Clinical cattle parasitology 1 + 2 Flashcards
List 3 abomasal nematodes of cattle
Haemonchus contortus
Ostertagia ostertagi
Trichostrongylus axei
List 3 Small intestinal nematodes of cattle
Trichostrongylus spp
Nematodirus
Cooperia
Name 3 large intestinal nematodes of cattle
Oesophagostomum
Chabertia
Trichuris
Describe the pathogenesis of ostertagia
- Abomasal wall damage
- Raised pH of gastric juice from 2 up to ~7
- Poorer digestion bacterial overgrowth
Describe the pathogenesis of Cooperia
Damage to intestinal mucosa
Impaired absorption of nutrients and water
Which animals are affected by PGE in cattle?
- First season dairy heifers
- Autumn born suckler calves
- Spring born suckler calves
- Immunity acquired over 1-2 grazing seasons
How is PGE in cattle diagnosed?
- Grazing history & signalment
- Clinical signs and seasonality
- Plasma pepsinogen- ostertagiosis
- Faecal egg counts
- PM
- Antibody ELISA
Which diagnostic test is not useful for type 2 ostertagiosis?
Faecal egg counts
Name the lungworm of cattle
Dictyocaulus viviparous
Describe the live cycle of Dictyocaulus
L1 larvae passed in faeces
Develop to L3 in the faecal pat
Infective larvae spread onto pasture
Larvae ingested and then migrate to lungs
L3 develop into adults in the lung tissue
Eggs produced
Eggs hatch and L1 larvae are coughed up and swallowed
Describe lungworm survival on pasture
Short
After 6 weeks, pasture can be considered ‘clean’ again
Larvae not necessarily present at turnout
What is the most important source of Dictyocaulus each year?
Carrier animals
Is the pattern of disease easier to predict in GIT nematodes or lungworms?
GIT nematodes - consistent, predictable annual disease pattern
Describe the epidemiology of Dictyocaulus
- Geographic variation of distribution
- Associated with wet summers and rainfall: dispersal from faecal pats
Describe the prepatent phase of a Dictyocaulus infection
L4 larvae in alveoli - migrate towards to bronchi
- Alveolitis, bronchiolitis, bronchitis
Describe the patent phase of a Dictyocaulus infection
Adult worms in larger airways, eggs and L1 larvae in alveoli
- Obstructive bronchitis
- Aspiration pneumonia
- Secondary bacterial infections
What are the clinical signs of a mild Dictyocaulus infection?
Intermittent cough when exercised
What are the clinical signs of a moderate Dictyocaulus infection?
Frequent cough at rest
Laboured breathing
Squeaks/crackles on auscultation
What are the clinical signs of a severe Dictyocaulus infection?
Severe tachypnoea
Dyspnoea
Air hunger position
Mouth breathing
Deep, harsh cough
Salivation, anorexia
Death
How is a Dictyocaulus infection diagnosed?
- Signalment, history & clinical signs
- Post-mortem
- Baermann for L1 larvae
- Antibody ELISA
Name the liver fluke species of cattle
Fasciola hepatica
Describe the life cycle of liver fluke
- Eggs shed in faeces
- Miracidium hatch out of the eggs after 2-4w
- Migrate into the mud snail
- Cercariae are shed from the mud snail
- Become metacecariae on pasture where they are viable for several months
- Ingested by cattle where they migrate to the liver
When are the levels of metacecariae on pasture the highest?
Autumn
When are the levels of metacecariae on pasture the lowest?
Summer
Which species are hosts of fluke?
Cattle and sheep
cant co graze
Describe a ‘flukey’ pasture
- Any area of wet or boggy ground
- Standing water, rushes etc. give clues
- Agri-environment schemes with wetland habitats
Describe the pathology and clinical presentation of acute fluke disease
- 2-6 weeks post-infection
- Juvenile flukes migrating through liver parenchyma
- Tissue damage and haemorrhage
- Uncommon in cattle- young calves with heavy challenge
Describe the pathology and clinical presentation of chronic fluke disease
- 10-12 weeks+ post-infection
- Adult flukes within bile ducts
- Chronic anaemia, hypoalbuminaemia (“bottlejaw”)
- Weight-loss & poor BCS
Describe the pathology and clinical presentation of a sub-clinical fluke disease
Very common
Ongoing losses with growth/ milk-yield/ reduced fertility etc.
List the methods available to diagnose fluke
- Signalment, history & clinical signs
- Serum biochemistry: Serum albumen, GLDH & GGT
- Fluke egg sedimentation
- Copro-antigen ELISA
- Antibody ELISA
- Forecasting
- Post mortem
Describe fluke egg sedimentation as a diagnostic method
- Individual or composite samples
- Patent infections only (12 weeks+)
- Relatively low sensitivity