My roughly half-year-old Malinois seems to have eaten something too greasy — dehydrated, vomiting and diarrhea, lying down weak, body cold, moaning

Hello. Based on your description, the dog is now dehydrated, and this situation requires taking the dog to a veterinary clinic promptly for fluid replacement, while keeping the dog warm. After the emergency care, relevant examinations are still needed to find the cause and provide targeted treatment.

Generally, greasy food alone does not cause such severe consequences; it may have led to secondary gastroenteritis or pancreatitis. This situation requires targeted treatment based on the examination results.