I have a 15 year old haflinger gelding, and his weight varies a lot. One day he’s at the perfect weight and then another day he’s either under or over weight. Is this just something common with the breed? Today I noticed that he is looking underweight, I could see his ribs a bit. I haven’t exercised him for about 4 days because of the weather I have had, yet somehow he has lost weight. Any ideas on why this is happening or suggestions on how to maintain his weight?