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Why Is My Guinea Pig Losing Weight? (Causes & Diet Suggestions)

Why Is My Guinea Pig Losing Weight? (Causes & Diet Suggestions)

Weight is a significant health indicator for guinea pigs. Losing weight can be a major concern for guinea pig owners. Many guinea pig owners struggle to find the answer to “why is my guinea pig losing weight?” So, I decided to do a little research and consult my veterinarian friend to find the answer to all of your concerns.

Malnourishment, improper diet plan, dental problems, stress & other health issues can trigger weight loss in guinea pigs. Continuous Weight loss in guinea pigs can be fatal for their life. Always visit a veterinarian if you see any signs of illness accompanied by weight loss in them.

There can be a variety of factors that can lead to weight loss in guinea pigs, although a small variation over weeks is normal(20-50grams).

Anything above a 100gram should trigger your alarm. There have been a lot of instances of high mortality rate in guinea pigs after continuous weight loss for a few days.

If you see any other symptoms of diseases or your guinea pig weight is going down every passing day, then you must consult a professional veterinarian immediately.

If you want to learn more about some common diseases in guinea pigs and what are its symptoms then you can read our article on it: Common health issues in guinea pigs?

Signs that guinea pig is underweight?

Guinea pigs are supposed to be slim; however, if they are underweight, they can become too skinny.

You can tell they are malnourished even with a slight touch of their bodies. However, experts recommend you to weight your guinea pigs every week to track their health.

Some guinea pig owners don’t weight their guinea pigs regularly, and it can be tough for them to decide whether their guinea pig is losing weight or not.

I personally use a digital kitchen scale. I place a guinea pig in a basket and place the basket on top of the scale. Pretty easy to do it this way and the scale is really precise as well.

Weighing Your Guinea Pig: What You Need to Know!

So, if you haven’t weighted your guinea pigs in the past or have just brought in a new guinea pig a few weeks back, then you can look out for these signs to find out if your guinea pig is underweight.

  • Their ribs, spine & pelvis can be felt or seen prominently.
  • The abdominal curve seems to be caved in. (Usually, guinea pigs have a smooth feel, and you won’t be able to tell the difference between their last rib and abdominal cavity.
  • The coat and skin feel rough and puffed up.
  • You will notice less dropping around the cage.
  • They squeak a lot.

Lethargy, Unwillingness to move & sleeping a lot is also a symptom that underweight guinea pigs have.

If you notice such symptoms, then it indicates something is definitely wrong with your guinea pig health. You should seek medical advice immediately.


If you are weighing your guinea pigs regularly, you can quickly tell if your guinea pig is underweight on not.

Although the weight might differ depending upon the breed, age, and size of your guinea pig. Still, here is a rough idea:

  • The average weight of an adult male guinea pig is between 900-1200 grams
  • The average weight of an adult female guinea pig is between 700-900 grams.

If your guinea pig is below these standards, then you can consider them underweight.

What causes weight loss in guinea pigs?

There can be a lot of reasons that can cause weight loss in guinea pigs. While it can be concerning for guinea pig owners if their guinea pig is losing weight consistently, it is crucial to address the issue immediately.

Many people often struggle to find the cause of weight loss in their guinea pigs. So, I decided to ask my veterinarian and share some primary factors that can trigger weight loss in guinea pigs. Here are a few to start with:

  • Overgrown teeth are often a common reason. Guinea pigs do have ever-growing teeth, and sometimes it can grow and hurt their food pipe or gums. This usually causes a lot of pain, and thus they cannot consume their food properly.
  • Malnourishment from an early age can often be the reason your guinea pig never reached their potential bodyweight or had a robust growth.
  • Gastrointestinal diseases & other health problems can often lead to abnormal growth and poor appearance.
  • Improper diet or poor quality hay often leaves the nutrients off-balanced. It is recommended to provide good quality hay and pellets to your guinea pigs.
  • Dominant guinea pigs get all the food, and the other one is left with remainings; thus, they are malnourished as the dominant guinea pigs consume most of the food.
  • Stress can also lead to loss of appetite in guinea pigs. Improper living environment, loud noises, other pets like dogs and cats in the house, etc. are some common factors that lead to stress in guinea pigs.

Apart from all these, there can also be some significant health issues in guinea pigs that can lead to a loss of weight in guinea pigs.

The metabolic issue, respiratory issue, Urinary tract infection, and organ failures are some of them. You need to look out for other signs alongside to determine if your guinea pigs have some other health issue as well.

Do guinea pigs lose weight in summer or winter?

The weight of your guinea pigs has nothing to do with the season. Whether it’s summer or winter, your guinea pig’s weight won’t be affected by it.

However, your guinea pigs might look a little bigger in winter as they grow some extra fur in the winter. They do so for extra insulation so that they can stay warm even if the temperature drops down.

They will shed their hair again before summer, which makes them lighter and a little smaller in appearance. Although the appearance has nothing to do with weight, the extra fur can increase or decrease weight by a few grams, but nothing significant to be noticed.

If your guinea pig is losing weight, then it might be due to some other reasons, and the weather has nothing to do with it.

Learn more about shedding in guinea pigs and what you need to do to take care of them during that time.

Guinea pig losing weight & drinking a lot of water

If your guinea pig is losing weight and drinking a lot of water(more than usual), then it can be a sign of diabetes in them.

Diabetes is common in guinea pigs, and losing weight is a common sign of the same. Look out for other symptoms like:

  • Rapid cataract formation
  • Frequent urination
  • Frequent Urinary tract infection
  • Chronic wet bottom

If you notice any of these signs, then we can confirm that your guinea pig is suffering from diabetes.

Emerson Animal Health 5/1/18 - Guinea Pigs

Diabetes can be treated by controlling their diet and medication. It is recommended to visit a vet ASAP for further diagnosis and prescription.

Guinea pig losing weight but eating

If your guinea pig is eating their regular diet and still losing their weight, it could be because of either of these reasons:

  • Diabetes
  • Unable to extract nutrients
  • Lack of proper balance in their diet

If your guinea pig is suffering from diabetes, then they can lose some serious weight very quickly. It is recommended to look out for other signs of diabetes and consult a vet ASAP.

Sometimes guinea pigs have some worms or parasites in their gut. These parasites often suck the nutrients out of the food your guinea pigs consume.

Also, some guinea pigs have a weak digestive system as it gets incapable of absorbing all the nutrients from the food. You will notice such guinea pigs will start eating their own poop a lot to reabsorbs the extra nutrients; however, it may not be enough.

A vet would be able to diagnose the guinea pig thoroughly to guide you for further treatment.

Apart from these, even an unbalanced diet can lead to weight loss in guinea pigs.

If your guinea pig eats more vegetables and less hay, then their body doesn’t gain enough calories and fiber, which they need to maintain their body weight.

It would be essential to make the necessary changes to their diet and consult a vet as well.

Guinea pig losing weight and not eating

A loss of appetite is directly proportional to the loss of weight. If your guinea pig is not eating their food properly, then they are going to lose weight ultimately. A loss of appetite could be because of various reasons:

  • Dental problems
  • Respiratory and urinary infection
  • Poor quality food

If your guinea pig is losing weight and has stopped eating, you should definitely visit a vet ASAP. There could be some serious health issues affecting the diet of your guinea pigs.

If your guinea pigs are not eating their veggies properly then we have an ultimate guide for you which can definitely help you. Check it out at: Why is my guinea pig not eating their veggies?

Guinea pig losing weight and hair

Weight loss accompanied by hair loss is usually a sign of mites in guinea pigs if your guinea pigs are suffering from mites, you might need to look out for other symptoms as well.

  • Thick skin coat followed by yellowish and crusty skin
  • Lethargy
  • Unwillingness to move
  • Hair and weight loss

If left untreated, mites can lead to convulsion and death in guinea pigs. It is recommended to visit a vet if you see signs of mites.

Sometimes, shedding can also lead to hair loss in guinea pigs. However, it doesn’t affect the diet or weight of your guinea pigs. So you might need to look out for signs of other diseases.

Old guinea pig losing weight

It is quite reasonable for old guinea pigs to lose weight. Once your guinea pigs pass a certain age(5-6years), some changes start to show up. The loss of weight can be because of various reasons, including:

  • Loss of appetite that happens naturally
  • Age-related illness
  • Slower gut-processing of food, thus not eating properly.

Whatever the cause is, your guinea pigs will lose weight as they get old. It is something unavoidable, and there is not much we can do about it apart from taking good care of them.

So, now that we have learned different causes of weight loss in guinea pigs, we can work around a solution for them.

How to help guinea pig gain weight?

If your guinea pig has lost weight or is underweight, then you can do a few things to increase their weight.

But before you try anything, you must consult your vet regarding any health issues which can be causing weight loss in guinea pigs.

Sometimes gastrointestinal parasites, dental problems, or even stress could be the reason behind weight loss.

Once everything is clear, we can try some other ways so that our guinea pigs gain some weight. Here are a few tips to follow

  • Introduce some extra pellets into your guinea pig’s diet. However, make sure your guinea pigs don’t have a history of bladder stones as pellets can be bad for such guinea pigs.
  • If you are using hay from tractor supply or some other cheap ones, replace them with 3rd cutting timothy hay.
  • Never try to put too many calories into their diet at once. If you decide to put on their weight at once, things might go even worse as their digestive system can get off-balanced. Introduce food lowly for gradual weight increase.
  • As experts recommend, Feed Oxbow critical care or Sherwood pet recovery formulae at least twice daily. It contains some vital nutrients which can help in putting up some weight as well.
  • Add occasional treat in the form of fresh fruits like apple, banana, kiwi, etc.
  • You can also add some oatmeal in their diet as it helps in gaining weight and is really healthy as well.
Feeding a guinea pig Oxbow critical care

Always keep in mind that guinea pigs have a sensitive digestive system, and introducing new food quickly or frequent changes in their diet can lead to health issues in guinea pigs.

Best food for an underweight guinea pig?

The balanced diet for a guinea pig is 80% hay and rest should be a mix of vegetables, fruits, and pellets.

If your guinea pig is underweight, you should focus on feeding good quality hay, a cup of fresh veggies, and some extra pellets. I would suggest starting with 3rd cutting timothy hay of a good brand.

It would be wise to split up the vegetables in two to three feeding of small sizes rather than one large one.

Try offering more Bell Peppers, lettuce, tomatoes, cilantro, etc. It would be best if you also feed the 1/6th cup of pellets to your guinea pigs daily.

Make sure you serve good quality pellets only. vitamin c fortified pellets would be a better choice.

High-calorie foods for guinea pigs

Some good choice of high-calories food mix which you can feed to your guinea pigs are as follows:

Corn kernelBanana
Bell peppersWatermelon
Lettuce(Except iceberg)Apple

However, make sure you don’t introduce new food quickly. Also, avoid feeding food more than once or trice a week as it also contains high sugar, which can further lead to health issues like diabetes & cancer in guinea pigs.

I would also highly recommend you read out these articles for learning more about guinea pig’s diet.

Sources: CARING FOR YOUR GUINEA PIG, Weight Loss in Guinea Pigs, THE DEPLETION OF VITAMIN C, Discussion with a vet, Guinea Pig Size-O-Meter

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