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Buttercups not to blame for Thoroughbred abortions

In the article “Abortions in Thoroughbred mares associated with consumption of bulbosus buttercups (Ranunculus bulbosus L),” Swerczek1 describes a herd of 54 Thoroughbreds with severe weight loss and emaciation, including 7 mares that aborted after having been confirmed pregnant between 30 and 45 days of gestation, and attributes the clinical signs to buttercup toxicosis. We contend that this conclusion is incorrect and inappropriate, as it rests on unsupported suppositions.

First, no fetuses were recovered from the mares that aborted, and no diagnostic tests were performed on any of the mares with pregnancy loss. In addition, the timing of the abortions cannot be pinpointed to anything less than a 6- to 8-month window. The author states that the mares were bred in April and May 2013 and that fetal heartbeats were detected ultrasonographically between 30 and 45 days of gestation. The mares were reportedly not examined again until early in the 2014 breeding season, at which time they were no longer pregnant. The author concluded from this that the pregnancy losses were due to buttercup exposure prior to July 2013, but this conclusion has no scientific basis. There are many causes of pregnancy loss in mares, and the diagnosis should be made on the basis of results of pathological examinations and ancillary testing. The simple presence of buttercups in the environment, with no confirmation of consumption, does not constitute evidence that they were the cause of later abortions. In central Kentucky, most pastures contain buttercups early in the year, yet the vast majority of pastured broodmares do not abort.

Second, the description of the herd's history is incomplete, as the author neglected to mention that both owners of this herd were charged with and pled guilty to 3 counts each of second-degree animal cruelty in association with this herd investigation.

Third, the author reports that in July 2013, he examined the forage in the farm's fields and found that “buttercup plants grew abundantly in all pastures and paddocks.” However, the author neglects to mention that a field investigation performed on July 17, 2013, by a county agriculture extension agent and a University of Kentucky weed scientist found buttercup growing only in small quantities. In addition, the report of that field investigation indicated there was evidence that poison hemlock was actively growing and accessible to these horses.

Fourth, the description of postmortem findings for the 2 horses in the herd that were euthanized because of severe emaciation (body condition score of 1 on a scale from 1 to 9) is incomplete and incorrect. Postmortem examinations were performed on a gelding and a filly, not 2 fillies as reported in this paper, and the pathologist who performed the necropsies on these 2 horses reported findings of emaciation, parasitic colitis, and gastric erosions but did not make a diagnosis of buttercup toxicosis in either case. Bone marrow fat percentage was extremely low in both horses (7.7% and 10.7%; reference range, 63% to 99%), and the pathologist did not find any ulcers in the oral cavity, esophagus, stomach, or intestines of either horse.

We believe that the author selectively focused on those elements of this case supporting a theory of buttercup toxicosis while minimizing evidence to the contrary. In particular, no other differential diagnoses for the weight loss, diarrhea, and emaciation in this herd (eg, severe malnutrition or parasitism) were provided, and no reasons were given for why these alternative possibilities were discounted.

We do not believe that this report provides sufficient evidence to substantiate the conclusion that weight loss, emaciation, and abortion in this herd were a result of buttercup ingestion. We are concerned that the report could mislead veterinarians to diagnose buttercup-induced abortion in mares on the basis of an unsubstantiated theory.

Cynthia Gaskill, dvm, phd, dabvt

David Bolin, dvm, phd, dacvp

Craig Carter, dvm, phd, dacvpm

Lynne Cassone, dvm, dacvp

Carney Jackson, dvm, dacvp, dacvpm

Jennifer Janes, dvm, phd, dacvp

Laura Kennedy, dvm, dacvp

Alan Loynachan, dvm, phd, dacvp

Veterinary Diagnostic Laboratory

College of Agriculture, Food and Environment

University of Kentucky

Lexington, Ky

1. Swerczek TW. Abortions in Thoroughbred mares associated with consumption of bulbosus buttercups (Ranunculus bulbosus L). J Am Vet Med Assoc 2016; 248: 669672.

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The author responds:

Although the evidence that buttercup consumption caused weight loss and abortion in the mares described in my report1 was only circumstantial, I believe it was strong enough to warrant that conclusion. The farm described in the report had been leased from 2010 through fall 2012 by an individual with 12 mares, who reported that all pastures and paddocks contained abundant numbers of buttercup plants. None of the mares were bred; therefore, there were no reports of abortions. However, 1 mare that reportedly sought out buttercup plants was described as having rapidly lost weight.

The herd described in the report was moved to the farm in March 2013, and the owners sought professional help in July 2013 after all of the horses experienced severe weight loss. Weight loss resolved quickly after the horses were moved to another farm, and the 7 mares that aborted during the 2013 breeding season delivered healthy foals during the next breeding season, with no reports of abortions. Also, all of these mares had previously carried foals to term while housed at another farm, and reproductive testing prior to the 2013 breeding season had not revealed any abnormalities. The 1 mare that did not abort was transferred off the farm in early June 2013. It is true that no fetuses were recovered from the mares that aborted. However, fetuses are frequently not recovered when mares abort early in pregnancy.2 In a report3 of cows that aborted early in pregnancy after consuming buttercup plants, many fetuses were not found, and fetuses that were found were mummified, with no diagnostic lesions seen or infectious agents isolated.

It is also true that the 2 owners of this herd pled guilty to charges of animal cruelty because they allowed the animals to become severely emaciated and did not seek professional help for the horses earlier. The owners did overstock the farm, and this likely forced horses to consume the buttercup plants.

Buttercup plants go dormant during the summer, which is likely why abundant buttercup plants were not seen when the farm was examined in July 2013. However, the plant aggressively emerges in the spring before other pasture forages, and some animals can seemingly acquire a taste for the plant even though other desirable forages are available.4 Poison hemlock was identified on the farm but was mainly growing along the fence lines, not in the pastures or paddocks.

A definitive diagnosis of buttercup toxicosis cannot be made on the basis of necropsy findings, because there are no known pathognomonic lesions and no tests for the plant's toxins. Therefore, the diagnosis must necessarily be presumptive.

Because buttercup plants can cause abortions in cows,3,5 it doesn't seem too much of a stretch to suggest that they may cause abortion in other animals, including mares. Thus, it seems prudent to alert veterinarians and livestock owners about the possible risks of grazing pregnant cows or mares on pastures infested with buttercup plants. If animals are displaying unexplained weight loss and abortions while grazing spring pastures infested with buttercup, buttercup toxicosis should, I believe, be considered as a possible explanation, especially if weight loss resolves and abortions cease after affected animals are removed from the buttercup-infested pastures.

T. W. Swerczek, dvm, phd

Department of Veterinary Science

College of Agriculture, Food and Environment

University of Kentucky

Lexington, Ky

  • 1. Swerczek TW. Abortions in Thoroughbred mares associated with consumption of bulbosus buttercups (Ranunculus bulbosus L). J Am Vet Med Assoc 2016; 248: 669672.

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  • 2. Swerczek TW. An overview on the etiologic factors and diagnosis of equine fetal diseases. In: Kirkbride CA, ed. Laboratory diagnosis of livestock abortion. 3rd ed. Ames, Iowa: Iowa State University Press, 1990;202206.

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  • 3. Morales H. Abortions in a dairy herd in the VIII region of Chile attributed to the consumption of creeping buttercup (Ranunculus repens, L). Arch Med Vet 1989; 21: 163166.

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  • 4. Forsyth AA. British poisonous plants. Bulletin No. 161. London: Her Majesty's Stationery Office, 1954.

  • 5. Pammel LH. A manual of poisonous plants: chiefly of eastern North America, with brief notes on economic and medicinal plants, and numerous illustrations. Cedar Rapids, Iowa: The Torch Press, 1911;460.

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Call for more easily attainable preveterinary requirements

I read with interest the JAVMA News story1 on proposed strategies to reduce the educational debt of veterinary students. In particular, Dr. John C. Baker, dean of the Michigan State University College of Veterinary Medicine, reportedly stated that he will work to reduce the preveterinary requirements so that they can be completed in 2 years.

It was not so long ago that students were regularly admitted to veterinary colleges in the United States after only 2 years of undergraduate education. I was one of many such lucky individuals, and since graduating many years ago, I have met many veterinarians and physicians from other countries who entered veterinary or medical college immediately after high school. Their veterinary or medical college training lasted only 5 or 6 years, with the first year or 2 involving preveterinary and premedical courses. The United States is one of few nations where veterinary and medical students typically complete 4 years of college education prior to entering professional school. The many graduates of foreign veterinary and medical colleges I have met did not seem any less educated or intellectual than those who graduated from US colleges. I believe it is time for all US veterinary colleges to change their preveterinary requirements so they can be completed in 2 years. Not only will it be cheaper for students, but it also makes sense for education.

Jerrold M. Ward, dvm, phd

Montgomery Village, Md

1. Larkin M. Veterinary colleges look within for debt-reduction strategies. J Am Vet Med Assoc 2016; 248: 13201321.

Putting students before institutional prestige

Several articles1–4 in the June 15 issue of JAVMA News discuss the disproportionate educational debt veterinary students accumulate, compared with starting incomes, and report on plans to address this problem by increasing governmental funding of higher education, growing scholarship funds, and developing financial literacy opportunities for veterinary students. But, little attention was paid to the role that increasing tuition and fees have played in this crisis or how schools of veterinary medicine can work to keep tuition increases in check.

As a recent graduate, I narrowly escaped recent tuition increases at the University of Wisconsin-Madison School of Veterinary Medicine, which included a doubling of yearly tuition for out-of-state students and a $7,000 increase in yearly tuition for in-state students. During this same period, an e-mail was sent assuring school faculty that the dean was doing everything in his power to protect the faculty's tenure and employment security. I graduated feeling as though the school had forgotten that it was created to serve veterinary students. I believe that as long as deans continue to put institutional prestige before the needs of the students they are supposed to be serving, educational debt will be a chronic and debilitating problem for the veterinary profession.

Nora Hickey, dvm

Olympia, Wash

  • 1. Larkin M. Pulling together to lower the debt-to-income ratio. J Am Vet Med Assoc 2016; 248: 13121317.

  • 2. Larkin M. Upcoming legislative activity to center on education. J Am Vet Med Assoc 2016; 248: 13181319.

  • 3. Larkin M. Veterinary colleges look within for debt-reduction strategies. J Am Vet Med Assoc 2016; 248: 13201321.

  • 4. Larkin M. Students press for personal finance education. J Am Vet Med Assoc 2016; 248: 13221325.

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