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PARASITES AND DEWORMING YOUR HORSES Control vs. Eradication. Karen Kalck, DVM, DACVIM Equine Medicine University of Tennessee Veterinary Medical Center. PLAN. Introduction Signs of parasitism Types of parasites Dewormers Diagnostics Designing a deworming program. QUESTIONS. - PowerPoint PPT Presentation
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PARASITES AND DEWORMING YOUR HORSES Control vs. Eradication
Karen Kalck, DVM, DACVIMEquine MedicineUniversity of TennesseeVeterinary Medical Center
PLAN•Introduction•Signs of parasitism•Types of parasites•Dewormers•Diagnostics•Designing a deworming program
QUESTIONS1. Raise your hand if you deworm
your horse(s) every 2-3 months?
2. Every 4-6 months?
3. Once per year?
4. Whenever you remember to?
COMMONLY ASKED QUESTIONS• What type of wormer should I use?• When should I worm my horse?• Should I rotate my wormers each time?• Should I use the same wormer all year long?• How often should I worm and when?• What are fecal egg counts and do I need to have
these done?• How effective are feed through wormers?• My horse is rubbing it's tail, is this because of
worms?
COMMON PRACTICES•Deworm 4 times per year•Deworm 2 times per year, once after the
first frost and once after the first hay cutting
•Deworm all year with the same dewormer•Rotate your dewormer each time•Only deworm if your horse is thin and not
putting on weight
PARASITES vs. BACTERIA•No replication of numbers within the host
•Life cycle
•No immunity to parasites
SIGNS OF PARASITISM•None•Lethargy•Loss of appetite•Dull, rough
haircoat•Tail rubbing and
hair loss•Loss of
condition/weight
•Slow growth in young horses
•Pot belly•Coughing, nasal
discharge•Diarrhea•Colic•Death
TYPES OF PARASITESLarge
strongylesSmall
strongylesRoundwor
ms
Tapeworms Pinworms Lungworms
Bots Strongyloides
Roundworms (Ascarids)
Large Strongyles
Small Strongyles
Pinworms
Tapeworm
LIFECYCLEEggs
• Manure of infected horse• Ground
Larvae
• Immature worms• Stomach/intestines
Adults
• Mature worms passed in feces
Grazing eggs/larvae swallowed
Larvae migrate out of intestines, into other tissues, and then return to intestine
STRONGYLES•Also known as bloodworms, red worms•Can cause anemia•Damage colon•Mesenteric arteritis (large only)
LARGE STRONGYLES
SMAL
L ST
RONG
YLES
ROUNDWORMS•Ascarids•Young horses (<2 years)•Large up to 15 inches in length!•Do not suck blood•Small intestinal obstruction•Can migrate through the lung, causing
damage and pneumonia
TAPEWORMS•Affect the last part of
the small intestine and cecum
•Can cause ileal impactions
•Eggs often not found in the feces
PINWORMS•Females deposit eggs around anus in a
“cement-like” mixture•This dries and cracks, causing
irritation•“Rat-tail” appearance
BOTS•Not worms, but fly
larvae•Female flies lay eggs
on horse legs•Horse ingests eggs •Larvae hatch and
migrate to the stomach
DIAGNOSTICS - Collection•Collect fresh feces in ziplock bag
•Label with horse name and date
•Send/take to veterinary laboratory
•Herd Collect individual samples on same day
DIAGNOSTICS•Fecal float
▫Good screening test for all parasites▫Does not quantify
•Fecal egg count (FEC)▫Not to be used for screening▫Will quantify numbers of eggs per gram of
feces▫Only for strongyles and roundworms
CONTROL VS. ERADICATION•Must encourage anthelmintic-sensitive
worms in population
•Do not want to become outnumbered by resistant worms
GOAL = CONTROL•Keep FEC low•Reduce transmission•Reduce the development of drug
resistance•Have happy, healthy horses•Kill adult parasites
NO!!!
DEWORMERS• Zimectri
n• Equimax• Eqvalan• Ivercare• Rotation
1
Ivermectin
• QuestMoxidectin
• Strongid T• Rotation 2
Pyrantel
pamoate
• Quest plus• Zimectrin
gold• Equimax
Praziquantel
• Panacur• Safe-
guardFenbendazo
le• Anthelci
deOxibendazo
le
DEWORMERSStrongyles Tape-
wormsRound-worms
Pin-worms Bots
Ivermectin / Moxidectin X X X
Pyrantel pamoate X X X
Oxibendazole X X X
Praziquantel X
Fenbendazole X X X
DAILY DEWORMER•Pyrantel tartrate (Strongid C)•Does not resolve existing infections•Not effective against tapeworms or bots•Resistance!•Only appropriate in very specific
situations
DESIGNING A DEWORMING PROGRAM•Do not deworm all horses every 8 weeks!
▫High levels of drug resistance▫Biology of parasites has changed▫Different worm demographics from horse
to horse
DESIGNING A DEWORMING PROGRAM•New recommendations – strategic
deworming▫Treat some horses more and others less▫Involves FEC▫Advantages
Fewer deworming treatments Less drug resistance Better worm control
POSSIBLE DEWORMING PLAN•First treatment in September
•Last treatment in March
•No further deworming until fall unless there is a very cool, wet summer
POSSIBLE DEWORMING PLAN•Determine which anthelmintics are
working in the herd
•September Egg counts on all horses•Categorize horses’ contaminative
potential▫<200 epg = low contaminators▫200- 500 epg = moderate contaminators▫> 500 = high contaminators
HYPOTHETICAL DISTRIBUTION OF STRONGYLE EGG COUNTS IN A HORSE HERD
NU
MB
ER
OF
HO
RSE
S
FECAL EGG COUNT (per gram of feces)
LOW(50%)
MODERATE(30%)
HIGH(20%)
LOW CONTAMINATORS (< 200 epg)
•September Treat with Ivermectin-Praziquantel
•March Treat with Moxidectin-Praziquantel
OR
MODERATE CONTAMINATORS (200-500 epg)•September Treat with Ivermectin-
Praziquantel
•November Treat with oxibendazole and/or pyrantel (together)
•March Treat with Moxidectin-Praziquantel
OR
+
HIGH CONTAMINATORS (> 500 epg)
•September Treat with Ivermectin-Praziquantel
•November Treat with oxibendazole and/or pyrantel (together)
•December Treat with Moxidectin
•March Treat with Moxidectin-Praziquantel•
OR
+
DEWORMING:Strategic vs. Every 2 months
Classification # of horses Number of doses/year Subtotal Grand total
Low 10 2 20
54Moderate 6 3 18
High 4 4 16
Every 2 mos. 20 6 120 120
DEWORMING IN FOALS/WEANLINGS•Start at 2 months of age•Deworm monthly•Alternate pyrantel and ivermectin
•At 8 and 12 months give a product with praziquantel as well
OR
ENVIRONMENTAL CONTROL•Moisture
▫Strongyle transmission occurs almost exclusively on pasture
▫Stall and dry-lots are negligible•Season (in TN)
▫Summer lowest pasture infectivity▫Winter cool enough to promote larval
persistence
ENVIRONMENTAL CONTROL•Manure management•Pasture rotation and management•Avoid over-stocking•Group horses by age•Feeders
EQUINE WELLNESS PROGRAMUT Equine Hospital and Field Services
•Comprehensive health care program for horses▫Pleasure horse▫Performance horse
•Yearly health care needs in one package•Packages are a 20% discount from
individual pricing•Eligible for additional discounts and
benefits•Sign-up beginning March 12th, 2011!
HORSE OWNERS CONFERENCE•March 12th, 2011 @ 8 am•At UT – Hollingsworth auditorium•Topics
▫Wellness program▫Small pasture management▫Fescue toxicosis▫Foot care and diseases▫Use of common medications in horses▫Lameness examinations
•$28/person ($15 for additional family members)•www.vet.utk.edu/continuing _ed
UTVMC OPEN HOUSE•Saturday April 16, 2011 from 9 am – 4 pm•Educational day for families
▫Teddy Bear Clinic▫Canine Parade of Breeds▫Equine Parade of Breeds – including Amigo!▫Farm Animals▫Wildlife and Exotic Animals▫Physical Therapy for Animals
•www.vet.utk.edu/openhouse
QUESTIONS??
•Thank you to Dr. Sharon Patton for providing information and pictures