A pet rat usually lives about 2 to 3 years, and a few reach 4 or more.1PubMed. The ancient rat Wild rats are a different story: most last only months, because predators, poison, disease and hard conditions get to them long before old age does.2Wildlife Research. Uncovering the secret lives of sewer rats (Rattus norvegicus): movements, distribution and population dynamics revealed by a capture – mark – recapture study
How Long Pet Rats Live
The average pet rat lives about 2.5 to 3 years.3PubMed. The ancient rat Some pet rats have been reported to reach 4 years or longer.4PubMed. The ancient rat Well-kept laboratory rats, which live in similar protected conditions, average about 3 years and range from 2.5 to 3.5.5PubMed Central. The laboratory rat: Age and body weight matter Lab rats are kept clean, fed a set diet and checked often, so they are a fair guide to a well-kept pet but not an exact match for your home.
Losing a rat at around two years is within the normal range and not a sign of failed care. Buying from a breeder who tracks health and longevity in their lines can tilt the odds a little in your favor.
Females tend to outlive males. In one common breed of rat, females lived about 2.2 to 3.7 years and males about 1.7 to 3.2 years.6PubMed Central. The laboratory rat: Age and body weight matter About half of the males in that breed had died by around age 2, and half of the females by around age 2 to 2.3.7PubMed Central. The laboratory rat: Age and body weight matter Different breeds and family lines also show noticeably different survival patterns even when kept the same way.8PubMed Central. Within- and between-strain variability in longevity of inbred and outbred rats under the same environmental conditions
Rats age fast compared with dogs or cats. A rat reaches adulthood within a few months of birth, and middle age arrives within its first year, often by six to twelve months. Owners often notice slowing down and weight changes in the second year.
Why Wild Rats Rarely Live Past A Year
Sewer rats tracked over time were typically present for only about 4 months.9Wildlife Research. Uncovering the secret lives of sewer rats (Rattus norvegicus): movements, distribution and population dynamics revealed by a capture – mark – recapture study A few individuals lasted up to 22 months.10Wildlife Research. Uncovering the secret lives of sewer rats (Rattus norvegicus): movements, distribution and population dynamics revealed by a capture – mark – recapture study
Researchers can’t ask a wild rat’s age, so they mark or track animals and see how long each one stays in the study area. A rat that disappears from a tracked site may have died, but it may also have moved away, so “present for 4 months” measures staying more than dying.
Predators and disasters take a large toll. In wild cotton rats, a different species that faces similar threats, survival was higher where mammal predators like foxes and raccoons were kept out.11The Journal of Wildlife Management. Effects of mesopredators and prescribed fire on hispid cotton rat survival and cause‐specific mortality After a field fire, half of 36 tracked rats were eaten by predators within a month and 5 died in the fire itself.12The Journal of Wildlife Management. Effects of mesopredators and prescribed fire on hispid cotton rat survival and cause‐specific mortality Losing cover to fire exposed the rats to hawks and owls almost at once.13The Journal of Wildlife Management. Effects of mesopredators and prescribed fire on hispid cotton rat survival and cause‐specific mortality
City rats face other dangers. Rat numbers vary sharply from one block to the next depending on food and shelter.14PubMed Central. The Characteristics of Wild Rat Populations from an Inner-City Neighborhood with a Focus on Factors Critical to the Understanding of Rat-Associated Zoonoses Pest control visits and rat poison leave surviving urban rats in poorer body condition.15PubMed Central. Demographic drivers of Norway rat populations from urban slums in Brazil
Illness adds to the toll. Most wild city rats examined had inflamed airways, and respiratory disease may be a major cause of wild rat illness and death.16PubMed. Respiratory Pathology and Pathogens in Wild Urban Rats (Rattus norvegicus and Rattus rattus)
Pet rats belong to the same species as the brown rats in sewers, and their bodies have about the same potential lifespan. The difference is what kills them first. A pet has steady food, warmth and no predators, so it can die of old age.
What Pet Rats Usually Die Of
Respiratory disease and tumours are the most common illnesses in pet rats.17FOUR PAWS International. Pet rats – their most common diseases Nose inflammation and mammary (breast) tumours were among the most frequent diagnoses in pet rats seen by vets.18PubMed. Morbidity and disease management in pet rats: a study of 375 cases A poor living environment raised the chance of respiratory disease.19PubMed. Morbidity and disease management in pet rats: a study of 375 cases The airway germs behind it, including mycoplasma, are very widespread in rats.20PubMed. Respiratory Pathology and Pathogens in Wild Urban Rats (Rattus norvegicus and Rattus rattus) Many pet rats carry the germ without symptoms; illness tends to appear when stress, a dirty environment or another infection tips the balance.
Early signs include sneezing, a rattling or clicking sound when breathing, and reddish-brown staining around the eyes and nose. Occasional sneezing can be harmless, but sneezing that continues for days, or any labored breathing, calls for a vet visit. Flare-ups can turn into pneumonia, and starting treatment early gives a better chance of keeping an infection from reaching the lungs; antibiotics usually control the infection rather than cure it. Ammonia from dirty bedding and dusty or scented bedding both irritate airways, so clean the cage often and choose low-dust paper bedding.
Lumps deserve attention too. Mammary lumps can appear anywhere along the belly, sides or armpits. Many are benign but grow large enough to impair movement, and early removal by a vet is easier than removing a big lump.
Kidneys wear out with age. Slowly worsening kidney damage is common in aging rats.21Toxicologic Pathology. Chronic Progressive Nephropathy in Aging Rats Protein leaks into the urine as the kidneys weaken.22Toxicologic Pathology. Chronic Progressive Nephropathy in Aging Rats In some rats this becomes serious enough to harm health, especially alongside other kidney problems.23PubMed. The nature of chronic progressive nephropathy in aging rats
How To Help Your Rat Live Longer
Eating less slows the rate of aging in rats.24PubMed. Caloric restriction and aging: controversial issues In one experiment, a strongly reduced diet that avoided serious weight loss made rats live nearly 50% longer.25PubMed. Paradoxical effect of severe dietary restriction on Long-Evans rat life span That was a controlled lab diet, not something to copy by starving a pet. Feed a balanced rat block in measured portions and keep treats small.
A lean adult rat has a visible waist, and you can feel its ribs under a thin layer of padding, rather than a round, bulging body. Weighing the rat every few weeks on a kitchen scale lets you notice weight gain or loss before it shows by eye.
Spaying females helps too. Removing the ovaries nearly eliminated mammary tumours in female rats.26Cancer Research. Development of Spontaneous Mammary Tumors over the Life-Span of the Female Charles River (Sprague-Dawley) Rat: The Influence of Ovariectomy, Thyroidectomy, and Adrenalectomy-Ovariectomy Spaying before about 5 to 7 months cut tumour rates from about 74% to 5%.27PubMed. Prevention of age-related spontaneous mammary tumors in outbred rats by late ovariectomy Spayed rats in that work also survived longer.28PubMed. Prevention of age-related spontaneous mammary tumors in outbred rats by late ovariectomy Spaying is surgery under anesthesia, so weigh the benefit against the risk and ask the vet about their rat surgery experience before deciding. Find an exotics vet before you need one, since not every vet treats rats; a yearly checkup can catch weight loss or lumps.
Enrichment matters as well. Older rats moved to cages with toys and changing layouts survived better than rats in plain or solitary cages.29PubMed. Environmental enrichment influences survival rate and enhances exploration and learning but produces variable responses to the radial maze in old rats Some older rats find sudden big changes stressful, though.30PubMed Central. The effect of late-life environmental enrichment on stress and anxiety: The role of sex and age-related differences in coping with aversive stimuli Add new toys and layouts gradually, especially for elderly rats.
Rats are social and usually do best with at least one same-sex companion. In the enrichment study, rats kept alone survived less well than rats housed together. Same-sex pairs or groups avoid the fighting and unwanted litters that come with mixing sexes. Introduce new cagemates gradually, often on neutral ground or through a barrier first, to lower the risk of fights.
Caring For An Older Rat
More owners now take aging pet rats to vets for age-related diseases.31Elsevier / PubMed Central. The ancient rat Vets can offer pain relief, tumour removal and support for older rats.
Old age shows up in a thinner, rougher coat and weight loss even when the rat eats as much as before. Weak back legs, slower climbing and more sleeping are common as a rat ages, often in its third year. Drinking and urinating more can point to kidney trouble and is worth mentioning to a vet.
The cage can change with the rat. Lower the shelves and add ramps so a rat with weak hind legs can get around without falling. Offer soft, easy-to-eat foods if teeth or appetite are failing, so the rat keeps its weight up. A warm, draft-free spot helps an old rat that can no longer regulate its body temperature well.
Eventually the question of when to say goodbye comes up. Refusing food, struggling to breathe or being unable to move are signs the end is near. A vet can assess pain and quality of life, and humane euthanasia spares a rat suffering at the end.
How Old Is Your Rat In Human Years
In adulthood, each rat day equals roughly 35 human days.32PubMed Central. The Laboratory Rat: Relating Its Age With Human’s One rat month is therefore about three human years.33PubMed Central. The Laboratory Rat: Relating Its Age With Human’s A 2-year-old rat is in its senior years, roughly equal to a person in their seventies.
The formula works only for adults. Rats mature within a few months, so the first weeks and months pass much faster than it suggests. It is a rough guide and not a precise age, since rats vary in how fast they age.
The Oldest Rats On Record
Male lab rats have been reported living up to about 4.5 years.34PubMed Central. The laboratory rat: Age and body weight matter A female lab rat in an anti-aging project lived 47 months, beating the 45.5-month record for her breed.35the Guardian. Anti-ageing scientists extend lifespan of oldest living lab rat A pet website mentions a 7-year-old rat, but that claim is not backed by scientific records.36PetMD. How Long Do Rats Live?