I have a large room that last summer started having a very strong odor. I had a carpet cleaning company come out and they told us that it was not mold nor was the carpet in any way stained that would cause this odor. All indications were that it was an animal that died and was smelling up the place! I checked our crawl space, our chimneys, our vents, our heater / ac vents, our outside duck work and never found any opening nor smells in any area. Eventually the smell went away, about 2 months later, but now (2-3 months later) the strong smell has returned.
Does anyone have any idea as to what this could be?
Or, does anyone have any suggestions on a professional service that would check this out? (I called animal control but they told me they would do exactly what I had done already).

Please help! Thanks!

Apparently something has crawled up from the bottom of your basement and crawled into the walls and died. Could be a mouse, cat, raccoon, etc. If the previous smell went away after 2 months this is about the time frame it takes for an animal to deteriorate. Investigate under the walls around this room. Some animals are getting into your walls somehow. In the meantime, get a good odor control product and spray it around the room to get rid of the smell until the animal disintergrates completely.

So you are thinking that a 2nd animal crawled in and is now dying, correct? That is the option I found to make sense only, my problem is that I have not (yet) been able to find any opening for animals to get in; but I will check again.
Thanks for your reply, I appreciate it!

Would be great if you all you had to do was remove the baseboard to gain access.

I have a large room that last summer started having a very strong odor. I had a carpet cleaning company come out and they told us that it was not mold nor was the carpet in any way stained that would cause this odor. All indications were that it was an animal that died and was smelling up the place! I checked our crawl space, our chimneys, our vents, our heater / ac vents, our outside duck work and never found any opening nor smells in any area. Eventually the smell went away, about 2 months later, but now (2-3 months later) the strong smell has returned.
Does anyone have any idea as to what this could be?
Or, does anyone have any suggestions on a proffesional service that would check this out? (I called animal control but they told me they would do exactly what I had done already).

Please help!! Thanks!
I'm curious, do you use any kind of poisons for rodent control? Do your neighbors?

I had a shrew in my heating and air conditioning vent this fall somehow get in the sealed vent! In the middle of the night I would hear the scratching of little feet on the metal. This went on until we actually caught the critter in a mousetrap. Apparently there was another shew in the vent also as we then had the repeat scratching nose about a week later. I got rid of him also. Shrews can literally flatten themselves to nothing the way mice do and flatten themselves. Shrews are about half the size of small mice. If you have even the teeniest crack these critters can get in.