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Pathogenes is a consulting company with a mission to develop molecular tools for the diagnosis and treatment of animal diseases.

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Dr. Siobhan Ellison DVM, PHD, received a PhD in molecular biology in 2001 from the University of Florida where she had previously completed a Masters program in veterinary microbiology in 1976 and a Doctorate of Veterinary medicine in 1983.  Her PhD thesis was a study in molecular biology, cloning a novel gene from Sarcocystis neurona with a goal to developing tests that assist in diagnosing EPM. After she left UF, she developed the first successful EPM horse infection model, licensing the technology to Bayer Animal Health and later Schering Plough for testing EPM treatments.

Since 2001 she has continued to work and publish, her publications tell the story of EPM.

Pathogenes Publications tell the story of EPM

Who we are
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 EPM, Equine  protozoal myeloencephalitis, was recognized in horses in the 1950’s. Sarcocystis neurona was isolated from a horse in 1991. Our approach to making EPM a treatable disease is a correct diagnosis. 

The tools we use for diagnosis are antibody tests using serum, we can test CSF but serum works well.  These tests are based on our equine model of infection-following others in the field, we patented the Trojan Horse model in 2001.  The model led to and understanding the early signs, understanding immune protection from S. neurona vaccines, and ultimately, the chronic inflammatory condition that leads to polyneuritis equi.

Sarcocystis fayeri is a  common infection in horses with a different life cycle and outcome.  Infection with S. fayeri is called Equine Muscular Sarcocystosis, EMS. We developed a test for the toxin present in disease causing strains, sidestepping issues with cross-reactivity seen in other tests.


Our tests use serum and are uniquely designed to distinguish between S. neurona, S. fayeri anti-toxin, and polyneuropathy.  The diseases caused by these three conditions are treated differently!  

Pathogenes collaborations with industry partners 

Pathogenes model exposed early signs of EPM

A recombinant EPM vaccine shows efficacy in the equine model

Polyneuropathies are linked to Sarcocystis neurona infections in horses!

About EPM
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Learn more about your case by using our highly specific tests.


You can understand more in a less technical format by reading the blogs about EPM, S. fayeri, pathogenesis of disease, and the role of polyneuritis.


You can follow our research by reading the peer reviewed literature.

Learn more

What is PNE?

Polyneuritis equi (PNE) is a rare,  condition that  presents clinically with chronic  signs that are progressive. Horses with early polyneuritis have damaged peripheral nerves that can heal if the disease is recognized and treated appropriately. PNE is rare and  often overlooked as a diagnosis or confused with  EPM. These horses are called "sidewinders" due to the hemi-paresis and a sidewinding gait.

Clinical Trial PNE treatment

Our polyneuritis equi IND is designated under MUMS (minor use in a minor species) for the control of clinical signs that are associated with polyneuritis equi (PNE) in horses. Effectiveness is determined in a field effectiveness trial and is the last step in bringing this much needed licensed treatment to veterinarians for PNE horses. Blood testing and trial drugs are provided at no cost for the trial participants. This trial does not use a placebo.

What causes PNE

PNE is caused by chronic inflammation.  Inflammation  comes an infection caused by protozoan parasites, viruses like herpes virus, gut parasites, or hind-gut ulcers. Sometimes PNE is  caused by  vaccinations that contain equine dermal cells. Chronic inflammation located on the peripheral nerves leads to the loss of myelin, myelin covers nerve fibers. Neurodegeneration and auto-immune disease are end stage conditions.  There are  no current treatments, the prognosis is poor and most horses are euthanized.  We are working to bring the horse community the first licensed treatment for PNE. 

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15471 NW 112th Ave
Reddick, FL 32686

Cell: 352-214-5209
Fax: 352-591-4318


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