Dogs shed to get rid of old, dead hair. All breeds shed; some, like Labrador retrievers, shed more than others. Indoor dogs tend to shed continuously while outdoor dogs have more seasonal sheds. Shedding is affected by a number of factors including grooming, hormones, sex, allergies, temperature and diet. You can't stop your Lab from shedding but you can take steps to reduce the amount of hair. A healthy, well-groomed Lab will shed less.
Feed your dog a healthy diet. A dog with an unhealthy diet is more likely to have an unhealthy coat and shed more hair. Veterinarians Race Foster and Marty Smith recommend adding a fatty acid supplement to your dog's diet to improve the health of its coat.
Address skin problems as they arise. If you notice your dog is losing more hair than usual and is scratching a lot, it may have an allergy that will cause it to shed more hair. Consult with a veterinarian about how to address allergies.
Brush your Lab regularly. Brushing makes your Lab less likely to shed. It also means you get the hair before it collects in little tumbleweeds around your house. There are many different grooming tools available from bristle brushes to shedding blades to slicker brushes. Try different types of brushes to see which one is most effective on your dog.
Bathe your dog occasionally, using a gentle dog shampoo so the dog's skin doesn't get irritated, causing it to shed more hair. Use a flea shampoo if your dog has fleas. Fleas cause your dog to scratch and lose more hair.