Pulmonary Parenchymal Disease, Pt. 2 Flashcards
How is parasitic pneumonia diagnosed? Treated?
airway sampling or fecals
Fenbendazole or Ivermectin
What are the 4 most common parasites affecting the lungs?
- Aleurostrongylus abstrusus - outdoor cats
- Paragonimus kellicot - dog/cat fluke
- Capillaria aerophilus - adults embed in mucosa of trachea and large bronchi
- Filaroides hirthi - terminal airways
What is the classical sign of Paragonimus kellicoti pneumonia? How are pets infected?
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
What are the 3 major diagnostics used for Paragonimus kellicoti pneumonia?
- CBC shows eosinophilia
- chest radiographs show air-filled cysts
- TTW or zinc sulfate fecal float show operculated ova
What is foreign body pneumonia associated with? What are 4 major risk factors?
pneumonia that relapses after treatment
- young sporting breeds
- environmental exposure to grass awns
- history of cutaneous or visceral foreign bodies
- history of spontaneous pneumothorax or pyothorax
What is idiopathic pulmonary fibrosis a common sequela of? What is it characterized by?
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
What are the main histological features of idiopathic pulmonary fibrosis? In what dog breeds is it commonly seen?
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
Why is diagnosis and treatment of idiopathic pulmonary fibrosis difficult? What are the most common clinical signs?
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)
What concurrent disease do most animals with idiopathic pulmonary fibrosis have?
mitral insufficiency —> pulmonary hypertension (especially in WHWTs)
What is the key clinical consequence of idiopathic pulmonary fibrosis? How does this typically affect the patient?
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
What is characteristic of thoracic radiographs in patients with idiopathic pulmonary fibrosis?
ground glass appearance (+ pulmonary hypertension)
What is required for a definitive diagnosis of idiopathic pulmonary fibrosis? What should be seen on arterial blood gases?
histopathology - RARELY DONE since patients are not typically good anesthetic candidates
increased alveolar-arterial gradient with moderate hypoxemia
How can Pirfenidone be used to treat idiopathic pulmonary fibrosis? What are some other options?
anti-fibrotic, anti-oxidant, anti-inflammatory, inhibits TGF beta stimulated collagen production
SUPPORTIVE CARE
- trial bronchodilators
- antitussives
- treat pneumonia if present
What respiratory signs are associated with pulmonary neoplasms?
- cough
- labored breathing
- tachypnea
- hemoptysis
What non-respiratory signs are associated with pulmonary neoplasms?
- weight loss (cancer cachexia)
- inappetence
- lethargy
- lameness due to hypertrophic osteopathy and digital mets
- dysphagia
- regurgitation
- edema of head/neck due to venous obstruction
What are the 3 major physical exam findings in patients with pulmonary neoplasms?
- tachypnea
- increased/decreased or abnormal lung sounds, like crackles and wheezes
- muffled lung sounds due to lobar consolidation or pleural effusion
How does primary neoplasia look on thoracic radiographs? What tumors are more common in cats and dogs?
usually focal single or multiple mass lesions/lobar consolidation of the diaphragmatic lobes (R > L)
- CATS = adenocarcinoma
- DOGS = bronchoalveolar carcinoma
How does metastatic neoplasia appear on thoracic radiographs? What 7 tumors are most likely to metastasize to the lungs?
smaller and more well-circumscribed nodules most common in the peripheral or middle portions of the lungs
- mammary carcinoma
- thyroid carcinoma
- HSA
- osteosarcoma
- TCC
- SCC
- oral/digital melanomas
How can thoracic radiographs be used to screen for metastasis to the lungs? What are they unable to see?
3-view “met check” - right and left laterals and VD
nodules under 0.5-1 cm cannot be reliably recognized
What is the most sensitive means of detecting pulmonary lesions?
contrast-enhanced CT can detect much smaller lesions compared to radiography
What is required for definitive diagnosis of pulmonary neoplasia?
cytology and histology
(may see neoplastic cells in BAL fluid, too)
What surgical treatment is recommended for pulmonary neoplasia? What neoplasia responds to chemotherapy?
resection if only one lobe is affected
lymphoma (usually chemotherapy is unreliable)
How do pulmonary adenocarcinomas and SCC compare?
adenocarcinomas can be slow growing and have a better prognosis compared to SCC
What is hypertrophic osteopathy? What is the most common root cause?
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
What are 3 other possible causes of hypertrophic osteopathy other than pulmonary neoplasia? What is thought to be its pathogenesis?
- urinary tract neoplasia
- heartworm disease
- bacterial endocarditis
increased peripheral blood flow, vascular connective tissue, bone formation —> VEGF, PDGF —> proliferative, not osteolytic!!
What is lung-digit syndrome? How do patients present?
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
In what breed is malignant histiocytosis (or histiocytic sarcoma) most common? What does it cause?
Bernese Mountain Dogs (+ Flat-coated Retrievers, Golden Retrievers. Rottweilers)
atypical histiocytic cells accumulate within bone marrow, CNS, abdomina viscera, and lungs, resulting in dysfunction
How is malignant histiocytosis diagnosed? What is required for a definitive diagnosis?
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)
What is pulmonary edema?
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
What are the 4 physiologic categories of pulmonary edema? What do they lead to?
- increased hydrostatic pressure - heart failure
- decreased oncotic pressure - low albumin, overhydration
- impaired lymphatic drainage - over capacity
- increased vascular permeability* - tissue/vascular damage
ventilation perfusion mismatching and hypoxmia
What causes non-cardiogenic pulmonary edema? What are some examples?
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
What are 5 extrapulmonary causes of non-cardiogenic pulmonary edema?
- neurogenic - seizures, electrocution, head trauma
- post-obstructive - strangulation, laryngeal paralysis, pulmonary re-expansion
- systemic disease predisposing to acute respiratory distress syndrome
- impaired lymphatic drainage - lymphangitis, lymphatic neoplasia
- trauma
- profound hypoalbuminemia - PLN, lymphangiectasia, liver failure
What are the most common physical exam findings in non-cardiogenic pulmonary edema?
- 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
What is the most common laboratory finding in non-cardiogenic pulmonary edema? Pulse oximetry? Thoracic radiographs?
stress-induced leukogram and hyperglycemia
poor oxygenation, increased alveolar-arterial gradient
bilateral symmetric infiltrates concentrated in the caudodorsal lung fields
What is acute respiratory distress syndrome (ARDS)? What is classically seen on radiographs?
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
How are patients treated for ARDS?
- 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
How do pulmonary contusions cause clinical signs? What are the 2 common clinical signs? What concurrent problems should be looked for?
trauma causes the leakage of blood into the lungs, which interferes with normal ventilation and perfusion
- respiratory distress
- crackles with severe consolidation
What concurrent problems should be looked for in patients with possible pulmonary contusions?
- rib fractures
- pneumo/hemothorax
- diaphragmatic hernia
- traumatic myocarditis
- cardiovascular shock
When are changes in radiographs typically seen in patients with pulmonary contusions?
localized areas of interstitial or alveolar patterns are seen 2-12 hours after the trauma
(pneumothorax outlines the lungs)
What is characteristic of eosinophilic bronchopneumopathy? How does it compare to allergic bronchitis? What is a common historical finding?
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
What is the most common signalment of patients with eosinophilic bronchopneumopathy? What are the most common clinical signs?
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
If eosinophilic bronchopneumopathy is suspected, which diagnostics should be done?
- HW and fecal tests (reaction to parasite antigens!)
- airway samples from transtracheal washes or bronchoscopy cytology should show eosinophils without bacteria
What is pulmonary thromboembolism?
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
What are some diseases that predispose animals to pulmonary thromboembolism?
- heartworm disease
- IMHA*
- nephrotic disease causing PLE and loss of antithrombin 3
- hyperadrenocorticism*
- DIC*
- infective endocarditis
- hypothyroidism
What is the most common finding in patients with pulmonary thoromboembolisms?
peracute onset of severe unrelenting dyspnea without radiographic evidence of severe lung disease
- pulmonary hypertension causes split S2
- cough, hemoptysis
- exercise intolerance, tachycardia
What is expected on blood gas analyses in patients with pulmonary thromboembolisms?
- hypoxemia
- carbon dioxide may be increased or decreased
How is contrast radiology used to diagnose pulmonary thromboembolism?
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
What is the gold standard for diagnosing pulmonary thromboembolism?
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
How are pulmonary thromboembolisms treated?
- 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
When is aspirin specifically indicated in treatment of pulmonary thromboembolism?
thromboprophylaxis in IMHA, PLN, and feline myocardial disease
