Can Guinea Pigs Eat Grass? Tips for Outdoor Guinea Pigs

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We’ve recently moved into a new house but the garden still needs a lot of work. Once we get around to sorting it and have some grass down we’d like to get an outdoor run for our guinea pigs. The question is though, can guinea pigs eat grass and is it good for them? Here is what I found out:

Yes, guinea pigs can eat grass as part of a balanced diet. They can eat fresh garden grass but may require more regular deworming and flea treatments. It is also important to introduce grass gradually to avoid causing stomach upset.

How Much Grass Can Guinea Pigs Eat

Guinea pigs are natural foragers and digest food very quickly. So as a result, they will continuously eat any food that’s put in front of them.

If you keep your guinea pigs outside on fresh grass they will eventually eat pretty much all of it. My family used to keep guinea pigs outside in the summer. Because of how quickly they ate the grass we would have to move the outdoor run every few days.

So how much grass is safe for guinea pigs to eat?

Generally, guinea pigs can eat as much grass as they like as it is a great source of vitamin C and other nutrients. However, it is important to introduce grass slowly to a guinea pig that isn’t used to consuming it or hasn’t had it for a while.

Can a Guinea Pig Eat Too Much Grass

Wild guinea pigs survive mainly on fresh grass so their stomachs are used to it, but this isn’t the case for most domesticated guinea pigs. As guinea pigs are grazing animals they will sometimes eat just a little more than they should.

A guinea pig that isn’t used to grass can and probably will eat too much, which could result in an upset stomach. You’ll be able to tell if this happens because they will have poops that are wetter and less solid. In rare cases, too much grass can cause bloat which is potentially lethal.

Grass is very rich so if you are just starting your guinea pig out on grass, or if they haven’t had any for a few months, it is recommended to limit how much they consume at first.

Introducing Grass Slowly

To avoid giving guinea pigs an upset stomach, you need to introduce them to grass gradually. So what is the best way to do this?

1. Firstly, give them small handfuls of grass along with or after their other food.
2. Let them outside on grass for a short period of time. Start with 10-15 minutes.
3. Bring them back in and monitor their poop to see if it remains solid and consistent.
4. If their poop becomes very wet and squishy, keep them off grass for a few days and start over.
5. If their poop remains normal, allow them outside for a little longer each day. Increase the time by 10-15 minutes each day and continue to monitor their poop.

Yup, there is a lot of poop monitoring involved here. But checking the consistency of their poop is the best way of determining how their stomachs are reacting to grass (or any food for that matter).

Can Fresh Grass Replace Hay

Did you know that hay is actually specific types of grass that have been cut and dried purposely to become animal feed? I know that probably seems obvious, but I was surprised to find in my research that not everybody knew this.

There are a few reasons I can think of why you might want to replace hay with grass. You may have allergies to hay, or perhaps you just want to save money. But can grass replace hay completely?

No, grass can’t replace hay in your guinea pigs’ diet. But you can provide your guinea pigs with a mixture of both grass and hay.

Grass and hay both have their advantages and limitations, so it is good to know what makes them different.

The Difference Between Grass and Hay

Even though hay is basically just specially dried grass, the two do have notable differences when used for guinea pig food.

Fresh grass is usually more nutritious and contains more vitamin C than hay. This is good news for guinea pigs as they can’t make their own vitamin C and need to consume food that contains it daily. Grass is especially nutrient-rich though, which is why it needs to be introduced gradually.

Hay, on the other hand, is much better than grass for grinding down their teeth, which will continuously grow otherwise. Whilst hay does also contain vitamin C, it usually won’t be as much as fresh grass. This is because hay loses its potency during the drying process. However, hay contains more fiber which helps guinea pigs digest food.

Another plus for hay is that it can and should be given to guinea pigs constantly. No matter how much you give them, good quality timothy hay won’t cause any stomach issues. In fact, hay should actually make up about 85% of a guinea pigs diet.

Important Tips For Outdoor Guinea Pigs

There are some things you need to do and look out for before letting your guinea pigs outside. Always remember to:

• Make sure the grass is dry – Avoid putting your guinea pig outside in early mornings when the grass is covered in dew, or if it has been recently raining.
• Check it is warm enough – Test the warmth of the ground with your hand. If it is cool to the touch it is not suitable for guinea pigs to be out in. Because their bellies are low to the ground they will get cold quickly, which can cause pneumonia.
• Provide shade & shelter – Guinea pigs will need a shaded area so they can escape the sun to avoid overheating. You may even want to place the entire run in shade in particularly warm weather. They also need somewhere to hide or they can become scared and stressed.
• Provide water – Attach a water bottle to their run or hutch. Guinea pigs need constant water especially in hot weather to prevent dehydration and heatstroke.
• Secure the run – Make sure the run is firmly touching the ground on all sides to stop them escaping, and you fully cover the run to prevent cats or other predators from getting to your guinea pigs.
• Check for harmful items – Check the area first for anything that may harm your guinea pigs. Look out for things like animal feces, sharp objects, and poisonous plants.

Extra Tip – Keeping guinea pigs outside puts them at a higher risk of getting worms and fleas. Because of this, they may need more regular deworming and flea treatment. You can read how to spot and treat fleas here.

Recommended Outdoor Enclosures

The easiest way to meet all the above requirements is by using an outdoor enclosure that is purposely suited for guinea pigs. Below are two types of outdoor enclosure I would recommend, depending on your needs.

Outdoor Playpens

If you plan to only have your guinea pigs outside for short amounts of time whilst you can supervise them, your best bet is going to be a simple cage pen with a net cover. These are perfect for short outdoor play sessions as they are fairly inexpensive. Click here to check prices on Amazon.

Outdoor Hutch with Run

If you need an outdoor run that you can leave your guinea pigs in for a few hours, then a more sturdy and protected run with a hutch compartment will be better suited. These are a great choice because you can leave your guinea unsupervised and they provide protection from the sun and predators. Click here to check prices on Amazon.