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What does an unhealthy rat look like?

You can learn the most about your rats through their behaviour, appearance, and body language. It’s important to continually observe for abrupt and subtle changes happening with your rats. Because they are a prey species, they will try and hide signs of illness – so when they look sick, they’re really sick! Picking up subtle changes early can make a huge difference to your pets’ health.

The first thing to do is to sit still, look, and listen. Waiting for a few minutes gives your rats a chance to stop pretending they’re healthy. They might be good at hiding signs of illness, but they can’t keep it up for long.

What to look for

The following are some things to look at and listen to once your rats have gotten used to your presence.


Check them morning and evening when they are normally active; observe the individual and group behaviour of the rats in their enclosure without disturbing them. Often the first sign of an unwell rat is the rat being isolated in the corner rather than nesting with enclosure mates.

Observe each individual rat in the enclosure to see if they are moving, breathing well, sitting normally, and have bright eyes and a shiny coat. Watch your rats closely. Any changes in their feeding, drinking, social behaviour, or general activity may be an early sign of a problem.


Listen for any sneezing, especially if more than a few sneezes over an hour or two. This can indicate respiratory problems that require veterinary investigation. Rats aren’t as vocal as many animals (that would attract predators) so, while vocalisations don’t automatically mean there’s something wrong, unusual noises should be investigated. This includes crying out, squealing suddenly, wheezing, coughing, etc. For example, it could indicate pain if your rat suddenly screeches, squeaks, whimpers, or makes any other sound that wasn’t made before when moving, interacting with their enclosure mates or you (e.g., being touched or picked up).


A stressed or sick rat will often have their ears pulled back flat against their head (compared to a happy, healthy rat whose ears will normally be forward facing or reacting to what is happening around them) and they may have squinted eyes (a grimace) too. Changes in facial expression are a useful way of assessing pain in rats and a standardised scale (called a “Grimace scale”) to assess these is available (developed for use in laboratory rats but equally applicable to pet rats). You can find out more about the Rat Grimace Scale here.

Rats are fastidiously clean animals – if they seem dirty, unkempt, or their fur is matted, they have diarrhoea/faeces stuck to their coat under their tail, or there is discharge from their eyes, ears or nose, something is going on. Excessive scratching and general signs of itchiness are also abnormal. Check that they do not have any red staining around the eye and nostrils. This is known as ‘Red Tears’ (chromodacryorrhoea). It is not blood, but rather a pigment and is produced when rats get stressed or unwell and seeing this should prompt you to seek advice from your veterinarian.


Rats love their food, and are constantly looking for, and eating it! If they seem less interested in food than normal or are refusing to eat, something is going on. This is never a symptom to ignore and could be caused by many different things.


Increased water intake, along with increased urination, can be a symptom of a bladder infection, kidney issues, or other health issues. Take note of any other symptoms you’re witnessing and discuss them with your veterinarian.


Stumbling, weakened legs, limping, shuffling, and any other changes in how your rat moves are all things to watch out for. They can indicate neurological problems, trauma, muscle weakness, etc. Favouring one leg could be due to something as simple as torn toenail or as serious as a broken bone.

What’s next?

If you have detected an abnormality by looking and listening, it’s time to take a closer look. Physically examine your rats regularly by running your fingers gently over their body to check for any lumps, bumps and that they are physically normal. It is a good idea to get your rats used to being gently handled and examined from a young age using positive reinforcement and reward-based training. See this article for more information on interacting with and handling your rats.

If the issue you have detected is not something simple, you will need to take your rat to a veterinarian experienced with rats, who can work with you to find out what is wrong and treat it appropriately.

Remember that anything that alters the smell of an individual rat may cause social disturbances within your group of rats, including aggression. So, if you need to take one of your rats to the veterinarian, take the others too, or at least one of their enclosure-mates, so that they smell similar when they return.


​​1. Frohlich J (2020) Rats and mice. In: Quesenberry KE, Orcutt CJ, Mans C, Carpenter JW (eds) Ferrets, rabbits and rodents, 4th ed. W.B. Saunders, pp 345–367

Updated on January 19, 2024
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