This section is from the book "The Farmers Ready Reference Or Hand Book Of Diseases Of Horses And Cattle", by S. C. Orr. . Also available from Amazon: The Farmer's Ready Reference;.
The heart is the great fountain-head of the circulatory system, and, in connection with its coverings, is subject to numerous diseases - generally sequelae of other diseases; but, as the symptoms are generally so obscure as to baffle the skill of the experienced physician, and as treatment is seldom more than palliative in the end, it is useless to occupy space here to give more than a few general symptoms: The horse will generally be very dull and not disposed to move about much; slight exertion will cause the heart to beat tumultously, often so hard as to visibly shake the shoulder; the blood in the jugular vein may often be seen regurgitating or flowing backward toward the head at each beat of the heart; the pulse will be weak and sluggish, notwithstanding the heart is beating violently.
Treatment. - When these symptoms become distressing place the animal in a well-ventilated stall, or out of doors if in warm weather; give stimulants, as spirits of nitre or whisky, and let him rest a few days.