Heat Stress

Heat stress occurs when the ability for the body to remove heat is overwhelmed by heat and stimuli, working to exhaust and distress the body.

This is of particular risk with outdoor rabbits and guinea pigs, as the weather gets warmer – suddenly the outdoors become a warm (too warm) place for our furry friends. Heat stress can be very common in rabbits, and can be fatal!

So if we are worried about heat stress, first lets think about heat loss,
Heat loss occurs through 4 pathways
  • Radiation
  • Convection
  • Conduction
  • Evaporation

Rabbits have a limited number of ways they can cool themselves, assuming that their body temperature is higher than the environment

  • Hyperventilation – as rabbits breathe out hot air, they can breathe in cooler air through their nostrils. Their are also humidification mechanisms in the nose which can help reduce body heat.
  • Ears! – Rabbits have very large ears, with large surface areas and numerous blood vessels, which allows a lot of cooling via these veins.

As rabbits have small bodies and a relatively large surface area, they are very susceptible to heat. When temperatures get higher than 30C, this is dangerous for rabbits and guinea pigs.

The best way to prevent heat stress is to give your rabbit plenty of water and shade, and ideally an indoor hutch!!!

Clinical examination

In rabbits and guinea pigs, we can see;
  • Fatigue
  • Lethargy
  • Inappetance
  • Diarrhoea
  • Decreased mentation, or moribund


You need to stabilise your patient with aggressive supportive care  and water cooling
  • Whole body wetting
  • Intravenous or subcutaneous fluids

Unlike with people, ice water baths not ideal, as they potentially quite distressing for the patient, which with rabbits and guinea pigs can be too much stress!


The best treatment for heat stress is to PREVENT HEAT STRESS!

You now have a lot of evidence for why rabbits and guinea pigs cannot tolerate heat, so what can we do?

  • House your rabbits and guinea pigs inside!
  • If inside is not an option, place your bunny or cavy hutch in the shade, well protected from direct sunlight with plenty of water available.
  • Limit play time to colder times of the day, but avoid dawn and dusk! You don’t want to expose your rabbits to mosquitoes and flies, as these are insect carriers of

In general, once you start seeing signs of heat stress in rabbits and guinea pigs the prognosis is guarded to poor. So, remember – Prevention is better than cure!
So treat fast, treat early, and  keep your rabbit and guinea pigs out of the hot sun!

  • Hopper, Silverstein. Small animal Critical Medicine