parasite control (mallicote) Flashcards
Goal for young horses
limit parasite burden until young horses develop their immunity
goal for adult horses
minimize disase without inducing a resistance to parasiticides
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
Minor internal parasites
- Gastrophilus intestinalis (Bots)
- Habronema muscae, Draschia megastoma (stomach worms)
- Oxyuris equi (Pinworms)
- Strongyles westeri (Threadworms)
- Dictyocaulus arnfieldi (lungworms)
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
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
small strongyles
progression
emergence of larvae =>
Intense inflammation =>
hemorrhage and edema of cecum and colon =>
Colic and diarrhea
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)
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)
Parascaris equorum (roundworms)
progression
- parasite lives in small intestine =>
- lymphatics =>
- lungs =>
- pharynx =>
- small intestine
Parascaris equorum (roundworm)
days to reenter SI
28 days
Parascaris equorum (roundworms)
days to produce eggs
72-80 days
-before you see eggs in fecal
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
ascarid resistance
*
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
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
Tapeworms
foal deworming
adult deworming
- Foals
- deworm prior to weaning
- Adults
- deworm 1-2 times/year
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