(Covers information from Anderson's universe)
"Let 'em loose!"
Research into Cerberuses took place prior to the global T-virus pandemic, either to observe the virus' effects on canines or as bio-weapons research. Several doberman test-subjects were inadvertently infected with an airborne strain in The Hive and escaped their cages. They were killed by Alice, who had entered the facility with Umbrella's Sanitation Team to investigate loss of contact. The following day, the T-virus escaped into Raccoon City itself, and the city's canines were infected. A police K9 unit escaped from their van which had crashed outside a school and made it their hunting ground. UBCS mercenary Nicholai Ginovaef was killed by the Cerberuses. The K9 unit Cerberuses were ultimately killed from a gas explosion in the school's cafeteria kitchen after Jill Valentine turned on the cooking ranges before fleeing the creatures with Angela Ashford. Alice then igniting the fumes with her cigarette after Jill's matches failed to work.
During the global T-virus pandemic, a group of about six Cerberuses were kept caged in the sub-level of a building by a family of murderers, kept for the sole purpose of finishing off victims as they watch. These Cerberuses had cataract eyes and were missing almost all of their skin, revealing bone and irritated red flesh that covered their body. When released upon Alice, she killed three of them before devising a plan. She then began to trap the remaining Cerberuses in thick electrical wires around a support beam, causing it to break loose and cause a partial collapse to the floor above. Alice climbed the debris as a means of escape, leading the Cerberus up to the family as bait, allowing the creatures to kill them as she reclaimed her weapons, leaving them to feed.
Albert Wesker was known to keep a pair of Cerberuses with him aboard the Arcadia as personal pets. These specimens were shown to have further evolved from T-Virus mutation, in a similar fashion as the Undead. They had the ability to split open their heads, revealing large, toothed maws and a bulbous inner mouth they would use for attack. They were killed by Alice with her coin-loaded shotgun, using it to kill one directly and the other with a large panel of shattered glass that fell from the ricochet.
A large pack of Cerberuses were also used by Umbrella to guard the secret entrance to the Hive, located in the massive crater that used to be Raccoon City. These Cerberuses lacked the aforementioned ability to split open their heads like Albert Wesker's dogs had. Instead, their bottom jaws could dislocate, revealing large webbed mandibles and multiple rows of teeth, with some of them even sporting multiple pairs of eyes. They were also notably suffering from mass necrosis, as most of their skeleton could be seen through rotted flesh. They have an inability to swim due to their decomposed state, as when submerged, the Cerberuses would harmlessly sink to the bottom of a large body of water. The Red Queen was able to input commands to these Cerberuses in a similar fashion to the Nemesis' programmable nature, implying some form of cybernetic augmentation.
The Cerberus would later be eradicated, alongside every other T-Virus mutant, following the release of the Anti-Virus into the air.
Cerberuses are created through exposing dobermans with T-Virus, which dramatically enhanced their strength and fighting instincts that they become fearless and undeterred by loud noises such as gunshots. In fact, mutation that altered these dogs' very being enable them to combat formidable targets such as armed humans with greater ferocity than their uninfected counterparts. These mutated dogs also retain their ability to follow basic orders, enable Umbrella personnel to control them. Despite these enhancements, their body visibly suffer necrosis as the side effect of the virus exposure just like the Undead, but it doesn't deter them in any way.
Following Global T-Virus pandemic, two more variants of Cerberuses are introduced: The first variant, which outwardly resembling their regular counterparts, possess the ability to split open their heads, revealing large, toothed maws and a bulbous inner mouth they would use for attack. This variant arguably came to existence as result of same wild mutation that gave birth to Majini Undead, but whether Umbrella managed to recreate their mutation like the latter is not fully explored, let alone whether Wesker's two cerberuses were result from such attempt (if any). The second new variant, which Alice and her companions encountered around the secret entrance to the Hive, have underwent extensive modifications and even more severe necrosis that they barely resemble the rest of known Cerberus variants. The most visible alterations includes the presence of webbed mandibles which revealed through dislocating the lower jaw, multiple rows of sharp teeth, multiple eyes, and slight cybernetic modification which allow the Red Queen to directly command them.
- One of the acting dogs in the first film, "Jasmine", re-appeared for Apocalypse.
- They are referred to as "Zombie Dog" in the film novelizations, likely due to their lack of an official name until its mention in The Final Chapter.
- The Cerberuses that appear in Resident Evil: Afterlife mutate in a similar fashion as the Adjule from Resident Evil 5.