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Internal parasites.ppt

Parasitism is where theparasite benefits at theexpense of the host byeither living within the host(Endoparasites) or on thehost (Ectoparasite)

Effect of Endoparasites  Endoparasites continue to be a significant threat to the health of the  Parasite infection causes loss of nutrients or blood from the host and serious economical and medical problems in managing horses  Depletion of nutrients and blood can cause severe loss in condition, decrease growth and reduce reproductive and athletic Prevalence of Endoparasites  More than 150 types of internal parasites are known  The five most significant ones are strongyles, ascarids, pinworms, tapeworms and bots  It is important to understand the life cycle of these parasites as successful prevention and control programs are effective because they interrupt the life cycle of parasites

Nematode Structure  A protective outer skin  Resistant to host digestive The basic nematode body consists ofan outer tube enclosing an inner tube No vascular system Circulation of nutrients is assisted bybody movements and locomotion

General Life Cycle Strongylus vulgaris Infection is by eating of the immature worms (L3) with grass fol owed by migration to the smal intestine (A) and penetration of the intestinal wal (B) 7 days approx Penetration of arteries (C) and migration to the large intestine arteries (D) 14 days approx Stay here for 3 months and form nodules in the wal of the intestine (D) Rupture of these nodules releases the young adult parasites L5 into the lumen of the intestine (6 to 8 weeks to mature) Mature adults mate and produce eggs that are passed with faeces  Pale mucous membranes  Poor weight gains  Weight loss combined with dul , staring coats  Clinical signs are related to the feeding habits of Small Round Worms Horses are infected by eating immature worms L3's while grazing Pass through intestines to large intestine Here, the larvae L4 burrow into the intestine wal s and muscle and become Can stay here for a number of years When conditions are right outside they Affects foals, adolescents develop immunity Eggs are swallowed with feed, pasture or water Eggs hatch, and the larvae burrow into the wall of the small intestine where they migrate into Next they travel to the liver, heart and subsequently to the lungs normally within 7- L3's are coughed up and swallowed L4 - Adults mature in the small intestine Eggs passed in 10 week old foals Can remain infective for years  Unthriftiness,  Rough hair coat  Cough and nasal discharge that does notrespond to antibiotictreatment Damage by Ascarids Damage to the foal or young horse begins during this migration Physical damage, inflammation and scarring of liver and lung tissue, are results of the migration Damage from adult worms can range from slight digestive irritations and decreased feed absorption to intestinal blockage and subsequent colic In heavy infections ascarids may be responsible for gut impactions and ruptures Adult pinworms lay their eggs around the anus of their host Eggs drop off and contaminate pastures, water, bedding and feeding areas The infective stage of Oxyuris equi is an egg containing a third stage larva (Egg + L3) Infected by ingestion Larvae (L3s) hatch in the smal intestine, pass into the large intestine Here they molt to the fourth stage (L4) about 8 to 10 days after infection A lengthy maturation phase of about 100  Severe anal itching which causes the horse to rub its tail and the  The hind quarters of affected animals should be washed to remove egg masses before

 Stomach bots are the larvae of a  The females lay eggs on the hairs of horses legs  Licking stimulates hatching  Attach to the tongue and burrow into the tissues of the  Three weeks, a second stage larvae emerges, is swallowed and attaches to the lining of the stomach Over wintering in the stomach, theypass out in the manure in spring anddevelop into adult flies The adult flies are active from latespring to the kil ing frost in late fal Treatment for bots should be scheduledfrom mid to late-summer and again aftera kil ing frost This schedule renders winter treatmentsunnecessary Young foals 4–47 days old Capable of both parasitic and free-living reproductive cycles After hatching, larvae may develop through four larval stages into free living adult male and female worms Foals infected by ingesting larvae in the dam's milk or by penetration of the foal's skin by infective larvae in the bedding The larvae migrate through the lungs and the smal intestine causing injury while passing

The life cycle can be completed in less than Foals quickly develop immunity to these The main problem caused by these parasites is diarrhoea, which may not respond to Some foals with threadworms may become dehydrated and develop other problems related to chronic diarrhoea Threadworms infections may accompany, but are not the cause for "foal heat" Tapeworms occur in horses of al ages Transmission requires an intermediate host, the oribatid mite which exists on Horse ingests the mite from pastures, and it takes about two to four months for the tapeworm to mature in the horse Mature worms first occur in weanlings Large numbers of tapeworms can cause ulceration in the large intestine and caecum, colic, and a severe form of intestinal blockage  Many different commercial products are available to remove internal parasites from horses  These drugs are administered in several different ways: Purge (kil ing of adults) Via stomach tube (drenching) Pel ets every 8 weeks in feed  Continuous drug control program  Intramuscular injection (moxidectin) Seasonal Influence De-worming programs work best if used when climatic conditions are favorable for hatching of eggs, development of larvae and transmission of infection The annual cycle to control parasites should begin in early autumn (September) and continue through February or March Research indicates that it is better to concentrate treatments in autumn and winter than to use the same number of treatments spaced evenly throughout the year Although this program is somewhat different from the traditional de- worming schedules, there is increasing documentation for its Praziquantal & Ivermectin

 One of the most effective classes of dewormers  Kills everything except encysted small strongyle larvae &  Since ivermectin became available, the incidence of large- strongyle-related colic has decreased dramatically  The use of ivermectin every five to six months should eradicate large strongyles on a farm in about two years

 Kil s 15% encysted smal strongyles and bots andprovides 84-day suppression of strongyle eggs  One of the least safe commercial worm medicines currently in popular use  There are reports of it kil ing horses who were in marginal condition, undernourished and/or a little  Telmin (Mebendazole) & Panacur (Fenbendazole)  Given at double dose according to the horse's weight for five days in a row, or at eight times the dose wil kil more encysted smal strongyle larvae than moxidectin  They are extremely safe when used alone x100  Wil not control bots and may require higher dosages to  Most resistance to wormer is found in this class  Strongid, Pyratape  They are effective against ascarids, strongyles andpinworms  A double dose of the pyrimidines has been effectivein control ing tapeworm Praziquantel & Ivermectin Effective against tapeworms No efficacy against roundworms Praziquantel & Ivermectin High efficacy against tapeworms and adult smal roundworms Roundworm Roundworm Ascarids Parasite Prevention Management programs which interrupt the life cycle of the parasite before infestation occurs are the key to successful control Sanitation in stal areas is essential. Manure should be removed and placed in a compost pile or spread on cropland or pastures not being grazed by horses. The larvae in composted manure wil be destroyed if sufficient heat is built up Alternative grazing with ruminants and pasture rotation schemes wil aid in disrupting the parasite life cycle Vacuuming or col ecting faecal material in pasture is expensive, but it can be very effective Parasite Prevention  Be sure to isolate and deworm al new arrivals to the  Feeding horses on the ground and not out of containers increases the risk of becoming infested  Check the efficacy of that program by evaluating faecal samples for parasite ova on an annual basis Adopt a rotational treatment protocol, which alternates between classes of anthelmintics

Source: http://www.redmills.fr/assets/files/pdf/internal-parasites.pdf