NAVIGATOR® (32% nitazoxanide)
Antiprotozoal Oral Paste—Veterinarian Testimonials

• Dr. Doug Byars—Lexington, Kentucky
• Dr. Wendy Vaala—Oldwick, New Jersey
• Dr. Stan Carroll—Ranson, West Virginia
• Dr. J. Lane Easter—Whitesboro, Texas
• Dr. Stephen Allday—Simpsonville, Kentucky
• Dr. Chris Morrow—Canyon, Texas
• Dr. Stephen Dey—Allentown, New Jersey
• Dr. Alan Dorton—Versailles, Kentucky
• Dr. Richard Mitchell—Newtown, Connecticut and Palm Beach, Florida
• Dr. Andrew Roberts—Lexington, Kentucky

Dr. Doug Byars, Lexington, Kentucky
Dr. Byars has an equine consulting practice focused on internal medicine, and each week he sees at least half a dozen horses with neurological issues. He is the former head of Internal Medicine at Hagyard, Davidson and McGee in Lexington, KY, where he practiced for 23 years before leaving in 2005. He’s a 1974 graduate of the University of California, Davis, School of Veterinary Medicine, and earned his board certification in internal medicine and also in veterinary emergency and critical care.

Case Study
"A Thoroughbred racehorse with EPM was referred to me in late 2005. He was sent specifically from another state with the request that I use Navigator as a treatment, since all other treatments had failed or relapse occurred over the previous 6-8 months. This horse’s ataxia prompted me to diagnose a high Grade 2/low Grade 3; a Grade 3 is when the animal is subject to making a mistake such as stepping on his own foot or slipping and falling. At this point, this represented a rider liability because the horse’s lack of coordination was becoming a safety issue. The horse’s trainer wanted the horse under observation if complications were to occur with the medication.

The course of Navigator was given along with corn oil. The response was very good, and Navigator was able to lower the horse down to a Grade I. Eventually, he was sent back into light training locally. He was considered within normal limits, did not relapse and was no longer a rider liability.

I’m pleased to say that he steadily improved and was returned to race training where he began to retrain himself and "move up the ranks" in increasingly higher levels of competition. He won a graded stakes race (Grade III) convincingly about 4 weeks ago and received a Blood-Horse write-up that suggested he may point to the championship races later in the fall.

Considering the chronicity of EPM and this horse’s eventual normal outcome, I give credit to the Navigator treatment for this horse’s full recovery."

Side Effects
"Navigator has not presented me with complications, and I’m comfortable with the safety and efficacy of this medication. I have not seen worsening of neurological signs during treatment. I find that the best time to re-evaluate the patient is at the end of the treatment period and again 30 days later. The 30-day later exam has been the most reliable in observing normalcy. Another Navigator-treated horse relapsed briefly, but is now back in training."

Conclusion
"I have since used Navigator with more horses, without complications. Most had already been treated without adequate success, and Navigator either seems to do the "clean up" or eliminate the organism on its own. Navigator appears to be a safe treatment that’s probably among the most efficacious available—if not the most efficacious."

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Dr. Wendy Vaala, Oldwick, New Jersey
Dr. Vaala is a diplomate of the American College of Veterinary Internal Medicine and practices at B.W. Furlong and Associates in Oldwick, New Jersey. Over the years she's treated many horses for EPM—including her own—and tried about every medication available, but with variable results. Finally, she tried NAVIGATOR® paste. In this interview, Dr. Vaala shares her experience with NAVIGATOR paste and explains why the drug has now become her first choice for EPM treatment.

I first used NAVIGATOR paste on two horses that had been on another EPM medication. They had improved somewhat on the other medication, but not to the extent I had hoped. Then I used NAVIGATOR paste on them for 28 days and had excellent results. Indeed, one horse that had been showing neurological deficits for many months improved far more than I expected due to the chronicity and severity of his signs. He even regained his old personality and his owner was thrilled. The outcome of these two cases impressed me and I decided to use NAVIGATOR paste as my first line of treatment.

Case Study
Curtis was a 1500-pound warmblood/draft gelding that was referred to our clinic for neurologic examination in August, 2004. When Curtis arrived, his neurological status was a grade 3.5–4.0. He could barely back off the trailer and was a danger to himself and his owner. Two days prior to the referral, he exhibited early signs of ataxia and weakness. He had been treated with DMSO and Banamine®, but the ataxia progressed. Curtis was afebrile and current on all vaccinations, including WEE, EEE and WNV.

Upon physical examination, Curtis was quiet and anxious, with normal vital signs. However, the neurologic exam revealed a subtle head tilt, left ear droop, bilateral horizontal nystagmus, generalized weakness and ataxia. There was a marked truncal sway observed at the walk and he was easier to tail pull to the left. He circumducted his outside hindlimb when circling, and stumbled when walking over uneven ground. Once in the stall, Curtis preferred to lean to the left against the wall. The differentials for his neurologic deficits included EPM, WNV and otitis. Bloodwork revealed that Curtis was positive for exposure to Sarcocystis neurona and negative for WNV. His white blood cell count was normal and there was no history of fever, which made otitis an unlikely cause of his neurological deficits.

I began treating Curtis with NAVIGATOR paste. During the first five days of treatment, we did not take him out of the stall due to the severity of his ataxia. By the end of the first week, Curtis' nystagmus and head tilt had resolved and he no longer needed a wall to lean against. Curtis was stable enough to transport, and I sent him home to his owner for the remaining three weeks of treatment. Every week I'd get ecstatic calls from his owner giving me updates and telling me how well Curtis was doing. By the end of the second week Curtis had regained his old personality and appetite. Just one week post-treatment, Curtis' neurological status was a grade 0 and he started back into training. Four weeks post-treatment, he was being ridden and hunted again. His owners were absolutely thrilled with the transformation.

Side Effects
I have not witnessed any side effects with NAVIGATOR paste in the four horses I've treated, no diarrhea, no GI problems. As part of my therapy for horses with EPM, I recommend daily supplementation with vitamin E, probiotics and corn oil together with NAVIGATOR paste. Horses experiencing an acute onset of neurological deficits often receive an initial course of intravenous DMSO and Banamine®. The technical services veterinarian at IDEXX Pharmaceuticals was very helpful with the treatment protocol. He also advised me of adverse effects that might occur.

I make it a point to discuss the treatment instructions and possible side effects in detail with owners, and as a result, they are very compliant. NAVIGATOR paste comes with more complete instructions than any other drug I have used. I think the calendar on the box is an excellent tool for recording daily observations such as temperature, manure consistency and any other pertinent clinical signs. I often wish other drugs I prescribe came with such a daily record that encourages owners to observe their horses frequently during the treatment period.

Experience with other EPM treatments
Before NAVIGATOR paste became available, I had tried just about every other treatment for EPM. With some of those early treatments, I often kept the horse on the drug for up to seven months while I waited for improvement in clinical signs. All the while, I knew that the longer it took to see improvement, the more likely it was that the horse would have permanent neurological damage. Some horses would improve, but many of them never fully recovered or returned to their previous level of performance.

Conclusion
My clinic and I have been extremely impressed with the results we have seen using NAVIGATOR paste to treat horses with EPM. The drug has earned our respect and is now my first line of treatment for EPM. I recognize the drug's potential side effects, but when administered according to the company's recommendations, I have not had any problems. My only concern would be using NAVIGATOR paste in horses that are off-feed or have pre-existing GI disease. A lot of the drugs we use, including some of the other EPM medications, allow us to get by with less-than-accurate dosing, and as a result, we, as practitioners, may have become a bit complacent. Most drugs have potential gastrointestinal, renal and/or hepatic side effects. For example, there are some antibiotics and NSAIDs that can cause life-threatening situations. When using NAVIGATOR paste, I ensure that horses are dosed accurately and monitored closely, and that means excellent veterinarian/client communication.

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Dr. Stan Carroll, Ranson, West Virginia
Much of Dr.Carroll's time and that of his two associates at Carroll & Butler Equine Associates in Ranson, West Virginia, is spent on the racetrack. Approximately 70% of his equine patients are Thoroughbreds, with the balance made up of hunter/jumpers, Tennessee walking horses and barrel horses. No stranger to EPM and its devastating effects, Dr. Carroll discusses his experiences with Navigator® (32% nitazoxanide) paste and compares it to other EPM treatments he's used.

Diagnosis
I've treated hundreds of horses with EPM over the past 16–17 years (over 70 in one year) and have become very astute in detecting the disease early. The clinical signs of the disease are vast and include everything from incoordination to personality changes. Right-rear lameness or weakness is a subtle clinical sign I see, but it seems any time there's something weird going on, it's often EPM. For example, I had one horse that died of respiratory paralysis, so I pulled a spinal tap—sure enough, the horse was positive for EPM. I often find EPM in prepurchase exams. I conduct cervical spinal taps to confirm the diagnosis because I find them easy, clean and efficient—I'm done in just five minutes.

I had an opportunity to witness nitazoxanide in use when I assisted Dr. Joe Bertone with some of his work in the clinical field trial with the drug a few years back. I was impressed with it, and since its approval, I've continued to use it. I treat as recommended, and have had excellent success—much better than with other EPM treatments I've tried.

Side Effects
I can understand why practitioners are reluctant to try Navigator if they've had no prior experience with it. If I'd read the label before I used the drug, I wouldn't have tried it either—that label would scare anybody! I think it's important for practitioners to speak with other veterinarians who have used Navigator. Fortunately, I had some experience with nitazoxanide prior to its FDA approval, so the label didn't scare me.

I've noted depression, inappetance and exaggerated clinical signs in horses I've treated with Navigator. Two horses may have had other reactions, but I can't say for sure because both horses were out of my hands. One horse reportedly went off feed and had low-grade founder while in the care of another veterinarian. I haven't witnessed any founder firsthand. In the other case, the trainer read the label and took the horse off treatment.

I find that the anti-inflammatory properties of an NSAID are useful in cutting back inflammation prior to EPM treatment, so I treat with Banamine® for six days prior to treatment with Navigator.

Conclusion
I've tried every EPM treatment available and I've had much better success with Navigator than any other treatment I've used. Treatment has been successful in a significant majority of the horses I have administered it to. All showed gradual progression and only one horse relapsed.

In my experience, I've found the approved EPM treatment to be under-dosed when used as labeled. I haven't had any luck with it—nothing but relapses. I believe the success I've had with Navigator is due to the dosage being closer to what's needed to kill the EPM parasite. I would definitely recommend Navigator to other equine practitioners.

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Dr. J. Lane Easter, Whitesboro, Texas
Dr. Easter is a diplomate of the American College of Veterinary Surgeons. Dr. Easter's practice, Performance Equine Associates, is located in Whitesboro, Texas, which is in the heart of north central Texas. North central Texas is to the Quarter horse industry as Lexington, Kentucky, is to the Thoroughbred industry. Performance Equine Associates is a full-service, 100% equine practice with six associate veterinarians and three interns. The practice includes two boarded surgeons and an internal medicine practitioner, and specializes in lameness, surgery, reproduction and the treatment of western performance horses. In this interview, Dr. Easter discusses his experience with Navigator® (32% nitazoxanide) paste and other EPM treatments.

Case Studies
My first experience with Navigator was prior to its approval. I was an associate at Katy Equine Clinic in Katy, Texas, and we had several horses that had been treated for EPM multiple times with potentiated sulfonamides. The horses would get better, and then relapse. When I entered my surgery residency at Texas A&M, I found out one of the medicine clinicians there was involved with a clinical trial using nitazoxanide. I provided three of these horses to him for the nitazoxanide clinical field trial, and kept track of them during the study. All three horses had the disease for several years and all had been treated multiple times with potentiated sulfonamides. In fact, one of the horses had been treated three times.

All the horses responded better to this new treatment than they ever had before. To my knowledge, none of the horses relapsed; and I followed them for at least a year. None of them had ever gone that long without relapse. The success with those horses excited me about this new drug.

We see a lot of EPM cases in our practice. I've been told by the lab that performs our CSF analyses that our practice runs more CSF analyses for EPM than anyone else in the country. Some weeks I tap five horses.

I work with a lot of young futurity horses that compete in cutting, reining, western pleasure and other western performance events. The average value of the horses I work with is approximately $35,000, but they range in value from $10,000 to $250,000 or more. It's been proven by the work done on gastric ulcer disease that these young horses are under high levels of stress, which can also make them more susceptible to infection. I believe this to be especially true for EPM, in which the body relies heavily on cell-mediated immunity. These training barns will start out with 10–15 horses to try to make it through futurities with 2 or 3. In late spring, we'll consistently have 2–4 horses per trainer that quit stopping and turning as well as they have, may look lame on some days, show proprioception deficits, but are less than grade 1 ataxic. I'll pull CSF on these horses and find that most that fit this scenario are positive on both blood and CSF for EPM.

We used to put these horses on other EPM treatments and they'd be normal for a while, but then by September and October when the stress is highest, some would relapse right before the futurity. Now I put them on Navigator. Indeed, I've treated several horses valued at over $100,000 with Navigator. This will be our first year through the futurities with Navigator, so time will tell if they relapse.

Another case that really stands out in my mind was a three-year-old with very severe acute neurologic disease—close to grade 5 ataxic. This horse was diagnosed with EPM with a strong positive titer in his CSF. The horse had aspiration pneumonia secondary to a paralyzed larynx. We initially used another EPM treatment, but the horse never regained complete normal neurologic function. It was ataxic enough that it couldn't be ridden. We then put him on Navigator and, in three weeks, he was improved enough to be ridden. He is now four months out and completely normal with normal laryngeal function.

Side Effects
I've had a couple of horses out of a significant number that I treated with Navigator develop forefoot soreness. We stopped treatment, then resumed when the clinical signs had subsided, and the horses did well. I can't truly link the effect to Navigator in these horses. I've had one horse on Navigator develop mild diarrhea, but it resolved when we stopped the medication, which we resumed when the horse normalized in five days.

My personal belief, based on my experience with the drug, is that Navigator is safe. I do inform owners about the possible effects, and I tell them that we're going to monitor the horse closely. If the horse shows adverse effects, we'll take it off treatment, treat the symptoms, then resume.

Conclusion
Navigator is my first choice to treat EPM. Based on my experience with horses relapsing after other treatments, I prefer to use Navigator and give the horses the best shot at getting rid of the parasite. I've treated enough horses with Navigator to feel that its benefits outweigh the chances of any side effects.

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Dr. Stephen Allday, Simpsonville, Kentucky
Dr. Allday's practice, Elite Veterinary Medicine in Simpsonville, Kentucky, is focused on the treatment of Thoroughbred race horses. He treats some of racing's most valuable horses, where stud fees alone go for $500,000. In this interview, Dr. Allday discusses his experience with Navigator® paste (32% nitazoxanide) and other EPM treatments.

I vividly remember the first time I used Navigator. It was with a two-year-old colt purchased at the sale in Ocala in March, but it never got into training because of problems. The colt was brought to Florida for the winter and that's when I first saw him. Other practitioners had examined the horse before me and one thought it had a fracture. The colt's masseter muscle on its right side was so completely atrophied that there was a hole there, and its jaw was caved in. I wish I'd taken a photo. It began to make sense—there was no innervation.

I treated the horse with another EPM treatment for 30 days, but there was no improvement whatsoever. I later attended the AAEP conference and spoke with someone at the IDEXX booth about Navigator. I felt I had no choice but to try Navigator with this horse. We began treatment in January and the horse was febrile for 2–3 days, but we kept him on the regimen. Then we put him under tack, then began walking, then galloping. By June, we knew we'd won. His recovery was dramatic.

Another client had 8–10 cases of EPM. After treatment with Navigator, the horses were so much better—one of them won two races in a row—and she was maiden prior to that for eight straight races! My clients will do the right thing. They will opt for spinal taps and, if positive for EPM, will do whatever it takes to be sure their horses are healthy and performing at their peak.

Side effects
You have to understand that the EPM infection is imbedded in the CNS, which is unique to anything we as veterinarians deal with. As a doctor, to expect a medication to be free of side effects is unrealistic.

Every one of the horses I've treated with Navigator was febrile for the first 3–6 days of treatment, so I treated them with bute and Banamine®. I have not witnessed any GI problems with Navigator, but all the horses I treat are already on a high-fat diet. I was one of the first to do research on high-fat diets in horses, and we've been using them for 15 years.

Conclusion
If you really have a positive case of EPM, then, in my opinion, Navigator is the only drug to choose. I've tried all the other therapies—approved and unapproved—and I don't use anything else now. I tell people straight up, use Navigator because it works.

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Dr. Chris Morrow, Canyon, Texas
Dr. Morrow is one of three equine practitioners at Timber Creek Veterinary Hospital, an equine referral practice located between Amarillo and Canyon, Texas. The hospital's primary focus is with lameness and embryo transfer work.

My close friend, Justin Mass, competes as a tie-down roper in ProRodeo, and has won a number of events. In August of 2003, Justin bought a sorrel Quarter horse gelding named Elvis, and in seven months—from August 2003 to February 2004—Justin and the others riding Elvis won a total of $50,000. But then in March of 2004, Justin came to me and said Elvis was having trouble stopping and turning. We hadn't previously tested Elvis for EPM, so I pulled serum, and the test results showed he was a strong positive.

We caught the disease in Elvis at a very early stage. Justin had been to the national finals three times, and is keenly aware of subtle changes in a horse's performance. The only time Elvis had problems was at speed, and we'd never seen any problems during his exams. I discussed our options with Justin and he elected to treat. I recommended Navigator because I'd used it before and had been impressed with it.

I kept Elvis at my place and maintained detailed notes during his treatment. Ten days into therapy, I began to notice mild ataxia, so I could see that the therapy was doing something for him. We stopped riding him, although he never became overtly ataxic. From days 10 to 18, Elvis developed a noticeably improved attitude and ability to move around. We completed the therapy and then began an exercise program that included turnout and walking, and I rode him two more weeks through May.

At that point, Justin picked Elvis up and began routine work with him, getting him back into regular training through the end of July. In late August of 2004, Justin and Cade Swor won again with Elvis, and Justin feels Elvis is better than ever.

Side effects
The possible side effects of Navigator have never been a concern to me. We use Dr. Dan Mark's suggested protocol, which includes feeding the horse a yeast culture twice daily two days prior to treatment, and administering vitamin E, vegetable oil and flunixin during treatment.

Based on my experience, a horse's reaction to the drug is a positive indication that the horse has EPM, and that the drug is working, killing the protozoa. I've noted that the longer a horse has EPM and the more parasites that have infested the central nervous system, the more pronounced the ataxia will be during treatment. We were fortunate that Justin recognized the performance issues with Elvis very early, but that typically doesn't happen with pleasure horses, and I find that the treatment is often harder in them because they have more protozoa.

Conclusion
Navigator is a great product and one I definitely recommend to other practitioners. After treating EPM cases with Navigator, my clients tell me their horses are better than ever—and those aren't my words—they're my clients' words.

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Dr. Stephen Dey, Allentown, New Jersey
Dr. Dey's equine veterinary practice is located in Allentown, New Jersey, where he and his associates focus on the treatment of Standardbred racehorses. In practice for 45 years, Dr. Dey works with world-renowned trainers and some of the most valuable horses in the industry.

I had my first experience using Navigator back in December, 2003. I treated two horses: a yearling and a four-year-old. Both horses had tested blood-positive and shown clinical signs. The yearling had incoordination walking out of the stall, and the four-year-old had muscle atrophy. Both treatments were successful. Three weeks into treatment, the yearling changed around and has been fine ever since. The four-year-old became sound and its muscle filled back in.

Since that time, I've used Navigator paste in other stables. One of the world's leading Standardbred trainers came to me with an incoordinated horse that had been previously treated unsuccessfully with other EPM treatments. Based on my experience and success with Navigator, I recommended that we try it on his horse. After 10 days with the horse on treatment, the trainer was so impressed that he wanted to use Navigator in several other horses.

Side effects
Since a drug's potential adverse effects are more likely to appear in yearlings, that early case with the yearling back in December confirmed with me that Navigator could be used safely. Most of my clients have heard about the potential side effects associated with the use of Navigator, and they do ask about them. They trust me when I tell them Navigator is safe and effective, but I also take time to discuss how the original clinical studies were conducted and explain that the veterinarians in the original study were not allowed to use supplemental treatments. Our Standardbred horses are already on a high-fat diet, so we don't suggest diet changes to enhance absorption, but my associates do follow the label directions.

Caveat to Navigator use
I have seen two adverse effects in horses when treating with Navigator. Some horses go off feed and can have significant weight loss, and administration of Navigator must be stopped. Others can develop anemia, hemoglobin less than 10 and high temperature of 104-plus. If these signs occur, the horse should not be worked or jogged. It seems that certain horses are more likely to develop these responses than others, so trainers should be advised to pay close attention and monitor their horses during treatment.

Summary
Navigator paste is my preferred EPM treatment, and I use it to treat every horse with neurological signs. I would certainly recommend it to anyone interested in curing EPM.

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Dr. Alan Dorton, Versailles, Kentucky
Dr. Dorton has battled cases of EPM for years. Here he describes his frustration with the many treatments he tried until he had the opportunity to participate in an open field study for a promising new weapon against EPM—nitazoxanide.

Estimated total number of EPM horses treated: 200–300
Estimated number of EPM horses treated with nitazoxanide: 50
Years in practice: 17

How I diagnose
About 85% of the horses here in Kentucky test positive on serology, so, unfortunately, that test is not a great value. I do CSF taps, but they're not always accurate, according to recent research. I primarily use the neurology exam, and then rule out other possibilities. At that point, I confirm the diagnosis with response to treatment. I've found that shortly after treatment is initiated—if the horse truly has EPM—many will get perceptively worse in their neurologic deficits. I credit that response to the effects of the dying organisms. I see this response in most horses I treat; they get worse before they get better.

Case studies
Thoroughbreds represent 85–95% of the horses in this area, and they represent the majority of the EPM cases I treat. This area can be a hotbed of EPM. I had a farm that raises foals for racing and there were 18–20 cases of EPM on that one farm each year. Most of my cases have been one- to two-year-olds that were a grade 2 or 2-plus. I had tried just about every treatment available without satisfaction, so when I learned about the open field trial for nitazoxanide, I was willing to try anything. The nitazoxanide treatment returned them to a grade 0, and they went right back into training. Without a doubt, the earlier we could diagnose and treat the disease, the better the outcome. My more severe cases were typically brood mares. They weren't in training, so their signs weren't recognized as early. In those cases, the parasites had obviously already done permanent damage, but the mares still improved 1.5 to 2 grades.

Treatment insights
During the trial we learned that we got better response with nitazoxanide when the horses were fed a high-fat diet. I had a couple of horses that relapsed, so after learning about the importance of the fat content, I began to pretreat with corn oil. The oil improved absorption and probably increased serum levels of the drug. I also add probiotics before and during treatment. Now these additions have become standard protocol.

Experience with other EPM treatments
As I mentioned, prior to using nitazoxanide, I think I had tried every EPM treatment out there. Nothing worked and it was very frustrating. I'd treat for three months, the horses would show improvement, then they would relapse, then improve for six months and then relapse again. Eventually, we'd keep the horses on treatment for 8–12 months.

Nitazoxanide is my preferred EPM treatment. I've found that no other treatment compares in efficacy to nitazoxanide and in the long run, it's actually cheaper than anything else. In my experience, 90–95% of the cases I treat with it will be cured in one treatment regimen, compared to 2–3 months or more with other EPM treatments. I actually recommend keeping horses on certain EPM products for a full twelve months.

Addressing client concerns
I address the potential side effects of nitazoxanide immediately with my clients. I explain that in the 50 or so horses I've treated with it, I've never seen anything severe—only fever, anorexia and going off-feed. We monitor the temperature twice a day during treatment, and I explain that if their horse shows any adverse effects, we'll discontinue the medication until the horse is once again clinically normal, then begin treatment again. Most clients are very accepting. Our discussion of the possible side effects makes them pay more attention to the horse, which I view as a positive.

Conclusions
Controlling the spread of EPM is so important. We sometimes forget to remind owners of the basics, like making sure the feed is not accessible to wildlife, reducing the wildlife population by removing their nearby habitat, such as wooded areas near the barn. And the incidence of EPM is lower if you have a natural water source for the wildlife, because the wildlife drinks from the natural source rather than the horses' water troughs and tanks.

In diagnosing, early recognition is the key. You have to know how to do a neurological exam and recognize that any problem you observe that's related to the neurological system could be EPM. Lots of horses can have problems before muscle atrophy shows up, and the sooner you diagnose and treat EPM, the better the outcome. When it comes to EPM treatments, I absolutely prefer nitazoxanide. There's simply no comparison to other treatments. I can't think of any improvements I would make in the drug.

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Dr. Richard Mitchell
Dr. Mitchell has twice served the U.S. Olympic equestrian team and is a past board member of the AAEP. He specializes in the treatment of sport horses and has cared for some of the world's most valuable equines. Dr. Mitchell participated in the open field trials with nitazoxanide prior to its FDA approval, and often receives calls from other practitioners asking for advice on the use of the drug.

Practice location: Newtown, Connecticut, and Palm Beach, Florida
Estimated total number of EPM horses treated: up to 100
Estimated number of EPM horses treated with nitazoxanide: 6
Years in practice: 30

How I diagnose
When presented with a horse demonstrating neurologic deficits, the first thing I run is an EPM titer. If it's positive, then I consider that the horse may have EPM. I know there's a move away from doing CSF taps, but if you have a good one, then a positive tap makes me feel better about putting a horse on $1500 worth of medication. Some clinics do A/O taps under anesthesia, but I don't like anesthesizing a neurologic horse, so I don't do A/O taps. I believe many horses are exposed to EPM, but the ones that develop the disease are immune-compromised in some way.

Case studies
The incidence of EPM in my area is much lower than places like Kentucky and the Ohio River Valley. In my area, I find that if the horses are in nice stables, don't get turned out on pasture, there are few opossums, and the food source is controlled, then we don't see the disease. However, when I see the disease, it is usually quite profound.

I was involved with the open field study for nitazoxanide and have treated six horses with it. All the horses were grade 2 ataxic and most had positive CSF taps. They were all quite neurologic. During the treatment, all experienced transient lethargy and some developed a fever. One horse got worse about a week into therapy, but we kept him on treatment and he came out of it and fully recovered. Thanks to the potency of the drug, if the diagnosis of EPM is correct, the horse will react. I did observe the yellow sweat and urine—actually I would call it orange. It did concern me, because at the time, we didn't know this was evidence of the drug's absorption.

I followed all the cases for about a year. All the horses I treated improved by at least a full grade and all went back to service. Then about a year later, one of the six seemed to be neurologic again and another practitioner put him on another EPM medication. But he did not improve. The horse was unsafe to ride and was euthanized, and then evaluated at Cornell, but no parasites were found. My conclusion is that nitazoxanide cleared the parasite, but the damage was done and there was only so much regeneration that could occur.

Treatment insights
While I was in Palm Beach recently, I had several inquiries from practitioners about adverse effects of nitazoxanide. They had observed early signs of depression, low-grade fever and swollen legs during treatment. There was nothing that was unmanageable, but they were unsure about what to do and were nervous about the drug's use. I explained that the signs were most likely related to the drug's potency and the death of the parasites, and suggested they treat the signs with appropriate treatments such as an NSAID and corticosteroid.

Experience with other EPM treatments
I no longer feel there's a place for the other drugs in treating EPM. Nitazoxanide is the only medication I'll use to treat EPM. It kills the parasite right away—in one month—which is more effective than a drug that starves the parasite. And because you only treat for 28 days, it's less expensive.

Addressing client concerns
I tell owners that nitazoxanide kills the parasite, rather than inhibiting it like other products. Therefore, there will likely be some immune response that doesn't happen with other products. I explain that the response is similar to vaccines—such as transient fever and limb swelling—and no one gets too excited about post-vaccinal reactions. I explain to the owners that the reaction is evidence that the horse was properly diagnosed, that we will treat any adverse effects and continue the medication, and that the effects will pass in 7–10 days.

Conclusions
This is a devastating disease and rapidity of diagnosis and treatment is imperative. When we treat, we need a product that will kill the parasite right away. That's why nitazoxanide is the only treatment I use for EPM. The longer you take to kill the parasite, the higher the risk of permanent neurological damage to the horse.

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Dr. Andrew Roberts, Lexington, Kentucky
Dr. Roberts focuses on the treatment of race horses in Lexington, Kentucky. In racing, second best doesn't cut it. Horses have to be able to perform at their peak.

Estimated total number of EPM horses treated: 50+
Estimated number of EPM horses treated with nitazoxanide: 5
Years in practice: 10

How I diagnose
In the horses I treated with nitazoxanide, I had hard evidence of EPM from the serology and Western blot results. However, I've found that the spinal taps frighten many trainers, and even the Ohio State University has questioned the validity, so I've backed away from them a bit. I've used an experimental ELISA test that gives good quantitative numbers, and have found it to be extremely valuable. If the test ever becomes commercially available, it will be very helpful.

Case study
I didn't try nitazoxanide until it was approved by the FDA. I had a high-dollar horse that had been previously treated unsuccessfully with another EPM medication. It was a three-year-old standardbred race horse. I had read the nitazoxanide label warnings and admit that I had quite a bit of uncertainty with that first treatment, so I personally checked the horse every day. The horse was a grade 1 or 2. After treatment, the horse was letter perfect—a grade 0. After treatment, the trainer told me the horse was training the best he ever had. Since then, I have treated four more horses with nitazoxanide and all have been successes.

Treatment insights
I use a weight tape to obtain a good estimate of the horse's weight before treatment. During treatment, we supplement the horse's ration with probiotics and two cups of rice bran oil every day. The trainer and I also watch the horse's temperature closely during treatment. The horses remain in light training, just jogging so they're not losing time. The more mild cases stay in light training.

Nitazoxanide is inherently pretty safe if used properly. In the five standardbreds I've treated with it, I've only seen one adverse event. That horse showed GI signs, depression and fever, and was hospitalized and treated with NSAIDs and fluid therapy for a few days and did well. I later learned that the trainer had withdrawn the oil from the horse's diet five days prior to the episode. All the other horses I've treated just sailed right through with no problems. We may have noted a rise in temperature by one degree or so, but that was it. We've never seen the yellow sweat that's mentioned on the label, but we have seen the yellow urine and some changes in fecal color.

Addressing client concerns
Most of my clients recognize that EPM is much more dangerous than the drug. I make clients aware of potential side effects because I don't want any surprises. I tell them that nitazoxanide is really good medicine, and that if there are problems, we are going to stay on top of them. Trainers are notorious for developing their own treatment regimens, and as a practitioner, you learn which clients have a low rate of compliance, so I read them the riot act. I tell them it's cidal to the parasites and it works, and if they use it—they must treat exactly as I tell them—no sideways treatment. I tell them they must comply with the way I specify or don't call me.

Conclusions
For my most serious cases, nitazoxanide has become my preferred EPM treatment, because every horse I've treated with it has responded positively. The drug is cidal to the parasites, and killing the parasites is the most important thing. In the long run, I also find it's the least expensive treatment. Early treatment is vital when treating EPM, so I keep a box on hand at all times. My advice to other practitioners? You can use nitazoxanide with good results.

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