=The weight of the heart= too can only be stated as an average or for medium sized animals. In the _horse_ it may be from 4½ lbs. to 9 lbs.; in the ox from 3 lbs. 5 oz. to 4½ lbs.; in the _sheep_ from 5½ oz. to 7 oz.; in the _pig_ from 9½ oz. to 14 oz.; and in the _dog_ from 5 oz. to 7 oz. This statement must be understood to apply to dogs approximating in size to the shepherd’s. Taking into account the size of the particular animal any considerable deviation from these measurements and weights may be accepted as abnormal. The ratio to the body weight is about:—horse and dog 1:100, ox, sheep and pig 1:220. This necessarily varies with condition—fat or lean. The =pulse= offers valuable indications in disease of the heart. The _number_ of the pulse in healthy full-grown animals may be set down as follows per minute:—horse, 36 to 46; ox, 38 to 42 (with loaded paunch or in a hot stable up to 70); sheep, goat and pig 70 to 80; dog 80 to 100; cat 120 to 140; goose 110; pigeon 136; chicken 140. In old age the pulse is less frequent. This diminution may extend to 5 beats per minute in the larger quadrupeds and to 20 or even 30 in the smaller. Youth and small size again are associated with a greater rapidity of the pulse. The pulse of the foal, at birth, is about three times that of the horse; in the colt of six months it is double; at a year old about one and a half times; and at two years old one and a quarter. The smaller the animal, _caeteris paribus_, the more rapid is the pulse. Hot buildings, exertion, fear or any other exciting cause likewise accelerates it. It is more frequent with the nervous temperament, as for example in the English race horse, or the greyhound, than in the dull lymphatic cart horse or mastiff. In advanced pregnancy it is increased in number. In the cow and mare it undergoes a monthly increase of four or five beats per minute after the sixth month. (Delafond) Independently of these conditions a rapid pulse indicates febrile excitement attendant on active inflammatory or other disease, or a state of weakness and debility. In this last condition the heart beats more frequently to secure a more rapid circulation in the capillary blood vessels, and thus make up to the craving tissues by frequency of contact, what is wanting in the quantity and quality of the nutritive fluid. This point cannot be too much insisted upon, as the fatal doctrine that a rapid pulse indicates force of the circulation is very misleading as to treatment.