Guinea pig heats up intensely on lap

[Tanuki]

I have a Guinea pig who spends a lot of time with us. We’ve had him for a few years. I notice when I hold him for a long time he will start to heat up his body temperature will suddenly get super super hot and he will give off this sort of warmth from his entire body. During this his ears turn red. He does this when he is visibly relaxed as well. I noticed he also does this on my moms lap when she holds him every time. Any idea why this happens? His ears stay red along time after putting him back in his cage

 

[Pound Shilling & Pig]

Hi. He will be feeling hot like this when he trying to cool down. Guinea pigs don't have the ability to sweat, so when they get hot they send more blood to their skin, especially their ears for the surrounding air to take away the excess warmth. Sitting on your lap will be nice and warm as your own body temperature will be warming him. If he starts to get warm during lap time I would put him back in his cage so he can cool down more easily.

 

[VickiA]

Great explanation by @Pound Shilling & Pig above. I always use their ears as an Indicator of how cold or how warm they are feeling. If their ears are hot and red, then they are feeling hot in the same way that if we get hot the blood rushes to our skin to try to cool our blood down. It may be that your guinea pig simply gets too warm on your lap during lap time. If you notice this happening, perhaps it’s a good idea to put him back in his cage so he can cool down again.