When does polyneuritis equi (PNE) begin in a horse? A polyneuropathy manifests in a horse that is susceptible to the disease. Which horses are susceptible? Horses that are particularly “inflammatory” or a horse that is allergic to vaccines, even a horse with endocrine issues. Some horses that contract a virus can succumb. Once typical signs are present, the disease can be recognized. But what about the pre-symptomatic phase, what does that look like in a horse with PNE?
Biomarkers could identify the earliest stage of PNE, if one were looking. At this stage the horse doesn’t have any outward appearance that there is anything wrong, and if you could ask, the horse would agree, all is well. At this phase it is entirely possible the horse clears the inflammatory issue, probably most of them do regain health and that is why this disease is so rare.
A few horses will start to show early signs of polyneuritis and these signs can be detected, although they are often attributed to other causes-like protozoal infections, EPM. The signs can be so subtle that an owner feels like there is something wrong but they can’t quite put a finger on it. In human disease the period between possible symptoms/signs and definite symptoms/signs is called prodromal. Once there is “phenoconversion” and the horse leaves the prodromal phase then enters the symptomatic phase, it isn’t hard to recognize the clinical presentation as PNE.
What is the duration of the sub-clinical phase of disease, the disease is present but there aren’t any outward signs? Polyneuritis equi is a rare neuromuscular disease that is difficult to recognize in the field even when clinical signs are present. We think a field diagnosis is difficult because it isn’t a disease that is forefront on a clinicians differential diagnostic list. As in other neurological disease syndromes, ones choice of descriptions has shaped concepts and paradigms in PNE-and that is that the disease is untreatable. Our work concentrates in early diagnosis and treatment options for horses with PNE because this is the time that damage isn’t permanent and the horse can be returned to normal. Veterinary training and the literature describe end-stage disease. Unfortunately, little can be done in the late stages, hence the grim prognosis and current recommendation of euthanasia.
It is our hope to change the way clinicians think about and diagnose PNE; that would change the paradigm. It would change the outcome. Paradigm-changing is a step-wise process. We spent years getting our ideas and research studies completed. Now we will complete a clinical effectiveness trial on horses recognized with PNE, and many of these will be end-stage. The study will allow us to collect effectiveness data and define biomarkers to detect treatable disease. The goal is to use biomarkers in a second effectiveness study. All the data will help us get answers to more questions. Can there be a genetic pre-disposition to disease? Is disease caused by a specific virus or microbial agent? Is it possible that environmental exposure to an “agent” is the inciting cause? A useful strategy to study PNE is to define a population of horses that have a high likelihood of developing PNE. can we define that population? You see, to change what’s ahead one has to continually look in a different direction.
We will be sending out requests to veterinarians and owners that have cases suitable for our effectiveness field trial. There are some criteria that make sure the horse can be included in the trial. We can answer questions for you, if you think you have a horse with PNE. We will provide study medications at no cost and we will pay for some of the pre-entrance testing. We need you to help us change the PNE paradigm.