Respiratory diseases - sheep Flashcards
What should you pay particular attention to when investigating a respiratory problem in sheep (often a flock problem)?
- age
- number affected
- CS, progression and whether acute/chronic
- time period
- management
What should you pay particular attention to when doing a distance exam of a flock of sheep when you suspect a respiratory problem
- demeanor
- size heterogeneity
- nasal/ocular discharge
- signs of dyspnoea, resp distress
- cough
- particularly bad animals
What should you pay particular attention to when doing an individual sheep when you suspect a respiratory problem
- temperature (normal is 38.8-39.9)
- RR (normal is <20/min)
- HR (normal is 70-80)
- Size and BCS
- MM and hydration status
Outline findings of the sheep respiratory system
- abdominal respiration
- normal RR <20/min (usually faster)
- lung sounds may be loud
- poor correlation between lung sounds an dpathology
How are most sheep respiratory diseases confirmed?
PME (£58.24 at APHA)
What tests can you do for sheep respiratory diseases
- BAL (but consider commensals and significance of findings)
- valuable animals –> ultrasound or radiography
What do you need to decide when you have a respiratory problem on the farm?
- risk to flock
- contributing factors
- short-term control
- long term preventative strategy
What are the 5 broad categories of ovine respiratory disease?
- sudden death
- acute or sub-acute ill-health, cough, +/- discharges and fever
- chronic ill thrift, occasional cough. lambs
- chronic weight loss, breathing difficulties, adults
- acute respiratory distress
What ovine respiratory disease is likely to cause sudden death?
- Peracute pneumonia (M.haemolytica, ‘enzootic pneumonia’) –> septicaemia –> death (typically lambs, can be gimmers)
What ovine respiratory disease is likely to cause acute or subacute ill-health, cough +/- discharges and fever? 3
- acute bacterial/viral pneumonias (fever)
- aspiration pneumonia (fever)
- parasitic pneumonia (fever)
What ovine respiratory disease is likely to cause chronic ill-thrift, occasional cough in LAMBS? 2
- chronic pneumonia (Mycopl., resolved pneumonia) –> Lung damage –> poor weight gain
What ovine respiratory disease is likely to cause chronic weight loss and breathing difficulties in ADULT SHEEP?
‘Slow virus’ diseases (Maedi-Visna, SPA) –> lung tissue replaced with solid tissue. Only 1-2 animals affected at one time.
What ovine respiratory disease is likely to cause acute respiratory distress?
URT problem e.g. laryngeal constriction (Texels, Suffolks etc) or damage, laryngeal chondritis (due to high RR –> damage)
What is the most common respiratory problem in sheeP/
- Ovine pneumonia. = enzootic pneumonia = pneumonic pasteurellosis*
- Usually young animals
- Endemic throughout UK
- Multi-factorial aetiology
- Predisposing factors (ventilation, age, stress)
What agents are principally involved in ovine pneumonia?
- BACTERIA - especially M.haemolytica (also P. trehalosi, P.multocida, B.parpetussis, others)
- MYCOPLASMAS
- VIRUSES - especially PI3 and adenoviruses (also RSV and reoviruses)
- Typically viruses cause the primary infection and bacteria and mycoplasmas follow secondarily*
Outline some risk factors involved in ovine pneumonia - 4
HOUSING - close contact, poor ventilation, high humidity
MIXING - ages (younger more vulnerable, up to 6mo and lambing ewes), sources
CLIMATE
STRESS - mixing, nutrition, housing
CS - enzootic pneumonia - 5
- sudden death possible
- fever (>40.3)
- depressed, not eating
- dyspnoea, cough, nasal discharge (sometimes foamy)
- death or poor thrift in recovered animals
Is isolation of PI3 or M.haemolytica from nasal cavity diagnostic for enzootic pneumonia?
No - usually rely on Hx and CS (vary with chronicity). PME for definitive diagnosis. +/- histopath and culture of LARGE number of Mannheimia from the lung.
How do you treat enzootic pneumonia in a.) outbreak b.) individual animals?
a. ) OUTBREAK - prophylactic LA oxytet (also used to reduce Chlamydophila so beaware of resistance issues) + vaccination
b. ) INDIVIDUAL - LA oxytet OR tilmicosin
Outline prevention of enzootic pneumonia in sheep
- Control of predisposing factors difficult
- Vaccination (doesn’t 100% protect against infection but reduces likelihood)
Describe the common vaccination protocol for enzootic pneumonia for sheep (ewes and lambs)
- EWE = sensitiser + booster 4-6 weeks later. Boost 4-6 weeks pre-lamb.
- LAMB (MAb lasts about 3-5 weeks). Vaccinate at 3-5 weeks old, boost 3-4 weeks later.
CS - atypical pneumonia
- reduced growth rates*
- occasional clinical case - dullness, reduced BCS
- flock signs - cough, nasal discharge
- death (rare)
What are PME findings of atypical pneumonia? 3
- clearly demarcated red-brown or grey areas of lung
- typically affects apical and cardiac lobes
- Mycoplasma ovipneumoniae
Which parasites cause ovine parasitic pneumonia?
- Dictyocaulus filaria* - the only important sheep lungworm
- peak larval contamination in autumn and winter
- lambs up to 1 yo affected
- variation in susceptibility
- non-pathogenic ovine lungworms are Muellerius and Protostrongylus
CS - parasitic pneumonia 5
- coughing
- increased RR
- nasal discharge
- severe weight loss
- death is rare
Dx - parasitic pneumonia
- Hx and CS
- larvae in faeces
- PME (adult worms clearly visible in bronchi, lesions usually in diaphragmatic lobes)
Control - parasitic pneumonia
- GIT parasite control measures (same anthelmintic susceptibility)
- NO vaccine
How important is sheep lungworm versus parasitic gastroenteritis?
No economic significance to farmers versus parasitic gastroenteritis. Severe lungworm infestations often seen in sheep with paratuberculosis (Johne’s) due to immunocompromise
What is Maedi-Visna?
- lentivirus
- causes visna (wasting) and mastitis
- TRANSMISSION - vertical (colostrum, milk, some horizontal transmission)
- Introduced to UK in 70s, now >100,000 infected
- Flock mortality about 2%
- Premature culling
- Reduced milk production
- TAKES 3-4 YEARS TO DEVELOP CS AFTER INFECTION
CS - Maedi-Visna - 6
- animals usually 3yo+
- SLOW progression of signs
- emaciation
- develops severe respiratory disease
- +/- cough, nasal discharge
- other flock problems - visna, mastitis, arthritis
Dx - Maedi-Visna
- Hx, CS
- serology (individual or flock)
- PME - voluminous lungs, uncollapsed, sink in water
What does SPA stand for?
Sheep Pulmonary Adenomatosis = Ovine Pulmonary Adenomatosis (OPA) or ‘Jaagsiekte’
Outline Sheep Pulmonary Adenomatosis (SPA)
Transmission
Mortality
- retrovirus (slowly progressive lung adenocarcinoma, common contagious tumour)
- long incubation
- TRANSMISSION: respiratory and vertical, newly purchased sheep
- MORTALITY: high in first instance, endemic –> losses of 2-10%
CS - Sheep Pulmonary Adenomatosis (SPA)
- adult sheep (usually 2-4 years)
- progressive respiratory disease
- weight loss
- wheelbarrow test = pathognomonic = when hindquarters are lifted and the head lowered, fluid comes out of nostrils.
Dx - Sheep Pulmonary Adenomatosis (SPA) - 4
- Hx and CS
- no serological tests
- PME: tumours in lung, enlarged consolidated lungs, frothy fluid in bronchi
- histopathology
