Lecture 19: Large Animal Cardiopulmonary Disorders (MacKay) Flashcards
importance of resp. diseases in LA
- 2nd only to MS system in limiting athletic performance of horses
- sig. cause of morbidity and mortality in cattle
where is sterdor generated?
nose
where is stridor generated?
larynx
What should be included in a history of animal with resp distress?
- signalment
- intended use
- nature, duration, and progression of CS
- only 1 animal affected?
- previous tx and response to therapy
- vax history
unilateral nasal d/c typical of:
sinus infection
bilateral nasal d/c typical of:
pneumonia or guttural pouch issue
malodorous nasal discharge assoc. with
gram = bacteria
steps of resp. system exam
- observe from distance
- presence of nasal d/c?
- evaluate airflow at nose
- MM and CRT
- palpate larynx/trachea/regional lymph nodes
- percussion of paranasal sinuses
- observe ventral abd, muzzle, and limbs for edema
char. of normal bronchovesicular lung sounds
- produced by turbulent air flow in the central airways
- louder ventrally than dorsocaudally
- attenuated by aerated lung parenchyma
char. of abnormal (adventitious) lung sounds
- crackles (short, non-musical)
- wheezes (musical, high-pitched)
- friction rubs
rebreathing CO2
helps to hear lung sounds
- make horse breathe in bag, and they will breathe deeper
- if takes longer than 6-8 breaths to recover, implies resp. insufficiency
percussion use
- delineation of lung boundaries
- identify consolidation, abscesses and pleural effusion
structures evaluated in endoscopy
nasal cavities ethmoid pharynx larynx and epiglottis trachea and bronchi guttural pouches
what do you hit with tube if you accidentally go up middle meatus?
ethmoturbinate
rima glottidis
opening to lower airways
tube usually goes into which bronchus?
R
upper airway rad can visualize what structures?
Head: nasal cavities, sinuses, ethmoid, teeth
Pharynx: epiglottis, soft palate, guttural pouches
lower airway rad can visualize what structures?
Lungs: normal/alveolar/interstitial/bronchial/mixed pattern
Heart
can you visualize whole lung field on rad in adult horse?
No. Requires about 4 rads on each side!
branching of pulmonary vessels over aorta and caudal heart in horses is a sign of cardiac health
:)
ad/disad. of ultrasonography
ad:
-technique of choice for evaluating pleural space and peripheral lung
-penetrates water filled structures very well
-widely available
disad:
-doesn’t penetrate normal lung parenchyma
-can’t detect deep lung lesions w/ overlaying normal lung
nasal washes useful for:
detection of microbes that don’t normally colonize the upper airways such as viruses and strep. equi equi
Tracheobronchial aspirate (TBA)
technique of choice to obtain a culture of the lower airways when pneumonia is suspected. Collects from horizontal portion of trachea which collects secretions from the whole lung.
- Normal cytology has mainly macs and ciliated epithelial cells
- think video of cutting into trachea!
- not a sterile procedure
Bronchoalveolar lavage (BAL)
cytology correlates well with histopath. of the lungs when a DIFFUSE dz is present, but not useful when a FOCAL dz is suspected, such as pneumonia. Culture not sterile
when to perform thoracocentesis?
when pleural effusion suspected. Includes cytology and culture.
complications of lung biopsy
hemorrhage, pneumonia
arterial blood gas analysis measures:
gas exchange (PaO2) and ventilation (PaCO2)
pulmonary function testing measures:
mechanical properties of lungs
2 obstructive dzs of the upper RT
laryngeal hemiplasia
dorsal displacement of the soft palate
4 infectious dzs of the URT
strangles
guttural pouch diseases
sinusitis
viral resp. diseases
5 dzs of the LRT
foal pneumonia rhodococcus equi pneumonia pneumonia/pleuropneumonia in adult horses exercise induced pulmonary hemorrhage heaves
most infectious upper airway disease still in the U.S.
Strangles
Strangles is caused by what bacteria
streptococcus equi subsp. equi
Strangles transmission
direct contact, fomites
morbidity and mortality of Strangles
high morbidity (30-100%), low mortality (<10%)
pathogenesis of Strangles
1) ingest/inhalation
2) attach. to tonsils and translocation below the mucosa in the lymphatics
3) multiply and abscess in local lymph nodes
4) possible dissemination via lymph or blood
CS of Strangles
- fever (1st)
- depression
- bilateral nasal d/c
- retropharyngeal and submandibular lymphadenopathy
- resp. distress
- abscesses throughout body
Which worse: retropharyngeal or submandibular abscesses from Strangles?
retrophar. Don’t rupture to outside very easily and put pressure on larynx which can cause inspiratory dyspnea
Explain Strangles and chronic carriers
Most horses stop shedding 3-6 wks after resolution of CS, however some will become chronic asymptomatic carriers. Carry bacteria primarily in guttural pouch and can shed for months-years
Dx of Strangles
- presumptive based on CS and abscessed lymph nodes
- Culture or PCR (PCR 10x more sensitive!) amplification
How do you dx/detect chronic carriers of Strangles?
-abscess aspirate
-nasal or pharyngeal swab 3x
-nasal flush 3x
-guttural pouch flush
submitted for culture or PCR**
Tx of Strangles
- horses exposed or with early CS BEFORE abscess: penicillin
- horses with abscess: promote maturation/drainage, no Abx unless anorexic or in resp. distress, supportive therapy
Complications of Strangles
- pneumonia
- guttural pouch empyema and/or chondroids
- bastard strangles
- myocarditis, endocarditis
- glomerulonephritis
- purpura hemorrhagica
purpura hemorrhagica
acute necrotizing immune-mediated vasculitis
Path of purpura hemorrhagica in Strangles
immune complex formation –> deposition in blood vessels –> complement activation and mediator release –> vessel wall necrosis
CS/Dx of purpura hemorrhagica
-warm/painful edema of limb, ventral abd, face
-petechial hemorrhage
-fever
-stiffness
Dx: history, CS, skin biopsy
Tx of Purpura hemorrhagica
- systemic antimicrobials (penicillin +/- gram negs)
- steroids
- NSAIDs, hydrotherapy, bandages
Strangles vaccination
-not very effective, but decreases severity/incidence
2 types:
1)IM: uses M protein extracts
2) Intranasal (Pinnacle IN): uses altered live virus, use in outbreaks, can cause CS in young horses, generates nasal immunity
What can be visualized in medial compartment of guttural pouch?
internal carotid a.
cn 9,10,11,12
cranial cervical ganglion
What can be visualized in lateral compartment of guttural pouch?
external carotid a.
maxillary a.
cn 7
guttural pouch empyema
accumulation of exudate in the guttural pouch(es). May solidify to form chondroids
CS of guttural pouch empyema
-nasal d/c when head down
rarely dysphagia, not usually malodorous
dx/tx of guttural pouch empyema
dx: -endoscopy -rads (fluid line, chondroids) -culture for Strep. equi Tx: -lavage with large volume of saline -systemic abx
guttural pouch mycosis
fungal infection often over a major blood vessel (internal carotid most common)
CS of guttural pouch mycosis
- epistaxis**
- dysphagia
- Horner’s, laryngeal hemiplasia, facial paralysis,etc.
