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Pet rats are a little too good at hiding symptoms of illness. As a result, diseases often go unnoticed for some time before symptoms are severe. Therefore, all rat owners need to be familiar with the normal parameters for pet rats. This can mean the difference between picking up disease early and treating it and possibly losing your pet rat to a treatable condition.
In this article, I will take you through a step-by-step process on how to do a health check on your pet rat at home so you can know when to get veterinary help.
Table of Normal Parameters for Rats
| Physical Parameter | Normal Range | Notes |
| Life Expectancy | 2.5 – 3.5 years | The current work record is for a rat named Rodney, who lived to be an astonishing 7 years and 4 months. |
| Weight | Male: 9.5 – 18 oz (260 – 503g) Female: 8 – 12 oz (230g – 350g) | Depending on size, it is better to keep your rat on the leaner side. |
| Breathing Rate | 70 – 150 breaths per minute | |
| Heart Rate | 260 – 450 beats per minute | |
| Temperature | 96.6 – 99.5°F (35.9 – 37.5°C) | Best taken per rectum using the smallest thermometer you can find. |
| Water Intake | 30 ml/oz bodyweight (10ml/100g) | Roughly 2 oz per rat per day on average. |
| Food intake | 60 calories per day or 0.5 – 0.6 oz (15 – 20g) | About 2 tablespoons, usually given divided into two meals. Monitor trends in body weight to make sure your rat eats enough and not too much. |
| Urine Production | 13 – 23 ml per day | |
| Blood Volume | 2ml/oz (70ml/kg) | This Will be lower in geriatric and obese rats. |
| Sexual Maturity | 6 – 8 weeks | |
| Gestation Lenght | 20 – 22 days | |
| Litter Size | 6 – 16 (average 10) | It can be as small as 3 pups per litter. |
| Birthweight | 4 – 7 grams | |
| Eyes Open | 12 – 14 days | |
| Earliest Weaning Age | 21 days |
If you would like to read more on how to know when your rat needs to see a vet, have a look at this article with details on which symptoms are serious and when they need to see a vet urgently. I also gave some useful tips to know when your rat is in pain and what to do when you think your rat might be busy dying.
How To Do An At-Home Health Check On Your Rat:
1. Hands-Off Exam
Before touching your rat for a physical exam, please take a moment to observe them in their environment. This may give you more clues to your rat’s health than you might have thought at first!
Check Their Evironment
How much have they been eating? Are there any leftovers lying around, or are they hiding food in the cage despite being fed the same amounts?
Is the amount of water you have to give every day consistent, or has it increased or decreased?
Do you notice more urine than normal? Are the feces a normal consistency and color? Any unusual discharge?
Observe Them Undisturbed For a Few Minutes
Do you notice them having difficulty moving around? Do they struggle to navigate multiple cage levels or obstacles?
Are they more sleepy than usual? Do the other rats pick on them?
Cagemates may start to bully other rats as they get older or if they are sick. Sick rats will also tend to hide away and try to avoid contact.
2. Picking Up And Handling Of Pet Rats
Knowing how to hold a rat for a physical exam properly is just as important as knowing the normal parameters for rats. You want your rat to feel well supported and safe in your hands while you examine it.
It is best to pick a rat up by grasping it around the shoulders and then using your other hand to support the hind feet (see the photo below).
Rats rarely bite when being handled but will do so if fearful or in pain. So be cautious; handle them gently and as little as possible, preferably with a thick glove if you think they might be experiencing pain.
Make sure to hold gently to allow unrestricted breathing. If a rat is aversed to being handled (for example, a rat that is unfamiliar with you or a doe that recently had pups), you can gently pick it up by the base of the tail. Do not pick a rat up by its scruff, as this causes them stress, especially if done by an unfamiliar human.
3. Assess Hydration Status
This may take some practice but should become easier the more often you examine your pet rats.
Have a look at the skin elasticity. In young and adult rats, the skin should ‘snap’ back into place within 1-2 seconds after slightly pulling or tenting it. Older rats will have reduced skin elasticity, so 2-3 seconds are generally considered normal for them. However, keep in mind that skin elasticity can be falsely increased in obese rats.
It may indicate dehydration if the skin does not snap back into place after gently pulling at it. Other signs of dehydration are slightly sunken eyes and lethargy.
4. Inspect The Eyes, Nose and Ears and Head
Eyes
Healthy rats should have clear eyes with no discharge. Albino rats with red eyes will have poor eyesight (similar to albino animals of most other species).
Sick, frail, or stressed rats will commonly have a brownish eye discharge that causes discoloration of the fur around the eye. This is called porphyrin staining.
Rats have a tear gland behind their eyes (the Harderian Gland) that tends to increase tear production when a rat is ill or stressed and contains a compound called porphyrin. When this compound reacts with UV light, it creates a brown discoloration that will stain the fur.
This stain is tough to remove, but wipes designed for animal eyes can help if used regularly. Angel’s Eyes Gentle Tear Stain Wipes are a good option for this purpose. Elderly or frail rats will also commonly have this type of tear staining around the eyes.
Runny eyes and constant blinking are signs of eye pain. A white or green discharge with red and slightly swollen eyelids are signs of eye infection and warrants an urgent vet visit. Most eye conditions are considered emergencies, and treatment will need to commence ASAP if eyesight is to be preserved.
Nose
A healthy rat’s nose should be clear, and the nostrils easily visible. If there is any discharge, sneezing, or crusting, it could indicate disease.
Sneezing now and then and a mild watery discharge is not a cause of concern, but constant sneezing, white, yellow or green discharge and severe crusting of the nose could indicate a respiratory infection – check with your vet urgently!
Ears
The ears should be clear of dirt and discharge.
If the ears are dirty, you can gently clean them using the same wipes you would use for the eyes or by using a damp piece of cotton wool. Do not insert a q-tip in the ear canal.
Take note of any signs of pain, redness, discharge, or heat that could indicate inflammation. For example, a large amount of sticky brown discharge from the ears or head tilting could indicate an ear infection.
5. Inspect The Teeth
Rats have 4 incisors that will keep growing all their lives. This is why rats need hard things to nibble on to help wear down the incisors as they grow. Yellow is the normal color of rat teeth.
They have 3 pairs of molars on the upper jaw and 3 pairs of molars on the lower jaw. That equates to a measly 16 teeth in total.
The lower incisors should sit behind the upper incisors in a rat with normal occlusion. The lower incisors should be roughly three times the length of the upper incisors.
It’s not easy to look inside a rat’s mouth without sedating them, but luckily tooth problems involving the molars are rather rare but can still occur (sometimes secondary to incisor problems).
Your rat’s eating habits will give you clues on their dental health as well. For example, are they eating slower than usual, or are they avoiding eating hard, crunchy or chewy food?
Overgrown incisors are a common dental condition in pet rats. This will cause difficulty eating and may eventually make eating impossible, leading to weight loss. If this is the case, a vet visit for sedation and teeth trimming may be needed.
Have a look at the gums as well. It should be light pink and moist. Pale, yellow, or red gums indicate serious disease, and urgent veterinary care is needed.
6. Measure The Respiratory Rate
Notice how your rat breathes when they are relaxed- there should be minimal effort, and only a slight movement of the chest should be seen.
To measure your rat’s breathing or respiratory rate, I find it easiest to use a watch face with a seconds hand. When the arm reaches any quarter on the clock, start counting the number of breaths your rat takes for 15 seconds and then multiply that by 4 to get the number of breaths per minute. Normal is between 70 and 150 breaths per minute.
We are usually not too concerned with a breathing rate that is slightly lower than normal (low breathing rate is normal while a rat is asleep, for example). Still, a breathing rate faster than normal in a relaxed, home environment is cause for concern. Lung disease, heart disease, and pain can all cause an increase in breathing rate.
7. Measure The Heart Rate
If you thought the respiratory rate was tricky to calculate, get ready to count super fast! Rats have high-speed heart rates compared to humans, making it tricky to get an accurate count.
If you have access to a stethoscope, this will help a lot. Use the small side of the bell (the pediatric side) and place it behind the elbow on the side of your rat’s chest. You may have to move it around slightly until you can clearly hear the heart. Start counting the number of beats in 15 seconds and then multiply it by 4 to get the beats per minute.
Another place you might be able to take the heart rate without a stethoscope is at the base of the tail on the bottom side of the tail. Use your index finger to lightly press against the bottom of the base of the tail. This may take some practice but should be palpable in most adult rats.
If you notice an abnormally high or low heart rate with other concurrent abnormalities on the examination of your rat, it will be best to consult your vet.
8. Examine The Trunk and Skin
Your rat’s fur should be smooth and groomed. A poor hair coat often indicates ectoparasites (mites, lice, fleas), chronic stress, or poor nutrition.
As white rats age, it is normal for their coat to start turning yellow.
Look for any wounds or lumps and bumps and red or crusty skin. Rats are predisposed to many types of tumors, of which mammary tumors are probably the most common. 30- 90 % of female rats will develop mammary tumors.
If you find a bump on your rat that rapidly increases in size and is painful to touch, get it checked out by your vet as soon as possible as it might be an abscess and will need veterinary care.
Pay close attention to the mammary glands of especially intact female rats and look for any lumps or bumps and note the size. If it gets bigger over the course of fewer than 2 weeks, get it checked out as soon as possible. It is beneficial to physically measure any suspicious lumps as ut can sometimes be difficult to monitor the size of a lump over a period of time if you see it every day.
If you find what you think might be a tumor, seek veterinary care as soon as possible to prevent the spread and aggressive and invasive growth of possibly malignant tumors.
9. Examine the Legs And Feet
Gently palpate the all the way from the shoulder blades down to the front feet and from the top of the pelvis down to the hind feet. Take note of any signs of discomfort, swelling, or asymmetry.
Rats have five toes on each foot. Most rat owners are slightly obsessed with the cuteness of rat’s feet, so I trust you are familiar with the normal appearance of rat feet.
It is important to look closely at the bottom of the feet and between the toes, as small wounds in these areas can often go unnoticed.
A dirty cage environment can, for example, lead to sores and ulcers on the bottom of your rat’s feet, so be sure to check the foot pads as well.
10. Examine the Genitals And Tail
A slightly sticky or oily feel to the tail is normal and is caused by the normal secretion of sebaceous glands on the tail- similar to the sebaceous glands in the skin of humans.
A male rat’s testes should sit within the scrotum from 30-40 days of age but can slide back into the inguinal canal as rats have huge inguinal canal openings that remain open throughout their adult life.
The testes should be an oval shape, and you should be able to extrude the penis from its sheath gently. Once again, check for any swelling or abnormal discharge (a small amount of mucoid material on the penis is normal).
You might even note a hard ‘plug’ at the opening of the penile sheath. This is known as an ejaculatory plug and is made up of skin and sperm cells. This usually does not cause any problems.
When examining a female rat’s external genital, check for any discharge. Female rats do not normally have any discharge, even when in heat. A vaginal discharge is normal in a female rat for the first week after giving birth.
In both sexes of particularly senior rats, check for urine scalding of the belly. This could indicate that they are having difficulty positioning themselves to direct the flow of urine away from the body or urinating more than usual. Let your vet know if this is something you have picked up on when examining your rat.
11. Take the Temperature
If you have ever seen how a vet takes their patient’s temperature, you might know that this is not the most pleasant of tasks as it involves sticking a thermometer into the anus, and I will therefore forgive any rat owner who would rather skip this step.
However, if your rat is suddenly ill and lethargic or not eating, checking for fever will give you some indication of how urgent the situation might be.
I would advise having a buddy help hold the rat for this exercise so that you can lift the tail with one hand and insert a small diameter thermometer with a lubricated tip into the anus. Only the metal tip has to be inside the rectum to measure an accurate temperature.
96.6 – 99.5°F (35.9 – 37.5°C) is the normal range, and any deviation from this warrants an urgent vet visit. In the meantime, you can start cooling or warming your rat gently using either a wet face towel to cool them or a warm bean bag to help warm them up.
12. Take Bodyweight
Weight is a beneficial indicator of general health as well as a prognostic indicator. One of the best things you, as a rat owner, can do to help keep your rat healthy as long as possible is to prevent them from becoming overweight. Obesity is very closely correlated with several diseases and shortened life span. Food is definitely not loved when you end up feeding your pet rats to the point of being overweight.
Unintended weight loss can be just as serious. If you notice your pet rat losing weight without consciously reducing their food intake, it definitely warrants a vet visit.
I always advise all rat owners to weigh their rats every week and note the weight. You will soon learn the normal range for your rat and will be able to pick up a downward or upward-trending weight and address it before it becomes a problem.
How Do I know If My Rat is In Pain?
Since rats are a prey species, they will often try to hide signs of pain or illness. Signs indicating pain in rats include hunched posture, decreased appetite, aggression, and avoidance behaviors. Rats experiencing pain also have a ‘pain’ facial expression characterized by slanted eyes, flattened ears, and whiskers pointing away from the body.
Interesting Facts on Rats
- Rats have large amounts of brown fat which helps them cope with cold weather.
- Rats can not vomit due to a limiting ridge at the juction of the stomach and the eosophagus.
- Rats do not have gall bladders.
- Rats do not have sweat glands and can not pant – this means that they are not well adapted to cope with warm weather. The dissipate heat through their ears, tails and feet.
- Rats are colorblind.
- If you see your pet rat eating poo, don’t worry – it’s normal!
Conclusion
Regularly doing a physical exam of your rat at home will definitely help you to know when your rat is sick. This will, in turn, help your vet better treat your rat as diseases are picked up earlier. Give your rat a good look over at least once per week so that you are familiar with what is normal for them and can pick up and address abnormalities as soon as they occur.
References
- Banks, R., 2013. Exotic small mammal care and husbandry. Hoboken: John Wiley, pp.81 – 92. https://onlinelibrary.wiley.com/doi/book/10.1002/9781119265405
- Meredith, A. and Redrobe, S., 2002. BSAVA manual of exotic pets. 4th ed. Quedgeley: British Small Animal Veterinary Association, pp.13 – 25. https://www.researchgate.net/publication/240493099_The_BSAVA_Manual_of_Exotic_Pets_4th_edn
- O’Malley, B., 2005. Clinical anatomy and physiology of exotic species. Elsevier, pp.209 – 225. https://www.sciencedirect.com/book/9780702027826/clinical-anatomy-and-physiology-of-exotic-species
