Wednesday, June 05, 2019

First (presumed) North American cases of tick-related paralysis in horses documented at Purdue University

Figure 1 in the article shows embedded and engorged Dermacentor variabilis ticks concentrated at the base of the tail in a 3‐year‐old American Miniature horse (Horse 1).

News about ticks is seldom good news. But when the bad news is well-documented and published in a timely manner in an Open Access veterinary journal, the news could be worse.

Veterinarians at Purdue University College of Veterinary Medicine in Indiana have published a detailed account in the peer-reviewed Journal of Veterinary Internal Medicine describing the possible occurrence of two cases of tick-related paralysis in horses in North America. Until these cases, this particular type of tick-borne disease was believed to have only affected horses in Australia, and was associated with a different species of tick.

The cases were referred to Purdue's Veterinary Teaching Hospital in May, 2018.

"Presumptive tick paralysis in 2 American Miniature horses in the United States" by Drs. Kelsey M. Trumpp, Ashley L. Parsley, Melissa J. Lewis, Joseph W. Camp Jr., and Sandra D. Taylor documents their treatment of two miniature horses who were found infested with ticks, mainly at the tail head and base of the mane. 

One horse was unable to walk and the other was ataxic (likely to stumble, fall or trip spontaneously). After removal of the ticks and a period of hospitalization, they improved to be neurologically normal.

Since this article is Open Access, it may be read by anyone with the link, which is provided below. The discussion of the cases in the full article is particularly interesting, and relevant to any other similar cases that may be found this summer or fall.

The article also contains helpful information from the authors on how the diagnosis was determined, and the process used to eliminate other diseases, such as botulism, and nutrition-related problems that might cause similar severe neurological symptoms.

Figure 2 from the article illustrates how Purdue's Veterinary Teaching Hospital staff set up a waterbed for a 3‐year‐old recumbent American Miniature horse presumptively diagnosed with tick paralysis (Horse 1).
The authors provide useful information for public health officials and veterinarians who may also face cases of tick paralysis or need to educate clients about the importance of its prevention. The authors list similarities and differences between tick paralysis in other species (including cats, dogs, and humans) and in Australian horses, where juvenile horses and miniature horses were highly represented in a review of cases there.

Associate Professor Sandy Taylor reported to The Hoof Blog today that the two affected miniature horses were still doing well since their hospitalization, and that she had heard of no other cases in North America.

The full article was published online on June 3, 2019.  These cases will also be presented this week at the 2019 American College of Veterinary Internal Medicine (ACVIM) Forum in Phoenix, Arizona.

To read, print, or download the full article, click this link to go to the Journal of Veterinary Internal Medicine.

Trumpp, KM, Parsley, AL, Lewis, MJ, Camp, JW, Taylor, SD. Presumptive tick paralysis in 2 American Miniature horses in the United States. J Vet Intern Med. 2019; 1– 5.

Note: This article, and others presented at the ACVIM Forum detailed internal medicine conditions related to lameness in horses, will be indexed and linked for your permanent reference in the upcoming June edition of HoofSearch.

HoofSearch is the interactive linked index of all new articles, proceedings, theses and patents related to equine lameness published in peer-reviewed veterinary journals and university repositories each month. It works on browser-equipped phones, tablets and computers (Internet connection required) and can be checked from anywhere, anytime. Recommended by leading academic and private practice veterinarians, researchers, and farriers. Used in vet school libraries and classes; subscription one year / 12 editions:  $119. Click here to learn more about how HoofSearch works.  Or, click here to subscribe easily online now.

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