Five different models for Boar (Spider is the replacer, ported from Metro Last Light), Bloodsucker, Flesh ("male" version, CoC default version coexists), Crow and Rat (ported from Metro 2033). Backup files included for all mutants/animals.
This is the sequence of Mutants Model Pack #1 - Moddb.com
Spider (replaces the boar) - Greshnik13rs
Bloodsucker - 3vtiger
Flesh ("male") - ferr-um
Crow - One_Shot
Rat - Greshnik13rs
There is a preview image inside each of the folders. Copy the "gamedata" folder related to the new models you want in game into CoC dir, overwrite files if asked. If/when you want to revert back to the previous models, apply into CoC dir the "gamedata" located inside the "gamedata_backup" folder of the corresponding mutant.
-If you want to play CoC with the spider and the wolf, from the Wolf Model Pack addon - Moddb.com , please apply after installing the spider, the "gamedata" located inside the "wolf_and_spider_patch".