You can feed your Labrador Beaphar's Top 10 Multivitamins. It's a good product. You can also buy it from this very website. It's cost is Rs 160. Apart from it, you can also feed your Labrador Himalaya's Liv 52 forte. It's a has a detoxifying nature, keeps the liver healthy, promotes growth and increase appetite. Always, keep fresh water available for your dog all time. Give him good exercise - late evening and early morning - in summers. If you use choke chains, stop using it as it's good.