Mouse

Is it just me or is the P/S Mouse extremely rare?

In the different zones I found countless of the other available breeds (B/B, S/S, S/B, H/B), including multiple blue ones of each, but I found literally exactly one P/S Mouse (poor quality, in The Exodar).

Finally I gave up and stoned the Poor P/S Mouse, which I —luckily— had kept.

(A P/S Mouse is a Must for every collection, since it’s the only P/S of the whole moveset.)

Although not listed as a location when you read the pet itself, Crystalsong Forest right below Dalaran is great for Mouse as primaries. Around the ruins, particularly. They are usually white skinned (I think because of the flavor of the zone) as primaries, but do sometimes come in brown as primaries as well. Regardless, Crystalsong Forest is a good location due to the very low number of pet TYPES there, and the fact that this will give you a higher level pet.

The location tab says that in the Wetlands this is only found as an added pet to a pet battle.  However, I found one as a primary pet, location (40.5,26.5).

There are very very many of these running around The Exodar.  Specially congragating at the tops of stairs/ramps between levels and in quiet empty areas in most of the "wings" off central gathering places.

Just found a lone, poor-quality Mouse just south of Camp Sungraze in Mulgore. No co-ords since I don't have a mod for them installed right now. Tried to kill it slowly with Onyxian Whelpling but I accidentally two-shot it. Either way, it's proof that they don't only spawn as companions.

I just want to point out, the mouse can be find as a primary pet in Westfall - since location tab for Westfall says it can only be found as a secondary pet. 

These are not only "added pets" in Dustwallow Marsh, I happen to be standing right next to one at this very second. :P

Got a "blue" Level 19 one in Netherstorm - changes colour - summoned a few times and got the white and brown skin.

Got one in mulgore, 52.0 28.8