Both of these factors enlarge the overall size of the prostate putting internal pressure on the remaining tissue. In many, the gland may not yet be painful, but as the condition continues with age, it will at the very least be a source of constant discomfort but, as stated, it can and often does cause problems with both urination and defection. Probably the second most common form of prostatic disease in the dog is bacterial infection. Bacteria can get into the prostate via the blood system or from the urinary tract. In the latter, bacteria can come from the bladder or come up the urethra through the penis.
Bladder infections are common in the dog and easily treated.
Many antibiotics that can be taken orally are excreted from the body by the kidneys and are therefore deposited unchanged into the bladder. Here they can quickly eliminate the bacteria present. Once the organisms have made their way into and colonized the prostate however, the infections are much more difficult to control or eliminate. Very little if any of the antibiotics that are deposited into the bladder via the kidneys make their way into the prostate gland even though the urethra passes through it. Additionally, there is a physiological barrier between the blood and the prostate gland.