A paper has been published on the trial drug Oroquin-10 and the use of the stall-side antibody test strips. Published in International Journal of Applied Research in Veterinary Medicine. Rapid diagnosis of EPM has always been an issue. The UC Davis test takes 7-10 days to get results back, and measures antibodies to protozoa that don’t cause EPM. The Multiplex strip is specific to Sarcocystis neurona, and is performed at the barn, while the vet is looking at the horse. The vet can perform a nerological exam, rule out other diseases, AND perform the antibody test while at the horse. This is a major step forward in diagnostics. The test packs are available from Prota.
Posts Tagged ‘EPM’
EPM has always been described as a disease of protozoa in the CNS. The protozoa cause lessions in the CNS when they reproduce. The lessions interfere with nerve signals, and the horse has limited feeling and awareness of the limbs (or face, jaw, tail). It has been known for years that inflammation of the CNS plays a large part in lessions and nerve damage. Anti-inflammatories have always played a part in the treatment for EPM.
What if, inflammation plays a much larger role than was previously recognized? Inflammation may be caused by the toxins produced by Sarcocystis neurona, but what if long, drawn-out EPM symptoms are a manifestation of inflammation, not the protozoa?
Researcher Siobhan Ellison, DVM is looking into this question. See the November 29th blog here: Pathogenes Research Blog.
EPM was certainly discussed at AAEP. In one class with Dr. Reed and Dr. MacKay, Dr. MacKay said he would wait for FDA approval to use the Oroquin-10. Dr. MacKay also promotes the use of Marquis at 7X the dose for loading, or at higher doses, longer duration, or mixed with sulpha/pyrimeth.
Marquis is only approved by FDA at 1X for 28 days. Dr. MacKay is using and publishing protocols that are not FDA approved. Why? Because Marquis at 1X doesn’t work very well. The FOI will tell you that 5X doesn’t work any better. At 10X the FDA approved dose Marquis does have a marginally better success rate. The published CNS values of Marquis are not high enough to kill at 1X.
Dr. Andrews is using a protocol with Sulpha/pyrimeth at a 2X dose. This was shown in the Rebalance trials (FOI) to be toxic. It is not FDA approved. Why is he using this? Because sulpha/pyrimeth at 1X for 270 days doesn’t work very well, and causes anemia. A 2X dose makes the anemia worse.
Protazil, using the blinded observers, was only 42% effective at 1X dose (it’s on the insert). MacKay suggests diclazuril be used at 7X the FDA dose, or for longer periods, or mixed with sulpha/pyrimeth. Only 1X for 28 days is FDA approved.
Dr. Reed suggested to me by consultation, that I use a higher dose of Marquis on Charlie. This is not an FDA approved protocol. He certainly did not let me know that.
Dr. Johnson said on the latest Intervet-sponsored EPM Webinar, they would only talk about FDA-approved drugs. Less than a minute later, Dr. Andrews is answering web questions about higher, longer drug protocols that are not FDA approved. (Intervet makes Protazil)
None of these used/published protocols are FDA approved. The veterinarians are not collecting information in a trial. They do not collect titers after the treatment to see if the horse’s immune system is winding down. They are simply throwing drugs at the problem, and hoping it will go away. Does this sound scientific to you? It shouldn’t. If your vet has prescribed one of these
protocols to you, they are running a non-FDA-approved mini field trial, with no back-up of proof that it works. Why? Because the existing FDA-approved drugs don’t work well.
At least the Oroquin-10 drug trial indicates ‘TRIAL’, is measuring titers before and after the treatment, provides support to vets, and is working its way through the FDA process. Oroquin-10 is based on a study of decoquinate by Dr. David Lindsay. This study shows a very high kill rate. Adding levamisole to the mix seems to help.
If MacKay, Andrews, Johnson and Reed want to use only FDA approved drugs, why are they promoting, using, and publishing non-FDA protocols? Seems like the pot is calling the kettle black.
In September I posted that I had seen great improvement with Fudge’s cranial symptoms with the preventative dose of decoquinate. I discussed giving Fudge a treatment of decoquinate to see if it would help with any latent infection. And the answer is… I have not seen additional improvement with the treatment dose. I think he is as good as he is going to get.
I know from testing the other horse that my two are getting multiple exposures to Sarcocystis neurona over the course of a year. There are a lot of opossums in my area, and I see them weekly. This re-exposure will help keep the IgG antibodies primed in their bodies. In this case, did a treatment dose of decoquinate help? I don’t think so, the preventative had already helped his immune system tackle any latent infection. Did the treatment dose hurt? I’m not seeing any downside to one treatment dose. It would not be a good idea to treat repeatedly, thinking he would get better.
I didn’t want to post on this until I saw clear improvement in Fudge. On August 17th I told you that I had worked with my vet to order the decoquinate preventative for Fudge, because he does have a low titer to Sn. Over the course of the month, I have given Fudge the prevention dose. And, well, I see great improvement in the amount of feed he drops. Will this convert to better work under saddle? I don’t know – he goes bitless:-)
I have done a lot of reading on decoquinate over the past month. It appears from published literature to be very safe. It’s over the counter (OTC) for all other farm animals. So… I get this hair-brained idea to see if a full treatment dose will help more. Some of you will read this, and pick an adjective from those in the title. Maybe you have another one. No, my vet was not consulted on this.
While safe, there is a trade-off with the immune system. At the preventative dose, the protozoa in the intestines are killed, and a few in the blood stream or intracellular. The few killed in the blood circulate. It primes the immune system to produce IgG antibodies specific to Sn. This cuts the two-week lag time for the horse to go from non-specific IgM antibodies to specific IgG antibodies. This is important when the protozoa reproduce and multiply by four every few hours.
At the treatment dose, all Sn protozoa in the body are killed within 10 days, and the body stops producing IgG antibodies because there are not any more dead protozoa in the system. I have shot the immune-training ability of the preventative. But, what IF Fudge had a sub-clinical infection? The only way to find out was to give the treatment dose. I’ll let you know what happens.
A word of warning. Decoquinate is OTC for other animals. It is also combined with Rumensin or Monensin which are both very toxic to horses. Don’t use OTC decoquinate for your beloved horse.