2. • Reduce risk of parasite-induced diseases
– Colic
– Diarrhea
– Respiratory
• Reduce competition with parasites for nutrients
– Weight loss
• Retain potency of medicines for the future
2
5. • The major target of parasite control in mature horses1
• Virtually all grazing horses are infected1
• Horses never develop total immunity1
• Part of life cycle spent in lining of large intestine2
– Mucosal and encysted stages
– Usually it is just a few days or weeks (may hibernate)
• Reported cases of disease from small strongyles
related to very high levels of infection2
– Horses with poor health care
– Poorly cared-for horses or repeated ineffective treatments
1
Reinemeyer CR. Rational approaches to equine parasite control. Eq Parasit Cont. Kentucky Equine Research, Inc. 64-72.
2
Urquhart GM, et al. Veterinary Parasitology. 2nd ed. Glasgow, Scotland: Blackwell Science; 1996:46.
5
6. • Of greatest concern for horses less than 6 months
of age without roundworm immunity1
• Most horses develop natural immunity after this
• Signs include coughing, nasal discharge, weight
loss, weakness, etc.1
• Adults cluster in the small intestine causing
impaction, often with colic, that may result in a
ruptured gut and death1,2
1
Clayton HM. Ascarids: recent advances. In: The Veterinary Clinics of North America: Equine Practice. Philadelphia, Pa; 1986;2(2):313-328.
2
Sellon DC, Long MT. Equine Infectious Diseases. St. Louis: Saunders Elsevier, 2007:486.
6
7. • A medical threat to horses all over the
United States1
• Potentially more life-threatening than small
strongyles in adult horses2 as they may
cause surgical colic disease3,4
• Rarely see segments in manure5,6
• No reliable fecal diagnostic test5,6
1
Reinemeyer CR, et al. 48th Annual Meeting of the American Association of Veterinary Parasitologists, Denver, CO, July 2003. Updated West Coast farm prevalence of tapeworm
infection data.
2
Reinemeyer, C. (November 2011), Personal communication.
3
Pavone S, Veronesi F, Genchi C, Fioretti DP, et al. Pathological changes caused by Anoplocephala perfoliata in the mucosa/submucosa and in the enteric nervous system of equine
ileocecal junction. Vet Parasitol. 2011;176(1):43-52. Epub 2010 Oct 27.
4 Veronesi F, Diaferia M, Fioretti DP. Anoplocephala perfoliata infestation and colics in horses.Vet Res Commun. 2009;33 Suppl 1:161-3.
5
Pavone S, Veronesi F, Piergili, et al. Pathological changes caused by Anoplocephala perfoliata in the equine ileocecal junction.. Vet Res Commun. 2010;34 Suppl
1:S53-6.
6
Reinemeyer C. Update on equine tapeworms presentation notes. Louisiana Veterinary Medical Association Equine Committee. September 21-23, 2003.
7
8. Results of a survey demonstrated that more
than half of all horses (54.2% nationwide) will
be infected with tapeworms at some time in
their lives.1,2
1
Reinemeyer C. Update on equine tapeworms presentation notes. Louisiana Veterinary Medical Association Equine Committee. September 21-23, 2003.
2
Reinemeyer C. Equine Tapeworms Prevalent in Western States, Study Shows. TheHorse.com. Available at: http://www.thehorse.com/viewArticle.aspx?ID=14571.
Updated July 21, 2009. Accessed December 9, 2010.
8
10. • Resistance: Parasites that used to be easily controlled
by a dewormer start surviving treatment.
• Parasite resistance means a dewormer doesn’t work as
well as it used to.
• Parasite resistance is a farm situation, not an individual
horse situation.
10
11. • Before the introduction of ivermectin in 1984, there was
already resistance to equine dewormers1,2
• Resistance of small strongyles — one of the major
parasites in horses — has long been a concern1
– A “reason” for rotational deworming recommendation …
we’ll come back to that
1
Barger IA, Lisle KA. Benzimidazole resistance in strongyles of horses. Aust Vet J. 1979;55:594-595.
2
Lyons ET, Tolliver SC, Ionita M, Collins SS. Evaluation of parasiticidal activity of fenbendazole, ivermectin, oxibendazole and pyrantel pamoate in horse foals with emphasis on ascarids
(Parascaris equorum) in field studies on five farms in central Kentucky in 2007. Parasitol Res. 2008;103:287-291.
11
12. 1958 Late 80s 2004
Small strongyles and Small strongyles with Significant small strongyle
phenothiazines1 piperazine and all resistance in SE U.S. to
benzimidazoles 3,4 (some as fenbendazole and pyrantel7
early as 1970 – FBZ)
1965 90s Mid to late 2000s
Small strongyles and Small strongyles and both Ascarids and macrocyclic lactones (KY, TX)
thiabendazole2 pyrantel salts5,6 Small strongyles and macrocyclic
(4 years after intro) lactones1,8,9,10
Egg Reappearance Periods (ERP) in KY
Resistance in other countries
1
Lyons ET, Tolliver SC, Ionita M, Collins SS. Evaluation of parasiticidal activity of fenbendazole, ivermectin, oxibendazole, and pyrantel pamoate in horse foals with emphasis on ascarids (Parascaris equorum) in
field studies on five farms in Central Kentucky in 2007. Parasitol Res. 2008;103(2):287-91. Epub 2008 May 10.
2
Drudge JH, Lyons ET. Newer developments in helminth control and Strongylus vulgaris research. Proceedings, 11th Annual Meeting, American Association Equine Practitioners, Miami Beach, Florida, 1965;
381-389.
3
Drudge JH, Lyons ET, Tolliver SC. Benzimidazole resistance of equine stronygles--critical tests of six compounds against population B. Am J Vet Res. 1979 Apr;40(4):590-594.
4
Lyons ET, Tolliver SC. Some historic aspects of small strongyles and ascarids in equids featuring drug resistance with notes on ovids. Emphasis on research at the University of Kentucky. Agricultural
Experiment Station. 2009;SR-102:1-10.
5
Drudge et al. Piperazine resistance in Population-B equine strongyles: A study of selection in Thoroughbreds in Kentucky from 1966 through 1983. AJVR. 1988;49:986-994.
6
Chapman MR, French DD, Monahan CM, Klei TR. Identification and characterization of a pyrantel pamoate resistant cyathostome population. Vet Parasitol. 1996;66(3-4):205-212.
7
Kaplan RM, et al. Prevalence of anthelmintic-resistant cyathostomes on horse farms. JAVMA. 2004;225(6):903-910.
8
Craig TM, et al. Evidence of Ivermectin resistance by Parascaris equorum on a Texas horse farm. Journal Equine Vet Sci. 2007;27:67-71.
9
Lyons ET, Tolliver SC, Collins SS. Reduced activity of moxidectin and ivermectin on small strongyles in young horses on a farm (BC) in Central Kentucky in two field tests with notes on variable counts of eggs
per gram of feces (EPGs). Parasitol Res. 2011 May;108(5):1315-9. Epub 2011 Jan 7.
10
Trawford AF, et al. Suspected moxidectin reistance in cyathostomes in two donkey herds at the Donkey Sancturary, UK. Proceedings, 20th International Conference World Association for Advancement of
Vet Parasitol. Christ Church, NZ, 2005, No 196.
12
13. • Current programs call for
deworming all horses at regular
intervals, often every two months
• Horse owners have been doing
this for years, and what do we
have?
– Percent of farms with small
strongyles resistant to:2
• Experts say it’s time to change
direction1,3
1
Kaplan RM. These ain’t your father’s parasites: An evidence-based medical approach to equine parasite control. The Practitioner . October 2008.
2
Kaplan RM, et al. Prevalence of anthelmintic-resistant cyathostomes on horse farms. JAVMA. 2004;225(6):903-910.
3
Reinemeyer, CR. Rational approaches to equine parasite control. Eq Parasit Cont. Kentucky Equine Research, Inc. 64-72.
13
15. • Rotating through different parasite control products is
not slowing development of resistance1,2
• Rotation can actually mask results of ineffective
products3
1
Uhlinger CA, Kristula M. Effects of alternation of drug classes on the development of oxibendazole resistance in a herd of horses. JAVMA. 1992;201:51-55.
2
Reinemeyer, CR. Rational approaches to equine parasite control. Eq. Parasit Cont. Kentucky Equine Research, Inc. 64-72.
3
Kaplan RM, et al. Prevalence of anthelmintic-resistant cyathostomes on horse farms. JAVMA. 2004;225(6):903-910.
15
16. • In the 1970s, no single dewormer controlled all major parasite species and
stages1,2
• Veterinarians rotated among several products to get the broadest spectrum of
control3
• Without good scientific evidence, this concept was thought to help prevent
resistance
• These concepts were commonly taught in veterinary schools
• Research and parasite control surveys have changed the thinking about
equine parasite control since 20004,5
1
Bello TR. Endoparasitism. Equine Medicine and Surgery .1982:67-85.
2
Robinson EN. Resistant cyathostomiasis. Current Therapy in Equine Medicine. 2003:161-164.
3
Reinemeyer, CR. Rational approaches to equine parasite control. Eq Parasit Cont. Kentucky Equine Research, Inc. 64-72.
4
Kaplan RM, et al. Prevalence of anthelmintic-resistant cyathostomes on horse farms. JAVMA. 2004;225(6):903-910.
5
Kaplan RM. Anthelmintic resistance in nematodes of horses. Vet Res. 2002;33:491-507.
16
17. • Rotation started because of:
– Lack of broad-spectrum anthelmintics
– Attempt to slow resistance
• Has not been shown to significantly slow progression of
resistance1,2
• May mask the clinical effects of ineffective dewormers3
within the rotation
• If drug is not broad spectrum, there is no efficacy
against some parasites
1
Uhlinger CA, Kristula M. Effects of alternation of drug classes on the development of oxibendazole resistance in a herd of horses. J Am Vet Med Assoc .1992;201:51-55.
2
Reinemeyer, CR. Rational approaches to equine parasite control. Eq Parasit Cont. Kentucky Equine Research, Inc. 64-72.
3
Kaplan RM, et al. Prevalence of anthelmintic-resistant cyathostomes on horse farms. JAVMA. 2004;225(6):903-910.
17
18. • Currently, the goal of most parasite control
programs is to eliminate all worms by treating all
horses all the time1,2
• This approach leads to resistance and failure, and
will continue to do so1,2
• Experts say it’s time for a new approach1,2
1
Kaplan RM. These ain’t your father’s parasites: An evidence-based medical approach to equine parasite control. The Practitioner. October 2008.
2
Reinemeyer, CR. Rational approaches to equine parasite control. Eq Parasit Cont. Kentucky Equine Research, Inc. 64-72.
18
20. • Monitor to determine which parasites exist on each farm
and which products are effective against them
• Selectively treat horses that need a dewormer with
products known to work on that farm
• Maintain a population of nonresistant parasites on the
farm (refugia)
Plus … environmental management
20
21. • Work with your veterinarian to run Fecal Egg Count Tests
(FECTs) and Fecal Egg Count Reduction Tests (FECRTs)
• Determine which medications are still effective for controlling
specific equine parasites on a specific farm1,2,3,4
– McMaster test most commonly used to determine eggs per gram (EPG)
– Compare eggs per gram (EPG) before treatment with after treatment5,6
– Test the same horses before and after treatment, using fecal egg count reduction
tests (FECRTs)3
• Remember: Results apply to specific parasites on a specific farm
1
Kaplan RM. These ain’t your father’s parasites: An evidence-based medical approach to equine parasite control. The Practitioner. October 2008.
2
Reinemeyer, CR. Rational approaches to equine parasite control. Eq Parasit Cont. Kentucky Equine Research, Inc. 64-72.
3
Kaplan R. Recommendation for standardization of fecal egg count reduction tests in cattle. AAVP. Washington, D.C. Abstract. 2007;78:84-85.
4
Lyons ET, Tolliver SC, Ionita M, Collins SS. Evaluation of parasiticidal activity of fenbendazole, ivermectin, oxibendazole and pyrantel pamoate in horse foals with emphasis on ascarids (Parascaris equorum) in field
studies on five farms in central Kentucky in 2007. Parasitol Res. 2008;103:287-291.
5
Evans PA, et al. Fecal egg count tests improve deworming programs. Utah State University Cooperative Extension. April 2009. Available at:
http://extension.usu.edu/files/publications/publication/AG_Equine_2009-01pr.pdf. Accessed June 3, 2009.
6
Swiderski C and French DD. Paradigms for parasite control in adult horse populations: A review. In: Proceedings. 54th annual meeting of the AAEP. 2008:316-321.
21
22. The Right Horses: Determine egg shedding levels via FECTs
•Treat based on shedding levels & parasite biology
– Some guidelines but no definitive levels1,2
– Low shedders treated 1-2 times per year
• < 200 EPG
– Moderate shedders treated 2-3 times per year
• 200-500 EPG
– High shedders treated 4-6 times per year
• > 500 EPG
– Time of year1
• Reduce small strongyle transmission greatly in spring
• Broad spectrum in fall
1
Reinemeyer, CR. Controlling Stronglyle Parasites of Horses: A Mandate for Change. AAEP Proceedings. 2009:352-360.
2
Kaplan RM. These ain’t your father’s parasites: An evidence-based medical approach to equine parasite control. The Practitioner. October 2008
22
23. • Use the most appropriate effective drug – broad
spectrum
– Use results of FECRTs to choose drugs that are still working
on your farm
– Add that to knowing which worms are key targets on your
farm. This could depend on:
• Age of horses
• Geographic location/time of year
23
24. • Only L3 stage larva is infectious1
• Takes 3-5 days from egg to L31,2
• Eggs killed by cold and very hot weather1
– <43 ºF and >85 ºF
• L3 larvae die rapidly above 90 ºF
(but survive freezing)
• So…No need to deworm during unfavorable
transmission season
– Saves $$$
– Better for the environment
– Decreases worm resistance
1
Reinemeyer, CR. Controlling Stronglyle Parasites of Horses: A Mandate for Change. AAEP Proceedings. 2009:352-360.
2
Nielson MK et al. Climatic influences on development and survival of free-living stages of equine strongyles: Implications for worm control strategies and managing anthelmintic resistance. The Veterinary Journal. (174)
2007:23-32
24
25. It all comes down to the weather
Northern Temperate Southern Temperate Overall
(NT) Region (ST) Region
• Optimal transmission is virtually • Optimal transmission occurs in the • Fall and spring provide moderate
perennial1 with access to the ground fall, winter and spring1 daytime and nighttime temperatures
• Even winter pastures serve as a • Daytime temperatures are warm and general high levels of
precipitation, making conditions
source of substantial infection, enough in the winter, permitting the
favorable for strongyle development
because larval survival is excellent in hatching of eggs and the
cold, even freezing conditions development of new larvae. and transmission
• The only relief for NT horses occurs However, the overall cool conditions Seasonality
allow for the persistence of infective
when they are stabled for substantial
intervals or turned out to non- stages in the environment.
vegetated dry lots and fed hay • In summer, when weather turns very
hot, development and persistence are
hindered. This is the only time ST
Seasonality horses experience relief. Winter
Spring
Seasonality
Summer
Fall
1
Reinemeyer, CR. Controlling Stronglyle Parasites of Horses: A Mandate for Change.
AAEP Proceedings. 2009:352-360.
25
26. Refugia: A portion of the parasites on a specific farm that are left
untreated, so that susceptible parasites (those not resistant to
dewormers) remain to breed with resistant parasites1
Another way to think of this is: diluting the resistant parasites in a
large “pool” of nonresistant parasites
You actually NEED nonresistant parasites to keep resistance
from taking off 1
1
Kaplan RM. These ain’t your father’s parasites: An evidence-based medical approach to equine parasite control. The Practitioner. October 2008.
26
27. • Where is this refugia?
– On the pasture
– In the large intestinal lining (except when a potentially
larvacidal treatment of fenbendazole or moxidectin is used)1,2
• How to do it?
– Treat some horses less often or not at all,
so there’s a place for susceptible parasites to live3
• Why do it?
– Refugia is the most important factor in slowing
the rate of development of resistance4,5
1
Quest® Plus Gel FDA Freedom of Information summary.
2
Panacur® product label.
3
Martin PJ. Development and control of resistance to anthelmintics.. 1987;17:493-Int J Parasitol501. .
4
Van Wyk JA. Refugia – overlooked as perhaps the most potent factor concerning the development of anthelmintic resistance. Onderstepoort.
J Vet Res. 2001;68:55-67.
5
Sangster NC. Pharmacology of anthelmintic resistance in cyathostomes: will it occur with the avermectin/milbemycins? Vet Parasitol.1999; 85:189-204.
27
29. • Manure management
– Compost ( >90º for 2 weeks)
– Spreading manure – not fresh
• Rotate age groups in pastures
• Rotate species in pastures
• Pasture management
– Mowing
– Dragging in heat of summer, off 2 weeks
29
30. • Know the active ingredient in your dewormer and which class it
belongs to
– There are often several brand options for each different active ingredient
– There are only three classes of equine dewormers
• If your farm has resistant parasites to one product, they are likely resistant to the other
products in that class
Chemical Class / Active Ingredients Common Product Names
Benzimidazoles SAFE-GUARD®, PANACUR®,
(e.g., fenbendazole; oxfendazole) ANTHELCIDE®
Tetrahydropyrimidines STRONGID® products, EXODUS®
(e.g., pyrantel pamoate; pyrantel tartrate) Paste, STRONGYLE WORMER®
Macrocyclic lactones ZIMECTERIN® Gold*,
(e.g., ivermectin; moxidectin) ZIMECTERIN®,EQUIMAX®*,
QUEST® Plus*, QUEST®
**These products also include praziquantel, an active ingredient that specifically controls tapeworms (Anoplocephala perfoliata).
30
31. • ZIMECTERIN Gold can be trusted to control more species and stages of parasites than
any other product1,2
– Effective against small strongyles resistant to benzimidazole products2
– More than 99% effective against natural tapeworm infections (Anoplocephala perfoliata)1
– Approved for use in adult horses and foals as young as 2 months old2
IMPORTANT SAFETY INFORMATION: Not for use in humans. Keep this and all drugs out of reach
of children. In horses, there have been rare reports of swelling and irritation of the mouth, lips and tongue
following administration of ZIMECTERIN Gold. These reactions have been transitory in nature. Do not use
in other animal species as severe adverse reactions, including fatalities in dogs, may result.
1
Based on data provided in FDA Freedom of Information summaries.
2
Based on data provided on the ZIMECTERIN Gold product label.
31
32. • Merial backs every ZIMECTERIN® (ivermectin) Brand Product with a 100%
product satisfaction guarantee
• Gives you confidence that your deworming program is always working hard
32
33. IMPORTANT SAFETY INFORMATION: Not for use in humans. Keep this
and all drugs out of reach of children. In horses, there have been rare
reports of swelling and irritation of the mouth, lips and tongue following
administration of ZIMECTERIN Gold. These reactions have been transitory
in nature. Do not use in other animal species as severe adverse reactions,
including fatalities in dogs, may result.
33
