4.3 Coughing Dog & Cat

what does cough indicate?

-quick, forceful expiration against closed glottis
-response to mechanical/
chemical irritation of larynx, pharynx, trachea, or airways-> can indicate disease in a variety of respiratory tract locations
-productive vs non-productive
-acute (sudden onset) vs chronic (more than 6 weeks)
-when to investigate depends on history, chronicity, & severity

major differentials for acute cough

allergic/inflammatory:
pharyngitis/laryngitis (irritants i.e. smoke, dust chemicals)

infectious:
CIRDC (dog)

distemper (dog)

lungworm
-A. vasorum, C. vulpis, F. osleri (dog)
-Aelurostrongylus abstrussus (cat)

heartworm (D. ommitus)

pneumocystis (dog)

herpes 1, cowpox, virulent calici (cat)

toxoplasmosis (cat)

miscellaneous:
aspiration pneumonia (d>c), might have bacterial component

tracheal/bronchial foreign body

non-cardiogenic pulmonary edema

airway trauma/iatrogenic

major differentials for chronic cough

allergic/inflammatory: feline lower airway disease (asthma, bronchitis)

eosinophilic bronchopneumopathy (dog)

chronic bronchitis (dog)

laryngitis/
pharyngitis

infectious: chronic/recurrent aspiration, possibly with bacterial component

lungworm
-A. vasorum, C. vulpis, F. osleri (dog)
-Aelurostrongylus abstrussus (cat)

fungal
-blastomycosis, histoplasmosis, coccidiomycosis, aspergillosis, pythiosis (dog, non-UK)

mycobacteria (C>D)

degenerative:
tracheal collapse (dog)

bronchiectasis (dog), secondary to other pathology

pulmonary fibrosis (dog)

neoplastic:
primary airway or lung tumors

metastasis

miscellaneous:
tracheal/bronchial foreign body

ciliary dyskinesia

cardiovascular:
left-sided heart failure (dog)

left atrial enlargement (dog)

cough rare in cats with CHF

signalment & history

signalment: infectious cause in young animals vs neoplastic/
degenerative in older animals

history: chronicity, acute vs chronic onset, nature of coughing, inciting event or management change, vaccination & anti-parasite treatment, contact with other animals, travel history, risks for aspiration ex. recent regurgitation, vomiting, swimming, laryngeal dysfunction

breed predispositions (image)

general physical exam

often stable, but may require gentle handling & stabilization

mucous membranes: cyanosis, pallor, ecchymoses

mass lesions

lymphadenomegaly

body weight & condition

body temp

hands-off respiratory exam

respiratory rate

effort (inspiratory vs expiratory, abdominal)

noise

orthopnea

hands-on cardiorespiratory exam

auscultate all lung areas & heart

wheezes- partial airway obstruction

crackles- alveolar disease, ex: pulmonary edema, fibrosis, & pneumonia

auscultate upper airway (referred sounds)

heart rate & rhythm

murmurs- location, intensity

investigative techniques: hematology & biochemistry

do not perform investigations in well CIRD cases

hematology & biochemistry: prior to GA, bronchoscopy, airway sampling etc.

possible findings: inflammatory leukogram, eosinophilia (allergic/asthma, parasitic, EBP), erythrocytosis, biochem often unremarkable

coagulation times: A. vasorum

investigative techniques: idexx angio detect ELISA

rapidly detects angiostrongylus vasorum adult worm antigen

sensitivity 95.7%, specificity 94%

may allow earlier detection than other methods

disadvantages: false negatives (first 3-6 weeks of exposure), false positives (treated or naturally cleared infections-antigen detectable for 3-9 weeks after), does not detect all canine lungworm species or feline lungworm

investigative techniques: Baermann's fecal sedimentation

detects all lungworm types

best for feline lungworm detection

use pooled sample

negative in pre-patent period

consider microscopic fecal smear examination-> sensitivity 54%, specificity 95%, also detects larvae of other lungworms

investigative techniques: distinguish cardiovascular vs respiratory

physical exam: sinus arrythmia or normal, regular heart rate excludes CHF, intensity of murmur (louder associated with CHF)

radiographic findings

NT-proBNP: N-terminal pro b-type natriuretic peptide, differentiation of CHF & pulmonary disease

echocardiography: left atrial enlargement, contractility, structural disease, identification of pulmonary hypertension

other miscellaneous tests

-blood gas analysis
-TFAST
-feline infectious rhinitis/
rhinotracheitis testing
-heartworm (D. immitis) antigen or antibody testing (adult worm antigen test, antibody detection in cat)

investigative techniques: radiography & computed tomography

radiography: widely available, radiographic lung pattern & distribution, helps refine differentials & target focal abnormalities for sampling

computed tomography: greater detail than radiography, better identification of focal abnormalities, surgical planning, less widely available

investigative techniques: fluoroscopy & bronchoscopy

fluoroscopy: referral procedure, performed conscious, real time evaluation of breathing & food ingestion, investigation of esophageal function in aspiration pneumonia or tracheal collapse

bronchoscopy: foreign body retrieval, airway examination, sampling, consider patient size & stability (cats)

investigative techniques: lower airway anatomy

right caudal-> inhaled FB

ventral, left cranial, right middle-> aspiration pneumonia

tracheal rings incomplete dorsally

investigative techniques: airway sampling

transtracheal wash, endotracheal wash or "blind" BAL, bronchoscopy-guided BAL, cytology brush samples, US guided FNA (airway biopsy)

samples submitted for cytology, bacterial C&S, PCR for infectious agents (histology or electron microscopy)

canine chronic bronchitis: etiology, clinical history, & physical exam

etiology: minimum 2 months, chronic inflammatory airway disease of unknown exciting cause

clinical history: middle-aged/older small breed, possible concurrent tracheal collapse, bronchiectasis, mitral valve disease, pulmonary hypertension, overweight/obese, paroxysmal, usually unproductive cough, exacerbated by excitement/
exercise/change in environmental temperature

physical exam: otherwise well, overweight, mild tachypnea, wheezes, murmur & location, sinus arrhythmia

canine chronic bronchitis: starting investigations & echocardiography

investigations: CBC, biochemistry, angiostrongylus/
heartworm testing

echocardiography: murmurs common, identification of pulmonary hypertension (may require treating)

canine chronic bronchitis: deeper investigations

diagnosis of exclusion

thoracic radiographs (or CT): bronchial pattern, bronchiectasis, other cardiopulmonary diseases

fluoroscopy: dynamic airway collapse

bronchoscopy: non-specific, erythema, irregular mucosa surface, mucous, bronchiectasis, bronchomalacia

BAL cytology: non-degenerate neutrophils with increased mucous, mild hemorrhage

bacterial culture & mycoplasma PCR

canine chronic bronchitis: management

set client expectations (no cure), remove airborne irritants & triggers, weight loss, harness, avoid infection risks

anti-inflammatories: 1-2mg/kg/day SID, taper to lowest effective dose, usually moderate to good initial response seen, inhaled fluticasone

bronchodilation: theophylline

pulmonary hypertension: sildenafil

antibiotics: confirmed/highly suspected infection

cough suppressants: butorphanol, codeine, or hydrocodone

progressive, chronic=> therapy likely to require alteration over time

tracheal collapse: history, clinical signs, & physical exam

history & clinical signs: toy breeds (chihuahuas, yorkies), honking, "quaking" cough, may progress to dyspnea or collapse episodes

physical exam: generally normal, characteristic cough on tracheal pinch, deformed tracheal cartilages might be palpable

tracheal collapse: diagnosis

-collapse often dynamic so might not be captured on radiographs
-fluoroscopy more effective
-tracheoscopy
-severity can be graded

tracheal collapse: treatment

similar to chronic bronchitis, esp. cough suppressants, avoiding triggers, & harness walking

surgical options: extraluminal rings for cervical collapse, intraluminal stents, reserved for severely-affected cases

eosinophilic bronchopneumopathy: etiology, clinical signs, & signalment

etiology: infiltration of bronchial mucosa and/or pulmonary parenchyma with eosinophils, cause unknown in almost all cases, better termed "idiopathic" EBP

clinical signs: coughing, gagging, retching, decreaed exercise tolerance, wide spectrum of severity, up to 50% have concurrent nasal discharge

signalment: female young adult dogs, huskies, malamutes, akitas, & dachshunds?, reported in many breeds, systemic hypereosinophilic syndrome in Rottweilers

eosinophilic bronchopneumopathy: diagnosis

consistent clinical signs & signalment

hematology: up to 50% have peripheral eosinophilia

exclusion of other causes of eosinophilia: angiostrongylus antigen test, fecal float & baermann;s, heartworm antigen if endemic region

airway sampling required for definitive diagnosis

blind BAL, bronchoscopy guided (examine respiratory mucosa, visualize sampling area, cytology-brush samples), cytology BAL fluid +/- cytobrush, bacterial culture of BAL

BAL findings

increased cellularity, increased eosinophil count BUT often not predominant cell type, increased neutrophil count, mucous

exclude parasite disease & bacterial pneumonia prior to EBP treatment

eosinophilic bronchopneumopathy: management

glucocorticoid therapy: prednisolone, tapered over several months, consider second immunosuppressive if necessary

inhaler therapy: fluticasone, likely best introduced shortly after starting oral prednisolone, long-term maintenance treatment if requiring on-going medication

eosinophilic bronchopneumopathy: prognosis

response to glucocorticoids generally good

monitoring response to therapy: peripheral eosinophilia, clinical signs

relapse possible: consider inhaler, low-dose prednisolone, second immunosuppressive

inhaler/2nd agent useful if severe steroid side-effects

lungworm: predilection & clinical signs

most common in dogs, A. vasorum most prevalent

clinical signs: cough, tachypnea, dyspnea, hemoptysis, generalized coagulopathy (A. vasorum)

lungworm: diagnosis

bloodwork, previous lungworm identification methods

thoracic radiography: peripheral alveolar pattern, bronchial & nodular-interstitial

larvae in BAL/TT wash samples, but ideally diagnose non-invasively

tracheal nodules (filaroides)

lungworm: treatment & prevention

treatment:
-7 day course oral fenbendazole (unlicensed)
-oral milbemycin (once weekly for 4 weeks)
-some spot-on moxidectin products
-anti-inflammatory steroids in severe cases
-supportive care

prevention:
-oral/spot-on moxidectin or oral milbemycin

feline asthma (and chronic bronchitis): etiology & clinical presentation

etiology: allergic, type 1 hypersensitivity to inhaled aeroallergens, findings overlap with other diseases, esp. chronic bronchitis, most common cause of chronic cough in cats

clinical presentation: young, siamese, asthmatic crisis-> tachypnea, open-mouth breathing, orthopnea, expiratory "push", longer term history of a cough, chronic
-> coughing, hacking, poss. vomiting?

feline asthma (and chronic bronchitis): physical exam findings

tachypnea, positive tracheal pinch, expiratory wheeze, can be remarkable

feline asthma (and chronic bronchitis): acute medical therapy

bronchodilation: inhaled albuterol/
salbutamol or terbutaline SQ/IM, epinephrine/
adrenaline IM (not widely-used, suggested in agonal situations, not with other B2 agonists)

anti-inflammatory: dexamethasone

feline asthma (and chronic bronchitis): laboratory work & thoracic radiographs

laboratory work: peripheral eosinophilia (17-40% of cases), baermann's to rule out aelurostrongylus abstrusus, fecal float, heartworm testing

thoracic radiographs: broncho/
bronchointerstitial pattern, hyperlucency, lung lobe collapse (right middle), pneumothorax, normal in approx. 25%, CT more sensitive

feline asthma (and chronic bronchitis): bronchoscopy & BAL

bronchoscopy: consider whether safe, pre-treat with terbutaline, mucous accumulation, hyperemia, epithelial irregularities, airway collapse, bronchiectasis, non-specific

BAL: blind or bronchoscopy-guided, asthma-> eosinophilic & neutrophilic, chronic bronchitis-> non-degenerate neutrophilic, can be overlap, bacterial culture, mycoplasma culture or PCR

feline asthma (and chronic bronchitis): management

oral glucocorticoids: prednisolone, side-effects, unsuitable for some patients

inhaled glucocorticoids: fluticasone, using spacer, prednisolone for at least 10-14 days, esp. if moderate to severe signs

allergen avoidance & weight management

bronchodilators: not as monotherapy, inhaled salbutamol during crises, theophylline

clinical signs: waxing & waning, correspond poorly with severity of inflammation

repeated BAL cytology? invasive, costly