There is a number of trades that don't exist anymore in our modern world of Europe or Northern America. One of those trades is being a knacker - in Czech pohodný, ras, drnomistr or antoušek, in German Abdecker, Wasenmeister or Kaffiler, in Latin excoriator or canicida. There were many families in Bohemia and Moravia in the past which were in this trade...
"A Dead Horse on a Knacker's Cart", drawing by Thomas Rowlandson (1756–1827).
So, who was a knacker? What did he do for living? Let's use Wikipedia on this one: it is a job title used for the centuries-old trade of persons responsible in a certain district for the removal and clearing of animal carcasses (dead, dying, injured) from private farms or public highways and rendering the collected carcasses into by-products such as fats, tallow (yellow grease), glue, bone meal, bone char, sal ammoniac, soap, bleach and animal feed.
There was a knacker in almost every larger village in our area. You can find knackeries on old maps - usually marked as Abdeckei as the maps were in German. Or pohodnice, if the map was in Czech.
Abdekerei (above) and Pohodnic (under) on maps from 1st half of 19th century.
Research of these families is always complicated - these people were often personally free (independent) men, ie. they weren't serfs of any estate. Even if they were serfs of one family, they moved a lot. Like... A LOT. They were able to move hundreds of kilometers during their lives which was really unusual in our past. Tracing such movement is very complicated and every note about the family counts - for example when they acted as godparents etc.
Interesting thing is many knacker families had German surnames - and there are some surnames which belonged just to knacker families, such as Neuberger, Holler, Eichler, Kolinger, Fierbach, Ubl or Pikl.
Here is an example of Neuberger family. They were originally from Blovice area in Western Bohemia but moved to Blatná and Písek area in Southern Bohemia during 18th and 19th century. It was complicated to trace the family as the places mentioned in the parish records of children and grandchildren weren't the same where the family lived when the children and grandchildren were born.
Places where direct line of one Neuberger family lived.
Life of knackers was complicated - they were living outside of the society as they belonged among the "filthy" people who were contempted by the others. But they were still highly needed as their work was very important for the society. This always caused tension between knackers and other people. That's why knackers didn't marry outside the knacker families, but a knacker almost always married a knacker's daughter. It's also a reason why it was impossible for knackers' children to do some other job until the beginning of 20th century.