Respiratory disease in Sheep

Question 1

Sheep respiratory system

Answer 1

Abdominal respiration
Normal RR <20/min - Usually faster
Lung sounds may be loud
Poor correlation between lung sounds and lung pathology

Question 2

further testing than PME

Answer 2

BAL possible if PM not appropriate
NB: many agents are commensals of sheep resp. tract
Valuable animals can use ultrasonography or radiography

Question 3

sudden death causes

Answer 3

Peracute pneumonia (Mannheimia haemolytica;
“Enzootic pneumonia”)
Septicaemia

Question 4

Acute or sub-acute ill-health, cough, +/- discharges & fever - diseases causing

Answer 4

Acute bacterial/viral pneumonias (fever) 
Aspiration pneumonia (fever) 
Parasitic pneumonia (no fever)

Question 5

Chronic ill-thrift, occasional cough - Lambs - diseases causing

Answer 5

Chronic pneumonia (Mycoplasma; resolved enzootic pneumonia) 
Lung damage – poor weight gain

Question 6

Chronic weight loss + breathing difficulties - adults - diseases causing

Answer 6

‘Slow virus’ diseases (Maedi-Visna, Sheep Pulmonary Adenomatosis)
Lung tissue replaced with solid tissue
Only 1-2 animals affected at one time

Question 7

Agents involved in ovine pneumonia

Answer 7

Bacteria – Mannheimia haemolytica + Pasteurella trehalosi, (Pasturella multocida), (Bordetella parpertussis)
Mycoplasmas
Viruses – Parainfluenza 3 (PI3), Adenoviruses, Respiratory syncytial virus, Reoviruses
normal inhabitants of resp tract - predisposing factor needed for disease

Question 8

Risk factors for pneumonia

Answer 8

Housing 
Mixing 
Young sheep = greater risk 
Climate 
Stress

Question 9

Enzootic pneumonia

Answer 9

Predisposing viral damage – PI3
Colonisation with M. haemolytica
Predisposing factors - Stress: husbandry, weather
Sudden death in young lambs (septicaemia)
Pneumonia in lambs and ewes

Question 10

enzootic pneumonia - clinical signs

Answer 10

May be sudden death 
Fever (>40.3’ish) 
Depressed, not eating 
Dyspnoea, cough, nasal discharge 
Death, or poor thrift in recovered animals

Question 11

enzootic pneumonia - diagnosis

Answer 11

History, clinical signs
Isolation of PI3/M. haemolytica from nasal cavity
Postmortem examination (PME)
+/- histopath & culture of LARGE number of Mannheimia from lung

Question 12

enzootic pneumonia - treatment

Answer 12

Outbreak: prophylactic LA oxytet + vaccination

Individual animals - oxytet or tilomycosin

Question 13

enzootic pneumonia - Prevention/control

Answer 13

Control predisposing factors (can be difficult)

Vaccination

Question 14

Atypical pneumonia - Clinical signs

Answer 14

Death is rare
Reduced growth rates
Occasional clinical case -underlying subclinical disease
flock signs – cough, nasal discharge
Clinical cases may show dullness, condition loss

Question 15

Atypical pneumonia - diagnosis

Answer 15

History + clinical signs/flock signs

PME - Clearly demarcated red-brown or grey areas of lung, apical and cardiac lobes. Mycoplasma ovipneumoniae

Question 16

Atypical pneumonia - prevention/control

Answer 16

Housing design, ventilation important
Reduce stocking density
uarantine introduced animals

Question 17

Maedi-Visna

Answer 17

Lenti virus (slow virus)
visna (wasting) and mastitis
Mainly vertical transmission - some horizontal
Mortality in flock ~2% (more if recently
introduced)
Premature culling

Question 18

Maedi-Visna - clinical signs

Answer 18

Reduced milk production
slow progression of signs
Emaciation
Development of severe respiratory disease
+/- cough, nasal discharge
Other flock problems e.g. visna, mastitis, arthritis

Question 19

Maedi-Visna - diagnosis

Answer 19

History, clinical signs
Serology: individual or flock
PME: voluminous lungs, uncollapsed
histopath

Question 20

Maedi-Visna - treatment

Answer 20

none

Question 21

Maedi-Visna - control

Answer 21

Cull clinical cases 
Cull ewes when 4-5 years old 
Cull offspring from affected ewes 
Testing and culling 
Snatch lambs from seropositive ewes 
Complete de-stocking and replacement

Question 22

Sheep Pulmonary Adenomatosis (SPA)

Answer 22

Aka ‘Ovine Pulmonary Adenocarcinoma (OPA)’
Herpesvirus and retrovirus = slowly progressive lung adenocarcinoma
Long incubation
Transmission by respiratory route, and vertical

Question 23

SPA - clinical signs

Answer 23

mortality - high in first incidence, endemic losses of 2-10%
progressive respiratory disease
Weight loss

Question 24

SPA - diagnosis

Answer 24

When hindquarters lifted and head lowered, fluid
out of nostrils: characteristic ‘wheelbarow test’
History and clinical signs
No serological tests
PME: tumours in lungs, enlarged consolidated lungs, frothy fluid in bronchi
Histopathology
May occur with other diseases e.g. maedi