Answer:
A chihuahua would not attack another chihuahua for the purpose of killing and eating it, since that would be too risky; one chihuahua is not notably stronger or more deadly than another, so it would be more or less an even fight, which for the purpose of getting a meal, is not worth it. However if we were to butcher a chihuahua and turn it into dog food, another chihuahua could easily eat it. It would just be another form of meat.