I like that , is that something we can buy?

What you are showing there is a common cyst that beavers will get. No biggie. The other pockets of pus they get are usually instigated by a small puncture wound of some type and bacteria form.

The smell of the castor probably has to do with their diet. Not much you can do about it.

Back in the mountain man era an expedition lead by Pete Skene Ogden ran into a population of beaver on a tributary of the Snake river (Malade river) that was eating poison hemlock roots. All the trappers that ate beaver flesh in the camp got deathly ill.

Your beaver are a very light color compared to mine in NY.
Mine are a very dark brown. Would love it if you could show the whole beaver pelt. Thanks

Only time I had funky smelling castors I was on top of a hill at a pond. No other water for a mile around and they were eating hemlock. That was some strange smelling castor but not rotten