Respiratory System Disorders Flashcards
DDX for serous nasal discharge
- normal
- viral infection
- early sign of etiology of mucopurulent discharge
DDX for mucopurulent (+/- hemorrhage) nasal discharge
- viral infection; Feline herpesvirus/calicivirus, canine influenza virus
- bacterial infection (usually secondary), Mycoplasma felis (possibly primary)
- fungal infection; aspergillus, cryptococcus, penicillium, rhinosporidium
- nasal parasites; Capillaria (Eucoleus), Pneumonyssoides
- FB
- Neoplasia; malignant Lymphoma, Carcinoma, Sarcoma
- Nasopharyngeal polyp
- Extension of oral disease; tooth root abscess, oronasal fistula, deformed palate
- Allergic rhinitis
- Feline chronic rhinosinusitis
- canine chronic/lymphoplasmacytic rhinitis
DDX for epistaxis (pure hemorrage)
- Nasal disease; acute trauma/FB, neoplasia, fungal infection
- Systemic disease;
- clotting disorders; thrombocytopenia/pathy, coagulation defect
- vasculitis
- hyperviscosity syndrome
- polycythemia
- systemic hypertension
depigmentation and ulceration of the nasal planum in dogs is highly suggestive of what?
nasal aspergillosis
what non-invasive tests can investigate infectious causes of canine chronic nasal discharge?
- Aspergillus titre
- Capillaria/Eucoleus fecael float
- tick-borne diseases (Ehrlichia spp., Rocky mountain spotted fever)
what non-invasive tests can investigate infectious causes of feline chronic nasal discharge?
- nasal swab; cryptococcosis (+cryptococcal antigen titre)
- viral testing; feline leukemia virus, FIV, Herpes, calicivirus
- Mycoplasma felis PCR/culture
define ‘reverse sneezing’
A paroxysm of noisy, laboured inspiration that can be initiated by nasopharyngeal irritation (result of FB dorsal to the soft palate, or nasopharyngeal inflammation (drinking/excitement).
A key historic feature is that dogs return to normal breathing and attitude as soon as the event is over.
Define stertor
refers to coarse, audible snoring or snorting sounds associated with breathing. it indicated upper airway obstruction. Most often the result of pharyngeal disease.
list intranasal causes of stertor
intranasal obstruction; congenital deformities, masses, exudate, blood clots
what are the most common causes of facial deformity in cats and dogs
- carnassial tooth root abscesses in dogs, then neoplasia
- dental disease, neoplasia and cryptococcosis in cats
radiographic signs of feline chronic rhinosinusitis
- soft tissue opacity within nasal cavity, possibly asymmetric
- mild turbinate lysis
- soft tissue opacity in frontal sinus(es)
radiographic signs of nasopharyngeal polyp
- soft tissue opacity above soft palate/ within nasal cavity (usually unilateral)
- mild turbinate lysis (possible)
- bulla osteitis; soft tissue opacity within the bulla, thickening of bone
radiographic signs of nasal neoplasia
- soft tissue opacity, possibly asymmetric
- turbinate destruction
- vomer bone and/or facial bone destruction
- soft tissue mass external to facial bones
radiographic signs of nasal aspergillosis
- well-defined lucent areas within the nasal cavity
- increased radiolucency rostrally
- increased soft tissue opacity possibly also present
- no destruction of vomer or facial bones, although signs often bilateral
- vomer bone sometimes roughened
- fluid density within the frontal sinus; frontal bones sometimes thickened or moth-eaten
radiographic signs of cryptococcosis
- soft tissue opacity, possibly asymmetric
- turbinate lysis
- facial bone destruction
- soft tissue mass external to facial bones
radiographic signs of canine chronic/lymphoplasmacytic rhinitis
- soft tissue opacity
- lysis of nasal turbinates, esp. rostrally
radiographic signs of allergic rhinitis
- increased soft tissue opacity
- mild turbinate lysis possible
radiographic signs of tooth root abscesses
- radiolucency adjacent to tooth roots, commonly apically
radiographic signs of foreign bodies
- mineral and metallic dense foreign bodies readily identified
- plant foreign bodies; focal, ill-defined, increased soft tissue opacity
- lucent rim around abnormal tissue (rare)
what size scope allows rhinoscopy in most patients?
2-3mm, rigid fiberoptic endoscope provides good visualisation through the external nares in most patients
DDX for rhinoscopic abnormality: Mass
- neoplasia
- nasopharyngeal polyp
- cryptococcosis
- mat of fungal hyphae or fungal granuloma (aspergillosis, penicilliosis, rhinosporidiosis)
DDX for rhinoscopic abnormality: Turbinate erosion
- Mild; Feline herpesvirus, Chronic inflammatory process
- Marked: Aspergillosis, Neoplasia, Cryptococcosis, Penicilliosis
DDX for rhinoscopic abnormality: fungal plaques
- aspergillosis
- penicilliosis
DDX for rhinoscopic abnormality: Parasites
- mites: Pneumonyssoides caninum
- worms; Capillaria (Eucoleus) boehmi
why is histopathologic examination preferred over cytologic in most nasal disease cases?
the marked inflammation that accompanies many nasal diseases makes it difficult to cytologically differentiate primary from secondary inflammation and reactive from neoplastic epithelial cells
- eg. carcinomas can appear like lymphoma and vice versa
what are nasal swabs useful for?
identifying cryptococcal organisms
- otherwise their findings are generally nonspecific
outline the technique for nasal pinch biopsie
- alligator cup biopsy forceps (min. size 2 x 3mm) are used
- when possible, adjacent to a rigid endoscope to allow visualisation
- no forceps should ever be passed into the nasal cavity deeper than the level of the medial canthus of the eye without visual guidance to keep from penetrating the cribriform plate
- min. of 6 tissue specimens/lesion, and if no lesion 6-10 random specimens from each side
outline the advantages of turbinectomy for nasal disease cases
- provides the best tissue specimens for histologic examination if diagnosis not made off biopsies
- allows clinician to remove abnormal or poorly vascularised tissues, debulk fungal granulomas and place drains for subsequent topical nasal therapy
outline the complications associated with nasal biopsies and how to manage them
- hemorrhage; packing the nasal cavity, cold saline solution with/without diluted epinephrine (1:100000), in rare events of uncontrolled haemorrhage ligation of the carotid artery
- trauma to the brain; mark the instrument with tape to not advance passed the medial canthus of the eye
- aspiration of blood/saline solution/exudate; cuffed ETT inflated, packed nasopharynx
which viruses are associated with feline upper respiratory infections?
- FHV (feline herpes virus/ feline rhinotracheitis virus)
- FCV (feline calicivirus)
which bacterias are associated with feline upper respiratory infections?
- Bordetella bronchiseptica
- Chlamydia felis (previously Chlamydia psittaci)
+ Mycoplasmas (M.felis) primary/secondary
clinical features of FHV
- corneal ulceration
- abortion
- neonatal death
clinical features of FCV
- oral ulcerations
- polyarthritis
- interstitial pneumonia
- systemic vasculitis (facial and limb oedema, focal necrosis) (rare - severe)
CS associated with acute feline URI
- fever
- sneezing
- serous/mucopurulent nasal discharge
- conjunctivitis and ocular discharge
- hypersalivation
- anorexia
- dehydration
how can chronic nasal discharge result from feline URI
- persistence of an active viral infection
- irreversible damage to turbinates and mucosa by FHV (predisposes cat to an exaggerated response to irritants and secondary bacterial rhinitis)
diagnosis of feline URI
- PCR, virus isolation, bacterial cultures of FHV, FCV, Bordetella, Mycoplasma, Chlamydophila on various samples (swabs/tissue specimen/mucosal scraping)
treatment of feline URI
- mucus clearing + steam vaporisation
- topical decongestants (0.25% phenylephrine or 0.025% oxymetazoline 1 drop/nostril for 3 days)
- ABs for 10 days if fever, anorexia, lethargy present (Doxycycline - efficacy against Chlamydia and Mycoplasma, or Amoxicillin)
- Famcyclovir for cats with FHV
treatment of Chlamydophila infection in cats
Oral ABs for minimum of 42 days (Doxycycline) + Chloramphenicol or tetracycline ophthalmic ointment should be applied at least three times daily and continued for 14 days after signs have resolved
treatment of FHV corneal ulcers
- topical antiviral drugs; trifluridine, idoxuridine, adenine arabinoside (1drop OU 5-6x daily for 2-3wks)
- tetracycline or chloramphenicol ophthalmic ointment q4-6h
- topical atropine for mydriasis as needed to control pain
- treatment is continued for 1-2wks
prevention of feline URI in individual cats
- avoiding exposure to infectious agents (eg. FHV, FCV, Bordetella, Mycoplasma, Chlamydophila)
- SQ modified live vaccines for FHV and FCV available in combo with panleukopenia (vax @ 6-10wks old, then again in 3-4wks, final @ 16wks old, booster at 1yo, then booster q3yrs)
feline vaccination protocol to help prevent URI
SQ modified-live vaccines for FHV, FCV + panleukopenia
@6-10wks old, then in 3-4wks, final one at 16wks, then booster at 1yr, then booster q3yrs
adverse effects of SQ mod-live FHV and FCV vaccines
can cause disease if introduced by the normal oronasal route
- vaccine should not be aerosolized in front of the cat
- any vaccine on skin should be washed off immediately
when are vaccines against Bordetella and Chlamydophila recommended for cats?
in shelters or catteries where these infections are endemic
list the organisms commonly involved in bacterial rhinitis
- rarely occurs as primary disease process but can be caused by Mycoplasma spp., Streptococcus equi subsp. zooepidemicus, Bordetella bronchiseptica
- commonly a secondary complication
treatment of feline bacterial rhinitis
- according to culture and sensitivity if significant growth obtained otherwise
broad spectrum ABs - amoxicillin 22mg/kg q8-12h
- Clindamycin 10mg/kg q12h
- doxycycline 10mg/kg q12h w/ water to follow
chronic infections require prolonged treatment; initial 7-10days if response seen continue for 4-6weeks
name two common nasal mycoses
- Cryptococcosis neoformans
- Aspergillosis fumigatus
clinical features of aspergillosis
- most common in young, male dogs
- mucoid, mucopurulent +/- haemorrhagic discharge
- sensitivity to palpation of the face
- depigmentation and ulceration of the external nares
*lung involvement is not expected
which organism generally causes systemic aspergillosis?
Aspergillus terreus
outline the diagnosis of aspergillosis
- no single test
- aspergillosis can be an opportunistic infection so must rule out underlying nasal disease
- radiographic signs; well-defined lucent areas within the nasal cavity with increased radiolucency rostrally, typically no destruction of the vomer or facial bones, fluid opacity in frontal sinus
- CT is preferred over radiographs
- rhinoscopy; erosion of nasal turbinates and fungal plaques (white-green plaques of mold)
- cytology and culture of plaques
- multiple biopsies
- positive serum antibody titres
what did the Pomerantz et al. 2007 study find in relation to Aspergillus serum antibody titres?
- serum antibodies had a sensitivity of 67%, specificity of 98%, positive predictive value 98%, negative predictive value 84% for the diagnosis of nasal aspergillosis
outline the treatment of aspergillosis
- topical treatment for nasal; aggressive debridement of fungal plaques + clotrimazole infusion
- oral itraconazole/posaconazole for patients with extension of disease beyond the nasal cavity and frontal sinuses
+/- terbafine - prolonged treatment ave. 9months (range 6-18months)
discuss the treatment success rates found by Sharman et al. 2010 when treating nasal aspergillosis
- success rate following single topical clotrimazole/enilconazole 46%
- with aggressive debridement 70%
outline two potential complications of topical clotrimazole treatment of nasal aspergillosis
- aspiration pneumonia
- meningoencephalitis; a risk when clotrimazole, polyethylene glycol carrier +/- organisms/debris make contact with the brain through a compromised cribriform plate
describe nasal mites
Pneumonyssoides caninum is a small, white mite approximately 1mm in size
- most infestations are clinically silent but some dogs have moderate to severe CS
clinical features of nasal mites
- sneezing (violent), head shaking, pawing at the nose, reverse sneezing, chronic nasal discharge, epistaxis
diagnosis of Pneumonyssoides caninum
- visualisation of mites via rhinoscopy or retrograde nasal flushing
** mites can be easily overlooks in retrieved saline solution - should be specifically searched for with slight magnification or by placing dark material behind the specimen for contrast
treatment of nasal mites
- Milbemycin oxime 0.5-1mg/kg PO q7-10d for 3 treatments
- Selemectin topical over shoulders q2wks for 3 treatments
- Ivermectin SQ q3wks x 2 doses (not safe for collies)
what is nasal capillariasis?
Nasal capillariasis is caused by a nematode (Capillaria (Eucoleus) boehmi)
- adult worm is small, thin, white and lives on the mucosa of the nasal cavity and frontal sinuses of dogs
- adults shed eggs that are swallowed and pass in the faeces
how do you diagnose nasal capillariasis?
- identify double operculated Capillaria (Eucoleus) eggs on routine faecal flotation or visualizing adultery worms during rhinoscopy
treatment of nasal capillariasis
ivermectin PO once, or fenbendazole PO BID for 10-14 days
what are feline nasopharyngeal polyps?
- benign growths that occur most often in kittens and young adult cats
- origin unknown but often attached to the base of the eustachian tube and can extend into the external ear canal, middle ear, pharynx, nasal cavity
- they are pink, polypoid growths often arising from a stalk
outline clinical features associated with feline nasopharyngeal polyps
- stertorous breathing
- upper airway obstruction
- serous to mucopurulent nasal discharge
- otitis externa/media/interna; head tilt, nystagmus, Horner’s syndrome
treatment of feline nasopharyngeal polyps
- surgical excision by way of traction via the oral cavity; recurrent if tissue left behind
+ Prednisolone 1-2mg/kg SID 2wks, then half dose for 1 week, then EOD for another week (improved outcomes)
+ amoxicillin course
prognosis of feline nasopharyngeal polyps
- excellent; but treatment of recurrent disease may be necessary
- signs of recurrence typically occur within 1 yr
outline features of canine nasal polyps
- rare
- often locally destructive to turbinates and bone
- aggressive surgical removal is recommended
most common nasal tumours in dogs
- adenocarcinoma
- squamous cell carcinoma
- undifferentiated carcinoma
- fibrosarcoma/sarcoma
most common nasal tumours in cats
- lymphoma
- adenocarcinoma
- fibrosarcoma/sarcoma
list benign nasal tumours
- adenomas
- fibromas
- papillomas
- transmissible venereal tumours (only in dogs)
outline treatment approaches for nasal tumours
- benign tumours (rare) may be treatable with surgical excision alone
- radiation therapy recommended for malignant tumours
- chemotherapy as adjunct for metastasis, or sole with lymphoma. Carcinomas may be responsive to cisplatin, carboplatin, multiagent chemo
- surgical excision alone is not successful for managing malignant nasal tumours
- palliation with radiation, piroxicam, anti-inflam steroids
prognosis for malignant nasal tumours
- poor without treatment; survival after diagnosis is usually only a few months
- euthanasia often request dt persistent epistaxis or discharge, laboured respiration, anorexia, weight loss
- epistaxis is a poor prognostic indicator
what is the median survival time of dogs with untreated nasal carcinoma in 2006 study by Rassnick et al. ?
- 88 days with epistaxis
- 224 days without epistaxis
- overall median survival time was 95 days
what was the median survival time in cats with nasal lymphoma treated with radiation and chemo in 2007 study by Arteaga et al. ?
511 days
explain the etiology of allergic rhinitis
generally considered to be a hypersensitivity response within the nasal cavity and sinuses to airborne antigens,
it is possible that food allergens play a role in some patients
*other antigens parasites, infectious diseases, neoplasia also possible
treatment of allergic rhinitis
- removing the offending allergen
- antihistamines; Chlorpheniramine 4-8mg/dog PO BID, 2mg/cat PO BID (cetirizine may be more successful in cats)
- glucocorticoids if antihistamines are not successful; Pred 0.25mg/kg PO BID - then tapered
- if treatment is effective signs will resolve within 3-4 days
explain the etiology of feline chronic rhinosinusitis
- long been presumed to be a result of viral infection with FHV, FCV; but studies have failed to show an association
- possible than infection with these viruses results in damaged mucosa that is more susceptible to bacterial infection or that mounts an excessive inflammatory response to irritants or normal nasal flora
clinical features of idiopathic feline chronic rhinosinusitis
- chronic mucoid/mucopurulent nasal discharge is the most common CS
- sneezing
- lack of specific findings; no funduscopic lesions, no lymphadenopathy, no facial or palate deformities, healthy teeth and gums
- nasal biopsy; neutrophilic +/- lymphoplasmacytic inflammation, nonspecific chronic inflammatory changes such as epithelial hyperplasia/fibrosis
treatment of feline idiopathic chronic rhinosinusitis
- facilitating drainage of discharge
- decreasing environmental irritants
- controlling secondary bacterial infections
- treating possible Mycoplasma or FHV infection
- reducing inflammation
- last resort; turbinectomy and frontal sinus ablation
outline management considerations of cats with idiopathic chronic rhinosinusitis
- Facilitate Drainage of Discharge
- vaporiser treatments
- topical saline administration
- nasal cavity flushes under anaesthesia
- topical decongestants - Decrease Irritants in the Environment
- Improvement of indoor air quality - Control Secondary Bacterial Infections
- long-term antibiotic treatment - Treat Possible Mycoplasma Infection
- Antibiotic treament - Treat possible Herpes virus Infection
- lysine treatment
- reduce inflammation; antihistamine, Pred, other unproven treatments with possible anti-inflammatory effects (azithromycin, piroxicam, leukotriene inhibitors, omega 3 FAs) - Provide Surgical Intervention
- turbinectomy
- frontal sinus ablation
explain the etiology of idiopathic canine chronic (lymphoplasmacytic) rhinitis
- originally reported to be a steroid responsive disorder
- characterized by inflammatory infiltrates seen in nasal mucosal biopsy specimens
- 2004 Windsor et al. study failed to find role of bacteria, canine adenovirus-2, parainfluenza virus, Chlamydophila, Bartonella spp. in affected dogs (supported by 2008 Hawkins et al. study)
- subsequent study (Henn et al. 2005) find possible association between seropositivity for Bartonella spp. and nasal discharge
outline treatment of idiopathic canine chronic rhinitis
- treated for secondary bacterial rhinitis
- decreased environmental irritants
- immunosuppressive Pred for 2 weeks, then taper to lowest effective amount
CS associated with laryngeal disease
- respiratory distress
- stridor
- gagging/coughing
- voice change
explain the cycle of respiratory distress resulting from laryngeal disease
- due to airway obstruction; often exacerbated by exercise/excitement/high ambient temperatures resulting in markedly increased respiratory efforts
- increased efforts lead to excess negative pressures on the disease larynx, sucking the surrounding soft tissues into the lumen and causing laryngeal inflammation and oedema
describe the characteristic breathing pattern of extrathoracic (upper) airway obstruction
- respiratory rate is normal to only slightly elevated (30-40)
- inspiratory efforts are prolonged and labored relative to expiratory efforts
- larynx tends to be sucked into the airway lumen as a result of neg. pressure within the extrathoracic airways that occurs during inspiration making inhalation
- during expiration, pressures are positive in the extrathoracic airways “pushing” the soft tissues open
- some obstruction to airflow may occur during expiration with fixed obstructions, such as laryngeal masses
- stridor is produced by air turbulence through the narrowed laryngeal opening
clinical signs associated with pharyngeal disease
- stertor
- reverse sneezing
- gagging/retching
- dysphagia
define stertor
- stertor is a loud, coarse sound such as produced by snoring/snorting
- stertor results when excessive soft tissue in the pharynx, such as an elongated soft palate or mass causes turbulent airflow
DDX for Laryngeal diseases in dogs and cats
- laryngeal paralysis
- laryngeal neoplasia
- obstructive laryngitis
- laryngeal collapse
- web formation
- trauma
- foreign body
- extraluminal mass
- acute laryngitis
DDX. for pharyngeal diseases in dogs and cats
- Brachycephalic airway syndrome
- elongated soft palate
- nasopharyngeal polyp
- foreign body
- neoplasia
- abscess
- granuloma
- extraluminal mass
- nasopharyngeal stenosis
when are radiographs useful in evaluating animals with pharyngeal or laryngeal disease
- identifying radiodense foreign bodies
- external compression of airways
- adjacent bony changes
how do you ensure good positioning of a neck radiograph when evaluating the larynx and pharynx
- superimposition of the left and right osseous bullae, mandibles, frontal sinuses
if a patient fails to take deep breaths during laryngoscopy what drug can be used
Doxapram hydrochloride 1mg/kg IV
define laryngeal paralysis
refers to a failure of the arytenoid cartilages to abduct during inspiration, creating extrathoracic (upper) airway obstruction
what nerve innervates the arytenoid abductor muscles?
left and right recurrent laryngeal nerves
list potential causes of laryngeal paralysis
- Ventral cervical lesion; trauma to nerves (direct, inflammation, fibrosis), neoplasia
- Anterior Thoracic Lesion: Neoplasia, trauma (post-op/other), inflammatory mass/lesion
- Polyneuropathy and polymyopathy: Idiopathic, immune-mediated, endocrinopathy (hypothyroidism), other systemic disorder, toxicity, congenital disease - myasthenia gravis
in what breeds has congenital laryngeal paralysis been documented?
Bouvier Des Flandres
Siberian Huskies
Bull Terriers
*Dalmations, Rottweilers, Great Pyrenees
*Labrador Retrievers
CS of laryngeal paralysis
- respiratory distress and stridor
- change in voice
- gagging or coughing; often noted with eating or drinking
what diagnostic tests should be considered when searching for an underlying cause of laryngeal paralysis?
- Thoracic + cervical radiographs
- thyroid hormone evaluation
- serum biochem
- evaluation for polyneuropathy/polymyopathy; electromyography, nerve conduction measurements, antinuclear antibody test, antiacetylcholine receptor antibody test
list treatment options for Laryngeal paralysis
even with underlying associated disease treatment complete resolution of clinical signs is rarely seen
- surgery; arytenoid lateralization (tie-back), partial laryngectomy, castellated laryngoplasty
- medical; Pred 0.5mg/kg q12h to reduce oedema (limited effect), limit exercise, trazodone
in 2016 paper by Wilson et al. what was the survival rate of dogs that underwent unilateral lateralization producedures to treat laryngeal paralysis
232 dogs had survival rates of 94% at 1y, 89% at 2yrs, 84% at 3y, 75% at 4yrs
what is Brachycephalic airway syndrome?
refers to the multiple anatomic abnormalities commonly found in Brachycephalic dogs (and to a lesser extent cats)
- includes stenotic nares, elongated soft palate, hypoplastic trachea, abnormal obstructing nasal turbinates
- prolonged upper airway obstruction can lead to eversion of laryngeal saccules and laryngeal collapse
- concurrent GI signs; ptyalism, regurgitation, vomiting are common
at what age can stenotic nares be safely corrected?
3-4months old; ideally before CS develop
- soft palate can also be evaluated and corrected at this time
define obstructive laryngitis
nonneoplastic infiltration of the larynx with inflammatory cells can occur in dogs and cats, causing irregular proliferation, hyperemia, and swelling of the larynx
- inflammatory infiltrates can be granulomatous, pyogranulomatous, or lymphocytic-plasmacytic
treatment of obstructive laryngitis
- glucocorticoid therapy; Pre 1mg/kg PO BID
+/- conservative excision of tissue obstructing the airway if large masses/severe upper airway obstruction present
neoplasms originating from the larynx are uncommon - what is more likely to be occuring?
tumours originating from adjacent tissues such as thyroid carcinoma and lymphoma
list laryngeal tumours
- carcinoma (squamous cell, undifferentiated, adenocarcinoma)
- lymphoma
- melanoma
- mast cell tumours
- other sarcomas
- benign neoplasia
lower respiratory tract disorders refers to…
diseases of the trachea, bronchi, bronchioles, alveoli, interstitium, and vasculature of the lung
DDx. for disorders of the trachea and bronchi
- Canine infectious respiratory disease complex
- Canine chronic bronchitis
- Tracheobronchomalacia (collapsing trachea and/or bronchi)
- feline bronchitis (idiopathic)
- allergic bronchitis
- bacterial, including Mycoplasma, infections
- Oslerus osleri infection
- Neoplasia
- Foreign body
- tracheal tear
- bronchial compression; LA enlargement, hilar lymphadenopathy, neoplasia
DDx. for infectious disorders of the pulmonary parenchyma and vasculature
- Viral:
- Canine influenza, distemper
- Calicivirus
- Feline infectious peritonitis - Bacterial pneumonia
- Protozoal Pneumonia; Toxoplasmosis
- Fungal pneumonia
- Blastomycosis
- Histoplasmosis
- Coccidioidomycosis - Parasitic
- Heartworm
- Pulmonary parasites; Paragonimus, Aelurostrongylus, Capillaria, Crenosoma
DDx. for disorders of the pulmonary parenchyma and vasculature
- Infections: viral, bacterial, protozoal, fungal, parasitic
- Aspiration pneumonia
- Eosinophilic lung disease
- Idiopathic interstitial pneumonias; Idiopathic pulmonary fibrosis
- Pulmonary neoplasia
- Pulmonary contusions
- Pulmonary hypertension
- Pulmonary thromboembolism
- Pulmonary oedema
define ‘cough’
an explosive release of air from the lungs through the mouth; generally protective reflex to expel material from the airways, although inflammation or compression of the airways can also stimulate a cough
ddx. for productive coughs in dogs and cats
- Oedema
- heart failure
- noncardiogenic pulmonary oedema - Mucus or Exudate
- canine infectious respiratory disease complex
- canine chronic bronchitis
- feline bronchitis (idiopathic)
- allergic bronchitis
- bacterial infection (bronchitis/pneumonia)
- parasitic disease
- aspiration pneumonia
- fungal pneumonia (severe) - Blood (Hemoptysis)
- heartworm disease
- neoplasia
- fungal pneumonia
- thromboembolism
- severe heart failure
- foreign body
- lung lobe torsion
- systemic bleeding disorder
a ‘goose-honk’ cough is associated with…
tracheal collapse
a ‘soft’ cough is associated with
pneumonias and pulmonary oedema
a loud, harsh cough is associated with…
airway inflammation (ie. bronchitis) or large airway collapse
why is time of day important when characterizing a cough?
coughing associated with heart failure tends to occur more at night, whereas coughing caused by bronchitis tends to occur more frequently upon rising from sleep, during/after exercise or exposure to cold air
define wheezes
continuous, high-pitched sounds occur with obstructive laryngeal conditions (laryngeal paralysis, neoplasia, inflammation, foreign bodies) and presence of airway narroowing
- stridor
define crackles
nonmusical, discontinuous noises that sound like paper being crumpled or bubbles popping
what diseases are associated with ‘crackles’
diseases resulting in the formation of oedema, or an Exudate within the airways (eg. pulmonary oedema, infectious or aspiration pneumonia, bronchitis) and some interstitial pneumonias, particularly interstitial fibrosis
what diseases are associated with wheezes
- airway narrowing
- bronchoconstriction, bronchial wall thickening, exudate or fluid within the bronchial lumen, intraluminal masses, or external airway compression
- commonly heard in cats with bronchitis
list techniques for collection of pulmonary specimens that can be performed without specialized equipment
- tracheal wash
- nonbronchoscopic bronchoalveolar lavage
- transthoracic lung aspiration
outline radiographic evaluation of the trachea
- obtain rads during inspiration and expiration to identify dynamic changes in luminal diameter
- only inner wall should be seen; if outer wall visible suggestive of pneumomediastinum
- elevated at the Carina is heart is enlarged/pleural effusion present
- cartilage can become calcified
- normal tracheal lumen is nearly as wide as the laryngeal lumen; tracheal diameter:thoracic inlet diameter can be used
- most foreign bodies lodge at the Carina/within bronchi
what are the four major radiographic lung abnormalities
- vascular
- bronchial
- alveolar
- interstitial
common DDx for cats and dogs with a cough and normal thoracic radiographs
- canine infectious resp. disease complex
- canine chronic bronchitis
- collapsing trachea
- feline bronchitis (idiopathic)
- acute foreign body inhalation
- gastroesophageal reflux
common DDx. for cats/dogs with respiratory distress and normal thoracic rads
- pulmonary thromboembolism
- acute aspiration/pulmonary hemorrhage/foreign body inhalation
ddx. for enlarged arteries on thoracic rads
- heartworm disease
- aelurostrongylosis (cats)
- pulmonary thromboembolism
- pulmonary hypertension
ddx. for enlarged veins on thoracic rads
left-sided heart failure
ddx. for enlarged arteries and veins on thoracic rads
= pulmonary overcirculation
1. left-to-right shunts; PDA, ventricular septal defects, atrial septal defect
ddx. for small veins and arteries on thoracic rads
= pulmonary undercirculation
- Cardiovascular shock
- hypovolemia; severe dehydration, hypoA, blood loss
- pulmonic valve sesnosis
= hyperinflation of the lungs; allergic bronchitis or feline bronchitis (idiopathic)
how are ‘tram lines’ produced on x-ray
thickened bronchial walls causing the appearance of parallel thick lines with an air stripe between when running transverse to the x-ray beam
what do the findings of ‘tram-lines’ or ‘doughnuts’ on thoracic rads indicate
- thickened bronchial walls; presence of bronchitis and results from an accumulation of mucus/exudate along the walls within the lumens, an infiltration of inflammatory cells within the walls, muscular hypertrophy, epithelial hyperplasia, or a combination of these changes
ddx. bronchial patterns on thoracic rads
- canine chronic bronchitis
- feline idiopathic bronchitis
- allergic bronchitis
- canine infectious resp. disease complex
- bacterial infection
- Mycoplasmal infection
- pulmonary parasites
define bronchiectasis
chronic bronchial inflammation can result in irreversible dilation of the airways
- Identified on rads by the presence of widened, nontapering airways
- can be cylindrical (tubular) or saccular (cystic)
how do alveolar patterns occur?
- when the alveoli are filled with a fluid-dense material
- oedema, inflammation, haemorrhage, neoplastic infiltrates
define a lobar sign
when fluid-dense regions are located at the edge of a lung lobe the curvilinear edge of the affected lung lobe is visible in contrast with the adjacent, aerated lobe
ddx. for alveolar patterns on thoracic rads
- Pulmonary Oedema
- Severe inflammatory disease; bacterial, aspiration pneumonia
- Haemorrhage; contusions, PTE, neoplasia, fungal pneumonia, systemic coagulopathy
what types of abnormal interstitial patterns occur
- reticular (unstructured)
- nodular
- reticulonodular
ddx. for nodular interstitial patterns on thoracic rads
- Neoplasia
- Mycotic infection; Blastomycosis, Histoplasmosis, Coccidioidomycosis
- Pulmonary Parasites; Aelueostrongylus infection, Paragonimus infection
- Abscess; bacterial, foreign body
- Eosinophilic lung disease
- Idiopathic interstitial pneumonia
- Inactive lesions
ddx. for reticular (unstructured) interstitial patterns
- Mild pulmonary oedema
- Infection; viral, bacterial mycotic, parasitic, toxoplasmosis
- Neoplasia
- Eosinophilic Lung Disease
- Idiopathic interstitial pneumonia; idiopathic pulmonary fibrosis (westies(
- Mild haemorrhage
ddx. lung lobe consolidation
- severe bacterial/aspiration pneumonia
- neoplasia
- lung lobe torsion
- haemorrhage
what lung lobes most commonly torse?
- right middle
- left cranial
in 2006 study by Nemanic et al. what % of pulmonary nodules detected by CT were identified on thoracic rads?
9%
larvae that may be present in fluid from tracheal or bronchial washings include…
- O.osleri
- Aelurostrongylus abstrusus
- Crenosoma vulpis
eggs that may be present in fluid from tracheal or bronchial washings include…
- Capillaria (Eucoleus) aerophila
- Paragonimus kellicotti
what specimen/stage of Toxoplasma gondii would be found in pulmonary specimens if causing pneumonia?
Tachyzoites
advantages of tracheal wash
- simple technique
- minimal expense
- no special equipment
- complications rare
- volume adequate for cytology and culture
disadvantages of tracheal wash
- airways must be involved for specimen to represent disease
- may induced bronchospasm in patients with hyper-reactive airways, particularly cats
indications for tracheal wash
- bronchial and alveolar disease (particularly bacterial bronchopneumonia and aspiration pneumonia)
- because of safety and ease, consider for any lung disease
- less likely to be representative of interstitial or small focal processes
advantages of BAL
- nonbronchoscopic technique requires no special equipment and minimal expense
- bronchoscopic technique allows airway evaluation and directed sampling
- resultant hypoxemia is transient and responsive to oxygen supplementation
- safe for animals in stable condition
- large volume of lung sampled
- high cytologic quality
- large volume for analysis
disadvantage of BAL
- GA required
- special equipment and expertise for bronchoscopic collection
- generally not recommended for animals with tachypnoea, increased respiratory efforts or resp. distress
- capability to provide oxygen supplementation for an hour or more is required
- may induced bronchospasm in patients with hyper-reactive airways, particularly cats
indications for BAL
- primarily diffuse interstitial disease; also small airway and alveolar disease
- routine during bronchoscopy
lung aspirate advantages
- simple technique
- minimal expense
- no special equipment
- solid masses adjacent to body wall: excellent representation with minimal risk
lung aspirate disadvantages
- potential for complications; pneumonia/hemothorax, pulmonary hemorrhage
- relatively small area of lung sampled
- specimen adequate only for cytology
- specimen blood contaminated
indications for lung aspirate
- solid masses adjacent to chest wall (for solitary/localized disease)
- diffuse interstitial disease
advantages of thoracotomy/thoracoscopy with lung biopsy
- ideal specimen
- allows histologic examination in addition to culture
disadvantages of thoracotomy/scopy with lung biopsy
- relatively expensive
- requires expertise
- requires GA
- major surgical procedure
indications for thoracotomy/scopy with lung biopsy
- localized process where excision may be therapeutic as well as diagnostic
- any progressive disease not diagnosed by less invasive methods
where do you insert the catheter in a transtracheal wash?
cricothyroid ligament (located in depression immediately above the cricoid cartilage)
how far do you insert the catheter when performing a transtracheal wash?
- measure distance along path of tracheal from cricothyroid ligament to 4th intercostal space for approximate distance to Carina and ensure catheter reaches just proximal to this position
outline the aftercare involved in a transtracheal wash
- sterile gauze sponge with antiseptic ointment immediately placed over catheter site and then a light bandage is wrapped around the neck and left in place for several hours while the animal rests quietly in a cage
- to minimize likelihood of SQ emphysema or pneumomediastinum
when size catheter should be used when performing an endotracheal wash?
5F is ideal
what does lymphocytic pulmonary inflammation indicate?
- viral, rickettsial infection
- idiopathic interstitial pneumonia
- lymphoma
overall uncommon finding
how much saline should be infused in a feline NB-BAL?
5ml/kg of body weight = 1 bolus (can rpt 2-3 times)
how much saline should be recovered in a NB-BAL?
50-80% of the total volume of saline instilled is expected to be recovered
- the rest will be absorbed
normal BAL fluid total nucleated cell count
<400-500/uL
what growth of organisms (colony-forming units/mL) has been reported to indicate infection?
1.7 x 10^3 CFUs/mL
BAL findings served as a basis for ? % of definitive diagnoses
25% of cases
what is the site for transthoracic lung aspiration and biopsy in animals with diffuse disease?
caudal lung lobe; 7-9th ICS approximately two thirds of the distance from the costochondral junctions to the spine
described the technique used when performing a transthoracic aspirate
- ID location, prep, lidocaine skin
- 22G 1.5-3.5 inch spinal needle advanced through the skin several rib spaces from desired biopsy site
- then move needle to biopsy site; less likely to cause air tracking through needle tract
- needle advanced through body wall to the pleura - stylet removed and 12ml syringe placed on hub (put finger on in the interim to prevent pneumothorax)
- during inspiration; needle thrust into chest at predetermined depth (rads/US guided) while suction applied to syringe
- needle withdraw with a minimal amount of negative pressure maintained
what an accidental liver biopsies look like when attempting transthoracic lung aspirates?
- may resemble adenocarcinoma
what sites are commonly used to collect arterial blood?
- femoral artery
- dorsal pedal artery
what is normal PaO2mmHg in arterial blood?
85-100
what is normal PaCO2mmHg in arterial blood?
35-45
what is normal HCO2mmol/L in arterial blood?
21-27
what is normal pH in arterial blood?
7.35-7.45
what causes cyanosis?
increased concentration of nonoxygenated hemoglobin in the blood
clinical correlation of decreased PaO2 and increased PaCO2 on arterial blood gas
- Venous specimen
- Hypoventilation
- airwayobstruction
- decreased ventilatory muscle function; anaesthesia, CNS disease, polyneuro/myopathy, myasthenia, extreme fatigue
- restriction of lung expansion; thoracic wall abnormality, pneumothorax, pleural effusion, excessive thoracic bandage
- increased dead space (low alveolar ventilation); severe chronic obstructive pulmonary disease/emphysema - End-stage severe pulmonary parenchymal disease
- Severe pulmonary thromboembolism
clinical correlation of decreased PaO2 and normal/decreased PaCO2 on arterial blood gas
- ventilation/perfusion abnormality = most lower resp. tract diseases
what causes a V/Q of zero
the flow of blood past a totally nonaerated tissue (venous admixture or shunt)
what causes a high V/Q
ventilation of areas of lung with decreased circulation - thromboembolism
what is the A-a gradient in arterial blood gases?
alveolar-arterial oxygen gradient - factors out the effects of ventilation and the inspired oxygen concentration on PaO2
explain the premise of the A-a gradient
the premise of the A-a gradient is that PaO2 (a) is nearly equal (within 10mmHg in room air) to the partial pressure of oxygen in the alveoli, PAO2 (A), in the absence of a diffusion abnormality of V/Q mismatch. In the presence of a diffusion abnormality of V/Q mismatch, the difference widens (greater than 15mmHg in room air). Examination of the equation reveals that hyperventilation, resulting in a lower PaCO2 leads to a higher PAO2. Conversely, hypoventilation, resulting in a higher PaCO2 leads to a lower PAO2.
how can you estimate the quantity of hemoglobin based off a PCV?
PCV divided by 3
what does pulse oximetry measure?
the value measured indicates the saturation of hemoglobin in the local circulation
what factors can affect pulse oximetry values?
- vasoconstriction
- low CO
- local stasis of blood
- anaemia
- hyperbilirubinaemia
- carboxyhemoglobinaemia/methemoglobinaemia
- external lights
- location of the probe
animals with a PaO2 value exceeding 85mmHg will have a hemoglobin saturation greater than what?
95%
If PaO2 values decrease to 60mmHg the hemoglobin saturation will be approx…
90%
what is CIRDC?
Canine Infectious Respiratory Disease Complex
“Kennel Cough”
what viral agents are associated with CIRDC?
- Canine adenovirus 2
- Canine influenza viruses (H3N8, H3N2)
- Canine parainfluenza virus
- Canine Herpes virus - type 1
- Canine respiratory coronavirus
- Canine pneumovirus
what bacterial agents are associated with CIRDC?
- Bordetella bronchiseptica
- Streptococcus equi, subsp. zooepidemicus
- Mycoplasma cynos
- Other mycoplasma spp
how does Bordetella affect host defenses?
Bordetella organisms infect ciliated respiratory epithelium and decrease mucocilliary clearance
what are the major pointers important in client education for CIRDC?
- More than one type of organism is responsible
- It is like colds and flu in people; some never get sick, some get sick frequently, most people recover without treatment others develop pneumonia and can die
- More likely to get sick if frequently exposed to others, being very old/young, immunocompromised, underlying respiratory disease, particularly virulent organisms
- Vaccines are not completely effective, antibiotics are not usually necessary and ineffective against viruses
clinical features of CIRDC
- sudden onset of a severe productive/nonproductive cough which is usually exacerbated by exercise, excitement or pressure of the collar on the neck
- tracheal pinch
- gagging, retching or nasal discharge
- a recent history (<2wks) of boarding, hospitalisation, exposure for a puppy or dog with similar signs
- mostly self-limiting but secondary bacterial pneumonia can develop in puppies, immunocompromised dogs, dogs that have preexisting lung abnormalities (ie. chronic bronchitis)
how long can positive PCR results be obtained for dogs post vaccination?
results can be positive for 28 days post intranasal B.bronchiseptica, Canine parainfluenza virus, canine adenovirus 2 vaccination
(Ruch-Galle et al., 2016)
treatment of CIRDC
- rest for at least 7 days, avoid exercise/excitement to reduce irritation of airways caused by excessive coughing
- cough suppressants ONLY if severe cough to allow sleep/prevent exhaustion…should not be given if cough if overtly productive (Dextromethorphan, Butorphanol, Hydrocodone bitartrate)
- antimicrobials to be considered within the first 10 days if fever, lethargy, inappetence is present with mucopurulent discharges; antibiotics to be administered for 5 days beyond the time clinical signs resolve, or for at least 10 days
what is the minimum isolation period for a dog with signs of CIRDC?
21 days
what is the recommended vaccination protocol for CIRDC prevention?
puppies must be vaccination with combination distemper vaccines every 2-4wks beginning at 6-8wks of age through to 14-16wks.
- at least 2 vaccines given initially with a booster after 1yr and subsequent vaccines q3ys - unless high risk
what pathogens involved in CIRDC have a vaccine available?
- injectable and intranasal for B.bronchiseptica, PIV, CAV2
- oral for B.bronchiseptica
- injectable modified-live for CAV2 and PIV
- killed, injectable for canine influenza virus (H3N8, H3N2)
which vaccine can cause some clinical signs similar to CIRDC?
Intranasal Bordetella vaccines occasionally cause clinical signs, predominantly cough.
define Canine Chronic Bronchitis
Canine Chronic Bronchitis is a disease syndrome defined clinically as cough that occurs on most days of 2 or more consecutive months in the past year in the absence of other active disease.
outline the histologic changes associated with canine chronic bronchitis?
Histologic changes in the airways are those of long-term inflammation and include fibrosis, epithelial hyperplasia, glandular hypertrophy and inflammatory infiltrates.
outline the etiology of canine chronic bronchitis?
Presumed that it is a consequence of a long-standing inflammatory process initiated by infection, allergy or inhaled irritants or toxins.
A continuing cyclone of inflammation likely occurs as mucosal damage, mucus hypersecretion and airway obstruction impair normal mucocilliary clearance and inflammatory mediators amplify the response to irritants and organisms.
clinical features of canine chronic bronchitis
- middle-aged/older, small breed dogs
- Terriers, Poodles, Cocker Spaniels
clinical signs of canine chronic bronchitis
- loud, harsh cough
- mucus hypersecretion is a component of the disease; but cough may sound productive/nonproductive
- usually slowly progresses over months to years, although can be presented acutely due to disease progression resulting in exercise intolerance, incessant coughing, respiratory distress
ddx. for canine chronic bronchitis (aka. diseases to rule out)
- Bacterial infection
- Mycoplasmal infection
- Left atrial enlargement
- Pulmonary parasites
- Heartworm disease
- Allergic bronchitis
- Neoplasia
- Foreign body
- Chronic aspiration
- Gastroesophageal reflux
Potential complications of Canine Chronic Bronchitis
- Tracheobronchomalacia
- Pulmonary Hypertension
- Bacterial infection
- Mycoplasmal infection
- Bronchiectasis
most common concurrent cardiopulmonary diseases associated with canine chronic bronchitis
- tracheobronchomalacia
- left atrial enlargement
- heart failure
radiographic findings of canine chronic bronchitis
- a bronchial patterns with increased interstitial markings but changes are often mild and difficult to distinguish from clinically insignificant changes associated with aging
- thoracic rads are most useful to identify OTHER CAUSES/SECONDARY DISEASE
BAL findings consistent with canine chronic bronchitis
- neutrophilic or mixed inflammation and increased amounts of mucus are usually present
what bronchoscopic findings are consistent with canine chronic bronchitis?
- increased amounts of mucus, roughened mucosa, hyperaemia
- major airway collapse during expiration dt weakened walls
- polypoid mucosal proliferation
- bronchial dilation (bronchiectasis)
what is ciliary dyskinesia?
- ciliary motion is abnormal, uncommon but should be considered in young dogs with bronchiectasis or recurrent bacterial infection
- abnormalities exist in all ciliated tissues and situs inversus is seen in 50% of such dogs
- sperm motility can be evaluated in intact males
- diagnosed on the basis of the rate at which radioisotopes deposited at the Carina are cleared and the findings from electron microscopic examination of bronchial biopsy, nasal biopsy or sperm specimens
general management considerations of canine chronic bronchitis
- Avoid exacerbating factors/triggers (ie. smoke inhalation, perfumes)
- Improve air quality at home
- Reduce anxiety/stress/excitement with anxiolytic drugs if causing acute worsening/episodes
- Routine dental/teeth brushing to maintain a healthy oral flora to decrease oral flora pathogen aspiration
- Airway hydration; systemic hydration + steam inhalation, saline nebulisation
- Weight loss
- Medications; bronchodilators, glucocorticoids, cough suppressants +/- ABs
how is theophylline effective in its treatment of canine chronic bronchitis?
- effective in treating the underlying inflammation of chronic bronchitis (at lower doses than bronchodilation dose)
- anti-inflammatory effects may be synergistic with glucocorticoids
- may improve mucociliary clearance
- inhibit the release of mast cell mediators of inflammation
- decrease fatigue of respiratory muscles
*theophylline alone is rarely sufficient to control chronic bronchitis unless mild case
list common bronchodilators used in cats and dogs
- Methylxanthines; Aminophylline, Theophylline
- Sympathomimetics: Terbutaline, Albuterol
what are the potential adverse effects of theophylline?
GI signs, cardiac arrhythmias, nervousness, seizures
*Note other drugs such as fluoroquinolone can delay its clearance therefore must reduce dose to 1/3 or 1/2, or double the dosage interval
*Serious AEs are extremely rare at therapeutic doses
what are therapeutic peak concentrations of theophylline?
Based on human study (Barnes, 2003).
- bronchodilation: 10-20ug/mL
- anti-inflammatory: 5-10ug/mL
outline the pros and cons of using glucocorticoids to control canine chronic bronchitis symptoms?
Pros: most effective for controlling signs of chronic bronchitis and may slow development of permanent damage by decreasing inflammation
Cons: increased susceptibility to infection, tendency towards obesity, muscle weakness and hepatomegaly which may adversely affect ventilation, risk of PTE
describe the types of organisms typically involved in bronchial infections?
- originate from the oropharynx
- frequently gram-negative with unpredictable AB sensitivity patterns
- protected by airway secretions
DDx for idiopathic feline bronchitis
- allergic bronchitis
- pulmonary parasites (Aelurostrongylus abstrusus, Capillaria aerophila, Paragonimus kellicotti)
- heartworm disease
- bacterial bronchitis
- Mycoplasmal bronchitis
- idiopathic pulmonary fibrosis
- carcinoma
- toxoplasmosis
- aspiration pneumonia
- idiopathic feline bronchitis
features of feline bronchial asthma
- reversible airway obstruction primarily resulting from bronchoconstriction
- hypertrophy of smooth muscle
- increased mucus production
- eosinophilic inflammation
features of feline acute bronchitis
- reversible airway inflammation of short duration (<1-3months)
- increased mucus production
- neutrophilic or macrophagic inflammation
features of feline chronic bronchitis
- chronic airway inflammation (>2-3months) resulting in irreversible damage (eg. fibrosis)
- increased mucus production; neutrophilic, eosinophilic, mixed
- isolation of bacteria or Mycoplasma organisms causing infection or as nonpathogenic inhabitants
- concurrent bronchial asthma
features of feline emphysema
- destruction of bronchiolar and alveolar walls resulting in enlarged peripheral air spaces
- cavitary lesions (bullae)
- result of or concurrent with chronic bronchitis
clinical features of idiopathic feline bronchitis
- most commonly develops in young adult to middle-aged adults
- cough or episodic respiratory distress or both
- slowly progressive signs
radiographic findings consistent with feline idiopathic bronchitis
- bronchial pattern
- increased reticular interstitial markings and patchy alveolar opacities
- lungs may be overinflated as a result of trapping air
- occasionally collapse (atelectasis) of the right middle lung lobe is seen
outline management of feline idiopathic bronchitis
- Environmental; improvement of indoor air quality and removal of triggers/irritants
- Glucocorticoids +/- bronchodilators
- Possible ABs; Doxycycline 14 days, Azithromycin
prognosis of feline idiopathic bronchitis
complete cure is unlikely - most cats require continued medication
- cats with persistent, untreated airway inflammation can develop permanent changes of chronic bronchitis and emphysema
- severe, acute asthma attacks are at risk for sudden death
define ‘tracheal collapse’
refers to narrowing of the tracheal lumen resulting from weakening of the cartilaginous rings, redundancy of the dorsal tracheal membrane or both
outline primary and secondary tracheobroncholamacia
- primary = congenital; toy breed related
- secondary = acquired; due to chronic airway inflammation
how do signs of extrathoracic and intrathoracic tracheal collapse differ?
- extrathoracic; upper airway obstruction = resp. distress pronounce on inspiration and audible stertorous sounds
- intrathoracic; pronounced on expiration and is usually associated with an audible, loud wheeze or cough
clinical features of Tracheobronchomalacia?
- middle-aged toy and mini dogs
- signs may occur acutely then slowly progress over months to years
- nonproductive, ‘goose honk’ cough worsening with excitement/exercise/pressure on neck
diagnosis of tracheobronchomalacia via rads
- radiographs of neck and thorax to evaluate the size of the tracheal lumen during expiration and inspiration
prognosis of dogs with TBM with medical management
1994 White et al. study found medical therapy resulted in a resolution of signs for at least 1yr in 71% of cases
treatment of TBM
- weight loss
- harnesses (not collars)
- prevention of excessive excitement/exercise (anxiolytics)
- cough suppressants
- anti-inflam. pred
- bronchodilators
what is stanozolol?
a novel TBM treatment studied in 2012 by Adamama-Moraitou et al.
- though to improve tracheal wall strength via enhanced protein or collagen synthesis, increased chondroitin sulfate content, increased lean body mass, and decreased inflammation
what is the prognosis for dogs following intraluminal tracheal stenting to treat TBM?
Rosenheck et al., 2017 study 27 dogs; medical survival 502 days; 78% to 6months, 60% to 1yr, 26% to at least 2 years. + ongoing medical management
Rate of serious complications ~40%
what is allergic bronchitis?
allergic bronchitis is a hypersensitivity response of the airways to an allergen or allergens
etiology of Oslerus osleri infection in dogs
- uncommon parasite of young dogs (<2yrs usually)
- adult worms live at the Carina and mainstem bronchi and cause a local, nodular inflammatory reaction with fibrosis
- first-stage larvae are coughed up and swallowed
- persistent cough, eventual airway obstruction due to nodule formation
diagnosis of Oslerus osleri?
- nodules at the Carina visualized via radiographs or bronchoscopy (+brushings of nodules for cytology - larvae)
- cytologic examination of tracheal wash (ova/larvae)
treatment of Oslerus osleri
- ivermectin q3wks for 4 doses
- fenbendazole for 14 days
feline viruses that can cause pneumonia?
- calicivirus (but rare)
- dry form of FIP (also rare)
feline viruses tend to cause URT signs
common bacterial isolates from dogs and cats with pulmonary infection
- B.bronchiseptica
- Streptococcus spp.
- Staphylococcus spp.
- E.coli
- Pasteurella spp.
- Klebsiella spp.
- Proteus spp.
- Pseudomonas spp.
what are some predisposing abnormalities seen in adult dogs with bacterial pneumonia (not associated with CIRDC)?
- aspiration of ingested material or gastric contents caused by cleft palates/megaO
- decreased clearance from the lungs of normally inhaled debris; chronic bronchitis, ciliary dyskinesia, bronchiectasis
- immunosuppression; drugs, malnutrition, stress, endocrinopathies
- inhalation or migration of foreign bodies
- rare but neoplasia, fungal or parasitic infection
outline the treatment considerations of bacterial pneumonia
- Antibiotics
- Airway hydration
- Physiotherapy; coupage, mild exercise if stable, turning of recumbent animals q1-2h
- Bronchodilators (esp. cats)
- Oxygen supplementation
- AVOID; corticosteroids, diuretics, cough suppressants
why is airway hydration important in treating bacterial pneumonia?
Drying of secretions results in increased viscosity and decreased ciliary function, which interfere with the normal clearance mechanisms of the lung.
why is nebulisation more effective than steam inhalation when treating bacterial pneumonia?
- provides moisture deeper into the airways as nebulisers generate small, variably sized droplets (0.5-5um diameter)
outline how to perform nebulisation
- sterile saline +/- premedication with a bronchodilator
- 2-6x daily for 10-30minutes
- deliver nebulised saline via face mask/enclosed cage
why do some clinicians use acetyl cysteine to treat bacterial pneumonia?
- it is a mucolytic agent and also an antioxidant
when should you discontinue antibiotics when treating a bacterial pneumonia?
- discontinue one week after clinical and radiographic signs have resolved
OR - 5-7 days after the normalisation of CRP
what is the thoracic radiographic pattern typically seen in toxoplasmosis in cats?
fluffy alveolar and interstitial opacities throughout the lungs in such animals
- less often, a nodular interstitial, diffuse interstitial or bronchial patterns, lung lobe consolidation or pleural effusion is seen
common fungal pneumonia pathogens
blastomycosis, histoplasmosis, coccidioidomycosis
- cryptococcal organisms (usually nasal in cats but can infect lungs)
what at the common thoracic radiograph findings with fungal pneumonia?
- diffuse, (miliary) nodular, interstitial patterns of the lungs
+/- alveolar, bronchointerstital, consolidated regions
+/- hilar lymphadenopathy (esp. with histoplasmosis - lesions can calcify)
what pulmonary diseases result in a similar radiographic pattern to fungal pneumonia?
- neoplasia
- atypical bacteria; Mycobacterium, Actinomyces, Nocardia
- eosinophilic lung disease
list the major pulmonary parasites of dogs and cats?
- Toxocara canis (GIT)
- Dirofilaria immitis
- Oslerus osleri
- Capillaria (Eucoleus) aerophila
- Paragonimus kellicotti
- Aelurostrongylus abstrusus
- Crenosoma vulpis
what is Capillaria aerophilia?
- a small nematode
- adult worms are located primarily beneath the epithelial surfaces of the large airways
- very few animals developed CS, but can show signs of allergic bronchitis
diagnosis of Capillaria?
finding the characteristic eggs in tracheal wash fluid or faecal flotation
treatment of Capillaria
fenbendazole 50mg/kg PO SID for 14 days
what is Paragonimus kellicotti?
- a small fluke, both snails and crayfish are necessary intermediate hosts
- pairs of adults are walled off by fibrous tissue (usually in caudal lung lobe) with connection to an airway to allow passage for the eggs
- a local granulomatous reaction may occur around the adults, or a generalized inflammatory response to the eggs may be noted
- infection more common in cats than dogs
- CS: allergic bronchitis, spontaneous pneumothorax (if cyst ruptures)
what parasite might cause a single cavitary mass lesion in the right caudal lung lobe?
Paragonimus kellicotti
treatment of Paragonimus kellicotti?
- Fenbendazole (as with capillariasis)
- Praziquantel 23mg/kg PO TID for 3 days
what is Aelurostrongylus abstrusus?
- a small worm that infects the small airways and pulmonary parenchyma of cats
- infects cats; usually no CS, or bronchitis, in young cats
what radiographic abnormalities are consistent with an Aelurostrongylus abstrusus infection?
- often consistent with bronchitis
+/- diffuse miliary or nodular interstitial pattern
+/- pulmonary arterial enlargement
treatment of Aelurostrongylus abstrusus?
fenbendazole 50mg/kg PO SID for 15 days
+/- bronchodilators
what is Crenosoma vulpis?
- a lungworm of foxes that can infect dogs (Atlantic Canada, Europe, rare in the US)
- snails and slugs are intermediate hosts
- worm resides in the airways
- CS; like allergic/chronic bronchitis
radiographic changes consistent with Crenosoma vulpis?
bronchointerstitial or patchy alveolar patterns, or occasionally a nodular pattern
treatment of Crenosoma vulpis?
single oral dose of milbemycin oxime (0.5mg/kg)
explain the etiology of aspiration pneumonia?
inflammatory lung disease that occurs as a result of the inhalation of overt amounts of solid or liquid material into the lungs (stomach contents/food)
- typically presence of aspiration pneumonia indicates an underlying predisposing abnormality
list underlying oesophageal disorders that may cause aspiration pneumonia?
- Megaoesophagus
- Reflux oesophagitis
- Esophageal dysmotility
- Esophageal obstruction
- Myasthenia gravis
- Bronchoesophageal fistulae
list underlying localized oropharyngeal abnormalities that may cause aspiration pneumonia?
- laryngeal paralysis
- cleft palate
- cricopharyngeal motor dysfunction
- laryngoplasty
- Brachycephalic airway syndrome
list underlying systemic neuromuscular disorders that may cause aspiration pneumonia?
- myasthenia gravis
- polyneuropathy
- polymyopathy
list major underlying problems that may cause aspiration pneumonia?
- esophageal disorders
- localized oropharyngeal abnormalities
- systemic neuromuscular disorders
- decreased mentation
- iatrogenic
- vomiting
radiographic findings consistent with aspiration pneumonia?
- diffuse, increased interstitial opacities with alveolar flooding (air bronchospasm) and consolidation of the dependent lung lobes
what is eosinophilic bronchopneumopathy?
a broad term that describes inflammatory lung disease in which the predominant infiltrating cell is the eosinophil
what is eosinophilic pulmonary granulomatosis?
a severe type of eosinophilic lung disease of dogs and characterized by the development of nodules and often hilar lymphadenopathy
treatment of eosinophilic bronchopneumopathy
- eliminating source of the antigen
- glucocorticoids when antigen source cannot be identified
- immunosuppressive therapy if more severe eosinophilic granulomatosis (Pred + cyclophosphamide)
if signs remained in remission for 3 months, discontinuation of therapy can be attempted
define idiopathic interstitial pneumonia
Generally denotes inflammatory infiltration and/or fibrosis of the lungs involving primarily the alveolar septa. The known etiologies of interstitial lung disease must be ruled out to diagnose “idiopathic”.
The alveolar septa include alveolar epithelium, epithelial basal lamina, capillary endothelial basal lamina, and capillary endothelium.
what are the 3 requirements to diagnose idiopathic pulmonary fibrosis?
- Exclusion of other known causes of interstitial lung diseases including domestic and occupational environmental exposures, connective tissue disease, and drug toxicity.
- Characteristic pattern on high resolution computed tomography in patients without surgical lung biopsy abnormalities AND
- Specific combinations of HRCT and surgical lung biopsy lesions in patients with biopsy
what are characteristic lesions that result in the histopathologic pattern of usual interstitial pneumonia
- fibrosis
- areas of fibroblast proliferation
- metaplasia of the alveolar epithelium
- mild to moderate inflammation
- honeycomb change (enlarged airspaces lined by abnormal alveolar epithelium)
- abnormal regions often subpleural, lungs are heterogenously affected
what breeds are predisposed to pulmonary fibrosis?
- West Highland White Terriers!
- Staffies, Jack Russels, Cairn Terriers, Schipperkes (to a lesser extent)
CS of pulmonary fibrosis
- signs slowly progressive over months
- respiratory compromise is the most prominent CSS; exercise intolerance, tachypnoea/dyspnoea
- crackles +/- wheezes
thoracic radiographs consistent with pulmonary fibrosis
- diffuse interstitial pattern
+/- bronchial pattern - cats often have patchy/diffuse infiltrates
- bronchiectasis
treatment of pulmonary fibrosis
- corticosteroids
- bronchodilators
+/- omeprazole (microaspirations speculated to play a role)
prognosis of pulmonary fibrosis
- poor
- dogs; mean survival time is 18months after onset of signs (Corcoran et al.,1999)
- cats; within weeks of onset of signs, <1/3 live longer than a year (Cohn et al., 2004)
list the most common primary pulmonary tumours
- carcinomas; adenocarcinoma, bronchoalveolar carcinoma, squamous cell carcinoma
common multicentric tumours that involve lungs
- lymphoma
- malignant histiocytosis
- mastocytoma
what is the survival time of dogs with primary pulmonary adenocarcinoma treated with surgical excision? (Ogilvie et al., 1989)
55/76 dogs went into remission - median survival time was 330 days.
Of those that did not achieve remission survival time was 28 days.
what is the median survival time of cats treated with surgical excision of a primary lung tumours? (Hahn et al., 1998)
115 days
define pulmonary hypertension?
when pulmonary systolic pressure exceeds 30mmHg - diagnosis it made by direct pressure measurements obtained via cardiac catheterisation
list possible causes of pulmonary hypertension
- obstruction to venous drainage as can occur with left-sided heart disease, increased pulmonary blood flow caused by congenital heart disease, increased pulmonary vascular resistance
OR - idiopathic/primary
causes of increased pulmonary vascular resistance
- PTE
- Heartworm
- complication of chronic pulmonary parenchymal disease (chronic bronchitis, pulmonary fibrosis) due to hypoxic vasoconstriction
CS of pulmonary hypertension
- exercise intolerance
- weakness
- syncope
- respiratory distress
drug used to treat pulmonary hypertension
sildenafil citrate - causes vasodilation through a Nitric oxide pathway (1mg/kg PO TID)
does pimobendan treat pulmonary hypertension?
- only if related to chronic valvular heart disease (Atkinson et al., 2009)
- Murphy et al., 2017 study found that it didn’t help in cases associated with lung disease
how do you diagnose PTE?
- clinical picture; severe dyspnea of acute onset with minimal/no radiographic signs of respiratory disease
- clinicopathologic evidence of a disease known to predispose animals to thromboemboli
- TEG indicating hypercoagulability
- if radiographic signs occur; caudal lung lobes most often involved with blunted pulmonary arteries, in some cases ending with focal or wedge-shaped areas of interstitial or alveolar opacity resulting from extravasation of blood or oedema
- arterial blood gas; can show mild-profound hypoxemia, tachypnoea leads to hypocapnia
- a D-dimer concentration >500ng/mL was able to predict the diagnosis of thromboembolic disease with 100% sensitivity with a specificity of 70%
- CT pulmonary angiography
- selective angiography (gold standard); sudden pruning of pulmonary arteries or intravascular filling defects and extravasation of dye are characteristic findings
treatment of PTE
- Stabilise; oxygen therapy, IVFT as needed
- Theophylline, sildenafil (if pulmonary hypertension)
- Anticoagulant therapy to prevent formation of additional thrombi
- Prevention; long term low-molecular-weight heparin, aspirin or clopidogrel
what is ALI?
Acute Lung Injury; an excessive inflammatory response of the lung to a pulmonary or systemic insult. The rapid leakage of high-protein edema fluid from damaged capillaries is a key feature of ALI. Epithelial cell proliferation and collagen deposition add to pulmonary dysfunction and can ultimately result in pulmonary fibrosis.
what is ARDS?
Acute Respiratory Distress Syndrome describes severe ALI based on degree of hypoxaemia
major different causes of pulmonary oedema
- Decreased plasma oncotic pressure
- Vascular Overload
- Lymphatic Obstruction (rare)
- Increased Vascular Permeability
- Miscellaneous Causes
list possible causes of hypoalbuminemia that can result in pulmonary oedema?
- GI loss
- Glomerulopathy
- Liver Disease
- Iatrogenic overhydration
- Starvation
list possible causes of increased vascular permeability that can result in pulmonary oedema?
- inhaled agents; smoke inhalation, gastric acid aspiration, oxygen toxicity
- drugs or toxins; snake venom, cisplatin in cats, paraquat
- electrocution
- trauma; pulmonary contusions or multisystmic
- sepsis or SIRS
- pancreatitis
- uremia
- disseminated intravascular coagulation
- inflammation (infectious or non-infectious)
how can you determine if oncotic pressure is the sole cause of pulmonary oedema?
Serum albumin concentrations are required to be <1g/dL (typically)
- generally there are also other factors such as volume overload/vasculitis contributing
what was the determined definition for ALI/ARDS by Wilkins et al., 2017?
At least four, ideally five of the following criteria must be met;
1. Acute onset (<72hours) of tachypnea and labored breathing at rest
2. Known risk factors
3. Evidence of pulmonary capillary leak without increased pulmonary capillary pressure (eg. bilateral diffuse pulmonary infiltrates on radiography or CT, proteinaceous fluid retrieved from airways)
4. Evidence of insufficient gas exchange
5. Evidence of diffuse pulmonary inflammation based on tracheal wash or BAL fluid analysis
treatment of pulmonary oedema
- Cage rest + minimal stress
- +/- Oxygen therapy
- +/- Positive-pressure ventilation in severe cases (PEEP/ventilator)
- +/- Methylxanthine bronchodilators; mild diuretics that also decreased bronchospasms and possibly respiratory muscle fatigue
- Frusemide is indicated for the treatment of most forms of oedema unless hypovolaemic
- Conservative fluid supplementation if hypovolaemic - if it is necessary to maintain vascular volume in animals with cardiac impairment or decreased oncotic pressure, then positive inotropic agents or plasma infusions (respectively) are necessary
- Oedema caused by hypoalbuminemia req. plasma or colloid infusions
why should thoracic radiographs be taken after thoracocentesis?
- the animal will hopefully be more stable
- the air/fluid have been removed and the lungs have time to re-expand to properly evaluate the pulmonary parenchyma
- the presence of fluid can also obscure mass lesions and the heart shape/size
common causes of a pure/modified transudate pleural effusion
- right sided heart failure
- pericardial disease
- hypoalbuminemia (pure transudate)
- neoplasia
- diaphragmatic hernia
common cause of pleural non-septic exudates
- FIP
- neoplasia
- diaphragmatic hernia
- lung lobe torsion
common cause of pleural haemorrhagic effusions?
- trauma
- bleeding disorder
- neoplasia
- lung lobe torsion
describe lab characteristics of a pure transudate
- low protein concentrations <2.5-3g/dL
- low nucleated cell counts <500-1000/uL
- primary cell types; mononuclear cells; macrophages, lymphocytes, mesothelial cells
describe lab characteristics of modified transudates
- slightly higher (than pure) protein concentrations of up to 3.5g/dL
- nucleated cell counts of up to 5000/uL
- primary cell types; neutrophils and mononuclear cells
mechanisms that cause transudates/modified transudates
- increased hydrostatic pressure
- decreased plasma oncotic pressure
- lymphatic obstruction
lab characteristics of non-septic exudates
- high protein concentrations >3g/dL
- NCC high >5000/uL
- cell types in non-septic exudates; neutrophils, macrophages, eosinophils, lymphocytes + no evidence of organisms
lab characteristics of septic exudates
- extremely high NCC 50000 to more than 100000/uL
- main cell types; degenerate neutrophils + bacteria observed within neuts/macs and extracellularly
causes of septic exudate pleural effusions
- spontaneously
- secondary to penetrating wounds (chest wall/oesophagus), migrating grass awns or other foreign bodies
- extension of bacterial pneumonia
why should a septic exudative pleural effusion be submitted for prolonged incubation and bacterial culture?
to identify Actinomyces and Nocardia spp.
what is a chylothorax?
- results from leakage of fluid from the thoracic duct which carries lipid-rich lymph from the body
- can be idiopathic, secondary to trauma, neoplasia, cardiac disease, pericardial disease, dirofilariasis, lung lobe torsion or diaphragmatic hernia
- chyle is milky, white and turbid, largely as a result of chylomicrons that carry fats from the intestines
lab characteristics of chyle
- cytologic characteristics of a mod.transudate or nonseptic exudate
- mod. concentration of protein, usually >2.5g/dL
- NCC low to moderate; 400-10000/uL
- predominant cell type; small lymphocytes (early disease), with time non-degenerative neutrophils and macrophages, and plasma cells
- diagnosed via measuring concentration of triglycerides in pleural fluid and serum
lab characteristics of a haemorrhagic pleural effusion
- > 3g/dL of protein
- > 1000 NCC/uL
- cell type; similar to peripheral blood; over time neuts and macs increase
how do you distinguish a haemorrhagic pleural effusion from blood recovered by traumatic thoracocentesis?
- effusions show erythrophagocytosis and an inflammatory response on cytology
- effusions do not clot
- PCV of effusions should be lower than periphery
ddx. for haemothorax
- trauma
- systemic bleeding disorder
- neoplasia; haemangiosarcoma of heart/lungs most common
- lung lobe torsion
outline the challenges of diagnosing a neoplastic effusion cytologically?
- neoplasm may not exfoliate cells into the fluid
- inflammation can result in considerable hyperplastic changes in mesothelial cells
** a cytologic diagnosis of neoplasia other than lymphoma should be made with extreme caution **
what radiographic abnormalities can be identified in the pleural cavity?
- pleural thickening; a thin, fluid-dense line between lung lobes arcing from the periphery toward the hilar region (pleural fissure lines)
- pleural effusion; generally visible after about 50-100ml accumulate
- pneumothorax; air opacity without vessels/airways - heart is generally elevated above the sternum
what disease processes can cause pleural fissure lines on thoracic radiographs?
- prior pleural disease and subsequent fibrosis
- mild active pleuritis
- low-volume pleural effusion
note: infiltration of the pleura with neoplastic cells generally results in effusion rather than thickening
outline the radiographic appearance of pleural effusion
- mild effusions = pleural fissure lines
- as volume increases; the lung lobes retract and the lungs lobe borders become rounded (esp. caudodorsal angles of the caudal lung lobes)
- fluid silhouettes the heart and diaphragm obscuring their borders
- lungs float on top of the fluid, displacing trachea dorsally and causing illusion of mediastinal mass/cardiomegaly
- collapses lung lobes
what major structures are found in the mediastinum?
- heart
- great vessels
- oesophagus
- lymph nodes
radiographic appearance of a pneumomediastinum
- the outer wall of the trachea and other cranial mediastinal structures (oesophagus, major branches of aortic arch, Cr.VC) are contrasted against air
what are the most common caudal mediastinal abnormalities?
- megaoesophagus
- diaphragmatic hernia
what may cause an abnormal shift in the mediastinum?
- atelectasis, lobectomy, adhesions of the mediastinum to the chest wall
- space-occupying lesions
where are the sternal lymph nodes located?
- immediately dorsal to the sternum near the thoracic inlet at the level of the first to third sternebrae
where are the hilar nodes located?
at the heart base around the carina
ddx. for hilar lymph node enlargement?
- lymphoma
- fungal infection (esp. histoplasmosis)
- metastatic neoplasia
- oesinophilic pulmonary granulomatosis
- mycobacterial infection
*any inflammatory disease that causes a lymphadenopathy
ddx. for increased perihilar opacity
- atrial enlargement
- heart base tumours
- hilar lymphadenopathy
landmarks for thoracocentesis
- 7th ICS
- two thirds of the distance from the costochondral junction towards the spine
- insert just in front of the rib
what size catheter should be used when performing a thoracocentesis?
21G is usually large enough to collect air and most fluids (unless extremely viscous such as FIP or pyothorax)
indications of chest tube placement
- management of continued pneumothorax after multiple thoracocenteses
- treatment of pyothorax
what are the major complications associated with chest tube placement?
- pneumothorax
- hemothorax
- iatrogenic pyothorax
outline the steps involved in the placement of a chest tube (non-surgical placement)
- Lateral size of animal over the caudal rib cage is shaved and prepped
- Animal is heavily sedated + local or anaesthetised
- Measure tube; should extend from the 10th ICS to 1st rib (with fenestrations not extending outside the point of exit from the pleural cavity)
- Stab incision made through skin at 10th ICS + purse string placed but not yet tied around opening
- Tube is tunnelled SQ (with hemostats/stylet) to the 7th ICS
- The palm of the hand is placed over the end of the stylet/hemostat handles and the tube is thrust through the body wall with one rapid motion. Once tube has entered pleural space, it is quickly advanced forward until the measured length and the stylet/hemostats are withdrawn.
- Air is removed from pleural cavity with 35ml syringe
- Purse-string is tied around the tube. The tube is then attached to the body wall (Chinese-finger trap)
- Light wrap around the tube and chest wall. Hose clamp + 3-way tap. E.collar.
- 2 view thoracic rads to check positioning; tube should extend a long the ventral aspect of the pleural space to the thoracic inlet. The absence of persistent fluid/air accumulation.
outline chest tube management
- repeat radiographs every 24-48hours
- cytologic assessment of fluid
- check skin site for inflammation/subcut emphysema
- rebandaged and cleaned daily (at least)
etiology of pyothorax
- idiopathic is most common (esp. in cats)
- otherwise results from foreign bodies (migrating grass awns (Foxails)), puncture wounds, oesophageal tears (usually from ingested FB)s, extension of pulmonary infection
outline the treatment of pyothorax
- Antibiotics; initial treatment with fluoroquinolone + a penicillin/clinndamycin (Lappin et al.,2017) injectable first then PO for 4-6 weeks
- Drainage of pleural cavity; chest tube with continuous drainage or q2h, pleural lavage with saline
- Supportive care
explain how to perform a chest lavage when treating pyothorax
- twice daily
- slow infusion of warmed sterile saline solution (~10ml/kg)
- roll animal side to side and then remove fluid
- should recover ~75%
- no benefit in adding antibiotics/antiseptics/enzymes
- Booth et al., 2010 study found benefit in adding heparin (1000-1500U/100mL) to lavage fluid to decrease fibrin formation
when should you remove the chest drain in pyothorax treatment
- volume of fluid recovered should be <2ml/kg/day
- fluid cytology; no longer septic, neutrophils are not degenerative
- no pockets of fluid on thoracic rads
OR if FAILURE TO RESPOND: need chest tube for >1wk after starting appropriate ABs and drainage –> surgery
prognosis of dogs with pyothorax not undergoing surgical treatment
- 1yr survival rate 29% (Booth et al., 2010)
- 25% successfully treated medically (Rooney et al., 2002)
possible causes of nontraumatic chylothorax
- generalized lymphangiectasia, inflammation and obstruction of lymphatic flow (neoplasia or increased venous pressures)
- cardiomyopathy, dirofilariasis, pericardial diseases, other causes of RSHF, central venous thromboses, lung lobe torsion, diaphragmatic hernia
complications of chylothorax
fibrosing pleuritis and pericarditis (common in cats)
what dog breeds appear to be predisposed to developing chylothorax?
Afghan hounds and Shiba Inus
outline the medical management of chylothorax
- generally required for weeks to months
- intermittent thoracocentesis PRN
- low-fat diet
- Administration of Rutin, a benzopyrone drug, has been used in humans to treat lymphoedema - it is through to decrease the protein content of the effusion by affecting macrophage function - the resorption of effusion may thereby be enhanced and fibrosis of the pleura minimised (available over the counter, dosage of 50-100mg/kg PO TID)
outline surgical management of chylothorax
- if failure to improve with medical management within 1-3months
- thoracic duct ligation + pericardiectomy +/- ablation of the cisterna chyli
- placement of pleuroperitoneal/pleurovenous chunts or mesh to allow fluid to drawing away from the pleural space if surgery is unsuccessful.
prognosis for chylothorax with surgical intervention
positive response in 50-80% of patients (Singh et al., 2012b)
list three cancers that commonly cause pleural effusions
- mediastinal lymphoma
- mesothelioma
- carcinoma
what is a tension pneumothorax?
occurs if a one-way valve is created by tissue at the site of leakage, such that air can enter into the pleural space during inspiration but cannot return to the airways or atmosphere during expiration
ddx. for pneumothorax
- traumatic injury/blunt trauma to chest
- tracheal tears (eg. overinflation of endotracheal tube cuffs in cats)
- spontaneous; pre-existing pulmonary lesions rupture
list common cavitary lung diseases
- blebs, bullae and cysts
- chronic airway disease (cats)
- Paragonimus infection
- necrotic neoplasms
- thromboembolised region (eg. dirofilariasis)
- abscesses
- granulomas
mortality rates after spontaneous pneumothorax in cats
Mooney et al.,2012
54% survived to discharge
what are common mediastinal neoplasias?
- lymphoma (cats)
- thymoma
- rarely - thyroid carcinoma, parathyroid carcinoma, chemodectoma
Neoplastic»_space; non-neoplastic
potential iatrogenic causes of pneumomediastinum
- tracheal washing
- tracheostomy
- ETT placement + overinflation of cuff
causes of pneumomediastinum
- trauma; bites to neck, blunt trauma, excessive resp. effort against obstructed airways, severe coughing causing sudden intrathoracic pressure changes, oesophageal tears (FBs)
- iatrogenic
treatment of pneumomediastinum
- strict cage rest to facilitate natural sealing of the tear
- surgical repair
define orthopnea
a certain position taken when there is difficulty breathing
- elbows abducted and neck extended
- movement of abdominal muscles to assist ventilation may be exaggerated
most common causes of upper airway obstruction?
laryngeal paralysis and BOAS
most common causes of intrathoracic large airway obstruction
- collapse of mainstem bronchi +/or intrathoracic tracheal (Tracheobronchomalacia)
define paradoxical breathing
refers to a breathing pattern in which the abdominal walls are ‘sucked in’ during inspiration
when is ventilation required?
- animals with an inadequate arterial oxygen concentration (<60mmHg) despite supplementation
- animals with arterial carbon dioxide pressures exceeding 60mmHg
why do you need a proper ventilator rather than ETT with manual ventilation for longer term oxygen supplementation?
- require air to be humified
- > 50% oxygen conc. is toxic to pulmonary epithelium –> function deteriorates and death can result
- DO NOT PROVIDE air w/ >50% OXYGEN for >12hours
list different methods to provide supplemental oxygen
- mask
- nasal catheter
- transtracheal catheter
- endotracheal tube
- tracheal tube
- oxygen cage
explain the placement of a tracheal tube
- Ventral midline incision is made just below the larynx
- Tracheal is entered through an incision made a few rings below the cricoid cartilage, parallel to the trachea and perpendicular to the rings, and through just enough rings to allow passage of the tube
- Stay sutures are placed on each side of the incision
- Tube is tied with gauze around the neck
- Tube must be cleaned every 30-60minutes initially (single or double-lumen tube)
what are the common complications associated with tracheal tubes?
- tube obstruction (26%)
- dislodgement (21%)
- aspiration pneumonia (21%)
- stoma swelling (21%)
Nicholson and Baines 2012 study
86% of patients had complications, most were clinically insignificant
how does positive pressure ventilation affect CDV parameters?
- increased intrathoracic pressure to fill the lungs with air results in decreased venous return to the heart –> systemic hypotension —> can result in AKI
