Guinea pig temperature guide: too hot, too cold and just right

Do guinea pigs need a heat pad?

Most indoor guinea pigs do not. In a room that stays at 17 to 20°C (63 to 68°F), a pair with a thick hay pile and a hide each will keep themselves warm. A heat pad earns its place in three situations: guinea pigs living in a hutch, shed or garage through a cold spell, a room that drops below 15°C (59°F) at night, and a guinea pig that is very young, elderly, thin or recovering from illness.

The safest kind is a microwave pet heat pad. SnuggleSafe, the best known, is a solid disc 21 cm (8.3 in) across and 28 mm (1.1 in) thick that stays warm for up to 10 hours. It can only be heated in a microwave, never on a hob or radiator, and the maker warns that water-filled and wheat-filled warmers are not bite-resistant. Burgess suggests a couple of microwave pads, warmed each evening, during cold snaps for outdoor rabbits, and the same approach suits guinea pigs.

Electric heat pads with a cable are a different matter. Guinea pigs chew anything at their level, and no charity guidance we found recommends a plugged-in pad inside a guinea pig enclosure. Our view, reasoning from that, is to skip electric pads unless the cable is fully outside the cage and the pad sits under the floor, never inside it.

How to use a heat pad safely

1. Heat it exactly as the maker says. Microwave the pad uncovered for the time given in its instructions for your microwave's wattage. Only reheat it once it has cooled right back to room temperature, or it can overheat and split.
2. Cover it. Slide it into its fleece cover, or wrap it in a folded towel, so no hard hot surface touches their skin.
3. Put it at one end only. Place it in or under the bedroom hide, under a layer of hay or fleece, so the rest of the floor stays at room temperature. A guinea pig that gets too warm must always be able to walk away.
4. Give one per hide. In a pair or group, offer a warm spot in more than one hide so a bossy guinea pig cannot claim the only one.
5. Check it every day. Look for chew marks, cracks or any leaking. A damaged pad goes straight in the bin.

What temperature is right for guinea pigs?

The RSPCA says room temperatures of 17 to 20°C (63 to 68°F) are ideal. The MSD Veterinary Manual gives a slightly wider comfortable band of 18 to 24°C (65 to 75°F), and Purdue University's vet school says they prefer about 18 to 20°C (65 to 68°F). We follow the RSPCA's narrower range, because guinea pigs cope with gentle cool far better than with warmth.

Stable matters as much as the number. The RSPCA warns that guinea pigs handle sudden changes poorly. A cage next to a radiator, a sunny window, a back door or a tumble dryer can swing by several degrees in an hour. Put the cage against an inside wall, out of direct sun and draughts, and away from heaters. Our guide to guinea pig cage setup has layouts that keep the warm bedroom and the cool open space apart.

How cold is too cold for guinea pigs?

Below 15°C (59°F) is too cold for most guinea pigs. That is the point where the RSPCA says outdoor guinea pigs should come indoors, because they can become chilled. Burgess adds that very young, elderly or unwell guinea pigs must come in once overnight temperatures drop below 10°C (50°F), and offers a handy rule: if it is too cold for you to sit outside in a jumper, it is too cold for them.

Cold on its own is only half the problem. Damp and draughts make it far worse, and Burgess notes that guinea pigs are at risk of pneumonia from chest infections. Signs a guinea pig is too cold include sitting hunched and puffed up, cold ears and feet, eating less and staying buried in hay. A guinea pig that is cold to the touch, floppy or breathing noisily needs a vet the same day. See our guinea pig health guide for other warning signs.

How to keep guinea pigs warm in winter

• Move them indoors, or put the hutch inside a shed or car-free garage with natural daylight.
• Move them gradually: a few days in a porch or shed first helps them adjust.
• Pile extra hay into every hide and the sleeping area, and top it up daily.
• Give a covered microwave heat pad in the bedroom on the coldest nights.
• Keep the hutch raised off the ground and covered against wind and rain, with a gap for fresh air.
• Check water bottles several times a day for ice, including the metal spout; a sock or bubble wrap round the bottle helps.
• Offer more hay than usual, as they burn more food keeping warm.
• Never feed frosty or frozen greens.
• Change wet bedding at once, because wet bedding can freeze overnight.

Once guinea pigs come in for winter, Wood Green says to keep them in until outdoor temperatures are close to indoor ones, rather than putting them back out on the first sunny day. Our guide to guinea pig bedding covers which bedding stays warm and dry.

How hot is too hot for guinea pigs?

Anything above 26°C (79°F) is dangerous for guinea pigs. The RSPCA says temperatures above 26°C can cause heatstroke, PDSA says above 27°C (81°F), and Purdue puts the line at 80°F (27°C). PDSA adds that they can be uncomfortable from 24°C (75°F). Guinea pigs cannot sweat, their thick coats trap heat, and Purdue warns that an overheated guinea pig can die within minutes.

The danger comes faster in a small space. A hutch or cage in direct sun, a glass conservatory, a plastic igloo or a room with the heating up can pass 26°C (79°F) even on a mild day. Wood Green warns that plastic pods and igloos can get hot enough to be fatal in summer, so swap them for wooden or fabric hides when the weather warms up. Long-haired breeds and heavier, older guinea pigs struggle soonest.

What are the signs of heatstroke in guinea pigs?

Purdue lists the key signs as being listless, lifting the head up, and fast, shallow breathing. In practice that often looks like a guinea pig lying stretched out flat that does not move when you come near, with ears that feel hot to the touch. Stretching out flat on a warm afternoon is normal on its own. Flat plus fast breathing plus not reacting to you is an emergency.

What to do if your guinea pig overheats

1. Move them somewhere cool. Take them out of the sun and into the coolest, shadiest room you have, away from other animals and noise.
2. Cool them gently. Purdue advises wrapping the guinea pig in a towel soaked in cool water, or spraying them with cool water. Use cool tap water, not ice water, which can shock the body.
3. Offer water. Hold a shallow dish of fresh water near them, but never force water into the mouth of a guinea pig that is not swallowing.
4. Ring a vet straight away. Call while you are cooling them, even if they seem to perk up. Purdue warns that overheating can kill within minutes, and a vet can check for harm you cannot see from the outside.

How to keep guinea pigs cool in summer

• Keep the hutch or run in full shade all day, remembering that shade moves as the sun goes round.
• Indoors, close curtains on sunny windows and keep the cage out of conservatories.
• Swap plastic hides for wooden, willow or fabric ones.
• Give two water sources and check them twice a day.
• Offer watery greens such as cucumber and lettuce as part of their normal veg.
• Give them a cool spot to lie against, such as a pet cooling pad or a frozen bottle of water wrapped in a tea towel.
• Keep airflow going, without a fan blowing straight at them.
• Check bottoms twice a day in warm weather for flystrike, as the RSPCA advises.

Short spells on the lawn are lovely in mild weather, but a vet in Chewy's outdoor guide says to skip them above 80°F (27°C), keep sessions to about 30 minutes and always give shade. Our complete guinea pig care guide covers the rest of their daily needs, and our page on guinea pig cage size explains why a roomy cage stays cooler than a cramped one.