resp notes Q and A 3

Question 1

List two nasal diseases of dogs for which biopsy provides a definitive diagnosis.

Answer 1

Nasal neoplasia, aspergillosis.

Question 2

Is immunosuppression a risk factor for nasal aspergillosis?

Answer 2

No, immunosuppression predisposes to systemic aspergillosis, but not nasal aspergillosis.

Question 3

List three predisposing factors for aspiration pneumonia in adult dogs, and two for puppies less than 5 months old.

Answer 3

Adults: anesthesia, neurologic disease, laryngeal disease, megaesophagus, myasthenia gravis, … Puppies: cleft palate, parvoviral enteritis.

Question 4

List two bacterial pathogens that can cause outbreaks of lung disease. What form of lung disease is expected?

Answer 4

Bordetella bronchiseptica, Streptococcus canis. Bronchopneumonia.

Question 5

What gross lesions in the lung are expected with heart failure?

Answer 5

Diffuse pulmonary edema and congestion: red, heavy lungs that ooze fluid from the cut surface and have excessive foam in the trachea.

Question 6

What 2 histologic lesions are characteristic of acute interstitial lung disease (ARDS) in dogs?

Answer 6

Hyaline membranes, alveolar edema.

Question 7

Briefly explain how a thymoma in an adult dog leads to bronchopneumonia.

Answer 7

Thymoma —> megaesophagus —> regurgitation —> aspiration pneumonia

Question 8

What is the most inexpensive method of identifying pulmonary emboli at postmortem examination?

Answer 8

Open the pulmonary arteries all the way to the caudal lobes of the lung!

Question 9

Other than lung, what 3 tissues are most often affected by blastomycosis?

Answer 9

Skin, eye, bone.

Question 10

What are the two main differential diagnoses for swelling and red discolouration of the right middle lung lobe?

Answer 10

Aspiration pneumonia, lung lobe torsion.

Question 11

Bastard strangles vs. purpura hemorrhagica: which of these is a consequence of bacteremia, and which is an immune complex-mediated disease?

Answer 11

• Bacteremia —> bastard strangles (visceral abscesses)
• Circulating immune complexes —> purpura hemorrhagica (vasculitis, petechiae, and edema)

Question 12

What is the gross appearance of guttural pouch mycosis?

Answer 12

A focal plaque of fungal growth, often with necrosis and inflammation of the adjacent tissue, and sometimes, with hemorrhage filling the pouch.

Question 13

List 2 clinically serious sequelae to mycosis of the guttural pouch in horses.

Answer 13

Hemorrhage from carotid artery, facial nerve paralysis, and others.

Question 14

What anatomic structure is targeted by the lesions of heaves (severe equine asthma)?

Answer 14

Bronchioles: small airways.

Question 15

What are 3 mechanisms of airway obstruction in heaves?

Answer 15

Bronchoconstriction. Mucus and neutrophils in the lumen. Edematous swelling of the airway mucosa.

Question 16

Describe the expected gross lesions of Rhodococcus equi infection of the respiratory tract.

Answer 16

Cranioventral bronchopneumonia, with abscessation or granulomas within the consolidated cranioventral areas of lung.

Question 17

Why is Rhodococcus pneumonia resistant to many antibiotics that are effective for other forms of pneumonia in horses?

Answer 17

Intracellular location within macrophages. Presence within abscesses. (Drug delivery is poor to both of these locations).

Question 18

In Rhodococcus infection, what are the two pathogeneses of the lesions in the colonic lymph nodes?

Answer 18

Ingestion of Rhodococcus equi from the environment (dust, soil)
Bacteria are coughed up from lung lesions, swallowed, and reach the intestine.

Question 19

How does the pathogenesis of fibrinous pleuritis in a feedlot calf differ from that in a racehorse?

Answer 19

• Feedlot calf: hematogenous spread of Histophilus somni results in pleuritis with normal lung tissue.
• Racehorse: the pleuritis is usually secondary to an underlying bacterial pneumonia.

Question 20

In 2–8-month-old foals with interstitial (bronchointerstitial) pneumonia, what is the gross appearance of the lung?

Answer 20

Diffusely firm, rubbery texture, fails to collapse.

Question 21

In 2–8-month-old foals with interstitial (bronchointerstitial) pneumonia, what is the common concurrent disease?

Answer 21

Rhodococcus equi pneumonia, which may be either mild or severe.

Question 22

What are three causes of diffuse interstitial lung disease in neonatal foals?

Answer 22

Hyaline membrane disease, septicemia, Equine herpesvirus-1, meconium aspiration syndrome.

Question 23

Indicate the distribution and likely cause of bronchopneumonia in a neonatal foal.

Answer 23

Cranioventral distribution.
Streptococcus zooepidemicus & others.

Question 24

Indicate the distribution and likely cause of interstitial lung disease in a neonatal foal.

Answer 24

• Generalized/diffuse distribution.
• Hyaline membrane disease, septicemia, EHV-1 infection, meconium aspiration.

Question 25

What is the pathophysiologic basis for dyspnea in a foal with interstitial lung disease? That is, what are two alterations in lung physiology that cause respiratory failure?

Answer 25

Obstruction to gas exchange, reduced lung compliance, reduced functional lung volume.

Question 26

List two ways that nasal tumours of dogs differ from those of sheep.

Answer 26

Sheep: infectious (retrovirus), expansile (benign).
Dogs: non-infectious, invasive (malignant).

Question 27

How do the lesions of pneumonic pasteurellosis differ from those of septicemic pasteurellosis in lambs?

Answer 27

• Pneumonic pasteurellosis: cranioventral consolidation of the lung.
• Septicemic pasteurellosis: widespread petechial hemorrhages in lung and other organs.

Question 28

Which could cause diffuse interstitial pneumonia in animals less than 6 months of age: Maedi visna virus or Caprine arthritis encephalitis virus, or both?

Answer 28

Only Caprine arthritis encephalitis virus affects youngsters. Maedi occurs only in adult sheep.

Question 29

What is the common lungworm of sheep? Can you see the worms in the centre of the nodules?

Answer 29

Muellerius capillaris; the worms are microscopic, not seen grossly.

Question 30

What is the key point in the pathogenesis of Pneumocystis infections in foals, pigs, and humans?

Answer 30

The fungus Pneumocystis is thought to only cause disease in immunosuppressed individuals.

Question 31

How do Mycoplasma hyopneumoniae and PRRS virus predispose to bacterial pneumonia?

Answer 31

• Mycoplasma hyopneumoniae binds to cilia and prevents mucociliary clearance of inhaled bacteria.
• PRRS virus infects macrophages, and suppressed macrophage function accounts for the secondary
  pneumonia or septicemia.

Question 32

What is the cause of fibrinous and necrotizing inflammation of the caudal lung lobe in a grower-finisher pig?

Answer 32

Actinobacillus pneuropneumoniae or Actinobacillus suis.

Question 33

List 2 specific causes of diffuse interstitial pneumonia in pigs.

Answer 33

PRRS virus, Porcine circovirus-2, septicemia, and others.

Question 34

What clinical sign is typical with porcine cytomegalovirus infection?

Answer 34

Sneezing and nasal discharge in baby pigs. Also stillbirths, mummies, and perhaps “failure-to-thrive” syndrome.

Question 35

What are the five locations of exudates, in pigs with polyserositis?

Answer 35

Pleura, pericardium, peritoneum, joints, meninges.

Question 36

What two bacteria are the most important causes of polyserositis in pigs?

Answer 36

• Streptococcus suis, Glaesserella (Haemophilus) parasuis, Mycoplasma hyorhinis (Mycoplasma hyopneumoniae causes pneumonia; M. hyorhinis causes septicemia)
• Erysipelothrix rhusiopathiae also causes septicemia, but without exudate in body cavities.

Question 37

Name a reportable disease of pigs that affects the respiratory system.

Answer 37

Pseudorabies