Small mammals, especially rodents, are kept as pets by roughly 3% of Australians. Well-known small mammal pets include guinea pigs, mice, and rats. Small and often short-lived, rodents can be seen as low maintenance pets or 'starter pets' for small children. This leads to many rats, mice and guinea pigs being given inappropriate care, including small enclosures, inadequate nutrition and poor handling. 

Common health problems

Rats and mice can easily suffer from heat stress, particularly at temperatures at or exceeding 30°C. Rats and mice will often commonly develop dental disease and overgrown incisor teeth. The teeth of rodents continue to grow, meaning that they require the right diet and things to chew on to maintain their dental health. 

Tumours are another common health issue in rats and mice, a fact which is exploited by the research and pharmaceutical industries who frequently use rodents for experimentation.  Tumours can be either benign or cancerous, however both kinds can impact their health and wellbeing. 

Rats and mice can live for up to five years. Most rats and mice will live between 1.5 - 3 years. 

Breeding

Rats and mice are social animals who would live in colonies in the wild. However, when left in close proximity and in confined spaces, aggression will often occur, particularly between males who have not been desexed. Rats, mice and guinea pigs will often be bought from pet shops, by people who may have little knowledge of the species. This can lead to accidental, unwanted pregnancies, which can lead to pets being abandoned or killed. 

Backyard breeding is unregulated and it is common to see ads for rats and mice on platforms such as Gumtree. Rats, mice and guinea pigs are rapid breeders, meaning that populations can quickly get out of control. In 2025, rescue organisations in Victoria responded to a hoarding case where over 600 mice had been kept in small, wire cages.  

Intelligence

Rats, mice and guinea pigs are animals who are often found abandoned by rescue organisations. Due to their small size, they can be seen as less important or intelligent than larger animals. In reality rodents are extremely intelligent. Studies show that rats may score higher on cognitive tests than humans in some cases. Mice also score highly on intelligence tests, proving an ability to solve complex problems and learn from experience. While guinea pigs are timid and can be fearful, they are also intelligent, with the ability to learn tricks and respond to commands. 

Regardless of their level of intelligence, all of these species are complex individuals with their own personalities and the ability to think and feel. Like all animals, they deserve kindness and compassion.