1. Parascaris equoru m
Infective eggs are swallowed, they hatch and liberate infective 2nd stage larvae, which burrow into the wall of the small intestine and are carried to the liver by the portal vein. After migrating through the liver tissue, they enter the hepatic vein and are carried by the posterior vena cava to the lungs, where they break the into the alveoli, molt and are coughed up and swallowed, returning to the small intestine to mature. (3months) Eggs have proteinaceous layer and is sticky. Eggs adhere to stall walls, mangers, buckets, etc.

2. Life Cycle

3. Ascarid
Can grow up to 12 inches in length within 4 weeks and block the small intestines.

4. Ascarids – Clinical Signs
Impaction colic – death
Pneumonia
Pot belly
Unthrifty appearance
Poor hair coat

5. Ascarid impactation and rupture

6. Parascaris equorum

7. Ascarid in the bile system of the liver

8. Diagnosis of ascarids
Clinical signs
Fecal flotation
Necropsy

9. Control of Ascarids Good sanitation
Eggs live in environment for many years
Avoid putting foals in same pastures year after year
Regular worming of foals and young stock

10. Treatment of Ascarids
Most common wormers are effective against ascarids (Safeguard, Panacur, Strongid, Ivermectin)
If a foal has a very heavy infection it should be wormed with less effective products to prevent impaction

11. Tapeworms
Three species of tapeworms are found in horses: Anoplocephala magna , A perfoliata , and Paranoplocephala mamillana
Found mostly in the cecum but may also be in the small intestine.
Young and older horses more susceptible -mite
Difficult to detect on fecal exam.

12. Tape worms (Anaplocephala)
Cause colic
Live at ileo-cecal valve
Disrupt motility
Use prazinquantel

13. Difficult to detect the eggs on fecal sample

14. Infection of A. perfoliata with intussusception of the ileum into the cecum.

15. A cluster of tapeworm segments at the ileocecal valve are of the cecum of a naturally infected horse.

16. Thread worms Intestinal Threadworm
Strongyloides westeri – (strongyle-like)
Life cycle as short at 2 weeks
Infects young foals (2 weeks-6 months)
Larvae passed in mare’s milk to foals
May cause diarrhea in young foals
Immunity quickly developed
DOES NOT cause foal heat diarrhea
Strongyloides is zoonotic, cutaneous larva migraines.

17. Thread worms

18. Can be free living in the soil

19. Cutaneous larva migrans
Larva can penetrate foal’s skin to cause infection
May species penetrate human skin and cause problems in people as well

20. Diagnosis of Strongyloides
Fecal exam for larvae
Fecal culture
VERY rarely may see eggs

21. Stronglyoides egg (larvae moving)

22. Treatment of Strongyloides
Worm mare prior to foaling to prevent larval migration to udder
Worm foals at 4 weeks of age

23. Control of Strongyloides
Sanitation
Keep stall dry to kill larvae

24. Diagnosis of internal parasites
Fecal egg counts can be very helpful
negative fecal does not always mean no parasites
Monitor multiple horses on the farm at the same time
Some parasites are difficult to diagnose – tapeworms
Smear, float, centrifuge, and Baermann apparatus

25. Baermann apparatus
Lung worms

26. Dewormers None are 100% effective
2 month interval (6 times a year) *think life cycles*
Use a broad spectrum product as basis for control (ivermectin, moxidectin)
Be sure to treat for tapeworms 1-2 time per year
Avoid creating resistance to anthelmintics
*Double dose strongid
*Product containing prazinquantel

27. Dewormers Avermectins
Ivermectin (Eqvalan, Zimectin, Equimectrin, Equimax)
Moxidectin (Quest, Quest plus)
Tetrahydropyrimidines
Pyrantal (Strongid, Rotation)
Benzimidazoles
Febendazole (Panacur, Safeguard)
Prazinquantel

28. Parasite control Manure removal at least 2x/week
Spread manure in hot weather away from fields where horses are grazing
Rotate Pasture- limit overgrazing (different species)
Group horses by age
Use feeder for hay and grain
Remove bot eggs from hair
Deworm new arrivals

29. Run a fecal on me before you pump me full of medication….