I started with 3 Rhode Island Reds and 3 Barred Rocks 3 years ago. Today I now have 2. I lost my first hen at 2 years, I thought she had an impacted crop, but cannot be sure. The next was eaten by a fox (at least I know what killed her). Then about 2 months ago a RIR suddenly became lethargic and couldn't stand up. It appeared that she had been injured as she wouldn't stand on her left leg. It became apparent that she was actually ill as she wouldn't eat. I brought her in the house and tried to feed her high protein foods and keep her warm. She ate one day, then would only drink. After a week she died. Other than her sudden inability to walk, she seemed fine, if not a little bit thinner than the others. Last week a BR seemed to be getting sick. She had a darkened comb, feathers were ruffled and she was staying back from feeder. I brought her in and she drank a lot of water and ate well. She seemed to not be getting enough water, so I started making sure she drank. Her comb remained a darker color and her feathers remained ruffled, but otherwise she seemed to be doing well. Yesterday she ate cat food with the others and again seemed to be doing well. Today she couldn't stand up and was in respiratory distress. I brought her in and she died about 20 minutes later. So, my question is, am I doing something wrong? The chickens are in a coop with a covered outdoor run with wood shavings for flooring and are fed a commercial pellet food, with calcium, grit and scratch grains. They also get "treats" like cat food or mealworms. They go outside and free range during the day in the warmer months (they refuse to go outside if there is snow on the ground, they'll stay in their run). The coop they sleep in has a heat lamp to keep the temps above freezing. They were vaccinated when I got them at one day old, but they have not received any medications since then. I don't wish to treat illnesses with antibiotics, but I don't want to be causing illness by improper care. I've read that chickens live an average of 8 years, so I'm not sure why at 3 years 3 have died from illness. Any ideas or advice would be helpful. My plan was to get some more birds this spring, but I want to be sure I'm not killing them first.