Hot cocoa contains several potentially toxic ingredients for guinea pigs, including:
Chocolate: Chocolate—especially dark chocolate—contains theobromine, a compound that can cause excessive thirst, urination, vomiting, and diarrhea in guinea pigs. In high doses, theobromine can even be fatal.
Caffeine: Hot chocolate also contains caffeine, which can be toxic to guinea pigs in large amounts. Caffeine can cause agitation, increased urination, and even heart problems in guinea pigs.
Sugar: Hot cocoa often contains a significant amount of added sugar, which can contribute to weight gain, tooth decay, and a range of other health problems in guinea pigs.
Therefore, it's best to avoid giving guinea pigs hot cocoa or any chocolate products.