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
Describe antibody ELISA as a diagnostic method
- 2-4 weeks post-infection
- Serum or milk samples
- BMT samples indicate >25% herd infected
- Exposure, not infection (consider treatment history)
How can fluke be controlled?
- Forecasting
- Plan strategy in advance
- Identify at risk animals
- Perform egg counts
- Move to safe pastures
How can anthelmintics be used strategically against fluke?
- Keep pasture contamination low in the early part of the season
- Can reduce treatment later in the season as overwintered larvae die off
How can anthelmintics be used therapeutically against fluke?
- Treat in response to disease monitoring
- Rotate grazing from early in the season
Name 3 benzimidazoles
Albendazole
Fenbendazole
Triclabendazole
What colour drench are benzimidazoles?
White drenches
Which benzimidazole treats fluke but not lungworm?
Triclabendazole
Levamisole can be used to treat which parasites?
Nematodes
Lungworm
- not fluke or tapeworm
Name 4 macrocytic lactones
Ivermectin
Doramectin
Moxidectin
Eprinomectin
Macrocytic lactones can be used to treat which parasites?
Nematodes
Lungworm
- not fluke or tapeworm
What colour drench are macrocytic lactones?
Clear
Describe strategic dosing for PGE
Ivermectin pour on - 14d residual activity
3 - 8 - 13w dosing schedule
Turnout in April
- dose 3 weeks later, then 5 weeks after that, then repeat 5 weeks later
How long is the residual activity of Doramectin?
5 weeks
When is lungworm vaccination reccomended?
If there is a history of disease on the farm
Describe the lungworm vaccine and its schedule
Irradiated L3 larvae (live vaccine)
- Calves >8 weeks old
- 2 doses, 4 weeks apart
- 2nd dose 2 weeks before turnout
Subsequent natural exposure is essential for full immunity to develop…
Describe how to treat animals with clinical lungworm disease
- Treat all animals in the effected group
- Move clinically affected animals to safe pastures or house (well ventilated building)
- Treat with long-acting group 3-ML if not able to move
- Check for secondary infections
- Antibiotics and NSAIDs possible indicated
What should be considered when timing fluke treatment?
Treat housed animals with adulticides
Reduce selection pressure on TCBZ
Consider milk-withdrawal for lactating animals
Treat during dry period
Which drug treats all stages of fluke?
Triclabendazole
- but high resistance
Name 2 other drugs that can be used against fluke
Albendazole
Closantel
What are the reasons for quarantine treatments?
Avoid introduction of new parasites
Avoid introduction of drug resistance
COWS guidelines to reduce likelihood
- Combination treatments
- Holding animals off pastures
For fluke how would you check treatment has been affected?
Day 0 egg count
Compare to an egg count 21d post treatment
- ideally a more than 95% reduction
Name the COWS 5 Rs
The right product for the type of worm
The right animal
The right time
The right dose rate
Administered in the right way
Which animals are affected by cryptosporidium?
Young calves 14-21do
How does cryptosporidium present?
Diarrhoea and dehydration
How is cryptosporidium diagnosed?
History & clinical signs
Faecal smears: Ziehl-Nielsen staining
Pen-side antigen test strips
How is cryptosporidium treated?
- Good hygiene practice: Disinfection of pens & feeding equipment
- Reduce stocking density
- Halofuginone: prophylaxis and reduces symptoms in clinical cases
- Supportive treatment: IVFT
What type of drug is halofuginone?
Coccidiostat - works against protozoa
Which animals are at risk of coccidiosis?
Young animals
Where are coccidiosis pathogens found?
Housed and grazing animals
Replicate in the caecum and colon
Describe the clinical signs of coccidiosis
Bloody dysentery and tenesmus
Chronic wasting/ poor appetite
How is coccidiosis diagnosed?
History and clinical signs
Postmortem and histopathology
Oocysts (Wet smears or McMaster)
How is coccidiosis treated and controlled?
- Reduce environmental contamination: all-in all-out with cleaning and disinfection
- Prophylactic treatment
- Treatment: Toltrazuril & Diclazuril
Which pathogen of cattle is identified in 25% of abortion cases?
Neospora
Describe the hosts of neospora
- Dogs are the definitive host
- Cattle are the intermediate hosts
Describe the life cycle of neospora
- Dogs pass oocysts in faeces which contaminate pasture
- Ingested by a cow (can affect foetus if infected)
- Infected carcass or placenta ingested by dog
What are the 3 outcomes for a calf if a cow if infected with neospora when pregnant?
- Birth of a healthy uninfected calf
- Birth of a persistently infected calf
- Aborted or premature calf
How is neospora caninum prevented/controlled?
- Keep a closed herd: don’t buy in any replacement stock
- Dispose of cattle tissues left over from a calving, or aborted foetuses, in a safe and timely manner.
- Prevent dogs from having access to calving areas or parts of the farm where pregnant cattle are kept.
- Deny dogs access to areas where cattle feed is kept or fields that are used for grazing to prevent dog faeces.
- Signage on public footpaths.
How can serum antibody testing be used to control neospora infections?
- Ideally 12-4 weeks pre-calving (recrudescence)
- Serum sampling of calves pre-colostrum for evidence of vertical transmission
- If positive, do not breed from mother or calf again
- False negatives may occur
Name 3 biting/nuisance flies of cattle
Hydrotea irritans
Muscidae
Culicoides
Name the condition caused by Hydrotea irritans
Summer mastitis
How are biting/nuisance flies in cattle controlled?
Spot-on/ pour-on synthetic pyrethroids
Tail bands/ ear tags
Pasture management & breeding habitat
When are mite/lice infections most common in cattle?
Over winter in housed animals
Name 3 mite species of cattle
Chorioptes bovis
Psoroptes bovis
Sarcoptes scabei
Name a chewing and sucking louse of cattle
Chewing = Bovicola
Sucking = linognathus
Ixodes ricinus is a vector of? (3 possible)
Babesiosis
Anaplasmosis
Louping ill
Compare treatments for chewing vs sucking lice
Pour-ons for chewing lice
Injectables for sucking lice
Name the rumen fluke parasite
Calicophoron daubneyi
Calicophoron daubneyi has the same intermediate host as which parasite?
Fluke
- Galba truncatula
