Equine practitioners frequently field inquiries about parasite control. Hardly a day goes by when you’re not asked to provide some advice about anthelmintic selection or optimal deworming schedules. Despite the acknowledged importance of deworming and widespread implementation by horse owners, goods and services pertaining to equine parasite control are not represented proportionally in practice revenue. Why not?
This article identifies current and future opportunities in health monitoring and parasitology consultation for equine practices that wish to rectify the disparity between client demand and associated revenue in the parasite control market.
Economic History
Many practitioners believe that the equine parasite control market has been lost forever, so they have invested little time or energy in related services that could be provided at a profit.
This negative outlook may be a consequence of historic changes that reduced the deworming market to a remnant of its former prominence. Prior to the 1970s, nearly all equine anthelmintics were supplied by a veterinarian. Most were formulated as high-volume suspensions with narrow safety profiles. Veterinarians administered these compounds via nasogastric tube. But veterinarians’ direct participation in treating individual patients began to wane in the 1970s when safe, convenient, low-volume paste dewormers were developed.
The need for veterinary services declined even further once these paste products were marketed over the counter. In addition, the volume purchasing power of large retailers often meant that a horse owner could purchase a dose of paste dewormer over the counter for less than it cost a practitioner to buy it wholesale. This pattern was interrupted briefly in the 1980s when ivermectin became available solely as an ethical, injectable product. Nonetheless, ivermectin paste soon joined its competitors on the shelf at the local co-op.
As a result of these changes in drug formulation and marketing strategies, equine veterinarians lost their primacy as retailers of equine anthelmintics. The disappearance of this revenue dealt a significant economic blow to the average equine practice, and it all occurred in the space of a single decade.
Current Affairs
If veterinarians aren’t selling many anthelmintics, and they’re not administering dewormers, what is their current role in equine parasite control? The related activities in many practices can be summarized in three categories: a) haphazard fecal examination, b) ad hoc advice, and c) dissemination of formal recommendations. Let’s examine the inadequacies and opportunities in each of these activities.
Fecal Examination Fecal examination is technically simple and inexpensive, and results are available in a matter of minutes. Veterinarians generally recommend fecal examinations for two purposes: diagnostic (unplanned) or monitoring (planned).
Examples of diagnostic applications include eliminating differentials for a mare with recurrent colic or investigating why some yearlings aren’t as big or as slick as other crops in recent years.
Monitoring usually consists of systematic collection of representative fecal samples from a herd during a specific season or after a particular management procedure, purportedly to assess the utility of the farm’s current parasite control measures.
Fecal examination techniques for horses can be categorized as either qualitative or quantitative. Regardless of whether qualitative or quantitative techniques were used, a single “diagnostic” fecal examination doesn’t provide as much information as commonly believed.
So what if that colicky mare is passing strongyle eggs, or even has high numbers thereof? Virtually all pastured horses are exposed to strongyles, and if a sufficient interval had passed since her last anthelmintic treatment, a positive fecal exam is easily predicted. The parasitic stages most likely to cause colic in a mature horse are migrating Strongylus vulgaris larvae, by means of the verminous arteritis lesions they induce. Because larval parasites cannot reproduce sexually, pathogenic larvae in the anterior mesenteric artery do not contribute a single egg to the hundreds per gram that might be observed in a fecal exam. Conversely, a negative fecal result for the colicky mare doesn’t rule out larval disease, for the same reason.
High fecal egg counts in a majority of the poor-doing yearlings would be useful data, but analyzing that information to assess management factors and anthelmintic performance is potentially more beneficial than using it diagnostically to support a single, therapeutic decision.
No matter how well-intentioned parasitologic “monitoring” might be, fecal examination of a herd or a proportion thereof at one point in time does not provide adequate information to assess the utility of a control program, or comprehensive guidance for future practices. On the other hand, sampling individuals or populations at precise intervals can provide invaluable information about the spectrum of effective dewormers, the optimal timing of anthelmintic treatments and the relative amount of expense and effort required by each individual horse in the herd.
Offering Ad Hoc Advice “Doc, what should I use to deworm my horse?” Most practitioners hear this question frequently, and many launch into a rote response without seeking much additional information about the patient, its environment or its history. Would practitioners respond similarly if asked, “Doc, how should I treat my lame horse?” That query would likely trigger a series of questions culminating in a strong recommendation that the animal be examined before a proper course of therapy could be prescribed.
Parasite control is a similarly complicated prospect that warrants systematic evaluation and customized recommendations, just like any important clinical condition. Rote advice about deworming often fails to provide an adequate standard of care.
Dissemination of Recommendations Compiling and distributing written recommendations for parasite control is usually just another way to deliver those same rote responses. Such written recommendations often address the varying needs of different age groups (e.g., foals, weanlings, adults), but without systematic evaluation and proper diagnostic monitoring, such recipe recommendations are frequently inadequate.
Typically, most practitioners’ present involvement in equine parasite control doesn’t generate significant practice revenue. Occasional fecal examinations don’t yield large fees, and ad hoc advice is usually rendered on the spur of the moment and may not even be billed as a professional service. Formal parasite control recommendations are often distributed free-of-charge in newsletters or posted on websites, and are probably viewed as potential practice builders. As a revenue stream, parasite control is currently a mere trickle. It’s not surprising that very few practitioners have sought to expand services in this sector.
Why is the Status Quo Untenable?
Quiet but dramatic changes are taking place in the field of equine parasite control and each modification generates new challenges for horse owners, and by extension, for practitioners.
In the United States, the most important change has been the ubiquitous emergence of populations of small strongyles (cyathostomins) that are resistant to one or more classes of anthelmintics. A recent survey of large horse farms in the southeastern United States found that cyathostomin populations in 95 percent of the herds were resistant to fenbendazole, and those in 53 percent and 40 percent of the herds were resistant to oxibendazole and pyrantel pamoate, respectively. Moreover, recent studies have found indications that resistance to ivermectin is developing in cyathostomin populations in Brazil and the United States.
In addition, populations of ascarids (Parascaris equorum) that are resistant to ivermectin and moxidectin have been reported in Canada, the European Union and in the United States (Reinemeyer, 2009). Recent discoveries of ascarid populations that are concurrently resistant to macrocyclic lactones and pyrantel pamoate are particularly disturbing (Craig et al., 2007; Lyons et al., 2007). And although anecdotal, many equine practitioners have encountered pinworm infections and cases of cutaneous habronemiasis that don’t seem to respond to standard therapies.
Blanket, rote parasite control recommendations are no longer appropriate because anthelmintic susceptibility and resistance profiles vary from farm to farm. And even if a farm’s current control measures are demonstrably effective, resistant strains can easily be imported with any new herd addition, juvenile or adult.
In the absence of tailored recommendations and often merely out of habit, many horse owners continue to use anthelmintics that no longer work in their herds. This practice must be detected and discontinued immediately because resistance is a permanent genetic feature of a parasite population. Drugs which fail today will never regain their efficacy, and demonstration of resistance to an anthelmintic translates into a recommendation that the entire class of related drugs should not be used again for certain target parasites on that property.
The expanding problem of anthelmintic resistance demands that progressive equine practitioners be prepared to offer evidence-based recommendations for effective parasite management.
Implementing Change
Abandonment of conventional parasite control practices is clearly necessary, but attempted change invariably encounters opposition. The first obstacle is a clientele that is steeped in tradition, habit, blind acceptance of efficacy and fanatical adherence to schedules and rotation. Convincing equine practitioners to embrace evidence-based control practices will be equally challenging for the same reasons. In addition, some financial incentive is essential for veterinarians, given the paucity of practice revenue currently generated by parasite control.
Changing client habits is always a challenge, particularly when it involves paying for veterinary services (see sidebar).
The key, of course, is motivation and perceived value. It is useful that many informed owners have heard about drug resistance—particularly MRSA in humans—from the news media. They know it is bad when drug “tools” don’t work as well as they once did, and understand why they would not want resistance problems for their horses.
Eventually, evidence-based approaches must be implemented for each and every farm, but in the initial phase, more success might be achieved with a select number of clients, preferably those who are considered “influencers” by the local horse community. As an introductory exercise, suggest a pilot evaluation with a limited number of horses.
Performing a fecal egg count reduction test (FECRT) would be a powerful demonstration, especially with a product that is more likely to fail than to succeed against strongyles (e.g., a benzimidazole). Just make sure you don’t include any horses with pretreatment egg counts <100 eggs per gram; nothing will deflate consumer confidence like an equivocal result, which is entirely feasible if inappropriate candidates are evaluated.
If a “hard sell” becomes necessary, practices might consider conducting the initial evaluations at no charge. The high prevalence of anthelmintic-resistant strongyles on well-managed farms translates into a very high likelihood of demonstrating treatment failure for most clients. Perhaps this single demonstration will motivate the client to learn more about other evidence-based approaches and to enroll your assistance. A few complimentary fecal analyses could turn into a good investment. It may not be a large amount, but it’s likely to be greater than current revenue from parasite control in most practices.
Practitioner Incentive
With minimal instruction and training, fecal samples can be collected by clients and delivered to the veterinary clinic. Recent studies have confirmed that feces can be collected from a stall floor with no loss of accuracy, as long as the sample is less than 12 hours old. Feces should be packaged in airtight, zip-lock bags and brought to the veterinary clinic the same day. If prompt delivery is impractical, refrigeration of feces does not affect egg numbers, as long as the samples are not frozen.
Numerous methods are available for performing quantitative fecal egg counts, but the McMaster technique is arguably the simplest and least expensive, because it does not require centrifugation. A microscope is the only expensive item of equipment necessary for fecal analysis, and most clinics already have one in their laboratory. The microscope should have a 10X objective lens, and a mechanical stage is very useful, although not essential. McMaster’s slides are relatively inexpensive, and can be re-used thousands of times. All other components necessary to perform a McMaster’s test are either inexpensive disposables (e.g., paper cups, tongue depressors, cheesecloth) or can be adapted from common items that are discarded every day (i.e., 35mL syringe casings, used 3mL syringes). The knowledge required is readily available, and most recent graduates were probably exposed to it during school.
In Denmark, Italy, Finland, the Netherlands and Sweden, use of anthelmintic drugs has been restricted by prescription-only legislation. Dewormers cannot be purchased over the counter by consumers, and veterinarians may only use anthelmintics therapeutically rather than prophylactically. A clear consequence of these restrictions has been that veterinarians are routinely performing surveillance of parasite egg shedding. Providing this service and the resultant diagnostic interpretation and consultation has become an area of specialization for some veterinary practices, just as others might specialize in lameness or reproduction.
A survey conducted in 2004 reported that typical Danish equine practices processed between 50 and 4,000 fecal samples per year. In addition, some referral laboratories have specialized in equine fecal analyses and these may analyze from 10,000 to 20,000 samples annually. Danish veterinarians typically charge $10 to $20 per fecal analysis, with “package discounts” for paired, pre- and post-treatment egg counts to determine drug efficacy or to characterize the egg reappearance period (ERP). In addition, some practices offer price reductions when large numbers of samples are submitted from the same client. Most Danish practices that specialize in this area have organized their clients in a system wherein fecal samples from all horses are analyzed twice annually. Others send regular reminders to their clients.
Potential practice revenue can be calculated from the number of likely fecal analyses in an annual cycle, but this figure includes no compensation for diagnostic interpretation and consultation. At a minimum, the potential revenue should be around 50 percent of each client’s current, annual deworming expenditures (see sidebar).
Conclusions
Historic, one-size-fits-all strongyle control programs have clearly failed and no longer represent an acceptable standard of practice. Virtually every horse-owning premises has an urgent need for customized parasite control recommendations that take into account the regional climate, local management, stocking rates, anthelmintic susceptibility patterns and individual horse characteristics. Conscientious horse owners will appreciate a customized approach, and many are already well-informed about anthelmintic resistance from information sources available on the Internet and in trade magazines. The evidence necessary to support such programs includes determination of anthelmintic efficacy on the farm, monitoring length of the ERP over time, determination of contaminative potential of individual herd members and routine surveillance of egg shedding by the herd (see full paper for details). Rather than making routine trips to the farm store to purchase dewormers, horse owners can be trained to submit samples on a regular basis.
More meaningful consultation might be provided if thorough records of deworming treatments and associated fecal egg counts were captured in spreadsheets, allowing one to detect emerging resistance and to investigate perceived anthelmintic failures. Advanced approaches with the same data sets should support economic analyses in which the costs of monitoring can be compared directly to the differences in historical and current treatment costs. Evidence-based approaches should lead to fewer anthelmintic treatments of a herd within an annual cycle, and in many cases, the number of deworming episodes can be reduced by 50 percent or greater per annum.
Although the price of a dewormer syringe is considerably lower than the cost of a fecal analysis, regular monitoring ultimately will save money, and more importantly, preserve anthelmintic efficacy.
In summary, there is significant revenue potential in providing diagnostic and consultative services related to equine parasite control. It is our personal experience that many horse owners are interested in these services. The demand in the U.S. appears to be rising and the veterinary community should take the necessary steps to meet this demand.
SIDEBAR
Questions to Engage Client Interest in Changing Parasite Control Practices
- Would you like to know whether the dewormers you are currently using in your herd are still effective?
- How much do you spend annually for equine parasite control? (Include the costs of drugs and diagnostic tests, plus reasonable labor per head for deworming.)
- Would you like to do a better job of parasite control in your herd, if the total annual expenditure could remain the same?
- Would you like to identify the horses in your herd that require intensive, average or minimal help in controlling their parasites?
- Are you aware that in the local climate, most horses in your herd only need to be dewormed six months out of the year, rather than perennially?
- Rather than adhering blindly to a rote schedule, would you allow us to design a deworming program which provides the greatest efficiency for your farm and simultaneously preserves drug efficacy?
- Would you be willing to spend less on dewormers and invest the difference (see #2) in monitoring and consultation services?
This paper was written by Craig R. Reinemeyer, DVM, PhD, East Tennessee Clinical Research, Inc., Rockwood, Tennessee; Martin K. Nielsen, DVM, PhD, Department of Large Animal Sciences, Faculty of Life Sciences, University of Copenhagen, Denmark; and Morgan McArthur, DVM, Vetspeak, New Berlin, Wisconsin.
