The best way to help a constipated dog is to contact your veterinarian, according to the American Society for the Prevention of Cruelty to Animals. The causes of constipation vary, and it can be a life-threatening emergency in some cases.
If your dog has a history of mild constipation, or your veterinarian does not believe it is an emergency, you can begin by inspecting the area around the anus, as recommended by PetMD. If there is fecal matter matted around the area or protruding from the anus, you can gently clean the area and remove the feces. Always wear rubber gloves while doing this. Never pull string out of the anus, because it can cause internal injury, and never use force to remove anything.
You can also try to relieve or prevent occasional constipation by adding certain foods to the diet, according to PetMD. Mineral oil can lubricate the intestines and keep waste moving, but too much may cause diarrhea. High-fiber foods, such as pumpkin, can also prevent many cases of constipation. Some supplements, such as Metamucil or stool softeners, may also be recommended. Consult your veterinarian before adding anything to your dog's diet to treat constipation, as the best treatment may vary depending on the underlying cause. Some dogs also do well with medications that improve intestinal strength.