Respiratory diseases of sheep and goats

Question 1

Cause of nasal myiasis

Answer 1

Oestrus ovis = sheep nasal bot fly
> lays eggs in nasal cavity and larvae migrate into sniuses

Question 2

Symptoms of nasal myiasis

Answer 2

Sinusitis, nasal discharge, restlessness, stanping feet

+ in rare cases can get neurological signs due to migration of larvae into brain

Question 3

How do we treat nasal myiasis

Answer 3

Macrocyclic lactones e.g Ivermectin

Question 4

What is laryngeal chondritis

Answer 4

= inflammation and erosion of the laryngeal cartilages which then allows secondary infection (T pyogenes, F necrophrum, E coli)
–> Chronic suppuration, smelly breath, swelling and occlussino of lumen

Question 5

Which breed of sheep is predisposed to laryngeal chondritis

Answer 5

Texels

Question 6

Treating laryngeal chondritis

Answer 6

Broad spectrum Abs e.g penicillin, corticosteroids to reduce immune response, may need to do emergency tracheostomy

Question 7

Two main viruses involved in pneumonia in sheep

Answer 7

Parainfluenza virus type 3
Ovine adenovirus

[in goats may see BHV]

Question 8

Main bacteria involved in pneumoina in sheep

Answer 8

Key one = MANHEIMIA HAEMOLYTICA

Also: B trehalosi, P multocida, Mycoplasma ovipneumonia

Question 9

Sheep lungworm example

Answer 9

Dictyocaulus filaria

Question 10

Which bacterial species causes ‘hepatinisation’ of lung tissue

Answer 10

M haemolytica

Question 11

Manheimia haemolytic involvement in pneumonia

Answer 11

= URT commensal; gram -ve
In times of stress can overgrow
> Causes fibrinous pneumonia with congestion and cranio-ventral consolidation
+ hepatinisation of lung
+pleursiy

Pathognomic sign = degenerate streaming of leukocytes

Question 12

Which bacteria is degenerate streams of leukocytes pathognomic of

Answer 12

M haemolytica

Question 13

Which bacteria causes systemic pasteurellosis

Answer 13

B trehalosi
So see septicaemia

Question 14

What is chronic enzootic pneumonia in sheep

Answer 14

= atypical or cuffing pneumonia
Caused by mycoplasma ovipneumonia
> Rarely fatal but causes poor growth

Question 15

Post mortem with chronic mycoplasma pneumonia

Answer 15

Cranioventral consoludation, non suppurative (unless secondary infection)

Peribronchial cuffs of lymphocytes on histology

Question 16

What is the first choice antibiotic for treating bacterial pneumonias

Answer 16

Oxytetracycline; good activity against M haemolytica and mycoplasma

Question 17

Vaccinating to stop bacterial pneumonia in sheep

Answer 17

Vaccinate ewes for M haemolytica and B trehalosi 4-6 weeks pre-lambing
Then can start vaccinating lambs from 4 weeks old

Question 18

Two causes of chronic viral respiratory disease in sheep

Answer 18

1) Ovine pulmonary adenocarcinoma from Jaagsiekte
2) Maedi-Visna

Question 19

How is ovine pulmonary adenocarcinoma caused

Answer 19

Via infection with Jaagsiekte retrovirus; infects type II pneumocytes

NB: usually 2-4 year incubation so see in 3-4 yo sheep

Question 20

(histo)pathology of ovine pulmonary adenocarcinoma

Answer 20

Proliferation of type II pneumocytes; these have greater height so worse exhange + lots of surfactant produced

> Lung is overtaken with solid tissue mass - see areas of grey consolidation
Can get secondary infections

Question 21

What do we do the wheelbarrow test to check for

Answer 21

Ovine pulmonary adenocarcinoma
Because surfactant will come out of the nose from the lungs

Question 22

Clinical signs of ovine pulmonary adencarcinoma

Answer 22

Progressive exercise intolerance
Resp distress
Crackles on auscultation
thoracic ultrasound shows black fluid b/w pleura and lungs

Question 23

What type of virus is Maedi-Visna

Answer 23

Lentivirus
Non-oncogenic

Question 24

What are the respective Maedi and Visna components of disease

Answer 24

Maedi = chronic progressive interstitial pneumonia; see air hunger
+ arthritis + chronic mastitis

Visna = chronic meningo-encephalitis; paralysis and death

SO: consider this if we see a combination of arthritis and pneumonia

Question 25

Which part of Maedi visna do we have in the UK

Answer 25

Just Maedia
They are the same virus but different strains

Question 26

Pathology of Maedi virus in sheep

Answer 26

Chronic INTERSTITIAL pneumonia; so reaction is in tissues and the airspaces remain clear

See thickening of alveolar septae with lymphocyte infiltration

Lungs are large, heavy and don’t collapse

Question 27

How can we control Maedi in a flock

Answer 27

Keep a young flock
Snatch and artificially rear offspring from affected animals

Question 28

What is the goat equivalent of Maedi-Visna

Answer 28

CAE
Caprine arthritis encephalitis
- See chronic progressive pneumonia, encephalitits, arthritis and indurative mastitis

Question 29

What do we use to test for dictyocaulus filaria

Answer 29

Baermann sedimentation test

Question 30

Basic life cycle of dictyocaulus filaria

Answer 30

L1s shed in faeces; develop to L3 on pasture
L3s ingested; become adults and migrate through circulation to trachea and bronchi
–> Here they produce eggs which are coughed up and swallowed

Question 31

Histology of a lung affected by dictyocaulus filaria

Answer 31

Caudal aspects affected first (because reach via circulation c/f inhalation which gives cranial distribution)

Question 32

Which parasitic lungworm causes grey-green nodules on lung surface

Answer 32

= Muellerius capillaris
Parasitic granulomas form due to immune response on dorsal surface of lung

Will mineralise over time as nematodes die

Question 33

Life cycle of muelleris capillaris

Answer 33

2 host
Uses snails/slugs as well as sheep