Rats make excellent pets, and they live their lives with exuberance and cheerfulness. But, whichever way we look at it, those lives are too short!
Today we are looking at how long rats live and several ways that we can positively impact the lifespan of our rats, through our care and connection. We all want to help our rats live longer and whether it’s through stress reduction or there are many ways that we can do this.
Rat Lifespan – What Do We Know?
It is generally agreed that most wild rats will not reach their first birthday! This means that most wild rats die from predation, food shortages, and human control while they are still young and fit.
Pet rat life expectancy is better, and the average lifespan is around 2 years, though some rats will live to see their third birthday. However, you’ll notice that claims for longevity vary greatly.
The Guinness Book of World Records (1995 edition) puts Rodney the rat – who lived to be 7 years and 4 months – as the oldest verified rat. To put this in context, the oldest verified dog was 29 years and 5 months, while the average dog’s lifespan is around 11 years.
We also know that humans tend to have difficulty accurately recalling when events (like getting a pet) happen. This is called the telescoping effect. That feeling of “knowing somebody forever” comes into play and it is common to find owners overestimating how long they have had a pet.
Sources of Rat Lifespan Data
Sadly, there are many sources of extremely misleading information regarding lifespan in rats. It’s hard not to be cynical about Petco’s Rat Care Sheet which quotes average lifespan as “up to 5 years with proper care”. This not only promises the impossible but puts the blame on the owner when the rat dies aged two!
Pets at Home plumps for “can live for around three years with the right level of care.” Better, but still unrealistic. They can live for three years, but by far the majority won’t – regardless of the level of care.
Wikipedia doesn’t help, stating “average lifespan is around 2 to 3 years.” Any source quoting average lifespan needs to put it somewhere around 2 years.
There are studies that look at lifespan in laboratory rats. The one linked states “Sprague-Dawley lab rats – average 707 days (almost exactly 2 years) with a range from just over 6 months to just over 3 years (757 rats).”
A survey of pet rat lifespan in the UK (figures are taken from obituary notices in ProRatA, the NFRS journal), by Angela Clark, 2004 concluded that “the average lifespan was 21.6 months, and 95% percent had died by age 3 years.”
Exciting Research Into Pet Rat Life Expectancy
In view of the advances in veterinary care and nutrition for pet rats, and the informal nature of Angela’s survey, a formal pet rat lifespan project is currently being undertaken on behalf of the NFRS by Mary Giles (UK breeder).
This survey is following various groups of rats, born in both the Spring and Autumn, throughout their lives. It will look at health issues as well as lifespan. Rats are also separated by source into 4 categories:
- Rats bred by registered NFRS breeders who will remain with the breeder for their full lives.
- Rats bred by registered NFRS breeders placed in a non-breeder home.
- Rats purchased from Pets at Home as kittens.
- Rats from litters outside of the fancy or the commercial pet trade, e.g. from an accidental litter, a rescue litter, from hobby breeders, etc.
The first rats were born in the March/April period of 2018 – so full results are expected late 2021. This will be the most comprehensive study of pet rats in terms of health and longevity ever completed and will give a more definitive answer to the longevity question.
Can You Extend Your Rats’ Lifespan?
The short answer to this is a qualified “Yes!”
While rats, like all animals, have some genetic predispositions to factors that affect longevity, such as weight, activity levels, and illness, there are many aspects of our care that can help them towards living their longest potential lifespan.
Let’s look at some of these factors in more detail.
1. Sourcing Your Rats Carefully (Minimizing Genetic Factors)
Genetic factors can be anything from the predisposition to illness, to poor immune system health. These issues mean the rat is more likely to end up with a life-shortening illness. In rare cases, obesity can also be down to genes, for example, in the Zucker strain.
More often the predisposition to put on weight is driven by changes to fat metabolism that occur when a juvenile rat is overfed. However, underfeeding and lack of protein during pregnancy and the first 8 weeks of life can also lead to an increased risk of early kidney failure and a shorter lifespan.
Choosing to buy rats from a well-informed, ethical breeder, who feeds a good diet but doesn’t overfeed, will mean that your rats are less likely to come to you with these issues. A good breeder will always breed from healthy parents, who are selected for the health and lifespan of their ancestors.
Of course, it’s always possible to hit lucky and buy rats with a strong genetic predisposition from a feeder bin or pet store, it’s just more of a lottery and one that may cause you great heartache.
There are other benefits to finding a great breeder, not least that they will have handled the babies from birth and provided them with an active and stimulating habitat, maybe even a wheel. We will come on to see why these things are helpful in promoting longevity in the following sections.
2. Providing an Open and Active Habitat
Rats who are raised in an open and active set up, with the opportunity to engage in natural behavior such as climbing, balancing, foraging, and digging are not only set up for active adulthood but are also less likely to experience stress as babies.
However, regardless of their upbringing, if you keep your rats in an active and open set up in a barred cage they are more likely to remain fit and active well into old age.
Rats suffer from a number of conditions that can lead to hind leg weakness as they age, but the fitter they are and the more that is expected of them physically, the longer they can remain active once this problem occurs.
Fitness – and particularly foraging for scattered food (rather than bowl feeding) – can help to maintain a normal weight throughout life. Since obesity is linked to shortened lifespan in rats, these practices can help increase longevity.
3. Feeding a Range of Fruit and Vegetables
Like humans, rats have a need for antioxidants in the diet to reduce the inflammation and cellular damage associated with normal aging. The best way to give your rats antioxidants is by feeding a daily portion of nutrient-rich vegetables and fruit.
Antioxidants in your rat’s fresh vegetables and fruit end up in their bloodstream and circulate around the body, mopping up free radicals and reducing oxidative stress. Chronic oxidative stress is linked to many disease processes and aging.
Make sure the fruit and vegetables that you choose are nutrient-dense, like berries, kiwi, nectarine, kale, dandelion greens, broccoli, carrot, red bell pepper, and beetroot. This way your rats are getting vitamins and minerals as well as antioxidants.
4. Restricted Feeding With Some Fast Periods
One of the easiest, most effective aids to longevity that we can provide for our rats is restricted feeding. By this, we mean not having a bowl of food available to graze on throughout the 24 hour period. The opposite of feeding adlib.
Rats, like humans, benefit greatly in terms of health and longevity from having fasting periods. One way of achieving this is to feed once a day and only feed the amount that will keep your individual group of rats at a fit lean weight.
Try starting off with 15g of dry food plus about a tablespoon of fresh veg and berries per rat. Then tweak the volume depending on whether your rats look like they are a perfect weight or not. Intermittent fasting has been shown to significantly extend lifespan in rats
5. Maintaining a Good Weight for Size
The adult weight of most rats – and whether or not they struggle with weight gain – is usually determined by how they are fed as youngsters. The following quote is taken from a study into dietary patterns that extend lifespan in rats:
In general, an early adult death age is associated with a high food intake prior to adulthood particularly when coupled with a high efficiency of food utilization during the post-puberty period, a rapid growth rate and early attainment of mature weight. Deviations from this pattern serve to increase the duration of life of the individual.
Source: Dietary habits and the prediction of life span of rats: a prospective test MH Ross, ED Lustbader, and G Bras. American Journal of Clinical Nutrition, Vol 41, 1332-1344
Put simply, rats should not be fed to their maximum capacity for growth. Adlib feeding encourages rats to eat as much as they want and grow rapidly to their adult size. Any intervention that slows their growth down – without negatively affecting their well-being is a good thing.
Obesity is frequently seen in rats, and those who are fed more as youngsters are often predisposed to weight gain as adults. This is because the feeding patterns of juveniles can actually alter fat metabolism for life.
Neutering also increases the obesity risk unless the intake of food is restricted. Obesity can negatively affect almost every system in the rat’s body and is linked to several illnesses that affect our rats:
- Mammary tumor
- Kidney failure
- Ovarian disease
- Fatty liver
Being overweight can also affect the progression rate of the symptoms of other diseases, like the hind leg degeneration that occurs with kidney failure, demyelination disease, and osteoarthritis.
Keeping your rats at a good lean weight for size is one of the best things you can do in maintaining their health and lifespan. This is most easily achieved by a combination of:
- a low-fat diet
- scatter feeding
- periods without food
- plenty of exercises
6. Wheel Running
The use of a wheel is controversial in some rat communities, but all potential issues are addressed by the size of the wheel (a 16-inch diameter is ideal). Wheel running has been shown to extend average lifespan in rats
To avoid spinal issues and tail curling, stay away from small wheels. A wheel needs to be big enough for the rat to run or bound in a normal horizontal position. For most rats, this is at least 16 inches.
Because of their rapid metabolism, exercise and activity can have a big impact on maintaining a rat’s healthy weight. A large running wheel and a tall barred cage that encourages climbing are two ways to achieve this.
7. Veterinary Access and Expertise
Over the past two decades, as more people have started keeping rats as pets, the number of veterinarians with experience of treating rats has grown too. This has led to many new treatment protocols with a variety of medications that are not necessarily licensed for rats.
In some countries, rats are lumped together with exotic pets and specialists tend to be trained in exotics. Elsewhere, vets have come to specialize by learning on the job, through personal interest or because they service areas where rats are popular pets.
Finding an excellent rat vet can be key to helping your rat live a long life, as many rat ailments can now be treated with surgery or medication. If you don’t know where to begin looking for a good rat vet, try finding local recommendations online.
8. Freedom From Environmental Toxins
There are a number of environmental toxins that are known to have the potential to shorten a rat’s life. These include cigarette smoke, phenols from untreated pine and cedar, and ammonia from the breakdown of urine over time.
Rats should be kept in a smoke-free environment and if you smoke indoors they will need to be in a separate room with the door closed. Exposure to smoke regularly can cause respiratory problems and even tumors.
Phenols are easy to avoid as you just need to purchase paper, card, hemp, aspen or kiln-dried pine products for use in your rats’ cage. Exposure to phenols can cause raised liver enzymes and tumors.
Ammonia build-up can be avoided by changing the cage litter and bedding before any ammonia smell develops. How often you need to do this will depend on which litter you have chosen to use. Ammonia can cause inflammation of the airways leading to respiratory symptoms.
9. Freedom From Severe Stressors
Rats, like all animals, suffer from stress as a response to fearful, uncertain or challenging circumstances. Biologically, the rat’s stress response is the same as ours. Understanding this can help us to understand why stress can shorten their natural lives.
While small, infrequent, day to day stresses (like a sudden noise) that come and go quickly can actually help to make a rat more resilient, prolonged or severe stress has been found to lead to symptoms that are similar to what humans describe as depression and PTSD.
Significant stressors are things like moving from home to home, changes in cage groupings, social stress (bickering, bullying and dominance struggles), illness, overcrowding, the death of a bonded cage mate or loss of a significant human (such as the main carer heading off to college or university).
Research has shown that social stress creates a stronger stress response in rats than negative experimental techniques such as immobilization and electric shocks. Never underestimate the impact of an unsettled cage group on the most vulnerable rats.
10. Adequate Undisturbed Sleep
Chronic lack of adequate rest and undisturbed sleep is known to shorten a rat’s lifespan. It’s important to make sure that your rat has a dark, quiet sleeping area, where they can rest undisturbed by any sudden noise and harsh light.
Remember rats do about two-thirds of their sleeping during daylight hours and spend more time awake overnight. A cozy bed that screens out some light and a quiet environment for at least some of the day are essential for deep sleep and longterm well-being.
11. Connection and Enrichment
Rats are social creatures and we would expect there to be health benefits from housing them in social groups. Research suggests that both positive social groupings and positive human handling (connection) can cause changes in the rat’s cells that reduce the rate of aging.
Social connection is important to rats and those who are more isolated have been found to experience chronic stress, which can shorten lifespan. So connection and social enrichment can prolong a rat’s life by more than one mechanism.
Positive noise stimulation (such as background higher-pitched classical music) has also been found to significantly reduce stress levels in rats. I am not aware of a musical study that has looked at lifespan, but many have looked at stress – and reducing lifelong stress would be likely to extend life.
One study in mice did look at the lifelong impact of enrichment noise (in this instance, rain forest recordings) and found a positive impact on lifespan in the group exposed to the noise at around 20 kHz, which is the peak frequency that rats hear – but outside of the range of most humans.
Rats are such wonderful animals that we all wish they could live for many years. Despite a short natural lifespan, we hope we have offered you several ways that you can help and support them in living the longest life possible.
But, however long your pet rats live, your job is to make sure their lives are rich and comfortable, in the company of their friends. Give them your attention and you’ll have many wonderful memories of whatever time you spend together.