Usual seat. Causes: house life, neglect of call to defecate, lack of exercise, overdistension, atony, watch dogs, over feeding, obesity, ill health, debility, loss of teeth, paraplegia, spiced and sweet food, matting of hair over anus, tumors round anus. Symptoms: small, hard, white, glazed stools, straining, no stools, hot, tender, swollen, bulging anus, abdominal manipulation, dullness, laziness, seeking seclusion, colics, tender abdomen, stiffness, arched back, drooping head and tail, vomiting—sometimes feculent, fever. Lesions: impacted mass of hard, gritty particles, catarrhal congested or necrotic mucosa, and outer coats, perforating ulcers. Treatment: air, exercise, laxative diet, mechanical extraction, purgatives, enemata, demulcents, laparotomy, enterrectomy. In the dog, atony and impaction are common especially in the rectum, where the fæces are unduly retained in connection with house life until accumulated and dried. The impaction tends to extension forward, the new material adding continually to the old, and the overdistended rectum becoming more and more atonic in proportion to the increase of the distension. _Causes._ The most prominent factor is denial of nature’s call to defecate, on the part of house dogs trained to habits of cleanliness. The accumulated mass distends and weakens the rectum, enabling it to hold more without suffering, making the call of nature less imperious, and diminishing the power of expulsion. Lack of exercise usually operates in the same animals, as it also does in watch dogs, the movements of which are limited by the length of their chains. Overfeeding contributes, in various ways, by increasing the amount of feculent matter passed on into the rectum, by hastening the food through stomach and small intestine imperfectly digested and therefore in a more irritating condition, and by contributing to obesity and lack of tone. In mastiffs, hounds, bull-dogs, etc., which are naturally gluttonous and swallow animal food in large masses without tearing apart, or mastication, portions pass into the intestine undigested and tend to disturb and block the terminal bowel. Dogs that are out of health, and which lack tone in general have usually torpid bowels and suffer from delay and impaction of contents. Hence all chronic and debilitating diseases are liable to become aggravated by this troublesome complication. Old dogs with the teeth worn out and the general tone of the stomach and intestines low are habitual sufferers. Paralysis of the posterior limbs is usually associated with paresis of the rectum and accumulation, and various other atonic nervous disorders act in the same way.