If a 3 year cow has blisters in his tough what is wrong with it?

Blisters in a cow's mouth, particularly on the tongue, can indicate several issues, with one common cause being a viral infection such as bovine viral diarrhea (BVD) or foot-and-mouth disease. These conditions can lead to painful lesions, affecting the cow's ability to eat and drink. It’s important to consult a veterinarian for an accurate diagnosis and appropriate treatment.