I had some chickens limping, turned out to be arthritis type infection in joint. I gave them tylan 200 1/2 cc IM and 1 cc of penicillin and eventually several got over it. One I finially had to cull never could get ther over it. But eventually I got rid of infection. Time, treatment and culling. I got this type of infection going from some duck eggs I had bought to hatch. I am very careful now.