Rapid Weight Loss In Guinea pigs – Causes, Treatment, Diet

When it comes to guinea pigs, weight is directly tied to health. Just like with humans, massive weight gains or losses can be a cause for alarm.

Cavies are such small creatures that even slight changes make a significant impact on their overall wellbeing. A shift in weight could signify a deeper health issue that needs to be addressed by your vet as soon as possible.

You should learn how to monitor your pet’s weight and keep them on a healthy diet to ensure they live a long and healthy life.

How much do guinea pigs weigh?

When they are born, guinea pigs only weigh around 100g. They reach their full weight within about eight months. The average adult male guinea pig weight around two to three pounds and females weigh 1.5 to 2.5 pounds, I recommend you to read this great book, very helpful for new guinea pig owner. 

Exact weights will be different for every piggy. To determine your cavies’ average weight, weigh them several times around the time they turn one because they are newly full-grown. Take the average weight and consider it the norm for your furry friend.

How can you maintain a guinea pig’s weight?

Guinea pigs can gain or lose weight very quickly, this is my guide to learn some nice tips & facts about the piggies. Given their smaller size, even slight changes in their weight can be drastic for their health. A quarter of a pound may not seem like much to a human, but it represents almost a fourth of their body weight.

Guinea pig owners should weigh their pets on a regular basis to keep track of their weight. Regularly weighing them may seem like a lot of work, but it can save their life if they experience health issues that lead to weight loss.

To help you remember this task, consider setting a reminder on your phone or some other alert. Consistently checking their weight will provide necessary insight into their overall health. You can also spot issues quickly instead of waiting for them to become more severe.

Is it normal for guinea pigs to lose weight?

If their weight goes up or down slightly, it is probably not a reason to be concerned. However, if you notice a dramatic decrease in their weight, you may need to take action, I’ve owned a lot of piggies over the years and this is my secret resource when you have any questions.

If they lose more than 5% of their body weight, you should check in on their health.

Guinea pigs lose weight for a variety of reasons. While some of these reasons may work themselves out over time, others can be severe or life-threatening.

It is essential to check in with your vet if you are concerned about their weight. The vet can help you find the root of their weight loss and determine an appropriate plan of action.

Weight loss may be caused by:

  • Changes in their diet: Are they eating less than usual? Do they seem uninterested in food? Have you started feeding them a new product, vegetable or fruit? A change in their diet can cause them to stop eating altogether.
  • Changes in their environment: Did you recently move homes? Is there a new guinea pig sharing their crate? Have you introduced them to new people? Even changes in the lighting and climate of a room can significantly impact a little piggy’s health and weight.
  • Extreme temperatures: If they are subjected to very hot or very cold temperatures, they can react poorly. One possible reaction is weight loss.
  • Infections: A bacterial or viral infection can cause them to lose an unhealthy amount of weight in a short period of time. Stopping their weight loss should be your first priority.
  • Ketosis: Their liver could be producing excess digestive byproduct, causing weight loss.
  • Teeth issues: If they have an overbite or under-bite, they may find it challenging to eat. Also, if they have broken teeth recently or are suffering from reduced tooth strength, they may not be interested in food.
  • Lack of water: Dehydrated cavies will suffer from weight loss. It is essential to keep them hydrated with plenty of freshwaters throughout the day.
  • Stress: Just like humans, higher levels of stress can cause drops in weight. Do they seem more skittish or nervous than usual? Look for changes in their environment that could cause additional stress.

Do guinea pigs lose weight as they get older?

Guinea pigs typically live between five and seven years. As they get older, they may be pickier about their food. If they gobbled up fruits, vegetables, treats, and hay when they were young, you could notice a significant reduction in their food consumption over time.

This change in their diet could cause guinea pigs to lose weight as they get older.

If you notice this pattern occurring with your aging cavy, break their meals up into smaller meals. Uneaten food should not be left out in a crate.

By providing only the amount they will eat, you can avoid wasting food and serving them unsafe items. Their intake of vitamin C can also help older guinea pigs as they lost weight.

This nutrient is essential in assisting them in fighting off illnesses and maintain their appetite.

Does my guinea pig need to lose weight?

Weight loss is not the only concern for most cavies. Significant weight gains can also be dangerous to their health. If they are overweight, they may suffer the following problems.

overweight guinea pig

  • Increased strain on their heart
  • A decrease in liver health
  • Poor join health
  • Development of diabetes
  • Difficulty breathing
  • Cancer

If your piggy needs to lose weight to return to a healthy status, you can change their diet. Stop giving them sugary treats and limit the number of fruits you provide each week.

These foods can dramatically increase their weight over time.

Also, make sure they are getting plenty of exercise. They should have enough room in their crate to run around. If not, give them ample time outside of the crate to stretch their legs or add a more extensive run onto their current cage.


Your cavy’s weight can be a great indicator of their health. If they weigh around the average (1.5 to 2.5 pounds), there is no need for concern.

However, if they gain or lose weight more than usual, you should check in with the vet. Weight loss can be a sign of a more severe health issue, and weight gain can lead to diseases and diabetes.

Monitoring their weight on a regular basis will help you keep track of even the slightest change in their health and make the necessary improvements.

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