Cattle parasitology Flashcards
What is the intermediate host for liver fluke (Fasciola hepatica)?
Mud snails
Galba truncatula
Mud snails (Galba trunculata) can become infected in fluke in which two seasons? What conditions increase fluke populations?
Summer
Winter
(When temp above 10 degrees C and rainy - can forecast fluke)
What are some risk factors for fluke?
Co-grazing sheep and cattle (both get fluke)
Overwintering sheep at pasture
Areas of wet, boggy ground
Wet and warm weather
Animals with little/no immunity or immune modulation
What are the 3 different clinical presentations of liver fluke infestation?
Acute disease - 2-6 wks post infection
Chronic disease - 10-12 wks post infection
Subclinical (very common)
What are the clinical signs of CHRONIC liver fluke infestation?
Chronic anaemia
Hypoalbuminaemia (bottle jaw)
Weight loss and poor BCS
Subclinical liver fluke infestation is very common. Although there are little clinical signs, what may be noticed about that animal’s production?
Ongoing losses with growth and milk yield
Reduced fertility
Acute liver fluke infestation can cause haemorrhage and anaemia. Why?
Juvenile flukes migrating through liver parenchyma
Cause tissue damage and haemorrhage
How can liver fluke be diagnosed?
Signalment, history, clinical signs (difficult if subclinical)
Serum biochemistry (non-specific for fluke)
Fluke egg sedimentation (low sensitivity)
Copro-antigen ELISA
Antibody ELISA
Post-mortem (gold standard)
What 3 GI nematodes do cattle get in their abomasum?
HOT
Haemonchus contortus
Ostertagia ostertagi (T. circumcincta in sheep)
Trichostrongylus axei
What 3 GI nematodes do cattle get in their small intestine?
CNT
Cooperia spp (C. oncophora, surnabada, pectinate, punctate)
Nematodirus spp (N. helvetianus and spathiger)
Trichostrongylus colubriformis
What 3 GI nematodes do cattle get in their large intesine?
COT
Chabertia spp
Oesophagostomum spp
Trichuris spp
PGE is commonly seen in what age animals? Why?
Youngstock
Immunity (incomplete) acquired over 1-2 grazing seasons
Ostertagia osteragi is a nematode found in the abomasum of cattle. What is it commonly known as?
Brown stomach worm
What are the two types of ostertagiosis and how do they differ?
Type I - infection in Summer, dairy replacement cows
Type II - yearling calves, late Winter/early Spring HYPOBIOSIS (less common)
Which species of worm cause PGE in cattle?
Ostertagia ostertagi
Cooperia spp
Co-infection causes D+, poor appetite, weight loss
How is PGE diagnosed?
Grazing history and signalment Clinical signs and seasonality Plasma pepsinogen - Ostertagiosis Faecal egg counts (not particularly useful for type II Ostertagiosis) Post mortem Antibody ELISAs
What is the main disadvantage of antibody ELISAs for diagnosis of PGE?
Indicates exposure, not infection
Control of cattle parasites should be focused on….
Management strategies - e.g. pasture movement
Limit reliance on anthelmintics –> resistance
There is a vaccine available for which parasite in cattle?
Lungworm
live attenuated vaccine
What are the 3 groups of anthelmintics that can be used to treat/prevent PGE and lungworm?
- Benzimidazoles - white drenches (oral)
- Levamisole - yellow drenches (oral)
- Macrocyclic lactones - clear drenches (injectable & pour on)
Which anthelmintics are licensed against type II ostertagiosis?
Group 3 macrocyclic lactones
Some group 1 benzimidazoles
When should the lungworm vaccine be given?
2 doses, 4 weeks apart
2nd dose 2 weeks before turnout
(calves > 8 wks old)
Does the lungworm vaccine provide full immunity?
No
Subsequent natural exposure essential for full immunity to develop
When a group of cows are affected lungworm, what should your treatment plan be?
Treat all animals in affected group (animals on same pasture also at risk)
Move affected animals to safe pastures or well ventilated housing (if cannot move, treat with long acting MLs)
Check for secondary infections - antibiotics, NSAIDs
Remember milk withdrawal in lactating animals
