Oh what a debate! So, you’ve made the decision to welcome a small pet into your family lives. You’ve discussed it and decided that you’re ready to provide everything they need: keep them fed, sheltered, happy, healthy and hopefully enjoy each other’s company. However, you just can’t decide which pet would be best for your family: guinea pig or rat?

On the surface of the discussion they’re a similar size pet, they’re both pretty cute and rewarding to have as part of your household, but what else do you need to know?

Size and breeds

There are different breeds of both guinea pigs and rats available, and many, many different colours.

Guinea pigs come in long haired, rex, smooth coated and even hairless (rare!) varieties. There are also the traditional pet rats and many breeds of ‘fancy rats’ such as the dumbo, rex and satin coated varieties. 

Of course – rats have tails and guinea pigs don’t, sometimes this is a deal breaker! (I love their scaly tails, some of our proofing team REALLY don’t – swings and roundabouts everyone! Ed.)

Housing and Handling

An enclosure can never be too large – the more space the better! However, it must be secure and safe, kept away from potential predators, noisy areas of the house and any draughts or direct sunlight. Housing must provide (for both species!) areas to hide and shelter and also areas to play. 

Large wire cages with plastic bases that can be easily cleaned as suitable for both species; wood is not suitable for rats due to their love of gnawing (and escaping!). As a minimum your pet must have enough space to run (at speed) from one end to the other, stand to full height and stretch in any direction. When choosing housing remember that your pet spends a large portion of their lives in here – would you prefer to live in a shed or a mansion given the choice? 

Remember temperament…

Guinea pigs tend to be of a slightly more nervous disposition than rats. Their scared response is to freeze and this can last for seconds to minutes before they pluck up the courage to run for safety and hide. Consider this if you have loud or young children. Both species can deliver a nasty nip when scared or not used to handling. 

Guinea pigs require access to an outdoor run for fresh air and grass. 

Soiled bedding must be removed daily and the entire bedding changed weekly. Where possible choose dust extracted bedding to reduce the chance of breathing issues. 

…and playtime!

Both species will enjoy human contact with gentle handling and positive interactions. Rats are very intelligent creatures and can even be trained to understand basic commands and do tricks.  Both need lots of mental stimulation to keep them happy. Guinea pigs will enjoy toys and games that mimic their natural foraging behaviours such as cardboard tubes with hay and treats stuffed in them and other ideas, rats love to climb and forage too. 

Dietary Requirements

Guinea pigs are herbivores – they eat a combination of high fibre foods, fruits and vegetables. 

  • They have a high requirement for fibre in their diets (hay/grass) this is because they have a unique digestive tract where the indigestible fibre is broken down in their caecum (part of the digestive tract) then passed out as sticky poos called caecotrophs which are eaten again to provide nutrients. Fibre also has an important role to play in dental health, helping to wear down teeth and prevent overgrowth. 
  • Vitamin C is essential in their diets as they are unable to produce their own and can develop serious health conditions such as scurvy if they don’t have enough. This can be provided by feeding a good quality commercial guinea pig diet (such as the grass nuggets) and supplementing with fruit and vegetables. These must be the guinea pig nuggets NOT rabbit nuggets which don’t contain vit-C. Tip: buy smaller bags of the nuggets as the vit-C decreases by roughly 50% after 6 weeks of being open. 
  • Fruit and veg should be fed alongside hay and pellets: leafy greens, peppers, herbs, small pieces of root veg or apple are good choices. 

Rats are omnivores – they eat both plant and animal based foods. 

  • Very important to feed a balanced diet for rats as they have specific requirements for vitamins, minerals and proteins that other small animals don’t. 
  • Feed a balanced commercial pelleted rat food (NOT a ‘muesli’ type) and supplement with fresh foods such as fruit, veg, small amounts of cooked egg and fish. 
  • Rats are prone to obesity and have a sweet tooth so be careful not to over feed them! 


Both rats and guinea pigs need companionship of at least one other of their own species. This is so important for their mental and physical health; if they don’t have this company then they show abnormal behaviours and signs of depression. Remember that mixed sex groups will breed even if they are litter mates (brother and sister) and for this reason this should be avoided, or males should be neutered. Unwanted pregnancies can cause life-threatening problems for females during the birthing process. 


Guinea pigs live for up to 4-8 years whereas the average life expectancy for a rat is 2-3 years. Remember that if you choose to welcome them into your lives you should plan to provide for them for the entirety of theirs. 


There are currently no routine vaccines available for either guinea-pigs or rats. 

Most common health issues with guinea pigs and rats seen in practice are: 

  • Dental health: teeth grow throughout their lives and can overgrown and cause issues. Provide safe things to gnaw to help with this. Keep guinea pigs diets rich in fibre. 
  • Respiratory disease: both are prone to infections that can progress to serious pneumonia. Keep a clean environment with low dust and good ventilation to help. 
  • Skin issues: mites, infections or allergies.
  • Obesity: don’t over feed them.
  • Abscesses: from trauma or fighting.
  • Tumours: skin tumours, mammary tumours in females of both species and ovarian tumours in female guinea pigs. 
  • Urinary problems: guinea pigs are prone to urinary calculi (stones in the urinary system) which are a serious condition.  
  • Scurvy: Vitamin C deficiency in Guinea Pigs is very serious.  

Both species are prey animals and because of this they won’t give you much warning if they’re not feeling very well and can deteriorate quickly. If you are ever worried about your pet you must contact your vet immediately for advice. 

Finding your pet

Hopefully this has helped you decide which pet is best for you and your family; it’s time to find the pet. There are many breeds and colours available of each species of pet but ultimately it is the personality and suitability to your family and lifestyle that is important. If you can, why not consider contacting your local rescue centre to see if they have any suitable pets looking for new starts and loving families.