Hello Preetham,
There could be a lot of underlying factors that could lead to your lab being weak, it could also be the starting signs of a deeper issue.Hence it’s better get a through check up done. Meanwhile in order to increase the appetite Syrup Hepamust can be given 40mins prior to serving food. You can also add multivitamins and check the app for palatable recipes for your Labrador. Most importantly deworm your dog periodically.