Parasites (Camila)

Question 1

what are the 2 disease syndromes we worry about with gastrointestinal nematodes?

Answer 1

haemonchosis and parasitic gastroenteritis (PGE)

Question 2

what does each line refer to?

Answer 2

black: eggs in ewe feces
blue: eggs in lamb feces
red: infective L3 on pasture

Question 3

what are the 2 sources of infective L3?

Answer 3

on pasture from previous grazing and from eggs deposited by animals on the pasture

Question 4

do some ovine parasitic nematode larvae over the winter in western canada?

Answer 4

some do YES! especially teladorsagia and trichostrongylus! (less so haemonchus)

Question 5

_____ is needed to build up a picture of pasture contamination and help inform grazing management

Answer 5

regular monitoring with fecal egg counts

Question 6

how long does it take for infective larvae to appear on a pasture?

Answer 6

as little as 1 week for haemonchus under the best conditions, or as much as 1 month or longer in worse conditions. it tends to happen faster in mid summer compared to spring or fall.

Question 7

true or false: it is a good idea to alternate sheep and goats on a pasture to control GIN?

Answer 7

FALSE!

Question 8

what are the two main categories of antihelmentic drugs?

Answer 8

fenbendazole, albendazole (benzimidazoles)
ivermectin (macrocyclic lacton)

BOTH have lots of resistance

Question 9

what is closantel used for?

Answer 9

this is a drug newly lisenced in canada and it has narrow spectrum for haemonchus only, and resistance to it is likely rare

Question 10

what route of drug is preferred for antihelmentics?

Answer 10

oral dosing>injectable>pour on

Question 11

true or false: recipe based approaches are preferred to prevent parasitic disease in sheep

Answer 11

false! they are not sustainable and not effective, they are BAD practice

Question 12

instead of recipe based approaches for parasite treatment, what are better alternatives

Answer 12

only treat animals that need it when they need it

use evidence based approaches that include monitoring of parasite burdens

assess drug efficacy and dose correctly: based on heaviest animal (goats need higher doses)

Question 13

list some tips for good antihelmentic drug use

Answer 13

minimize doses;only treat when needed
always use full dose; do not under dose
fo fecal egg counts every 2 weeks to check if drugs are working
use targeted selective treament, especially when refugia is low
annual rotation of the drug doesn’t do anything!

Question 14

explain the concept of refugia

Answer 14

the portion of parasite population not exposed to drug treatment is said to be in refugia, so the more refugia, the less selection pressure by drug treatment

Question 15

in order for refugia to be high, you should treat when?

Answer 15

when there are many larvae on pasture and only treat SOME animals, not all! aim to treat no more than 1/3 the flock

Question 16

how do you decide who to treat with antihelmentics?

Answer 16

haemonchus: clinical anemia–>treat 4s and 5s, sometimes 3s depending on situtation, can also use fecal egg count as adjunct

teladorsagia or trichostrongyles: condition scoring for ewes, growth rate for lambs, diarrhea assessment (DAG score)

Question 17

what are 3 important things to remember about ovine coccidiosis?

Answer 17

some species are pathogenic and some are not
they all live in different parts of the GI tract
they are highly host specific

Question 18

true or false: ovine coccidiosis can occur indoors

Answer 18

true! both indoor and outdoor

Question 19

what age is commonly affected with coccidiosis?

Answer 19

3 weeks to 3 months

Question 20

why are the oocysts such a problem in coccidiosis?

Answer 20

they are very resistant in the environment and can survive months up to a year and can survive freezing!!

Question 21

what are some risk factors for coccidiosis in sheep?

Answer 21

high stocking density, poor hygeine, moisture, stress, other diseases, poor nutrition, (shipping or relocation, shearing, other parasites, etc)

Question 22

what is unique about anti coccidial drugs?

Answer 22

they act at different parts of the coccidia life cycle

drugs that act on early stages: only useful for prevention and doesn’t allow any immunity to develop

drugs that act on later stages: useful for treatment and prevention and allow immunity to develop

Question 23

what is the best anti coccidia drug

Answer 23

Toltrazuril (single oral dose) or Amprolium (in water 5 days)

Question 24

how is treating coccidia different than treating gastrointestinal nematodes?

Answer 24

coccidia treatment: should treat all animals in a group not just those affected
remove animals from contaminated environment
if any are severely sick separate them to treat them