Well my boy jack russell has lost weight first my dad thought it was from the flea collar we put on him and he is eating fine, but we took it off and it has been at least i think 3 days and he hasnt gained anything back yet it looks like he has very little. My girl jack russell has gained weight and i think it might be from the flea collar she does eat alot but not enough to gain weight, but she runs around like crazy and i play with her all the time. What do u think on his weight. Thanks. they are both short haired jack russell terrier's.View Thread