In a study on dog mycoplasmas 61 samples collected from 28 street dogs, out of which 15 are normal, 2 were suspected for arthritis, 5 for pneumonia, 3 were infertile and 2 were parvovirus suspected. Samples from 33 domestic dogs were also collected out of which 11 were from infertile dogs, 7 were from pneumonia, 8 were parvo virus suspected, 3 were from fever and digestive problems and one each was suspected for paralysis and abortion. These samples were tested for possible presence of pathogenic mycoplasmas causing pneumonia, arthritis, infertility and abortions. Out of 61 samples two species of mycoplasma were detected in present study from german shepherds dogs having genital problems. These mycoplasmas were able to reproduce the disease in control dogs and produced death in control pups. The study also showed the importance of mycoplasmas in breeding and rearing practices in canines.