Guinea pigs are vulnerable to heat. Originally native to the cold heights of the Andes, these animals are better suited to cooler temperatures¹. Guinea pigs have no sweat glands, and heat regulation by means of sweating is not possible for them, meaning these rodents are exposed to great health risks in summer². 

Temperatures of 26°C and above can leave them susceptible to heat stress, which can cause fatal heat stroke.^2,3 Long-haired breeds of guinea pigs, those with thick fur, older animals, and overweight guinea pigs are especially at risk.^4,5 However, whether kept indoors or outdoors, a few simple measures can be used to keep guinea pigs cool in the summer.

Providing shade and good air circulation is essential for guinea pigs kept both indoors and/or outdoors. Simple but helpful measures are:

Indoors:

• Darken windows: this provides relief from direct sunlight
• Allow air to circulate the room when it is cooler in the evening (but be sure to protect guinea pigs from draughts!)
• Place bags of frozen ice, or cool packs wrapped in cloth in the enclosure

Outdoors:

• Choose a shaded place for the enclosure
• Use umbrellas, cloths, sun sails, or similar items to provide shade over unprotected areas of the enclosure
• Include tunnels for additional shady spaces
• Include simple, well-ventilated huts made from natural materials such as branches and twigs
• Provide thicker, shade-giving stems which the animals can shade behind
• Use marble tiles or similar cool materials inside the huts, which the guinea pigs can lie down on
• Place bottles of frozen water wrapped in cloths inside the huts to help keep the area cool

Lots of water
Guinea pigs should have unlimited access to plenty of fresh water. Make sure to provide several different water sources in the enclosure, but also give them foods with a high water content such as:

• Cucumber, paprika, fennel and lamb's lettuce
• Melon and apple

But be aware that these foods must be replaced regularly as they ferment quickly in heat, which can cause gastrointestinal problems for the guinea pigs.

Guinea pig owners must be aware of the dangers of hot weather due to the following:

Heat stress: is defined as ‘[…] a physiological condition that occurs when a species’ core body temperature rises above the range that is recommended for normal activity as a result of a total heat load (internal production plus environment) that is greater than the capacity for heat dissipation.’⁶

Heat stroke: occurs when the body core temperature of the guinea pig has risen above normal.⁷ This situation can become fatal. Symptons of heat stroke include the follwing:^8,9

Lethargy

• Heavy and rapid breathing with open mouth
• Inflation of the nostrils
• Restlessness
• Excessive salivation
• Lying stretched out on the side
• Convulsions
• Coma

The following steps can be taken to save the guinea pig's life:⁷

By following these measures, you can help ensure your guinea pigs stay safe, healthy and happy during the summer heat.