At this age, intestinal parasites as a primary cause for constipation is less likely than the younger dog and puppy, however, it still must be considered as a possible cause, especially for dogs that spend a lot of time outdoors. Likewise, many dogs this age are behaviorally mature enough to not engage in the dietary indiscretion of eating items that potentially can get stuck in the gut, but still some just cannot resist the lure of the garbage can or chewing of risky items requiring us to necessarily include GI foreign body obstruction as a possible cause for constipation. In this age range, it is more likely that constipation results from pain and neuromuscular deficiency caused by disease of the intervertebral discs of the spine or from anal sac disease. For more information on these diseases, please refer to the articles below. If you still seek further information, please visit our Ask The Vet page to submit a one on one consultation with a licensed veterinarian 24 hours a day, 7 days a week.