Small Dog Sling My Dog Is Losing Hair Like CRAZY!!?

My dog is losing hair like CRAZY!!? - small dog sling

I have 3 research laboratories, and all allergic to the salt water pool, so he bought a small pool just for them! But the Black Lab (she is 1 1 / 2 years) loses hair on his chest and belly ... wuts with that? We do not allow a paddock in the pool and ... r also swim in the pool only about a foot deep and a half, not broad. We have 6 acres of land and went every day and have a huge slingshot that used 2 play with them ... do not look Any1 why it lost so much hair? It is the most active dog and knows many tricks and tips and is always happy, and I began to dump in February of this year. or something ...