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PNE (polyneuritis) case analysis

Updated: Jan 4, 2023

Case analysis:

Blue Eyed Playboy

Before we get to the case, let me introduce you to Blue Eyed Playboy. He was a beloved member of the family, a "husband" horse and faithful trail companion. About Christmastime, in 2012, Blue's mom contacted us. But her nightmare began in March of 2010.

Blue was a little stiff, the veterinarian was called and his exam was unremarkable. He found radiographs and vitamin E levels were normal. There wasn't much change in the stiffness after palliative treatment and Blue was radiographed again in July. By September an anti-inflammatory was prescribed. A fluoroscopy exam was normal.

Possible EPM

Most likely not EPM

Blue was taken to the large animal clinic at Purdue in March 2011. By now he was hypermetric in the forelimbs and he was very weak behind. He was wobbly. He was ataxic. The provisional diagnosis was EPM in spite of the negative on the UC Davis panel using serum and CSF. His EPM treatment made no difference.

Over the next year he had his head, back and pelvis radiographed and injected. He received a diagnosis of psoas injury, Lyme disease, and was tested for PSSM. He returned to Purdue in July 2012 because he had a shifting leg lameness. More diagnostics. More radiographs. Steroids were injected in the ankles and feet, but that didn't last. Purdue's analysis was that he weaker, he was more ataxic, and the hypermetria persisted. Stifles and sacral-iliac joints were injected. Blue was failing, his prognosis was poor and euthanasia was recommended. But his family just couldn't let him go.

Pathogenes tested Blue

Blue was seronegative on the SAG 1, 5, and 6 test in December of 2012 A negative serum test is fortunate because it rules out S. neurona EPM. He was treated for PNE but after returning to almost normal, he relapsed in 3 months. Relapses are not uncommon in PNE. For the next 3 years Blue's owner would call and catch us up on his progress, and discuss the relapses, and the family. Blue would respond to treatment and hit the trail, only to relapse again, sometimes in 3 months and sometimes in 12 months. Blue was a conundrum for his veterinarian, a puzzle for Purdue, and a frustration and heartache to those that loved him. To us he was a challenge.

We developed an algorithm and searched over 3000 cases for similar histories and we found 19. We called the veterinarians taking care of those horses and found that 18 of the horses had been euthanized. Not surprisingly, the 19th horse succumbed a few months after our call.

Polyneuritis explained

Over the next few years we compiled our data, made recombinant proteins, collected antibodies and mapped epitopes. We incorporated what we learned from the literature, especially Fordyce (1987). We selected sera from populations of abnormal horses and compared to sera from normal horses. Our test predicted disease with accuracy similar to the 1980's scientists. Our data was published and we presented the data to the EPM Society at the meeting in 2015. We reported an increase in chronic inflammation measured by c-reactive protein to a statistical probability that a sample would contain antibodies against equine myelin 2 proteins. And especially against antibodies to a cytokine receptor found on myelin protein 2.

Been there done that

Surprisingly, other researchers had explored the Fordyce test and didn't make a correlation with disease. At least one researcher had injected myelin proteins in horses and didn't induce antibodies or disease. Our work was met with lukewarm dismissal. Yet, our work predicted their prior failure because they didn't use recombinant proteins. They used a slurry of protein from solubilized spinal tissues. They didn't investigate the cytokine receptor found on equine myelin 2 protein. And they didn't realize how to change the course of disease. Perhaps they will and some day realize what we already know. Or not.

Blue 2015

We last heard from Blue's folks in 2015. Life had been tough on the family, cancer. And Blue's expenses hadn't helped. Our last memories of him are from a video we received. Blue's owner astride after a chemo treatment, we see them from behind, both were peacefully ambling down a sunlit trail with birds singing in the background. This was just prior to Blues last relapse.

Had we known in 2012 what we know in 2022, I have no doubt we would report a different outcome for Blue. His legacy is that others benefitted from his journey. And Zhoni is here because Blue preceded her on the trail.

Note: if Blues case sounds familiar, please call us and see if your horse qualifies for our PNE study. Every enrolled case brings a treatment closer to licensing. We are over half way there, please help.


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