which surfaces are we dealing with — carpet, hard floor, sofa? And are most of these stains fresh or have some had time to set in?

Got it — carpet, large dog, mix of fresh and set-in stains. That combination means you need an enzyme cleaner with a high enough concentration to break down the volume of uric acid a GSD produces, and it needs to penetrate deep into the carpet pile and underlay, because that's where the odour-causing crystals sit. A couple of days is enough for urine to wick down and start crystallising, so you'll need to soak the area properly, not just surface-spray it. Before I give you my recommendation — is he mostly square on the carpet beside the bed, or is he catching the hard floor too?

Perfect, that simplifies things. For this exact situation — high-volume urine, set-in stains, carpet with underlay — I'd go with Simple Solution Extreme Pet Stain and Odour Remover. It's a professional-strength enzyme formula, comes in a large trigger-spray bottle (you can also get it in bigger refill sizes which makes sense for a GSD), and it's specifically designed to penetrate carpet fibres and underlay rather than sitting on the surface. For the set-in patches, saturate the area thoroughly, lay a damp cloth over it, and leave it for 10–15 minutes before blotting — the enzymes need time and moisture to work. Don't use any steam cleaner or heat beforehand on those old stains; heat sets uric acid and makes it permanent. The hard floor edges will be easy — a quick spray and wipe with the same product handles those fine.

Worth knowing: bicarbonate of soda is fine after the enzyme cleaner has fully dried, if you want to use it as a short-term deodoriser between washes. But don't apply it before or during enzyme treatment — it changes the pH of the area and can inhibit the enzymes from working properly. Same goes for vinegar, which some people reach for with pet stains. Vinegar is acidic and will neutralise the enzymatic activity. Stick to the Simple Solution on its own, let it dry fully, and only then use anything else if you feel you need to. For the ongoing situation with his arthritis, it's also worth asking your vet whether a lower-sided tray or a designated pee pad area beside his bed might reduce the miss rate — but the cleaning side, you've got covered.

Good call — the larger size works out much better value for a big dog, and you'll want enough to treat generously rather than ration it. The key thing to remember is saturation and dwell time on those older stains. Once the odour signal is fully gone from those patches, you should find he stops targeting the same spots, which makes the whole situation easier to manage alongside his arthritis.