90 Milk Sickness (Tremetol Poisoning)

Milk sickness, usually called milksick by early nineteenth-century American pioneers, denotes what we now know to be poisoning by milk from cows that have eaten either the white snakeroot or the rayless goldenrod plants.

Milk sickness has been called variously alkali poi­soning, puking disease, sick stomach, the slows or sloes, stiff joints, swamp sickness, tires, and trem­bles (when it occurs in animals). It is now known as tremetol poisoning after an identified toxic ingredi­ent of the white snakeroot and rayless goldenrod. Tremetol, obtained from the leaves and stems of these plants by extraction with ether, is an unsatu­rated alcohol with the empirical formula C₁₆H₂₂O₃. In consistency and odor, it resembles turpentine.

Distribution and Incidence

Milk sickness was unknown in Europe or in any other region of the world except North America. It appeared in North Carolina as early as the Ameri­can Revolution near a mountain ridge named Milk Sick. Its highest incidence was in dry years when cows wandered from their brown pastures into the woods in search of forage. As more forests were cleared so that cattle had more adequate pasture, and as fences were built, the incidence of milk sick­ness decreased rapidly.

The disease wrought havoc in the Midwest, espe­cially in Illinois, Indiana, and Ohio, and in the upper southern states of Kentucky, North Carolina, Tennes­see, and Virginia.

Epidemiology and Etiology

In 1811, an anonymous author wrote that milk sick­ness was a true poisoning because it involved no fever. He also believed that it was caused by poison­ous milk that had a peculiar taste and smell. The source of the poison, he wrote, was vegetation eaten by the cows. He further advised that finding the offending plant would remove a major stumbling block to emigration westward.

In the years that followed, the theories as to the cause of milk sickness were numerous. One sug­gested that the cause was arsenic; another claimed it was a mysterious soil organism, whereas another attributed the disease to a mysterious exhalation from the soil. Still others incriminated various poi­sonous minerals and springs. Nonetheless there was no definite identification of one specific toxic plant during the nineteenth century. In the 1880s, the medical revolution following the discoveries of Louis Pasteur in France and Robert Koch in Germany led to the expectation that many obscure diseases such as milk sickness would prove to be Ofbacterial etiol­ogy. This expectation appeared to have been realized when Edwin Jordan and Norman Harris (1909) re­ported that Bacillus Iactimorbi was the cause of milk sickness in humans and trembles in cattle.

Beginning in 1905, however, Edwin Moseley of what is now Bowling Green State University in Ohio began a scientific study of the white snakeroot that lasted for over three decades. In careful animal­feeding trials, he established the toxic dose of snake­root for animals at 6 to 10 percent body weight. He also found that the stems were less poisonous than the leaves and that neither freezing nor drying de­stroyed the poison. His book, published in 1941, is the definitive work on milk sickness.

Finally James Couch (1928) reported that he had isolated three poisonous substances from the white snakeroot: a volatile oil and a resin acid that did not produce trembles, and an oily liquid with the charac­teristics of a secondary alcohol that did. The last he identified as C₁₆H₂₂O₃ and, drawing on the Latin tremere meaning “tremble,” named it tremetol.

Heating reduces somewhat the toxicity of poi­soned milk, and oxidation readily destroys the toxic properties of tremetol. Because only a small number of cows are likely to be secreting toxic milk at one time, human illness is seen chiefly when milk from a single animal or herd is consumed. It is now thought that the dilution that occurs in the usual dairy collec­tion and distribution of milk from a large milk source, rather than pasteurization, is the reason for the failure of milk sickness to develop in urban ar­eas. For that reason, milk sickness has become ex­tremely rare. Moreover, in rural areas, farmers are now well aware that to avoid trembles or milk sick­ness, one need only abandon woodland grazing, for the white snakeroot is a woodland plant and almost never found in bright and open pastures.

Clinical Manifestations

When milk sickness occurs in animals, chiefly cattle, it is called trembles. The animals suffer from an­orexia, weakness, falling, stiffness, and trembling.

In humans the symptoms of milk sickness include anorexia, Iistlessness, severe constipation, and - most important of all, and underlying most of the symptoms - profound acidosis; the latter, if un­treated, leads to coma and death.

The lethargy that characterizes the patient who has not completely recovered from an attack of milk sickness helped give it the name of slows (or sloes). Abraham Lincoln knew it by that name, and, an­noyed by the desultory progress of the Army of the Potomac in the early months of the Civil War, he once tartly remarked that General McClellan “seemed to have the slows.”

History and Geography

Milk sickness has vanished from the list of major concerns of modern Americans. Although endemic in the Midwest and upper South, it had never been seen elsewhere in the United States, in Europe, or in any other continent. The settlers along the Atlantic seaboard knew nothing of it, and if the Indians or their cattle suffered from the disease, they did not inform the early settlers. Not until the pioneers be­gan to push westward beyond the Alleghenies did the disease attract attention.

The first sporadic cases to be recognized occurred in North Carolina in the years preceding the Revolu­tion. It was generally known that on the western side of the Allegheny Mountains from Georgia to the Great Lakes a disorder called trembles prevailed among cattle, and that wherever it appeared, the settlers were likely to get a disease, which from its most prominent symptom received at first the name “sick stomach” and from a theory concerning its cause that of “milk sickness.”

In 1811, the Medical Repository of New York con­tained an anonymous report entitled “Disease in Ohio, Ascribed to Some Deleterious Quality in the Milk of Cows.” This appears to be the earliest surviv­ing reference to a disease that was to become a frequent cause of death and a major source of misery and mystification in the rural South and Midwest through a large part of the nineteenth century.

William Snively and Louanna Furbee (1956) de­scribed a discovery made in 1834 by Anna Pierce Hobbs, a pioneer doctor, in southeastern Illinois. Having learned from a Shawnee medicine woman that white snakeroot caused trembles and milk sick­ness, she had a calf fed several bunches of the root. The calf developed typical trembles, enforcing her conviction that she had found the cause of milk sick­ness. John Rowe, a farmer of Fayette County, Ohio, wrote in 1838 that he had discovered through simi­lar experimentation that trembles was caused by ingestion of white snakeroot.

During the second half of the nineteenth century, milk sickness occurred sporadically, which made se­quential observations difficult to make, and the rea­son for its cause was lost in the widely held medical belief in miasmas and exhalations from the ground. Moreover, because milk sickness was limited to the Midwest, upper South, and Southwest, influential eastern physicians tended to ignore it or even dis­count the possibility that it really existed as a dis­ease sui generis.

Nonetheless, the solution was eventually found when attention was turned back to the poisonous plant theory advanced during the first half of the century. Although many plants were suspected, such as poison ivy, water hemlock, Virginia creeper, coral­berry, spurge, mushrooms, and march marigold, scru­tiny finally centered once again on white snakeroot. Yet it was not until 1928 that the white snakeroot was established with certainty as the cause of milk sickness - over a century after the anonymous 1811 article appeared.

The question that Snively has asked remains: “How could a disease, perhaps the leading cause of death and disability in the Midwest and Upper South for over two centuries, go unrecognized by the medical profession at large until 1928?”

Thomas E. Cone, Jr.

Bibliography

Anon. 1811. Disease in Ohio ascribed to some deleterious quality in milk of cows. Medical Repository [N.Y.] 3: 92-4.

Couch, James F.

Furbee, Louanna, and William D. Snively, Jr. 1968. Milk sickness, 1811-1966: A bibliography. Journal of the History of Medicine 23: 276—85.

Hartmann, Alexis F., Sr., et al. 1963. Tremetol poisoning — not yet extinct. Journal OftheAmerican Medical Asso­ciation 185: 706-9.

Jordan, Edwin 0., and Norman MacL. Harris. 1909. Milk sickness. Journal OfInfectious Diseases 6: 401-91.

Jordan, Philip D. 1944. Milk sickness in the western coun­try together with an account of the death of Lincoln’s mother. Ohio State Medical Journal 40: 848-51.

McKeever, George E. 1976. Milk sickness: A disease of the Middle West. Michigan Medicine 72: 775-80.

Moseley, Edwin L. 1941. Milk sickness caused by white snakeroot. Ann Arbor, Mich.

Snively, William D., Jr. 1967. Mystery of the milksick. Minnesota Medicine 50: 469—76.

Snively, William D., Jr., and Louanna Furbee. 1956. Dis­covery of the cause of milk sickness. Journal of the American Medical Association 196: 1055-60.