Test 2 Flashcards
Trace air through the horse’s respiratory tract starting at the nares
Nares > nasal passage > ethmoid > nasopharynx > guttural pouch > larynx > trachea
2 distinct circulations in respiratory tract
Pulmonary and bronchial
Pulmonary – low pressure, high volume, oxygenation of blood. Resting PAP = 25-30mmHg, exercise PAP = 125mmHg
Bronchial – high pressure, low volume, distribution of pulmonary tissues. Resting = 100mmHg, exercise = 220mmHg
Why do we rebreathe horses?
increase rate + depth of respiration, used to elicit or accentuate abnormal lung sounds
Which mainstem bronchi is larger?
Right
How can you tell which ethmoid turbinate you are looking at?
The first most superficial comes from the lateral side
Which is the most relevant test in diagnosis of upper airway diseases and involvement?
Endoscopy
T/F: Radiographs are good to evaluate pulmonary disease while US is good to evaluate thoracic disease.
TRUE
Transtracheal wash
sterile
focal, infectious diseases
can culture sample
Bronchoalveolar lavage
non-sterile
diffuse, non-infectious diseases
cannot culture sample
Upper airway disease
unilateral or bilateral nasal discharge
inspiratory component
lung sounds are normal
lower airway disease
bilateral nasal discharge
expiratory component
lung sounds = abnormal
Most common cause of epistaxis
trauma (nasogastric intubation
Guttural Pouch Mycosis
young horses
minor bouts of hemorrhage then unpredictable major bleeding episode, bilateral epistaxis
usually internal carotid artery, also external carotid artery +/- maxillary artery
CS: epistaxis and dysphagia
Treatment: if not bleeding - topical + systemic antifungals (temporary indwelling catheters), if bleeding, surgical (occlude both ends of vessel bc Circle of Willis)
complication - blindness
Progressive Ethmoid Hematoma
old, male, thoroughbred
CS: unilateral epistaxis, mild, spontaneous, intermittent
Dx: endoscopy, rads, CT
Tx: laser ablation (transendoscopically preferred), cauterize while you cut, medical can use formalin (necrosis, desiccate lesion)
Exercise induced pulmonary hemorrhage
INTENSITY, not duration of exercise
Capillary stress theory - high intrathoracic pressure, inflammation, bronchial angiogenesis, pulmonary fibrosis
CS: poor performance, epistaxis in only 1-10%
Dx: endoscopy for direct observation of blood in tracheobronchial tree –> 30-90mins post race, can see up to 7 days, graded 0-4. Hemosiderophages in secretions
Tx: LASIX (furosemide)
what condition of epistaxis do you see hemosiderophages?
EIPH
top Ddx for old horse with bilateral epistaxis
ethmoid hematoma
Top Ddx for young horse with unilateral epistaxis
guttural pouch mycosis
Airway epithelium takes ______ to heal
7 weeks
Clara cells
terminal + resp bronchioles, source of surfactant like substance which aids in maintaining patency of airway
_______ is a constant component of cough
bronchoconstriction
maximal expiratory flow maneuver
forceful inspiration -> compression: close glottis -> expression: rib cage, abdomen, diaphragm -> relaxation
Specific lung sounds for pneumonia, pleuropneumonia, pleural effusion
pneumonia - increased lung sounds, crackles, wheezes
Pleuropneumonia - ventral dull sound
pleural effusion - cardiac sounds larger area than normal bc better sound conduction
Equine influenza
young-3yr olds crowding, transport, stress major cause resp distress aerosolized >35 feet destroy ciliated epithelium
Equine herpesvirus
young-3yr olds
destroy ciliated epithelium
EHV-1 - resp + repro
EHV 4 - resp + neuro
CS: conjunctivitis, lymphadenopathy, edema, vasculitis, polysynovitis
EHV5 - equine multi nodular pulmonary fibrosis
Bacterial causes of cough
Aerobic - streptococcus zooepidemicus
Anaerobic - bacterioides fragillis (treat with metronidazole)
Most common secondary organism of fungal pneumonia
aspergillus spp.
Equine multinodular pulmonary fibrosis
Diffuse bronchointerstitial lung pattern with multiple coalescing circular nodules throughout lung field
US - multiple circular hypo echoic masses
Tx: corticosteroids, NSAIDs, antivirals, antifibrotic agents
EHV5
Foal pneumonia Ddx for <1 month vs 1-6 months
<1 month - meconium aspiration, aspiration pneumonia, iatrogenic, surfactant inactivation, equine viral arteritis, EHV
1-6m - S. zooepidemicus or R. equi, resp viruses
Foal pneumonia
Dx: rads allow evaluate deep parenchyma, lung consolidation
Tx; antimicrobials against most common bacteria based on C/S
two diseases encompassed by the term “equine asthma”
inflammatory airway disease (IAD) and recurrent airway obstruction (RAO)
Inflammatory airway disease (IAD)
young, non-seasonal
CS: occasional cough, poor performance, normal RR, tracheobronchial fluid accumulation, normal lung
Inflammation of lower airway as response to possible allergens
BAL - neutrophilia >10%, mast cells >5%, eosinophils >5%
Tx: improves spontaneously or with minor treatments
Recurrent airway obstruction (RAO)
old animals, seasonal
CS: regular cough, increased RR, accentuated expiratory effort (heave line), abnormal lung sounds w/ rebreathing bag
environmental source
goblet cell hyperplasia, over inflation alveoli
suppurative, non-septic inflammation, neutrophilia >25%, no change in mast cell or eosinophil numbers
endoscopy: distal airways edematous + inflamed
Tx: environmental management is most important, bronchodilators, corticosteroids (dexamethasone, prednisOLONE)
T/F: Prednisone is drug of choice to treat RAO
NO, use PREDNISOLONE. prednisone –> treatment failure
Guttural pouch empyema
Strep zooepidemicus, strep equi var equi
CS: intermittent nasal discharge, lymphadenitis, parotid swelling, dysphagia, chondroids
Dx: rads, endoscopy + culture
Tx: penicillins, flush pouches w/ retention catheter (LRS then Abs, acetylcysteine to dissolve concretions), Sx - drain then heal by second intention
Strangles
highly contagious, young horses, gets into guttural pouch via retropharyngeal LN
strep equi var equi
CS: high fever w/ depression, purulent yellow green discharge, respiratory distress
Pathophysiology - organism infects macrophages in upper resp tract, replicates in pharynx (fever w/o any other CS), engulfed by macrophages, to regional LN -> rupture + drainage
highest environmental contamination - water sources
day 7-14 (LN rupture) = most contagious
Dx: C/S, PCR
How do you treat bastard strangles?
let disease run its course, if complicated give penicillin
Purpura hemorrhagica
leukocytoplastic vasculitis - neutrophilic infiltration of venues
CS: hot and painful edema in all 4 limbs
Tx: steroids (is immune mediated), penicillin (for infection) hydrotherapy on limbs to avoid skin slough
Pleuropneumonia
pleural effusion assoc w/ pneumonia secondary to abscessation
CS: fever, resp dz, weight loss if chronic, pectoral edema (depending on drainage)
Dx: pulmonary sounds absent ventrally, louder dorsally, straight line across thorax, crackles and wheezes
CBC: early - early fibrinogen, CBC of ill endotoxic horse; later - elevated fibrinogen, neutrophilic leukocytosis
Rhodococcus equi
gram +, intracellular facultative aerobic
subacute to chronic bronchopneumonia
foals 1-6m
MC in dry season, inhalation
Rads: abscessation, miliare, broncho-pneumonia, interstitial
Tx: erythromycin estolate, rifampin
Foal pneumonia associated with rad patterns:abscessation, miliare, broncho-pneumonia, interstitial
Rhodococcus equi
Special pneumonia that we treat with erythromycin estolate and rifampin
rhodococcus equi
What shows remarkable sensitivity as indicator of myonecrosis?
creatine kinase (CK)
CK vs AST
- elevations in CK and AST reflect recent or active myonecrosis
- CK remains persistently elevated - myonecrosis likely ongoing
- elevated AST with normal or decreasing CK - myonecrosis not continuing
Positive hemastix test
urinalysis
in absence of hemolysis or RBC in urine - highly suggestive of myoglobinuria
Exercise challenge
measure CK pre and post work out (4-6h)
slow trot
increase >5x indicative of exertional rhabdomyolysis
Biopsy of muscle
pathological alterations that cant be seen in formalin fixed tissue but can be seen with histochemical stains
local anesthetic SQ, 1 inch square sample minimum
Sweeney
atrophy of supra scapular muscles due to denervation bc damage of supra scapular nerve
