3. Diseases of the lungs in dogs and cats Flashcards
Clinical evaluation of the lungs?
Clinical evaluation of the lung
Can be extremely challenging; Evaluation & treatment is usually performed on an emergency basis
§ Signalment
§ General history
§ Physical exam
§ Lab. D
§ Diagnostic imaging
§ Bronchoscopy
§ Respiratory sampling
§ Blood gas analysis
SIGNALMENT
Juvenile patients: Infection; Congenital diseases (brachycephalic)
Old patients: Chronic inflammatory disorders; Tumour
STAGE I STAGE II STAGE III STAGE IV
Siamese cats: Feline asthma
HISTORY
§ When did the owner obtain the animal?
§ Travel history
§ Environment
§ Known hypersensitivities
§ Previous respiratory problems
PHYSICAL EXAM
§ Varying degrees of respiratory distress
§ Coughing
§ Dyspnoea
§ Panting
§ ↑Resp. rate
§ Adventitial sounds upon auscultation
LAB. D
§ Anaemia (hypoxia; toxicosis)
§ Leucocytosis (infection; neoplasia)
§ Leukopenia (acute bronchopneumonia; sepsis)
§ Eosinophilia (eosinophilic broncho-pneumopathy; asthma;
bronchitis; lungworm)
§ Hypoalbuminaemia
§ Pancreatitis (ARDS)
§ Coagulopathy
§ Thrombocytopathy
§ Hypercalcaemia (neoplastic; fungal)
DIAGNOSTIC IMAGING
Radiography
VD; LL (Make sure you perform the LL last to avoid lung
compression in the other x-rays)
Bronchial pattern
Interstitial pattern
Alveolar pattern
Nodular pattern
Dx: Bronchitis; Oedema; Pneumonia; Haemorrhage;
Granuloma
Ultrasound
US-guided thoracocentesis in cases of fluid accumulation
Fine needle aspiration
CT
Dx: Neoplasia; Abscess; Pulmonary fibrosis;
Bronchiectasis
CT Angiography: Pulmonary thromboembolism
BRONCHOSCOPY
Direct visualisation (oedema; inflammation; foreign body; ulcer;
tumour)
RESPIRATORY SAMPLING
BAL; TTL (Transtracheal lavage) Cytology brush
Biopsy (Open chest lung biopsy; Transbronchial biopsy)
ARTERIAL BLOOD GAS ANALYSIS
PaO2 = 90-100 mmHg; PaCO2 = 36-40 mmHg; pH = 7.35-7.45
Indicator of alveolar ventilation & oxygenation of pulmonary arterial blood
Diseases of the small airways?
Diseases of the Small Airways
BRONCHITIS (GENERAL)
Multiple causes & anatomical locations (tracheobronchitis;
bronchitis; bronchopneumonia)
Infectious
§ Canine infectious respiratory disease complex (CIRDC):
CRCoV
CIV
Kennel cough
FHV in cats
Parasites
Fungal infections
Non-infectious
§ Aspiration
§ Canine chronic bronchitis
§ Feline asthma
Canine Chronic bronchitis?
CANINE CHRONIC BRONCHITIS (CCB)
Middle aged/Older dogs; Small breeds > Large breeds
History: Daily cough for > 2 months (productive/non-productive);
Exercise intolerance
Dx
Physical exam: Good BCS or overweight; Tracheal
sensitivity; Inspiratory crackles; Expiratory wheezes
Prolonged expiration & an expiratory push
↑Vagal tone → Sinus arrhythmia
Lab. D → Bloods: Usually negative
Radiography: Donut sign; RS cardiomegaly; Cor
pulmonale; May also be negative
Bronchoscopy: Hyperaemic mucosa; Mucoid/purulent
secretions; Fibrous nodules on the mucosa
BAL; TTL: Bacteria; Nondegenerate neutrophils;
Eosinophils; Mucus
DDx
§ Infection (Kennel cough; Parasite; Fungi; D. immitis)
§ Aspiration
§ Eosinophilic broncho-pneumopathy
§ Endocardosis (CHF)
§ Pulmonary fibrosis
Tx
The condition can be controlled, but never cured!; Goals include
controlling any inflammation & prevent any worsening airway
diseases
§ Short-acting glucocorticoids (Prednisolone)
§ Bronchodilators (Theophylline; Terbutaline; Albuterol)
§ Antitussives (if inflammation has been treated effectively)
§ Antibiotics (If BAL cytology & microbiology are positive)
§ Ancillary therapy: Weight loss; Clean environment;
Nebulisation
Inadequate treatment may lead to: Pulmonary hypertension;
Bronchiectasis; Vascular remodelling
Bronchiectasis?
BRONCHIECTASIS
Irreversible dilation of the bronchi, with accumulation of pulmonary
secretions
Susceptible breed: Cocker Spaniel
Histopathologic response to long-standing inflammation/irritation
(CCB; Primary ciliary dyskinesia; Foreign body; Smoke; Dust)
History: Chronic productive cough; Frequent bouts of pneumonia
CSx: Loud bronchial sounds; Nasal discharge (pneumonia);
Haemoptysis (coughing blood)
Dx: Radiography; Bronchoscopy; CT
§ Lobar bronchiectasis → Lobectomy & antibiotics
§ Bronchodilators
§ Antitussives MUST be avoided!
Prevention: Appropriate Abx therapy if infectious; Removal of
foreign bodies ASAP; Appropriate CCB management
Prognosis: Chronic recurrent infection; Abx resistance; Pulmonary hypertension; Cor pulmonale
Feline lower airway diseases and feline bronchitis?
Feline asthma?
FELINE ASTHMA
Dx
§ Blood test: Eosinophilia in 30% of cases; Heartworm
antibody tests; (Echocardiography)
§ Faecal exam: Paragonimus spp.; Aelurostrongylus;
Capillaria
§ Radiography: Interstitial, bronchial or alveolar pattern;
May appear normal; Hallmarks: Peribronchial cuffing, infiltrated
medial lung lobe & pulmonary emphysema
§ Bronchoscopy: BAL cytology: Eosinophilia!; Culture
DDx
§ Infection
§ Aspiration
§ Allergic bronchitis
§ Idiopathic pulmonary fibrosis
§ Neoplasia
Tx
§ Acute (emergency) (Cyanosis & open mouth breathing)
Oxygen cage; Terbutaline; Glucocorticoids
§ Chronic
§ Glucocorticoids: Prednisolone; Fluticasone
§ Bronchodilators
§ Antibiotics
Prevention
Avoid use of beta-blockers, cigarette smoke & aerosol spray
Prognosis: Anti-inflammatories & bronchodilators alleviate acute
CSx; Recurrence of CSx
Foreign bodies?
FOREIGN BODIES
Incidence: Accidental; Laryngeal paralysis; Dental procedures
CSx: Acute/chronic cough; Cyanosis; Recurrent airway infection
that partially responds to abx therapy
Dx: Radiography; Bronchoscopy
A bacterial culture may be taken to diagnose any bacterial
contamination
Tx: Removal
Incidences of pulmonary abscess/bronchiectasis → Lung lobectomy
& long-term abx
Neoplasia?
NEOPLASIA
CSx: Cough; Obstructive breathing pattern (loud respiratory
sounds); Haemoptysis
Auscultation: Harsh wheezing noises
Dx: Radiography → Solitary mass
Tx: See “pulmonary neoplasia” later
Pneumonia in general?
PNEUMONIA IN GENERAL
Types based on Anatomy
§ Bronchopneumonia
§ Pneumonia
§ Interstitial pneumonia
§ Lobar
§ Diffuse
Types based on Origin
§ Infectious: Bacterial; Viral; Fungal; Parasitic
§ Non-infectious: Aspiration; Idiopathic
Types based on Duration
§ Acute
§ Subacute
§ Chronic
Bacterial pneumonia?
BACTERIAL PNEUMONIA
E. coli; Bordetella spp.; Klebsiella spp.; Pasteurella spp.;
Pseudomonas spp.; Mycoplasma spp.
Common complication of:
§ Laryngeal dysfunction
§ Viral pneumonia
§ Aspiration pneumonia
§ GI disease
§ Encephalopathy
Protection mechanisms: Laryngeal function; Coughing reflex;
Mucociliary clearance; Epithelial barrier; IgA; Alveolar
macrophages; IgG
CSx: Lethargy; Fever; Dyspnoea; Coughing; Exercise intolerance;
Nasal discharge; Haemoptysis
Acute/chronic
↑Lung sounds, crackles & wheezes
Dx
§ Haematology:↑WBC
§ Radiography: Focal or diffuse alveolar pattern;
Bronchiectasis; Megaoesophagus; Mass
§ Bronchoscopy: Mass; Foreign body; Broncho-oesophageal
fistula; Lobar pneumonia
§ BAL/TTL
Tx: Abx; Bronchodilators; Lobectomy; Saline nebulisation; Tx of
underlying disease
Viral bronchopneumonia?
VIRAL BRONCHOPNEUMONIA
Distemper virus; Morbillivirus (paramyoxviridae family)
CSx: Mucopurulent oculonasal discharge; Fever; Lethargy; CNS
symptoms
Dx: Radiography – Interstitial/alveolar pattern
Tx: Supportive (Abx; Bronchodilators; IVFT); Seizure control
(if necessary); Antibodies
Prevention: Vaccination
Fungal Pneumonia?
FUNGAL PNEUMONIA
Histoplasma capsulatum; Blastomyces dermatitidis; Coccidioides
immitis; Cryptococcus neoformans; Aspergillus fumigatus;
Pneumocystis carinii
Dx
§ BAL; FNA of lung → Cytology; Microbiology; PCR
§ Bloods → Serology
Tx
§ Itraconazole
§ Pneumocystis cases: Trimethoprim + sulfamethoxazole
Aspiration pneumonia?
ASPIRATION PNEUMONIA
Aspiration of fluid, food or gastric contents; Results in pulmonary inflammation
Disposition
§ Megaoesophagus
§ Laryngeal & pharyngeal dysfunction: Neuromuscular
disease; Anaesthesia; Encephalopathy; Brachycephalic airway
conformation; Forced feeding
Factors affecting the severity of lung injury
§ Volume; pH; Toxicity
§ Obstruction
§ Pulmonary haemorrhage
§ Oedema
§ Inflammation
§ Necrosis
§ Bronchoconstriction
§ Infection (see bacterial pneumonia earlier)
CSx: Cough; Tachypnoea; Acute respiratory distress syndrome
(ARDS); Fever; Lethargy; Shock
Cats only: Wheezing (bronchospasm)
Dx
§ History of vomiting/regurgitation
§ Radiography: Interstitio-alveolar pattern in cranioventral
& middle lung lobes
§ CBC: Leucocytosis
§ Bronchoscopy: BAL for culture; Cytology
Tx
Respiratory distress
Oxygen therapy; IVFT; Removal of content
Antibiotics: Culture & sensitivity; After fever/radiographic
lesions
Saline inhalation
Glucocorticoids are CONTRAINDICATED
Prognosis: Dependent on the severity of lung injury & and
underlying conditions
Eosinophillic bronchopneumopathy
EOSINOPHILIC BRONCHOPNEUMOPATHY
Inflammatory disease with unknown aetiology
Observed in all breeds, but especially in Huskies
History: Coughing; Gagging; Dyspnoea; Nasal discharge; Lethargy;
Anorexia
CSx: Nasal discharge; Crackling;↑Lung sounds
Dx
It is important to rule out outher causes before jumping to this
conclusion – Pathogens; Allergic causes
Radiography: Diffuse interstitial pattern; Alveolar pattern;
Bronchial pattern or a combination of these; Nodules;
Mass-like lesions
Bronchoscopy: Green; Green-yellow mucus; Mucosal
thickening; BAL; Mucosa brushing shows a large number
of eosinophils
Tx: Glucocorticoids (at immunosuppressive dosage) coure for weeks
to months
Prognosis: Generally good
Pulmonary oedema?
Smoke inhalation?
SMOKE INHALATION
Direct injury: Heat; Particulate matter; Toxic gases
Aetiology
§ Acute phase (0-36 hours): Oedema & tissue hypoxia
§ Carbon monoxide inhibits oxygen binding to Hb → Tissue hypoxia
§ Later phase (2-4 days): Tracheobronchitis; Pneumonia
CSx: Singed hair; Smell of smoke; Upper airway stridor; Ocular & nasal discharge; Cyanosis
Dx
History; CSx; BAL
Radiography: Oedema & pneumonia
Carboxyhaemoglobin can’t be distinguished from oxyhaemoglobin by
blood gas nor pulse oximetry.
Tx
Observation for at least 48 hrs
§ Tracheostomy: Severe laryngeal oedema or obstruction
§ Oxygen cage
§ Bronchodilators; Abx
§ IVFT: But be aware that this may affect any oedema
§ Analgesia
§ Glucocorticoids
Prognosis: Poor in cases of severe respiratory distress, infectious
pneumonia, neurological signs or cutaneous burns.
Acute respiratory distress syndrome (ARDS)?
ACUTE RESPIRATORY DISTRESS SYNDROME (ARDS)
Acute hypoxemic respiratory failure caused by lung injury &↑
pulmonary capillary permeability
Secondary to: Sepsis; Pancreatitis; Aspiration; Shock; Microbial
pneumonia
Pathogenesis (poorly understood)
§ Early phase: Proteinaceous fluid
§ Later phase: ↑Inflammatory cells, hyaline membrane
formation & fibrosis → Pulmonary hypertension
CSx: Anxiety; Tachycardia; Cyanosis; Crackles; Wheezes
Dx
§ Non-cardiogenic lung oedema → Auscultation;
Radiography; Echocardiography
§ Protein (oedema) / Protein (plasma): 80-90%; or in
cardiogenic oedema: 50%
Tx: Oxygen therapy; IVFT; Furosemide; Glucocorticoids
Blood gas analysis may be used to assist with the desired tx
Prognosis: Poor
Pulmonary fibrosis?
PULMONARY FIBROSIS
Interstitial lung disease
Susceptible breeds: White West highland terrier; Staffordshire bull
terrier; (Cats)
CSx
§ Dog: Chronic & progressive pulmonary signs
§ Cat: Rare; Dyspnoea; Exercise intolerance; Cough;
cyanosis; crackles
Dx
§ Radiography: Diffuse interstitial pattern
§ Echocardiography: Pulmonary hypertension
§ Biopsy
Tx: Ø Effective treatment; Cough suppressants; Glucocorticoids;
Bronchodilators
Prognosis: Poor
Lung lobe torsion?
LUNG LOBE TORSION
Susceptible breeds: Large, deep-chested dogs; Afghan greyhounds
Consequences: Torsion → Venous congestion → Exudation;
Necrosis; Anaemia
CSx: Respiratory distress; Tachypnoea; Cough; Hypotension;
Dyspnoea; Fever; Lethargy
Dx: Radiography; Bronchoscopy; CT; Surgical exploration
Pleural effusion is expected to be seen in these cases
Tx: Fluid drainage; Oxygen tx; IVFT; Shock therapy; Surgery
Pulmonary thromboembolism?
PULMONARY THROMBOEMBOLISM (PTE)
Middle-aged/older animals
Secondary to: Heartworm; IMHA (immune-mediated haemolytic
anaemia) ; Neoplasia; DIC; Cushing’s; PLE (protein-losing
enteropathy) ; PL-nephropathy
Consequences: Abnormal gas exchange; Pulmonary infarction
CSx: Acute respiratory distress; Tachypnoea; Cyanosis
Dx: Pulmonary angiography (gold standard); D-dimer;
Antithrombin-III; Blood gas analysis; Radiography;
Echocardiography (potential lesions in the pulmonary artery)
Tx: Thrombolytic therapy (Surgery; catheter; drugs: Tissue
plasminogen activator); Tx of any underlying disease
Pulmonary Neoplasia?
PULMONARY NEOPLASIA
Metastatic > Primary (Carcinoma; Osteosarcoma)
Physical exam: Try to locate the origin of metastasis; Auscultation;
Percussion
CSx: Chronic cough; Exercise intolerance; Respiratory distress;
Dyspnoea; Weight loss; Anorexia
Dx: Radiography (The key tool for diagnosis)
§ False negative result may be caused by: Size; Obscuring
by viscera; Periosteal proliferation
§ False positive result may be caused by: Eosinophilic
Broncho-pneumopathy
§ Definitive Dx: Biopsy/Fine-needle aspiration
Tx
Primary pulmonary neoplasia → Lobectomy
Metastatic neoplasia → Tx may vary on case-by-case basis
