How to Find and Remove a Dead Animal inside a House: Unfortunately, there are no magic tricks to finding the body of a dead animal that you can't locate inside your home. It's all about sniffing around until you hit the spot. A wildlife control pro should have no problem in quickly locating the source of the smell and deciding how to best perform extraction. If you don't want to use the services of a professional, you can simply do what they would do. Start smelling around until you're sure you've found the exact spot in which the carcass is.
If you're lucky and the animal died somewhere accessible, then you have your work cut out for you – all you need is a strong stomach. But if you simply can't identify the odor source, knowing a little bit about your drain-waste-vent system will come in handy. Example of possible scenario: you've looked in the attic, and the smell there was almost non-existed. Downstairs the odor is becoming more and more maddening. The carcass is, in fact, in the attic, right above the room or hallway that smells the worst. But why didn't you smell anything when you checked the attic? Well, that's air flow and ventilation for you. Intensity of odor is influenced by even more factors, not just by air flow. High temperature and high humidity will accelerate the decomposition process, and the smell will be more intense. Another annoying thing with dead animals inside the home is the appearance of swarming flies. This could be a plus if the carcass is in an unrestricted space, because you can hear and see where the flies gather, and that will take you right to the dead animal. However, if the animal died in the wall, flies won't help.
Different animals will actually smell different as they rot, and it would be very helpful if you could to be able to identify what animal you're dealing with, because then you'd have a better chance of knowing where to look for it. Size of the animal also matters in terms of smell intensity, and in terms of how much time has to pass for the carcass to decompose completely and for the smell to disappear.
You may find the carcass in the attic, but have no way of reaching it. This means that you will have to remove it by cutting a hole in the celling, and then repairing the hole, of course. Animals sometimes die inside walls, especially rats or mice, but also raccoons, as they can get stuck in there while making their way through in or out of the attic. Animals may also make their nests inside the wall. And if for any reason the animal can't get back to its young one day, the babies will starve to death and start to decompose.
It can be hard for the untrained nose to establish the exact spot of the decomposing animal body, and drilling holes inside the wall willy-nilly is not an option. You might decide to wait out the smell. I do not recommend this. Yes, the smell will slowly disperse and disappear in time, but it might be appetizing for other animals that feed on carcasses, which will probably get stuck in there as well, start decomposing, and you're back where you started. If you at least have identified from within which specific wall the smells comes, you should try and see if you can possibly fish the carcass out from up with a snare pole or something of this nature.
If you are successful in retrieving the odor-producing decomposing animal, you should put it in a bag, and do some research on how it is best to deal with the remains in your specific region. Dead animal removal should be approached with proper protective gear, so make sure you at least wear gloves, but I also recommend a face mask, preferably a HEPA filter mask – when it comes to decomposing corpses, you never know what you could be exposing yourself to, so taking precautionary measures is always a good idea.
Dead wildlife inside the house is a major problem not only because of the obvious reasons discussed above, but also because it means you not only have a dead animal problem, you also have, or at least had, a live animal problem. Once the carcass situation is dealt with, you should start doing a thorough home inspection in order to check for signs of wildlife inhabiting the area. Don't look only for possible access holes the wildlife could use, look also for tracks, as all wildlife leave their marks, and you can easily spot them if you know what it is you're looking for. If you haven't found anything, but you start smelling rotting flesh again at some point, there's really no more use in delaying contact with a wildlife removal expert – you have a nuisance animal problem in your home, and you need to deal with it before it gets worse than it already is.