Diagnostic Procedures for Respiratory Problems

Question 1

Heartworm testing

Answer 1

• dogs or cats presented for chronic cough or respiratory distress
• Ag test in dogs
• combine Ag and Ab tests in cats
• echo for cats?

Question 2

FeLV & FIV testing

Answer 2

• infections with FeLV and FIV have not been directly linked to respiratory clinical signs
• both diseases may cause immunosuppression and thus acquisition of opportunistic infections

Question 3

parasite testing

Answer 3

• multiple potential parasites
• fecal exam should be performed for almost all patient with cough
• float, Baermann

Question 4

infectious disease testing

Answer 4

• serology
• PCR
• isolation
• culture
• Ag vs Ab vs DNA vs live organism
• exposure vs infection vs disease

Question 5

blood gas evaluation

Answer 5

• pulse oximetry
• arterial blood gas (ABG)
• capnography
• can help determine severity, differentiate pulmonary dz from hypoventilation, determine need for intervention and monitor response to tx
• respiratory compromise must be severe to detect abnormalities
• Hgb-dissociation curve

Question 6

pulse oximetry

Answer 6

• relatively easy, non-invasive
  
  • confirm accurate reading
• measures saturation, not total content

Question 7

blood gas evaluation

Question 8

radiographs

Answer 8

• cannot provide specific dx in most cases (only pictures)
• nasal, dental, thorax, cervical
• fluoroscopy
• angiography
• scintigraphy

Question 9

thoracic radiographs

Answer 9

• rarely provide definitive dx
• may help localize, narrow dx, direct further testing, alter prognosis…
• high quality films necessary
  
  • 3 views
  • DV for pulmonary vessels
  • I vs. E

Question 10

basic pulmonary patterns on thoracic radiographs

Answer 10

• alveolar
  
  • fluid or tissue w/in alveolar spaces
• intersitial
  
  • increased tissue in interstitium
• bronchial
  
  • obvious bronchial markings- “train tracks” and “doughnuts”
• nodular
• pleural space evaluation

Question 11

cross-sectional imaging

Answer 11

• CT & MRI
• visualization of internal structurse
• direction of further dx and tx
• expensive
• requires general anesthesia
• cannot provide specific dx

Question 12

oropharyngeal exam

Answer 12

• requires anesthesia
• primary use is respiratory clinical signs localized to the URT
• may identify palatal problems, oropharyngeal masses, dental or periodontal disease…

Question 13

nasal cytology

Answer 13

• 3 main types
  
  • FNA/impression smear of mass
  • FNA of regional lymph nodes
  • nasal flush samples
• may be helpful for fungal rhinitis or neoplasia
• bacteria are normal
• very easy
• usually of little or no benefit

Question 14

rhinoscopy

Answer 14

• direct visualization of nasal cavity
• indications: suspect foreign bodies, nasopharyngeal dz, sample collection (+/- neoplasia, infections)
• rigid vs. flexible instruments, otoscope?
• general anesthesia
• nasal tissue is highly vascular (hemorrhage)
• only specific dx for foreign bodies and nasal mites

Question 15

nasal biopsy

Answer 15

• best test to get specific dx for most primary nasal dzs
• general anesthesia
• invasive
• very little specialized equipment
• cost is generally reasonable
• if owners decline a more complete work up, blind nasal biopsies

Question 16

nasal culture

Answer 16

• nasal swab cultures from normal individuals yield multiple bacterial isolates
• deep nasal cultures positive in ~50% of dogs
• very high colony counts or single isolates associated with neutrophilic inflammation may be significant
• consider other organisms as well (mycoplasma, fungi)

Question 17

bronchoscopy

Answer 17

• direct visualization of airway interiors
• facilitates sample collection from lower RT
• general anesthesia
• specialized equipment, skill

Question 18

tracheal washing

Answer 18

• samples of fluid and cells from large airways
  
  • should bypass normal flora and debris from oral and pharyngeal cavities
• useful for large airway and severe diffuse alveolar diseases
• two main techniques
  
  • TTW
  • endotracheal lavage

Question 19

bronchoalveolar lavage

Answer 19

• sample from the small airways and alveoli
• two main techniques
  
  • bronchoscopy-guided
  • endotracheal lavage

Question 20

TW/BAL

Answer 20

• TTW is only procedure that doesn’t involve anesthesia
• transient hypoxemia
• crackles may be auscultated for several hours
• specimens should be processed rapidly

Question 21

TW/BAL cytology

Answer 21

• large mononuclear cells should predominate in normal respiratory secretions
  
  • increase neutrophils may indicate inflammation or infection
  • increase eosinophils may occur in allergic and parasitic conditions
• organisms contained w/in phagocytes are normally considered to be pathogens, esp if one species predominates
• rare findings include parasite ova, larvae, fungus, and neoplastic cells
  
  • these are significant

Question 22

TW/BAL culture

Answer 22

• require small volume of fluid
• what to culture?
  
  • aerobes
  • anaerobes?
  • Mycoplasma?
  • fungal cultures?

Question 23

trans-thoracic aspiration

Answer 23

• for cytology and/or culture
• best in patients with solitary lung mass, or diffuse dz
• sterile technique, adequate restraint/sedation
• complications are fairly common, potentially serious (10% develop pneumothorax)

Question 24

thoracocentesis

Answer 24

• useful diagnostic and therapeutic technique
• remove as much fluid or air as possible
• only contraindication is prsence of a known coagulopathy
• reasons for a negative tap: no fluid or air present, fluid more ventral or deeper than needle, fluid walled-off..
• always get cytology
• culture when appropriate
• +/- cholesterol and triglyceride levels

Question 25

lung biopsies

Answer 25

* very invasive, often costly * may be necessary for definitive dx * thoracoscopy vs. thoracotomy * **best way to sample interstitium**