Abstract: A clock for the attachment of a dog's collar or the like that indicates the passage of time according to the dog's or pet's frame of reference. For example, the rate of passage of time may be such that for each human day of time passage, seven dog or pet days are reflected by the clock's display. Additional data, displays, and information may be carried, manipulated, entered and chosen by the use of user control buttons or the like. A battery may supply power to internal circuitry that drives a display of liquid crystals (LCD). The data carried by the pet chronometer and identification tag may be held in EEPROM such that a power failure does not erase the data. This is particularly useful for any health data or contact information that is incorporated or recorded into the pet chronometer and identification tag.