With no magnification at 100 yards, it can be difficult sometimes to differentiate between deer and hogs with even higher resolution thermal scopes if the deer has its head down and is feeding. Often what is used to help make identifications is the assessment of movement. The two animals often behave and move in different ways that will help with identification, but the key trait that stands out is the neck. You look for a long neck sticking out from the body. At 100 yards with my FLIR PS-32 (320x240 resolution), it can take some study before making a determination of identification, especially if the animal doesn't present a nice profile. Head/tail-on or quartered can make ID difficult and so with the lower res of the MX-1, you will have an even tougher time.
So you have detection (when you see a heat signature but don't know what it is), recognition (when it looks like a deer/hog/calf/large dog), and identification (when you can specifically tell what animal it is).
So you might get recognition at 150 yards on a deer/hog in profile, but not get actual identification beyond maybe 60-70 yards. The distances will likely be much less if the animal isn't in good profile.
At 100 yards, raccoons, opossums, and armadillos are just small blobs in my FLIR. In the MX-1, you would probably just see heat signature spots.
The cool thing about thermal scopes is their ability to detect and this is how a lot of us use such scopes for spotting. If we see a heat signature that looks about right, we then go to NV to make an identification.