Cybershades were a animal version of the Cybermen. They served the Cybermen and Miss Hartiga.
When Davros and the Daleks attempted to launch the reality bomb, the void was weakened and Cybermen who had been sucked into the void along with millions of Daleks after the battle of Canary worf and some Cybermen escaped into 1851 era Britain in the city of London.
The Cybermen needed new footsoldiers and slaves, using the brains of dogs and cats they created rug like creatures which could run on all fours and had a bronze Cyber like head. At least sixteen Cybershades were created.
They were incredibly fast and agile. Being able to jump 5 metres off the ground and could overpower two grown men. However as they had the brains of animals they could not speak and only abey simple commands.
When the Cybermen made contact with Miss Hartigan, the Cybershades were placed under her command. One was assigned to drive her buggy. At least one Cybershade was being hunted by "The Doctor", but it always evaded him. When Miss Hartigan became the Cyber King and took control of a the Cybermen and entered a large, mobile Cyber factory, at least two Cybershades accompanied her. When the Tenth Doctor gave her back her emotions, the Cybershades exploded along with her and the Cybermen.
As only two were present, it could be assumed the others survived although they would of most likely died when the Cybermen were killed.