PRACTICAL: Respiratory pathology 2

Question 1

What 2 patterns of pneumonia are characterised by these changes?

Answer 1

• Embolic suppurative pneunomia (i.e. from blood) - Suppurative bronchopneumonia (from airways)

Question 2

Describe these nodules

Answer 2

bovine TB (lung) multiple nodules varying diameter across pulmonary parenchyma white - yellow, pale Granulomatous inflammation central areas of calcification

Question 3

Describe a granuloma structure (as seen in TB)

Answer 3

necrotic centre of caseous necrosis with some calcification/mineralisation. main cell type that surrounds this are macrophages. further out, lymphocytes and plasma cells surround the lesion. the outer layer is a fibrous wall

Question 4

What cell is this in the lungs?

Answer 4

Multinuclear giant cell (MNGC) - fused macrophages. This is a Langerhans type MNGC.

Question 5

Where may congenital melanosis show up? 3

Answer 5

lungs, meninges, uterus (remember lung countour is flat)

Question 6

How common is malignant melanoma in dogs?

Answer 6

one of the commonest oral tumours in dogs

Question 7

How can you tell if black spots in lung are melanosis or malignant melanoma?

Answer 7

Melanosis = flat contour Malignant melanoma = raised contour (extra cells because of neoplastic infiltrate)

Question 8

What are sulphur granules? What do they indicate?

Answer 8

multiple small granules (e.g. found in thoracic cavity with purulent exudate). They suggest filamentous bacteria (Actinomyces, Nocardia or Actinobacillus)

Question 9

What causes atrophic rhinitis?

Answer 9

Dual infection - B.bronchiseptica and P.multocida. Toxins cause direct bone destruction and increase bone breakdown (i.e. dual effect)

Question 10

Clinical signs - atrophic rhinitis - 4

Answer 10

• snout deviation - tear stains (nasolacrimal duct compression/narrowing) - nasal inflammatory exudate with haemorrhage - snuffling

Question 11

Ddx for multifocal nodules in lung parenchyma - 3

Answer 11

• Neoplasia (primary or secondary) - Granuloma - Abscess (Granulomas and abscesses composed of inflammatory cells, also usually single).

Question 12

Where might a carcinoma that has metastases in the lung have originated from? 3

Answer 12

• Mammary gland - Thyroid gland - Another epithelial organ

Question 13

What is another name for clinical lungworm disease in cows?

Answer 13

Husk

Question 14

What might a granuloma surrounding a single D.viviparus in the lung parenchyma of a calf suggest?

Answer 14

The calf has had previously exposure to the parasite or its antigen which has caused this delayed type hypersensitivity.

Question 15

How can clinical disease due to husk be prevented? 2

Answer 15

• Vaccines - LAV - 6 weeks and 2 weeks pre-turnout - Strategic anthelmintic (often drugs with a prolonged period of residual activity). Often ivermectin 3, 8 and 12 weeks post-turnout, 28 day residual activity

Question 16

Outline D.viviparus lifecycle. What is the PPP?

Answer 16

Adult worms in trachea and larger bronchi - females lay embryonated eggs which are coughed up and swallowed - eggs hatch during passage through body - L1 passed in faeces (doesn’t have an S shaped tail like other lungworms) - develops to L2 and L3 (infective) in dung - infection - swallowed - penetrate GIT - migrate via lymphatics to blood to lungs. Ascend respiratory tree - mature to adult worms. PPP 3.5 weeks.

Question 17

How is D.viviparus carried on to next year? 2

Answer 17

• Low numbers of L3 overwintering on pasture - Carrier animals

Question 18

What time of year is husk usually seen clinically?

Answer 18

July - September (same time as Ostertagiosis)

Question 19

Outline immunity to D.viviparus

Answer 19

rapidly acquired immunity following heavy exposure to infection (within a few weeks)

Question 20

What are the 2 main lesions of husk?

Answer 20

• Bronchitis (due to adult worms) - Parasitic pneumonia (aspiration of eggs/larva leading to cellular infiltration) - In 25% cases, clinical signs flare up later (in the post patent phase, 8-12 weeks after infection) as a result of epithelialisation which may be accompanied by interstitial emphysema and pulmonary oedema or secondary bacterial infection.

Question 21

How many D.viviparus worms are needed to cause disease?

Answer 21

only 200-300 worms (c.f. >40,000 Ostertagia)

Question 22

Diagnosis - calf parasitic bronchitis - 3

Answer 22

• seasonal incidence, grazing hx, CS - faecal exam - larvae - Baerman technique - PME - worms flushed out of lungs

Question 23

Diagnosis - adult cow parasitic bronchitis - 5

Answer 23

• seasonal incidence, grazing hx, CS - faecal exam (Baerman), often no larvae - blood/milk ELISA - Grass examination (larvae around dung) - response to anthelmintics