At a boarding house, a vicious dog gets loose from his chain and chews up a tenant's ass that was teasing him with a piece of raw meat. As a result, the dog is shot to death. Another tenant, a very high strung book editor, is picked on a lot. Soon he starts having dreams that the dog has returned and dead chewed up tenants begin popping up everywhere.
Practical Effects
Jerry's dog puppet nightmare fuel on approximately $12
Production
Robert A. Burns' only directorial feature, tragically

Director
Robert A. Burns
Trivia, insights & behind the scenes
Robert A. Burns was the legendary production designer on Texas Chainsaw Massacre and The Hills Have Eyes; Mongrel was his attempt to direct, shot in Austin with local theater actors and apparently sheer desperation.
The dog was played by multiple dogs, a puppet, and occasionally just a sound effect and someone's imagination. The budget was reportedly under $100,000, most of which clearly went to Aldo Ray's three scenes.