Guinea pigs are vulnerable to heat. Originally native to the cold heights of the Andes, these animals are better suited to cooler temperatures. 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 summer. Temperatures of 77°F and above can leave them susceptible to heat stress, from 86°C there is a high risk of death from heat. Long-haired breeds, very young/very old animals, pregnant or overweight guinea pigs are particularly susceptible to heat stress. However, whether kept indoors or outdoors, a few simple measures can be used to keep guinea pigs cool in the summer.

Keep cool  
Providing shade and good air circulation is extremely important for both 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 
• Place frozen ice bags wrapped in cloth in the enclosure
• Alternatively, cool packs/ice bags wrapped in wipes can be placed in the enclosure

Outdoors:

• Choose a shaded place for the enclosure
• Provide shade over unprotected areas of the enclosure using parasols, cloths, sun sails, etc.
• Provide tunnels
• Provide simple well ventilated huts of natural materials such as branches and twigs
• Provide thicker, shade-giving stems which the animals can shade behind
• Use marble tiles/tiles in the huts on which the animals can lie down
• Place bottles of frozen water wrapped in cloths in the huts

Lots of water
Guinea pigs should have unlimited access to plenty of fresh water. This is guaranteed by providing several water containers in the enclosure but also by giving them foods with a high water content such as:

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

These foods must be replaced regularly as it ferments quickly in heat, which can cause problems in the gastrointestinal tract of guinea pigs.

Guinea pig owners must pay attention to the summer dangers for their animals such as:
Heat stress is defined as 'Stress to the animal organism caused by heat with a negative influence on the metabolism, in particular on the water balance (danger of dehydration). In animals, the cardiovascular system is also affected'.

Heat stroke occurs when the body core temperature of the guinea pig has risen above normal. In a heat stroke, the pulse of the animal is accelerated and hardly perceptible. The animal lies apathetically on its side and shows fast, flat flank breathing. If it is not brought immediately to the veterinarian, heart cycle failure threatens.