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Flashcards in parasite control (mallicote) Deck (46):
1

Goal for young horses

limit parasite burden until young horses develop their immunity

2

goal for adult horses

minimize disase without inducing a resistance to parasiticides

3

Major internal parasites

  • small strongyles (Cyathostomes)
    • seasonally transmitted
    • winter in FL, summer in north
  • Large strongyles
  • Anoplocephala perfoliata (Tapeworms)
  • Ascarids - Parascaris equorum
    • year round infection of young horses

4

Minor internal parasites

  • Gastrophilus intestinalis (Bots)
  • Habronema muscae, Draschia megastoma (stomach worms)
  • Oxyuris equi (Pinworms)
  • Strongyles westeri (Threadworms)
  • Dictyocaulus arnfieldi (lungworms)

5

Small strongyles / Cyathostomes

  • Most important parasite to manage in adult horses
  • Significant concern for resistance in these populations
  • prepatent period - minimum 5 weeks
    • relatively short period of time

6

Small strongyles / Cyathostomes

life cycle issues

  • larvae migrate in cecum/colon walls for 4-6 weeks
    • may encyst for months to years
  • mature and encysted cyathostomes are not significant in causing disease if moderate numbers

7

small strongyles

progression

emergence of larvae =>

Intense inflammation =>

hemorrhage and edema of cecum and colon =>

Colic and diarrhea

8

Large strongyles

  • migrate through abdominal tissues
    • liver, pancreas, arteries
  • LIve in lume of gut
  • long prepatent period (6 months)
    • don't have to treat very often
  • CS
    • colic, poor growth, weight loss

*we rarely see this parasite (since advent of ivermectin)

9

Parascaris equorum (roundworms)

  • adult horses develop immunity
  • eggs persist in environment for years
  • deadly for young foals

*only parasite that will be in the small intestine of the horse (others in colon....I think)

10

Parascaris equorum (roundworms)

progression

  • parasite lives in small intestine => 
  • lymphatics =>
  • lungs =>
  • pharynx =>
  • small intestine

11

Parascaris equorum (roundworm)

days to reenter SI

28 days

12

Parascaris equorum (roundworms)

days to produce eggs

72-80 days

-before you see eggs in fecal

13

clinical signs of ascarid infection

  • coughing
  • diarrhea, colic
  • pot belly
  • rough  hair coat
  • weight loss
  • can't be diagnosed prior to 80-90 days of infection by fecal float

14

ascarid resistance

  •  

15

Control of ascarids

  • control fecal egg count reduction efficacy test
  • deworm at 60 days of age (exposure, possibility of ascarids in spite of neg fecal)
  • deworm q 60 days (ivermectin) until 8-12 months of age or
  • q 30 days (pyrantel/benzimidizole group) until 8-12 months of age

16

Anoplocephala perfoliata (Tapeworms)

  • live at narrow ileo-cecal valve
    • spasmodic colic
    • intussusceptions
    • ileal impactions
  • praziquantel
    • 1 mg/kg-2.5 mg/kg
  • pyrantel
    • 13.2 mg/kg

*don't really see resistance to praziquantel

*intermittantly shed so may not see them on a fecal even if they are infected

17

Tapeworms

foal deworming

adult deworming

  • Foals
    • deworm prior to weaning
  • Adults
    • deworm 1-2 times/year

18

Gastrophilus intestinalis (botfiles)

  • little yellow eggs on legs
  • treatment
    • remove bots from legs
    • Ivermectin or Moxidectin
  • cause very few clinical signs
  • very susceptible to ivermectin

 

19

Habronema, Draschia spp (stomach worms)

  • transmitted by stable flies
  • no significant internal damage
  • cutaneous infections => granulomas (sometimes bx)
    • eyes, sheath, ventral midline
  • treat with ivermectin
    • sometimes plus steroids

*if in their normal spot don't cause lots of clinical dz

20

Oxyuris equi (pinworms)

  • live in small colon
  • female cements eggs to skin of anus
  • prepatent period 3.5-5 months
  • diagnosis probs
    • usually found as adult worms
    • difficult to find on fecal float

*tape test around anus good for this

*some resistance to ivermectin...?

21

DDX for tail rubbing

  • pin worms
  • dirty gelding sheath
  • dirty mare udders

22

strongyloides westeri (threadworms)

  • cause of diarrhea in foals
    • 5 days - 4 months
  • Infectio via milk
    • stress of foaling induces larval activation in dam
  • Parasite resides in SI
  • Immunity quickly developed (4-5 months)
  • prepatent period 5-7 days

*imp DDX for diarrhea in foals

23

Strongyloides westeri

treatment

  • treat mares in late gestation/foaling
    • macrocyclic lactones
  • treat foals PRN

24

Lungworms (Dictyocaulus arnfeldi)

  • donkeys the problem
    • can harbor with no CS
  • Horses exposed parasite via donkeys
    • cough
    • decreased performance
  • Treat with ivermectin
  • DX: BAL (eosinophilia or parasites), Fecal (Baermans float-settle to bottom)

25

Parasites of concern for the adult horse

  • Small & Large Strongyles
  • Tapeworms
  • Gastrophilus
  • Oxyuris

26

Parasites of concern for the juvenile horse

  • Ascarids-impaction
  • Strongyloides
  • Small and Large Strongyles

27

Refugia

  • want to maintain a population of parasites that has not been exposed to parasiticides
  • Wild type parasites that have not be exposed to anthelmintic pressures (lack resistance genes)
  • Minimal deworming favors survival of 'wild type' parasites

28

New Paradigm

  • Resistance as emerging problem
    • use fecal egg reduction testint to determine to effective antihelmintics
    • treat horses with high FEC
    • treat during peak transmission season

29

Fecal egg counts

  • Quantitation of strongyle burden
    • < 200 epg (don't treat)
    • 200-500 epg (may not treat)
    • > 500 epg (treat)

30

Fecal egg count reduction test

[(pre-treatment EPG) - (post-treatment EPG)] X 100

samples pre and 10-14 days post deworming

31

FECRT interpretation

  • > 90% for pyrantel and BNZ = good
  • 80-90% for Pyrantel and BNZ = suspicious
  • < 80% for Pyrantel and BNZ = resistance
  • macrocyclic lactones < 98% = resistance

32

deworming

new paradigm

  • south: (85 deg F - death to larvae)
  • north: (<45 F - will not support hatching)

33

Egg reappearance Period

  • expected egg reappearance period
    • interval between treatment and resumption of FEC > 200 EPG
  • Benzimidazoles - 4 weeks
  • Pyrantel salts - 4 weeks
  • Ivermectin - 8 weeks
  • Moxidectin - 12 weeks

34

Take home message

  • Preserve refugia: deworming least often as possible
  • Deworm individuals instead of populations
  • keep season in mind

35

Normal foal behavoir

1-2-3 rule

  • sternal recumbency within 2 min of birth
  • suckle reflex within 30 minutes
  • standing within 60 minutes
  • nursing from mare within 120 minutes

*1-2-3 rule => 1 hour to stand; 2 hours to nurse; 3 hours to pass placenta

36

Physical exam

  • first 12-24 hours of life
  • systematic
  • record
    • monitor trends
    • detect slow changes

37

foal temps

  • normal 99-102 deg F
  • hypothermia common in sick neonates
  • unable to adequately cool in very hot climates
    • FL

38

Cardiac auscultation

  • HR immediately post partum 40-80 bpm
  • inc to 100-120
  • 80-100 bpm during week 1
  • murmurs
    • PDA
    • innocent flow mumurs (not cont, discrete, etc)
    • ventricular septal defect

39

Foal mucus membranes

  • color, injected (red), yellow, abrasions, evidence of sepsis
    • also look at conjuctiva (injected vessels consistent with dystocia)

40

Respiratory rate/Auscultation

  • crackles usually last several hours from birth
    • transition from fluid filld to air filled lung
  • inc in minute ventilation
    • rate x tidal volume
  • 80 - 30 breaths/min
  • inspiratory and expiratory crackles
    • dependent atelectasis
  • normal 30-40 breaths/min

41

Umbilical care

  • very important
  • dilute chlorahex
    • dip several times per day until dry
  • No tincture of iodine: toxic to tissues

42

Enema

  • Give in first few hours of life
    • fleet enemas
    • warm soapy water ok too
      • ivory
  • Do NOT give repeat enemas

43

Colostrum

  • critical for foal to receive to provide antibodies
  • foals need about 2 liters in first 24 hours
  • first 2 hours life most critical
  • gut closure

44

Immunoglobulin (IgG)

  • Measure IgG at 12-24 hours of age (Snap test)
    • if < 800 consider transfusion
    • if < 400 definite transfusion

*colostrum replacers NOT USEFUL

45

Vaccinations and antimicrobials

Newborns

  • Tetanus antitoxin
    • if mare was not properly vaccinated
  • Routine antimicrobials not necessary
    • Non-observed birth - risk of sepsis - ok to give ABX
    • History of problems on the farm - ok to give ABX

46

Newborn Check list

  • 1-2-3 rule
  • Dip umbilicus
  • give enema
  • DVM exam < 24 hours old
  • IgG check between 8-24 hrs of age
  • +/- vaccinate/antimicrobials