Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you today.
How long has he been showing signs?
Any retching, gagging, lip licking, drooling, or vomiting?
Did the increased thirst start before or with the appetite loss?
Are his gums pink or white/pale? Moist or sticky?
If you press on his belly, any tensing, tenderness, discomfort, or pain?
Could he have eaten anything harmful (ie bones, toys, plants, chemicals, human meds, etc)?