Respiratory disease in sheep SDL Flashcards
List 5 ice-berg diseases in sheep
Maedi Visna
Ovine Pulmonary Adenocarcinoma
Caseous Lymphadenitis
Johne’s
Border Disease
What is Maedi Visna
A chronic infectious retrovirus disease
infects lungs and nervous system
How is Maedi Visna transmitted
aerosol transmission, increased by close contact
also milk and colostrum
virus does not live long in the environment
What are the clinical signs of Maedi Visna
increased pneumonia and mastitis incidence is a chronic wasting disorder which also includes laboured breathing
low milk production leading to poor lamb growth
What age sheep does Maedi Visna affect
All ages of sheep can be affected
>3 years old
What is the presentation of Maedi Visna post-mortem
Animal have heavy grey coloured lungs
How can Maedi Visna be diagnosed
blood testing is the only reliable method of detection
How can you treat Maedi Visna
ultimately a fatal condition - no vaccine available
Describe how you can reduce the risk of Maedi Visna
sourcing animals from accredited flocks
monitoring and testing new stock
reducing stocking density
increasing biosecurity
What is Jaagsiekte also known as
Ovine pulmonary adenomatosis
What causes OPA
a beta retrovirus which infects cells in the lungs
what is OPA
a contagious tumour of the lungs of sheep
tumours can produce high levels of a white foaming fluid increasing the risk of secondary infections such as pasteurella
How is OPA transmitted
typically aerosol and can also be passed through colostrum and milk
Which animals are most susceptible to OPA
younger stock
but olders can also be infected
infection typically peaks in ewes around 4yrs and tups at 1-2 yrs
What are the clinical signs of OPA
severe weight loss
laboured breathing
some animals may cough or produce a nasal discharge
infection can often appear as a sudden death
How can you detect OPA
No blood test available
ultrasound lungs for tumours - scan and cull system
wheelbarrow test- will see fluid come out- not allowed now due to animal welfare concerns
How can you diagnose OPA
fluid production
post mortem
PCR in the future
What is the presentation of OPA post mortem
lungs are larger/ heavier than normal with areas of solid grey tumour
Where should the probe be located when ultrasound scanning for OPA
at 6th/7th intercostal space
Describe how you can control OPA
slaughter affected animals
buy from trusted sources
minimise common trough use
reduce stocking density
What is caseous lymphadenitis (CLA) caused by
is a bacterial infection
Corynebacterium pseudotuberculosis
Describe the transmission of contagious lymphadenitis (CLA)
enter through skin abrasions (may be microscopic), inhalation or ingestion
How does CLA cause disease
infected wound will spread infection to the draining lymph nodes
bacteria will multiply and form a micro-abscess
this will coalesce into a larger abscess which will then wall off and the bacteria will grow and release an exotoxin
T/F antibiotics are not effective against CLA
True - because they are not effective inside the abscess
How long can CLA bacteria survive in the environment
up to 8 months- but is killed by sunlight
up to 24 hrs in sheep dip
Describe how CLA tends to be introduced to a flock
bought in infected animals
potentially via fomite transmission through infected pus
shearing is a risk time for spread
aerosol if abscess is in lung
Describe how you confirm CLA
bacteriology on the pus from a ruptured abscess or a blood antibody ELISA test
Describe the clinical signs of CLA
vary depending on the location of the abscesses
typically lumps and bumps on the head and neck
List some potential ways to prevent CLA
buy stock from trusted sources
increase boundary biosecurity
separate infected animals
no vaccine in the uk
Which breeds is laryngeal chondritis associated with
texels, beltex and southdowns
what is laryngeal chondritis associated with
short thick neck and high concentrate feeding
How does laryngeal chondritis occur
suppurative lesions form within the arytenoid cartilage and narrow the lumen of the larynx causing severe dyspnoea with laryngeal stridor which can often be fatal
Describe how you treat laryngeal chondritis
one-off dexamethasone injection
with a week’s course of antibiotics (amox/clav - off licence)
does laryngeal chondritis normally reoccur
yes
List the 5 main causes of bacterial pneumonia in sheep
Mannhaemia haemolytica
mycoplasma speceies
bibersteinia trehalosi
pasturella multocida
bordetella parapertussis
What are the 5 differential diagnoses for coughing lambs
pasteurellosis
atypical pneumonia
viral pneumonia
lungworm
mycotic pneumonia
What are the 2 types of pasturellosis
pasturellosis caused by Mannheimia haemolytica
Pasturellosis caused by bibersteinia trehalosi
How does pasteurellosis- Mannheima haemolytica, affect sheep and lambs
older sheep- pneumonia
lambs- septicaemia (<12 weeks)
List 8 clinical signs of pasteurellosis- mannheimia haemolytica in sheep/lambs
cough
inappetence
ocular-nasal discharge
pyrexia
toxaemia
hyperpnoea
tachypnoea
dyspnoea
what are 3 clinical signs of mycoplasma involement in pasteurellosis in sheep
fewer acute signs
persistent dry soft cough
poor growth rates
List 5 risk factors for the development of pasteurellosis- Mannheimia haemolytica
concurrent infections with other resp pathogens
environmental conditions- housing, stock density, temp
extreme weather
stress
diet change
List 4 post morteum signs of mannheima haemolytica
lungs purple-red, swollen and heavy
sink in water
straw yellow pleural exudate with fibrin clots
tracheobronchial lining is red-purple with pink froth in airways
List 4 post mortem changes seen with Bibersteinia trehalosi
coalescing haemorrhages in thoracic regions
necrosis and ulceration of mucosa in pharynx, stomachs and oesophagus
enlarged purple pharyngeal lymph nodes and lung consolidation
pin point of hepatic necrosis
Describe how to treat pasteurella in sheep
Oxytetracycline - first choice
List 6 ways to reduce the risk of pasteurellosis in lambs
reduce stress
avoid mixing sources of sheep
good ventilation and airflow, no draughts
introduce food change gradually- plenty of forage
ensure sheep healthy- good immune response to challenge
vaccinate to improve immune response
What can be seen on PM with Mycoplasma ovipneumoniae
Dark red to grey raised areas on apical & cardiac lobes
