Pulmonary Parenchymal Disease, Pt. 2

Question 1

How is parasitic pneumonia diagnosed? Treated?

Answer 1

airway sampling or fecals

Fenbendazole or Ivermectin

Question 2

What are the 4 most common parasites affecting the lungs?

Answer 2

1. Aleurostrongylus abstrusus - outdoor cats
2. Paragonimus kellicot - dog/cat fluke
3. Capillaria aerophilus - adults embed in mucosa of trachea and large bronchi
4. Filaroides hirthi - terminal airways

Question 3

What is the classical sign of Paragonimus kellicoti pneumonia? How are pets infected?

Answer 3

create cysts and bullae that rupture and cause PNEUMOTHORAX or hemoptysis (mature flukes use communication tunnels in the bronchioles, which allows ova to be coughed up and swallowed)

eating infected crayfish, commonly around the Great Lakes, Midwest, and South

Question 4

What are the 3 major diagnostics used for Paragonimus kellicoti pneumonia?

Answer 4

1. CBC shows eosinophilia
2. chest radiographs show air-filled cysts
3. TTW or zinc sulfate fecal float show operculated ova

Question 5

What is foreign body pneumonia associated with? What are 4 major risk factors?

Answer 5

pneumonia that relapses after treatment

1. young sporting breeds
2. environmental exposure to grass awns
3. history of cutaneous or visceral foreign bodies
4. history of spontaneous pneumothorax or pyothorax

Question 6

What is idiopathic pulmonary fibrosis a common sequela of? What is it characterized by?

Answer 6

severe lung insult, likely due to injured alveolar epithelium that has an aberrant wound healing process

inflammation and fibrosis of pulmonary interstitium and alveolus of unknown origin

Question 7

What are the main histological features of idiopathic pulmonary fibrosis? In what dog breeds is it commonly seen?

Answer 7

interstitial pneumonia with interstitial fibrosis with collagenous thickening of the pulmonary interstitium leading to impairment of gas exchange

terriers —> middle-aged to older West Highland White Terriers

Question 8

Why is diagnosis and treatment of idiopathic pulmonary fibrosis difficult? What are the most common clinical signs?

Answer 8

permanent loss of pulmonary function has often occurred before clinical signs are recognized

• inspiratory or velcro crackles
• abdominal breathing, HYPOXEMIA
• cough, tachypnea, exercise intolerance
• exercise intolerance and syncope (6 minute walk test)

Question 9

What concurrent disease do most animals with idiopathic pulmonary fibrosis have?

Answer 9

mitral insufficiency —> pulmonary hypertension (especially in WHWTs)

Question 10

What is the key clinical consequence of idiopathic pulmonary fibrosis? How does this typically affect the patient?

Answer 10

HYPOXEMIA - arterial blood gas analysis and pulse oximetry show PaO2 < 80 mmHg (PaCO2 is normal, exhaling fine)

most dogs will not be in respiratory distress because they adapt to a chronic, slowly/insidiously progressing disease

Question 11

What is characteristic of thoracic radiographs in patients with idiopathic pulmonary fibrosis?

Answer 11

ground glass appearance (+ pulmonary hypertension)

Question 12

What is required for a definitive diagnosis of idiopathic pulmonary fibrosis? What should be seen on arterial blood gases?

Answer 12

histopathology - RARELY DONE since patients are not typically good anesthetic candidates

increased alveolar-arterial gradient with moderate hypoxemia

Question 13

How can Pirfenidone be used to treat idiopathic pulmonary fibrosis? What are some other options?

Answer 13

anti-fibrotic, anti-oxidant, anti-inflammatory, inhibits TGF beta stimulated collagen production

SUPPORTIVE CARE

• trial bronchodilators
• antitussives
• treat pneumonia if present

Question 14

What respiratory signs are associated with pulmonary neoplasms?

Answer 14

• cough
• labored breathing
• tachypnea
• hemoptysis

Question 15

What non-respiratory signs are associated with pulmonary neoplasms?

Answer 15

• weight loss (cancer cachexia)
• inappetence
• lethargy
• lameness due to hypertrophic osteopathy and digital mets
• dysphagia
• regurgitation
• edema of head/neck due to venous obstruction

Question 16

What are the 3 major physical exam findings in patients with pulmonary neoplasms?

Answer 16

1. tachypnea
2. increased/decreased or abnormal lung sounds, like crackles and wheezes
3. muffled lung sounds due to lobar consolidation or pleural effusion

Question 17

How does primary neoplasia look on thoracic radiographs? What tumors are more common in cats and dogs?

Answer 17

usually focal single or multiple mass lesions/lobar consolidation of the diaphragmatic lobes (R > L)

• CATS = adenocarcinoma
• DOGS = bronchoalveolar carcinoma

Question 18

How does metastatic neoplasia appear on thoracic radiographs? What 7 tumors are most likely to metastasize to the lungs?

Answer 18

smaller and more well-circumscribed nodules most common in the peripheral or middle portions of the lungs

1. mammary carcinoma
2. thyroid carcinoma
3. HSA
4. osteosarcoma
5. TCC
6. SCC
7. oral/digital melanomas

Question 19

How can thoracic radiographs be used to screen for metastasis to the lungs? What are they unable to see?

Answer 19

3-view “met check” - right and left laterals and VD

nodules under 0.5-1 cm cannot be reliably recognized

Question 20

What is the most sensitive means of detecting pulmonary lesions?

Answer 20

contrast-enhanced CT can detect much smaller lesions compared to radiography

Question 21

What is required for definitive diagnosis of pulmonary neoplasia?

Answer 21

cytology and histology

(may see neoplastic cells in BAL fluid, too)

Question 22

What surgical treatment is recommended for pulmonary neoplasia? What neoplasia responds to chemotherapy?

Answer 22

resection if only one lobe is affected

lymphoma (usually chemotherapy is unreliable)

Question 23

How do pulmonary adenocarcinomas and SCC compare?

Answer 23

adenocarcinomas can be slow growing and have a better prognosis compared to SCC

Question 24

What is hypertrophic osteopathy? What is the most common root cause?

Answer 24

paraneoplastic syndrome where there is diffuse periosteal proliferation in the long bone of dogs secondary to neoplastic or infectious masses in the thoracic or abdominal cavity (tend to be bilaterally symmetrical in the distal limbs)

primary lung tumors

Question 25

What are 3 other possible causes of hypertrophic osteopathy other than pulmonary neoplasia? What is thought to be its pathogenesis?

Answer 25

1. urinary tract neoplasia
2. heartworm disease
3. bacterial endocarditis

increased peripheral blood flow, vascular connective tissue, bone formation —> VEGF, PDGF —> proliferative, not osteolytic!!

Question 26

What is lung-digit syndrome? How do patients present?

Answer 26

primary lung tumor with digital metastasis

cats with swelling and reddening of the digit, purulent discharge from the nail bed, and dysplasia or fixed ensheathment of the associated nail

Question 27

In what breed is malignant histiocytosis (or histiocytic sarcoma) most common? What does it cause?

Answer 27

Bernese Mountain Dogs (+ Flat-coated Retrievers, Golden Retrievers. Rottweilers)

atypical histiocytic cells accumulate within bone marrow, CNS, abdomina viscera, and lungs, resulting in dysfunction

Question 28

How is malignant histiocytosis diagnosed? What is required for a definitive diagnosis?

Answer 28

radiographs or CT demonstrates thoracic lymphadenopathy (tracheobroncial and sternal), pulmonary nodules in the right middle lung lobes, and interstitial infiltrates or pleural effusion

histiopathologic assessment of tissue

(most chemo is ineffective - prognosis is guarded to grave)

Question 29

What is pulmonary edema?

Answer 29

fluid accumulation in the lungs where there is effusion of fluid into the alveoli and/or interstitial spaces faster than it can be reabsorbed

• cardiogenic: left-sided heart failure
• non-cardiogenic

Question 30

What are the 4 physiologic categories of pulmonary edema? What do they lead to?

Answer 30

1. increased hydrostatic pressure - heart failure
2. decreased oncotic pressure - low albumin, overhydration
3. impaired lymphatic drainage - over capacity
4. increased vascular permeability* - tissue/vascular damage

ventilation perfusion mismatching and hypoxmia

Question 31

What causes non-cardiogenic pulmonary edema? What are some examples?

Answer 31

direct pulmonary insults

• aspiration/bacterial pneumonia
• lung lobe torsion
• severe upper airway obstruction
• pulmonary contusions
• parasitic pneumonitis
• inhalant injury: smoke inhalation, noxious gases, oxygen toxicity, radiation pneumonitis, near drowning

Question 32

What are 5 extrapulmonary causes of non-cardiogenic pulmonary edema?

Answer 32

1. neurogenic - seizures, electrocution, head trauma
2. post-obstructive - strangulation, laryngeal paralysis, pulmonary re-expansion
3. systemic disease predisposing to acute respiratory distress syndrome
4. impaired lymphatic drainage - lymphangitis, lymphatic neoplasia
5. trauma
6. profound hypoalbuminemia - PLN, lymphangiectasia, liver failure

Question 33

What are the most common physical exam findings in non-cardiogenic pulmonary edema?

Answer 33

• thoracic auscultation shows tachypnea, bilateral moist and fine crackles with stridor if upper respiratory obstruction is underlying etiology
• systemic disease: peripheral edema, neurologic signs, burns

Question 34

What is the most common laboratory finding in non-cardiogenic pulmonary edema? Pulse oximetry? Thoracic radiographs?

Answer 34

stress-induced leukogram and hyperglycemia

poor oxygenation, increased alveolar-arterial gradient

bilateral symmetric infiltrates concentrated in the caudodorsal lung fields

Question 35

What is acute respiratory distress syndrome (ARDS)? What is classically seen on radiographs?

Answer 35

severe form on non-cardiogenic pulmonary edema from severe, diffuse lung parenchymal damage, leading to increased endothelial permeability, coagulation disturbance, loss of surfactant, and perfusion adbnormalities —> animals are already affected by something!

diffuse, severe intertitial to alveolar pattern without signs of cardiac enlargement

Question 36

How are patients treated for ARDS?

Answer 36

• aggressive control of primary disease process
• oxygen supplementation with supportive care (careful with overload from fluids!)
• animals with overload and acceptably renal function respond to a decrease in supplemental fluids
• diuretics can help with overhydration, but they are not efficacious for helping with the edema

Question 37

How do pulmonary contusions cause clinical signs? What are the 2 common clinical signs? What concurrent problems should be looked for?

Answer 37

trauma causes the leakage of blood into the lungs, which interferes with normal ventilation and perfusion

1. respiratory distress
2. crackles with severe consolidation

Question 38

What concurrent problems should be looked for in patients with possible pulmonary contusions?

Answer 38

• rib fractures
• pneumo/hemothorax
• diaphragmatic hernia
• traumatic myocarditis
• cardiovascular shock

Question 39

When are changes in radiographs typically seen in patients with pulmonary contusions?

Answer 39

localized areas of interstitial or alveolar patterns are seen 2-12 hours after the trauma

(pneumothorax outlines the lungs)

Question 40

What is characteristic of eosinophilic bronchopneumopathy? How does it compare to allergic bronchitis? What is a common historical finding?

Answer 40

eosinophilic infiltration of the lung and bronchial mucosa demonstrated by examination of BAL cytology or histology of bronchial mucosa (Type 1 hypersensitivity)

allergic bronchitis is more of a severe reaction

lack of response to antibiotics

Question 41

What is the most common signalment of patients with eosinophilic bronchopneumopathy? What are the most common clinical signs?

Answer 41

young to middle ages (1-8) larger breed dogs, especially Siberian Huskies

• harsh cough accompanied by gagging
• progressive respiratory difficulty
• exercise intolerance associated with dyspnea
• nasal discharge (eosinophilic rhinitis)
• systemically ill with lethargy and anorexia

Question 42

If eosinophilic bronchopneumopathy is suspected, which diagnostics should be done?

Answer 42

• HW and fecal tests (reaction to parasite antigens!)
• airway samples from transtracheal washes or bronchoscopy cytology should show eosinophils without bacteria

Question 43

What is pulmonary thromboembolism?

Answer 43

obstruction of pulmonary arteries and arterioles due to vascular stasis, endothelial damage, and systemic hypercoagulability (Virchow’s triad), resulting in ventilation-perfusion abnormalities and platelet mediated vaso/bronchoconstriction

Question 44

What are some diseases that predispose animals to pulmonary thromboembolism?

Answer 44

• heartworm disease
• IMHA*
• nephrotic disease causing PLE and loss of antithrombin 3
• hyperadrenocorticism*
• DIC*
• infective endocarditis
• hypothyroidism

Question 45

What is the most common finding in patients with pulmonary thoromboembolisms?

Answer 45

peracute onset of severe unrelenting dyspnea without radiographic evidence of severe lung disease

• pulmonary hypertension causes split S2
• cough, hemoptysis
• exercise intolerance, tachycardia

Question 46

What is expected on blood gas analyses in patients with pulmonary thromboembolisms?

Answer 46

• hypoxemia
• carbon dioxide may be increased or decreased

Question 47

How is contrast radiology used to diagnose pulmonary thromboembolism?

Answer 47

not practical —> selective angiography (requires anesthesia) is used by placing a catheter in the pulmonary artery and a contrast is injected, which can show filling defects or sudden interruptions in blood flow

Question 48

What is the gold standard for diagnosing pulmonary thromboembolism?

Answer 48

ventilation-perfusion snac

IV radiolabeled albumin is injected for perfusion scans and radiographic inert gas is inhaled for ventilation scans —> should result in a normal ventilation scan and abnormal perfusion scan

Question 49

How are pulmonary thromboembolisms treated?

Answer 49

• treat underlying disease and supplement oxygen to keep PaO2 above 60 mmHg
• chronic anticoagulants: warfarin, rivaroxaban, apixaban, heparin, lovenoc (LMWH)
• chronic antiplatelets: aspirin, clopidogrel
• support with fluids to avoid hypercoagulability of the blood

Question 50

When is aspirin specifically indicated in treatment of pulmonary thromboembolism?

Answer 50

thromboprophylaxis in IMHA, PLN, and feline myocardial disease