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How To Help Your Guinea Pig Gain Weight Safely

Guinea pigs typically have no problem gaining weight, and if you are not careful, you will end up with an overweight pet.

However, weight loss in guinea pigs may be a clinical sign of a serious illness or parasite infestation.

If you notice weight loss or a lack of appetite in your guinea pig, you need to seek veterinary care as soon as possible.

Once you have determined the underlying condition causing your guinea pig’s weight loss, your pet will be able to gain weight again after treatment.

But how do you safely help your guinea pig gain weight?

It is important to offer your guinea pig foods to help it gain weight, but the process must be done slowly. If you overfeed your guinea pig, they will gain weight too rapidly. Their body will not adjust correctly, and your pet will suffer from new health issues.

When a guinea pig gains weight too quickly, it could lead to diabetes or digestive problems.

Fatty deposits may accumulate around the guinea pig’s organs, such as the heart or liver, leading to heart disease or organ failure.

Read on to learn how to help your guinea pig gain weight safely to avoid causing more health issues.

how can i help my guinea pig gain weight

What Causes Weight Loss in Guinea Pigs?

Guinea pigs will lose weight for various reasons, including dental issues, diseases, a lack of nutrition, and environmental changes.

Weight loss is the most common symptom of guinea pig health issues.

It is crucial for guinea pig owners to monitor their pets regularly so signs of illness or weight loss are spotted more easily.

If your cavy has lost more than 5% of its body weight, it is crucial to seek veterinary care as soon as possible for a proper diagnosis and treatment.

This section provides details on some of the major causes of weight loss in guinea pigs.

Dental Issues

overgrown guinea pig teeth

Malocclusion, or misaligned teeth, may happen to any guinea pig more than a year old, and it is often an inherited problem.

When a guinea pig has a severe underbite or overbite, the animal will have difficulty chewing.

Eating may be painful for the cavy, and it will eventually stop eating altogether.

Other dental problems common in guinea pigs include the formation of abscesses, irregular tooth wear, and elongated teeth or tooth roots.

Sharp spurs may also develop, causing ulcerations on the guinea pig’s cheeks or tongue.

If these dental issues are left untreated, the cavy could very easily starve to death.

Disease or Parasites

Viral or bacterial infections will cause a guinea pig to lose weight rapidly, and gastrointestinal diseases are very dangerous and painful for the small animal.

Urinary tract infections are common in cavies, and they may be severe enough for the animal to lose its appetite.

Respiratory infections will also cause a guinea pig to eat less.

Diabetes is also a common disease in guinea pigs, and weight loss is a very notable symptom along with excessive thirst.

Guinea pig obesity is the number one cause of diabetes in these small animals.

If a guinea pig has a worm or parasite infestation in its stomach, the animal will not be receiving enough nutrients from its food, and the digestive system will be weakened.

Many of these diseases are treated with medication, so your cavy can eat again.

Lack of Nutrition and Dehydration

When a cavy is not receiving essential nutrients, it will fail to thrive and grow.

A vitamin C deficiency will cause lethargy, hair loss, and weight loss.

If you have more than one guinea pig, the dominant guinea pig may be bullying the other one and eating most of the food.

The bullied guinea pig will suffer from malnourishment and begin to lose weight.

Dehydration is an often overlooked cause of weight loss, and your guinea pig needs to drink water.

Provide your cavy with a varied and nutritious diet, and always make sure it has access to fresh, clean water at all times.

Environmental Changes

Sudden changes to a guinea pig’s habitat will cause the animal to become stressed and eat less.

These include changes in temperature or lighting and the addition of another cavy.

Aim to keep your guinea pig’s environment stable to avoid causing your pet any unnecessary stress.

If you decide to get your guinea pig a new companion, their introduction should be done slowly.

What Is The Appropriate Guinea Pig Weight Range?

what is the appropriate guinea pig weight range

It is important to weigh your guinea pig regularly to monitor any weight gain or loss changes.

A baby guinea pig will rapidly gain weight when growing, sometimes between 20-30 grams per week.

Eventually, this weight gain will taper off until your guinea pig has reached its full adult size in 9-12 months.

The table below illustrates the average weight of a healthy guinea pig according to its age.

Guinea Pig AgeAverage Weight
2 weeks150-250 grams
4 weeks285-400 grams
6 weeks350-550 grams
8 weeks400-700 grams
10 weeks500-800 grams
12 weeks550-900 grams
14 weeks600-950 grams
12+ months800-1100 grams

Is your guinea pig too heavy? Look at our article on how to help a guinea pig lose weight.

Tips For Helping Your Guinea Pig Gain Weight Safely

If your guinea pig has suffered weight loss, it is your job to help it gain weight safely.

Feeding your pet loads of high-calorie foods or fatty treats will not only result in a fat guinea pig but may cause more health problems.

A guinea pig needs to gain weight slowly for its body to adjust properly.

Weigh your guinea pig every week to monitor any weight gain or loss changes.

Consult A Veterinarian

The most critical step in helping your guinea pig gain weight is to make an appointment with a veterinarian to determine the underlying cause of the weight loss.

If your pet is sick, the veterinarian will give the animal medication to make it healthy again.

Sometimes the weight loss occurs due to a poor diet, and the vet will be able to provide you with a nutritious diet plan for your cavy.

Offer A Balanced Diet

guinea pigs eating watermelon

Providing your guinea pig with a varied and nutritious diet will help your pet gain and maintain a healthy weight.

For a cavy to stay healthy, its diet should consist of 80% hay, 15% vegetables, and 5% pellets every day.

Treats may also be given to your guinea pig, but you must be careful not to offer them too much, or you put your pet at risk of becoming overweight.

Always feed your pet high-quality hay, a healthy variety of vegetables, pellets enriched with vitamin C, and clean freshwater.

Feed Critical Care

Critical Care is a supplement powder you mix with water and give to your guinea pig when it is having trouble eating due to an illness or recent surgery.

Critical Care provides the nutrients and fiber your pet needs, but it should always coincide with a nutritious diet.

If your cavy does not seem to like the flavor of the Critical Care supplement, mix it with plain organic baby food in a banana or apple flavor.

If the animal still refuses it, you may need a syringe to feed your guinea pig Critical Care.

Offer Oats

Plain, uncooked steel-cut oats are another food to help your cavy gain weight.

Be careful not to give your pet too many oats, as they may cause the animal to become overweight.

You only need to add about one teaspoon of oats to your guinea pig’s pellets every day until the animal has reached a healthy weight.

Provide Alfalfa Hay

guinea pig eating alfalfa hay

Alfalfa hay is very high in calories and rich in calcium.

Baby cavies are fed alfalfa hay to help them gain weight and grow strong bones.

Alfalfa hay also helps pregnant or nursing guinea pigs by providing them with the extra calories they need for their growing babies, and the added calcium keeps their milk flowing.

Once the guinea pigs are six months old, they need to be weaned off of alfalfa hay and given a lower-calorie nutritious option, such as orchard or timothy hay.

Healthy adult cavies should not be fed alfalfa because they will quickly gain weight and become obese.

Handfeed Separately

If you have more than one guinea pig, it may be challenging to determine if the animals are receiving enough nutrition.

Dominant cavies may bully smaller ones and prevent them from getting enough food.

If one of your guinea pigs seems smaller than the others, remove the animal from the enclosure and feed it by hand.

It may also be helpful to have two bowls of food in the cage so each cavy will have access to food without separating them.

Provide Pea Flakes for a Snack

Pea flakes are made from dried split green peas, and they are a very healthy snack to offer your guinea pig.

Add some pea flakes to the pellet food to help an underweight guinea pig gain weight.

Once the guinea pig has reached a healthy weight, cut back to just one or two pea flakes a day as a treat.

Give Your Pet Benebac

If your guinea pig has lost weight due to an infection, it is likely the animal has been taking antibiotics.

Antibiotics will disrupt the healthy bacteria in a guinea pig’s stomach, making it difficult for their body to properly absorb nutrients from food.

Benebac is a probiotic designed to replace the healthy bacteria in your pet’s stomach.

The probiotic comes in a gel form, and it is given to a cavy within two hours of its dose of antibiotics.

It is recommended to keep giving the guinea pig a dose of Benebac every day for the week after the antibiotics run out.

This ensures your pet’s healthy gut bacteria is completely restored and stable.

Feed Extra Vitamin C

Vitamin C is a natural immune booster, and it will also provide your guinea pig with some energy.

Giving your pet a boost of vitamin C will increase its appetite and help the animal recover more easily after being sick.

Aside from enriched pellets, there are also several foods rich in vitamin C, including:

  • Bell peppers
  • Strawberries
  • Snow peas
  • Parsley
  • Mango

Avoid using vitamin C drops, as they will change the taste of your guinea pig’s water and cause the animal to avoid drinking it.

Foods To Help Your Guinea Pig Gain Weight

foods to help your guinea pig gain weight

It is essential to provide quality nutrition to help your guinea pig gain weight.

Avoid feeding your pet high-calorie “junk food,” as this will easily lead to obesity and other health issues.

Instead, choose foods loaded with essential nutrients to help your cavy gain weight naturally.

When adding new foods to your guinea pig’s diet, do it slowly to avoid digestion issues.

For a deep dive, check out what a guinea pig can eat in our detailed guide.


Hay is a staple of a guinea pig’s diet, and you may provide them with unlimited amounts of it.

The most common hay varieties for cavies are timothy hay, orchard grass, botanical hay, and meadow hay.

Other types of hay contain more calories, which will significantly benefit sick and underweight guinea pigs.

Alfalfa is the most common high-calorie hay, and it is only given to underweight, pregnant, nursing, or baby guinea pigs.

Do not feed alfalfa hay to healthy adult guinea pigs.

Not only will the excess calories in alfalfa cause them to become overweight very quickly, but the high amounts of calcium may cause urinary tract issues, such as bladder stones.

However, alfalfa works well as a temporary food to help a guinea pig gain weight, and it is also a good source of protein.

Readigrass is another hay with a high protein and fiber content, but it is more difficult to find.

A moderate amount of readigrass may be added to your guinea pig’s staple hay for a boost in weight gain.

Oat hay is also high in fiber but low in calcium, so it is safe to add to a guinea pig’s diet.

The high amount of fiber will help with weight gain and overall gut health.


It is important to provide your guinea pig with at least one cup of fresh vegetables every day as part of a healthy diet.

guinea pig eating vegetables

Vegetables are rich in vitamin C and other essential nutrients your guinea pig needs.

Limit cruciferous vegetables because they may cause gas, and instead focus on leafy vegetables.

Here are some cruciferous vegetables that should be off your guinea pig’s menu:

Carrots and fruits contain a lot of sugar, so they need to be given in moderation.

We have compiled a table of safe veggies that you can feed your piggy.

Best Vegetables for Guinea PigsOptional Vegetables for Variety
Bell peppersClover
TomatoDandelion greens
Non-iceberg lettuceChickweed
Pesticide-free grassSweet corn, corn silks, and husk

Always feed your guinea pig organic produce and wash it thoroughly to prevent pesticide ingestion.


Your guinea pig will benefit from eating a small amount of high-quality pellet food every day for variety.

A guinea pig only needs 1/8 of a cup of pellets in its daily diet.

Most pellets are derived from timothy hay and contain vitamin C and other nutrients.

Always read the label on the pellet package to ensure they are not expired, and choose a brand offering stabilized vitamin C since it will degrade over time.

If your guinea pig is suffering from bladder stones, do not feed pellets because this will worsen the animal’s condition.

To help a guinea pig gain weight, you may temporarily choose alfalfa-based pellets.

Since alfalfa pellets are very high in calories, they are usually reserved for sick, underweight, pregnant, or baby guinea pigs.

If your guinea pig has trouble eating, you may add water to the pellets to make them easier to eat.

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