Yes, worms left untreated can lead to serious illnesses in dogs and can sometimes even be fatal. (dogsbarn.com)
It is more likely for bacteria to lead to a serious illness like meningitis, septicemia, kidney or urine infections or even pneumonia. (newkidscenter.com)
«It is important never to underestimate the significance of a healthy diet and lifestyle as not only does it impact upon our general wellbeing but can alter the metabolic behaviour of our cells, tissues and organs leading to serious illnesses.» (sciencedaily.com)