1 Health monitoring: BMI, weighing, poo out and body changes
- The importance of the weekly health and grooming body check
- Different feedback from BMI, weight, poos and body changes
2 Regular weight monitoring
- How often should I weigh?
- Weighing tips
3 Guidelines for changes in weight
- Weight loss guidelines
- Sudden weight gain and fluctuations
4 Ideal Weight and BMI/'Heft'
- What is a healthy weight and how does it change through life?
- Feeling for the 'heft': Is my guinea pig the right weight for their size (BMI)?
5 Underweight
6 Overweight
- Obesity and overweight
- A long term healthy diet
- Exercising time tips
7 Healthy treats and dealing with pester power
1 Health Monitoring: BMI, weighing, poo output and body changes
The importance of the weekly weighing and body check
Regular life long weighing is a vital health monitoring tool. It can help you to spot developing health problems early on when treatment and recovery/chronic illness management are generally much easier to manage.
Knowing how much weight your guinea pig has lost in which space of time can also help you to judge when to see a vet and will help your vet with their own assessment. Being able to put that weight gain into its correct perspective is even more crucial.
Giving the body a weekly onceover at the same allows you pick up slowly developing changes sooner. It also means that you are familiar with the personal quirks and can spot gradual changes better.
Different feedback from BMI, weighing, poo output and body check
But weighing is not your only tool.
Knowing the BMI/'heft'
Equally important is checking a guinea pig’s heft around the ribs. Knowing the BMI is crucial for working out whether your guinea pig is the correct weight for its personal size, or whether it is over- or underweight, so you can put any weight loss into the correct perspective.
Losing 100g in a small or underweight guinea pig is a much more concerning loss than the same in a large or overweight guinea pig. Each guinea pig has a different ideal weight range and this will change over the course of a lifetime. A quick feel whether your piggy's body weight is still in the healthy range or whether they are feeling a bit underweight or overweight can tell you better than the scales whether the change is cause for immediate concern or not; especially with a fluctuating weight or if you haven't been able to monitor regularly for some reason.
Weighing
The body weight doesn't just change over a lifetime but it also changes during the day. Ideally you do the weekly weigh-in and body check at a similar time of the day so you have a direct comparison. If you do it at a different time in the feeding cycle, please don't panic if the weight is a few grams out. The difference between a full and an empty bladder can be as much as 10g and the difference between a big veg dinner can make 40g.
If there are health concerns, please switch to weighing daily first thing in the morning. This does two things at once:
- The weight is at its lowest before breakfast so the feedback is the most honest and best for day to day comparison.
- It also helps you to plan the next 24 hours in terms of any feeding support care needs as to how often to feed etc.
Poo output
It is important to know that it takes about a day for any food to pass from the mouth to the anus (longer if the gut is slow). This means what is coming out at the far en is never up to date; it always running behind events. If you just monitor the poos, you can lose that crucial extra day of stepping in with feeding support and will have to make up a much larger weight loss.
The same goes for monitoring the food intake by eye: you can never tell whether a piggy is eating enough hay (which makes over three quarters of the daily food intake) is eating enough or not by just watching them chew on some cud in their mouth.
What poos can tell you in a general way is whether there is a disturbance in the digestive system and how severe it is. It can also tell you whether you have been feeding enough over the last couple of days or should feed more.
A little guide to 'poopology' - interpreting poos - with some pictures is in this link here: Wiebke's Guide to Poops
Weekly body check during grooming
This helps you to find changes to the body - lumps, swellings, sore feet, a quick look at whether the incisors are looking fine (which generally means that all is well at the back, too), there are no problems with the eyes, ears, genitalia, nipples, skin/hair loss, a distended or hard belly, scabs etc.
Each guinea pigs has their individual quirks, like the shape of the bald patch behind the ears. It may help you to document the body with reference pictures once a year; especially if you have anxiety issues so you have a comparison to check against and you cn avoid some unncessary panics, like discovering that boars have two nipples or the swelling on the side of their genitalia are descending testicles...
As a very rough rule of thumb: If both sides of the body are the same it is more likely to be normal altough you want to check any thinning of hairs.
This guide here also explains how you can use the combination of all these methods for illness support: Weight Loss Explained: BMI, Weighing, Poos and Feeding Support
Wiebke's Guides to the Body is a series of articles about how the body works, what is normal and what are the most common illnesses related to it.
2 Regular weight monitoring
How often should I weigh?
Please weigh once weekly on your normal digital kitchen scales in combination with a quick top-to-toe health check throughout the whole life of your guinea pigs.
If possible, note down your weights and any small body changes, like the appearance of a small lump. Your log can help your vet when assessing any developing health issues and in making their decisions. Taking pictures of the normal features doe use as reference can help you spot changes, especially if you have anxiety or memory issues.
Guinea pig body quirks - What is normal and what not?
Please keep in mind that over 80% of what your guinea pigs eat in a day is hay. You cannot control this just by watching a guinea pig nibbling slowly on a stalk or chewing on some crud in its cheeks. If you only judge the food intake by how your guinea pigs eat their veg (one tenth of what it should eat!), you can easily miss a massive weight loss because hay is often the first food group that is impacted when your guinea pig is in pain or not feeling well. Guinea pigs are so good at hiding any illnesses until it is often nearly too late, like all prey animals. That is where weighing once weekly is really coming into its own!
Switch to weighing daily at the same time of the feeding cycle (ideally before you feed veg or pellets) if your guinea pig is suddenly looking thinner, ill or is not eating properly.
Because the weight is fluctuating around 30-40g (ca. 1 oz) in a weigh band over the course of 24 hours depending on how full the bladder and the tummy are, weighing at the same time in the feeding cycle will help you to eliminate these fluctuations as much as possible.
I find weighing either first thing in the morning or before serving the evening veg the best times.
When weighing more than once a day, you will have to factor in this weight bandwidth. Especially if you have anxiety/control issues, please ask a partner or family member to weigh your guinea pig for you. Weighing too often will not help your guinea pig and will only increase your anxiety. Recovery and illness support is always somewhat of an up and down; that is why you have to think in in weight bands with a general trend rather than in absolute weights.
We are speaking of weight loss or weight gain only when the difference is beyond this daily swings bandwidth , i.e. when the loss/gain is 50g/1 oz or more.
We would be very grateful if you please could give any weight in grams if you have a weight/health connected problem. We have members from all over the world. Using grams prevents any confusion and misunderstandings for anybody.
Here is a link for converting UK and US pounds into grams: Pounds to Grams conversion
Weighing tips
Normal kitchen scales from a supermarket usually work just fine for your purposes, whether they are mechanical or digital.
Unlike your vet, who needs exact scales to compute dosages, at home you are mainly looking for changes in weight but not exact weights that help you decide when and how quickly you need to see a vet.
Of course if you prefer exact scales for weighing your guinea pigs, you can also find good quality ones in places like amazon or ebay.
Many people find the scales with bowls that sit on top to be ideal, but as long as the pig can fit on the scales almost any type should be fine!
With jumpy pigs you best use a tunnel or a lidded cardboard box, which you weigh separately so you can work out your guinea pig’s weight.
This video guide shows you how you can safely pick up and weigh your guinea pigs without having to handle them and risking blind jumps or accidental falls:
3 Guidelines for changes in weight
Weight loss guidelines
Here are the guidelines along which you can judge whether and how quickly you need to see a vet.
If in any doubt, please see a vet sooner rather than later. In an emergency, please make an appointment first before asking us!
- 30g / 1 oz: Normal daily weight swing
Any weight gain or loss within this band does not count because the difference between a full bladder and a full gut and an empty bladder and gut can be up to 40g and because the weight is swinging in this bandwidth throughout the day.
- 50g / 2 oz: Go on alert!
Switch to weighing daily at the same time and book a vet appointment if the weight loss continues. See a vet within 24 hours if a guinea pig is losing this amount within 24 hours (i.e. 'promptly') and step in with syringe feeding top up. If the weight loss is much slower but steady, see a vet during regular opening hours within a week, ideally as soon as you can get an appointment during regular opening hours.
- 100g / 3 oz: You need to see a vet as an emergency if the weight loss has happened within in 1-2 days!
If your guinea pig has lost 100g within 24 hours, it has not eaten or drunk at all during this time and is in acute danger of dying.
See a vet or emergency service at any time of the day or night ASAP!
Step in with syringe feeding and watering if your guinea pig can still swallow and process food. Never simply empty a syringe full into the mouth of a severely ill guinea pig!
If the weight loss has happened over a period of weeks or months, please see a vet during regular opening hours within a week, ideally as quickly as you can make an appointment.
Emergency, Crisis and Bridging Care until a Vet Appointment
Sudden mystery weight gain and weight fluctuations
Any sudden weight gain in adult or older guinea pigs should also be investigated. It can be caused by a fluid build-up in the body (potential heart insufficiency) or bloating.
The same goes for any major weight swings in a short time (50-100g repeated up and down)
There can be some seasonal weight fluctuations, especially around the lawn season when guinea pigs gorge on rich fresh grass or during weather extremes.
It also pays to check the water bottles to make sure that they are not blocked or runny, and that the water is drinkable (neither boiling hot nor frozen/ice cold in winter before you make a vet appointment.
Hot Weather Management, Heat Strokes and Fly Strike
Guinea pigs coming from a background of neglect can put on as much as 50-60g/2 oz of weight per week for a short while.
Any major weight gain in a pregnant sow usually happens only during the last 2-4 weeks of a 9-10 week pregnancy when there should be usually other signs visible (noticeably moving and growing baby balls). You won’t notice any signs and certainly not any large weight gain much earlier. How large this late stage weight gain is, depends very much on the size of the litter: whether your pregnant sow carries a single pup or 6-7 babies will have a big influence on any weight gain!
If you are worried about a potential pregnancy, please open a thread in our pregnancy support section. You need to register with the forum and accept our explicit no intentional breeding forum rules in order to access this specially monitored non-breeding section and our comprehensive practical information guides.
- The importance of the weekly health and grooming body check
- Different feedback from BMI, weight, poos and body changes
2 Regular weight monitoring
- How often should I weigh?
- Weighing tips
3 Guidelines for changes in weight
- Weight loss guidelines
- Sudden weight gain and fluctuations
4 Ideal Weight and BMI/'Heft'
- What is a healthy weight and how does it change through life?
- Feeling for the 'heft': Is my guinea pig the right weight for their size (BMI)?
5 Underweight
6 Overweight
- Obesity and overweight
- A long term healthy diet
- Exercising time tips
7 Healthy treats and dealing with pester power
1 Health Monitoring: BMI, weighing, poo output and body changes
The importance of the weekly weighing and body check
Regular life long weighing is a vital health monitoring tool. It can help you to spot developing health problems early on when treatment and recovery/chronic illness management are generally much easier to manage.
Knowing how much weight your guinea pig has lost in which space of time can also help you to judge when to see a vet and will help your vet with their own assessment. Being able to put that weight gain into its correct perspective is even more crucial.
Giving the body a weekly onceover at the same allows you pick up slowly developing changes sooner. It also means that you are familiar with the personal quirks and can spot gradual changes better.
Different feedback from BMI, weighing, poo output and body check
But weighing is not your only tool.
Knowing the BMI/'heft'
Equally important is checking a guinea pig’s heft around the ribs. Knowing the BMI is crucial for working out whether your guinea pig is the correct weight for its personal size, or whether it is over- or underweight, so you can put any weight loss into the correct perspective.
Losing 100g in a small or underweight guinea pig is a much more concerning loss than the same in a large or overweight guinea pig. Each guinea pig has a different ideal weight range and this will change over the course of a lifetime. A quick feel whether your piggy's body weight is still in the healthy range or whether they are feeling a bit underweight or overweight can tell you better than the scales whether the change is cause for immediate concern or not; especially with a fluctuating weight or if you haven't been able to monitor regularly for some reason.
Weighing
The body weight doesn't just change over a lifetime but it also changes during the day. Ideally you do the weekly weigh-in and body check at a similar time of the day so you have a direct comparison. If you do it at a different time in the feeding cycle, please don't panic if the weight is a few grams out. The difference between a full and an empty bladder can be as much as 10g and the difference between a big veg dinner can make 40g.
If there are health concerns, please switch to weighing daily first thing in the morning. This does two things at once:
- The weight is at its lowest before breakfast so the feedback is the most honest and best for day to day comparison.
- It also helps you to plan the next 24 hours in terms of any feeding support care needs as to how often to feed etc.
Poo output
It is important to know that it takes about a day for any food to pass from the mouth to the anus (longer if the gut is slow). This means what is coming out at the far en is never up to date; it always running behind events. If you just monitor the poos, you can lose that crucial extra day of stepping in with feeding support and will have to make up a much larger weight loss.
The same goes for monitoring the food intake by eye: you can never tell whether a piggy is eating enough hay (which makes over three quarters of the daily food intake) is eating enough or not by just watching them chew on some cud in their mouth.
What poos can tell you in a general way is whether there is a disturbance in the digestive system and how severe it is. It can also tell you whether you have been feeding enough over the last couple of days or should feed more.
A little guide to 'poopology' - interpreting poos - with some pictures is in this link here: Wiebke's Guide to Poops
Weekly body check during grooming
This helps you to find changes to the body - lumps, swellings, sore feet, a quick look at whether the incisors are looking fine (which generally means that all is well at the back, too), there are no problems with the eyes, ears, genitalia, nipples, skin/hair loss, a distended or hard belly, scabs etc.
Each guinea pigs has their individual quirks, like the shape of the bald patch behind the ears. It may help you to document the body with reference pictures once a year; especially if you have anxiety issues so you have a comparison to check against and you cn avoid some unncessary panics, like discovering that boars have two nipples or the swelling on the side of their genitalia are descending testicles...

As a very rough rule of thumb: If both sides of the body are the same it is more likely to be normal altough you want to check any thinning of hairs.
This guide here also explains how you can use the combination of all these methods for illness support: Weight Loss Explained: BMI, Weighing, Poos and Feeding Support
Wiebke's Guides to the Body is a series of articles about how the body works, what is normal and what are the most common illnesses related to it.
Wiebke's Guides are giving you a very practical overview in learning how a part of the body works, knowing what is normal and learning about various common health problems associated with an organ or part of the body.
Most of these guides are based on articles I have written for Guinea Pig Magazine starting in 2023 and there are hopefully going to be more over time.
The urinary tract
Wiebke's Guide to Pees and Stones
The digestive tract
Wiebke's Guide to Poops
Wiebke's Guide to Tummy Trouble...
Most of these guides are based on articles I have written for Guinea Pig Magazine starting in 2023 and there are hopefully going to be more over time.
The urinary tract
Wiebke's Guide to Pees and Stones
The digestive tract
Wiebke's Guide to Poops
Wiebke's Guide to Tummy Trouble...
- Wiebke
- Replies: 1
- Forum: Health & Illness Support Corner
2 Regular weight monitoring
How often should I weigh?
Please weigh once weekly on your normal digital kitchen scales in combination with a quick top-to-toe health check throughout the whole life of your guinea pigs.
If possible, note down your weights and any small body changes, like the appearance of a small lump. Your log can help your vet when assessing any developing health issues and in making their decisions. Taking pictures of the normal features doe use as reference can help you spot changes, especially if you have anxiety or memory issues.
Guinea pig body quirks - What is normal and what not?
Please keep in mind that over 80% of what your guinea pigs eat in a day is hay. You cannot control this just by watching a guinea pig nibbling slowly on a stalk or chewing on some crud in its cheeks. If you only judge the food intake by how your guinea pigs eat their veg (one tenth of what it should eat!), you can easily miss a massive weight loss because hay is often the first food group that is impacted when your guinea pig is in pain or not feeling well. Guinea pigs are so good at hiding any illnesses until it is often nearly too late, like all prey animals. That is where weighing once weekly is really coming into its own!
Switch to weighing daily at the same time of the feeding cycle (ideally before you feed veg or pellets) if your guinea pig is suddenly looking thinner, ill or is not eating properly.
Because the weight is fluctuating around 30-40g (ca. 1 oz) in a weigh band over the course of 24 hours depending on how full the bladder and the tummy are, weighing at the same time in the feeding cycle will help you to eliminate these fluctuations as much as possible.
I find weighing either first thing in the morning or before serving the evening veg the best times.
When weighing more than once a day, you will have to factor in this weight bandwidth. Especially if you have anxiety/control issues, please ask a partner or family member to weigh your guinea pig for you. Weighing too often will not help your guinea pig and will only increase your anxiety. Recovery and illness support is always somewhat of an up and down; that is why you have to think in in weight bands with a general trend rather than in absolute weights.
We are speaking of weight loss or weight gain only when the difference is beyond this daily swings bandwidth , i.e. when the loss/gain is 50g/1 oz or more.
We would be very grateful if you please could give any weight in grams if you have a weight/health connected problem. We have members from all over the world. Using grams prevents any confusion and misunderstandings for anybody.
Here is a link for converting UK and US pounds into grams: Pounds to Grams conversion
Weighing tips
Normal kitchen scales from a supermarket usually work just fine for your purposes, whether they are mechanical or digital.
Unlike your vet, who needs exact scales to compute dosages, at home you are mainly looking for changes in weight but not exact weights that help you decide when and how quickly you need to see a vet.
Of course if you prefer exact scales for weighing your guinea pigs, you can also find good quality ones in places like amazon or ebay.
Many people find the scales with bowls that sit on top to be ideal, but as long as the pig can fit on the scales almost any type should be fine!
With jumpy pigs you best use a tunnel or a lidded cardboard box, which you weigh separately so you can work out your guinea pig’s weight.
This video guide shows you how you can safely pick up and weigh your guinea pigs without having to handle them and risking blind jumps or accidental falls:
1 Picking up your guinea pigs without chasing or touching (video and pictures)
2 Weighing (video and pictures)
1 Picking up your guinea pigs without chasing or touching
This video shows you what you can train your guinea pig to do for a stress-free pick up.
Alternatively, you can use a small walk-in cardboard box for pick-up and transport. Please make sure that you cover the opening with your hand! If necessary, please cut finger holes into the cardboard box and face the opening...
2 Weighing (video and pictures)
1 Picking up your guinea pigs without chasing or touching
This video shows you what you can train your guinea pig to do for a stress-free pick up.
Alternatively, you can use a small walk-in cardboard box for pick-up and transport. Please make sure that you cover the opening with your hand! If necessary, please cut finger holes into the cardboard box and face the opening...
- sport_billy
- Replies: 0
- Forum: Handling and Making Friends
3 Guidelines for changes in weight
Weight loss guidelines
Here are the guidelines along which you can judge whether and how quickly you need to see a vet.
If in any doubt, please see a vet sooner rather than later. In an emergency, please make an appointment first before asking us!
- 30g / 1 oz: Normal daily weight swing
Any weight gain or loss within this band does not count because the difference between a full bladder and a full gut and an empty bladder and gut can be up to 40g and because the weight is swinging in this bandwidth throughout the day.
- 50g / 2 oz: Go on alert!
Switch to weighing daily at the same time and book a vet appointment if the weight loss continues. See a vet within 24 hours if a guinea pig is losing this amount within 24 hours (i.e. 'promptly') and step in with syringe feeding top up. If the weight loss is much slower but steady, see a vet during regular opening hours within a week, ideally as soon as you can get an appointment during regular opening hours.
- 100g / 3 oz: You need to see a vet as an emergency if the weight loss has happened within in 1-2 days!
If your guinea pig has lost 100g within 24 hours, it has not eaten or drunk at all during this time and is in acute danger of dying.
See a vet or emergency service at any time of the day or night ASAP!
Step in with syringe feeding and watering if your guinea pig can still swallow and process food. Never simply empty a syringe full into the mouth of a severely ill guinea pig!
If the weight loss has happened over a period of weeks or months, please see a vet during regular opening hours within a week, ideally as quickly as you can make an appointment.
Emergency, Crisis and Bridging Care until a Vet Appointment
Sudden mystery weight gain and weight fluctuations
Any sudden weight gain in adult or older guinea pigs should also be investigated. It can be caused by a fluid build-up in the body (potential heart insufficiency) or bloating.
The same goes for any major weight swings in a short time (50-100g repeated up and down)
There can be some seasonal weight fluctuations, especially around the lawn season when guinea pigs gorge on rich fresh grass or during weather extremes.
It also pays to check the water bottles to make sure that they are not blocked or runny, and that the water is drinkable (neither boiling hot nor frozen/ice cold in winter before you make a vet appointment.
Hot Weather Management, Heat Strokes and Fly Strike
Guinea pigs coming from a background of neglect can put on as much as 50-60g/2 oz of weight per week for a short while.
Any major weight gain in a pregnant sow usually happens only during the last 2-4 weeks of a 9-10 week pregnancy when there should be usually other signs visible (noticeably moving and growing baby balls). You won’t notice any signs and certainly not any large weight gain much earlier. How large this late stage weight gain is, depends very much on the size of the litter: whether your pregnant sow carries a single pup or 6-7 babies will have a big influence on any weight gain!
If you are worried about a potential pregnancy, please open a thread in our pregnancy support section. You need to register with the forum and accept our explicit no intentional breeding forum rules in order to access this specially monitored non-breeding section and our comprehensive practical information guides.
Please note that you have to register with the forum and accept our no intentional breeding rules in order to access our Pregnancy and Baby Care section and the following guides.
Any advice and support on this forum will only be given with the express aim to prevent any further pregnancies.
Anybody found in deliberate breach with our very explicit no breeding rules will be summarily banned.
Terms of Service And Forum Rules
Our no breeding and no breed showing forum policy explained
1 Detailed diet information for pregnant and nursing sows...
Any advice and support on this forum will only be given with the express aim to prevent any further pregnancies.
Anybody found in deliberate breach with our very explicit no breeding rules will be summarily banned.
Terms of Service And Forum Rules
Our no breeding and no breed showing forum policy explained
1 Detailed diet information for pregnant and nursing sows...
- sport_billy
- Replies: 0
- Forum: Sexing, Pregnancy & Baby Care (forum members only)