Approach to Coughing Horse Flashcards
what are the clnical signs of respiratory disease (7)
- cough
- nasal discharge +/- lymph node enlargement
- alterations in rate, pattern or effort of respiration
- respiratory noise
- altered airflow at nostrils
- poor performance
- weight loss
what is the diagnositc approach to coughing (6)
- detailed history provides vital information
- routine exam
- provisional diagnosis
- therapeutic trial
- further investigations if required
- prognosis
what are some questions to ask the owner if a horse has a cough (7)
- duration, frequency
- character
- nasal discharge at any stage
- cough related to feeding, stabling, exercise?
- eating and drinking normally
- dewormed recently
- in contact with donkeys
what are some questions to ask the owner if the horse has nasal discharge (8)
- duration
- quantity increasing or decreasing
- unilateral or bilateral
- clear, mucoid purulent or bloody
- malodorous
- related to feeding or head posture
- any change in facial contours
- associated cough
what are questions to ask the owner of a horse with dyspnea (6)
- normal at rest
- if only at exercise, what speed does it occur
- nasal discharge or cough
- if apparent at rest is it related to housing
- seasonal
- worsened by feeding
what history questions can be asked if a horse has respiratory signs (5)
1, duration: infection vs. allergic
- health of individual: prev episodes, medication/vaccination, deworming
- recent travel: competitions, long distances
- health of cohorts
- environment and seasonality: changes in environment, severe equine astham (SEA), summer pasture associated
what are breed dispositions to coughing (4)
- idiopathic tachypnea of clydesdale foals
- laryngeal disease less common in ponies
- mini horse/pony: tracheal collapse
- mild-moderate equine asthma: thoroughbred and standardbred
what can be clinically observed in the coughing horses environment (4)
- mucopus on the floor (coughed from mouth or nasal discharge)
- bedding/forage (including adjacent stables)
- location of forage and bedding storage/muck heap
- ventilation
what should be observed of the horse before you start clinical exam
- breathing at rest: rate, pattern, depth
what are rapid deep breaths associated with
respiratory distress
what can rapid deep dyspnea be caused by (4)
- hypoxemia due to cardiorespiratory compromise
- severe anemia
- hypovolemia
- endotoxemia
what can rapid shallow breathing be indicative of
pain
particularly pleural pain
what can slow deep breathing be indicative of
increased effort
uderlying pathology such as equine asthma (ROA, heaves)
how do you tell if there is increased breathing effort or distress
nostril flare and/or thorax including abdomen
noise inspiratory/expiratory or both, URT or LRT
what are the signs of URT obstruction during clinical exam
- predominately inspiratory
- often associated with noise (stertor/stridor)
what can cause upper airway obstructions (6)
- severe trauma
- swelling
- edema of head
- nasal passages
- pharyngeal obstruction
- laryngeal dysfunction
what can cause pharyngeal obstruction
severe strangles
streptococcus equi
what can cause laryngeal dysfunction
laryngeal swelling/edema
bilateral laryngeal paralysis (trauma, hepatic encephalopathy, primary neurological, idiopathic)
what areas can be examined in the head and neck for cause of cough (7)
- nasal discharge (colour, volume, uni or bilateral, odour and character, epistaxis)
- uniform air movement at nostrils
- lymph nodes (submandibular, retropharyngeal region)
- swellings/asymmetry of head
- eyes: conjunctiva, epiphora, nasolacrimal tract
- tracheal palpation & sensitivity (positive tracheal pinch response)
- URT noise (usually inspiratory)
how should you evaluate swellings/asymmetry of the head
particular attention to sinus surface anatomy
percussion over sinuses –> hollow/resonance
what can cause epistaxis at rest (3)
- guttural pouch mycosis
- ethmoidal hematoma
- nasal polyp
what can cause epistaxis after exercise
exercise induced pulmonary hemorrhage
what can cause epistaxis after trauma (2)
- sinus hemorrhage
- ethmoidal: post nasogastric intubation
how is thoracic auscultation done (5)
systemic exam
- palpation of thorax: pain pleuritis? rib fracture in foals
- lung fields on both sides
- trachea
- assess the audibility and distribution of breath sounds (normal)
- are adventitious sounds (abnormal) audible? wheezes, crackles, friction ribs
what are normal breath sounds
soft, blowing, low pitch
what can be heard with thoracic auscultation
attenuation and reflection of sound waves
inspiration > expiration
loudest over trachea (inspiration = expiration)
what is the rebreathing test
- exacerbation of lung sounds
- depth of respiration increases due to increased CO2
- large bag used for 60 seconds
- any coughing abnormal
- accentuates
what are wheezes sounds
continuous, musical
associated with flow limitations (obstruction/constriction)
when are wheezes hear
expiratory: common in ROA
inspiratory
or
inspiratory & expiratory
are wheezes mono or polyphonic
monophonic
polyphonic
what are crackles
short, non musical (paper crumpling)
associated with small airways opening or air moving through mucus
when are crackles heard
expiratory: associated with inflamed airway epithelia
inspiratory: associated with excessive mucus in small airways
inspiratory and expiratory
what do pleural friction rubs sound like
sandpaper
inspiration/expiration
what other sounds can be heard on auscultation
- expiratory grunt if in pain
- GIT sounds
- muscle tremors
- thumps (hypocalcemia): phrenic nerve runs over heart and contracts with a heart beat
describe the differential diagnosis for bronchovesicular sounds, pleural friction rubs, absence of sounds
what is thoracic percussion
detect alterations in density of intrathoracic structures
what are ancillary diagnostic tests (6)
- infectious disease sampling: nasopharyngeal swab, serology
- endoscopy
- lower resp tract sampling: tracheal wash, bronchoalveolar lavage
- ultrasonography
- thoracocentesis
- radiology
what are infectious causes of respiratory diseases
- bacterial resp disease: streptococcus equi (strangles)
- viral: equine influenza A, equine herpes virus type 1 & 4, equine viral arteritis, equine adenovirus, equine rhinitis virus A & B
what type of bacteria causes strangles
Streptococcus equi
is streptococcus equi gram - or +
gram positive
what is the acute disease of strangles
highly contangious mainly in young, naive horses
how do horses become infected with strangles
nose or mouth
invade URT lymphoid tissue
what are the signs of acute disease of strangles (3)
- pyrexia
- pharyngitis
- lymph node abscessation
how is acute strangles disease treated
with antimicrobials
how do horses recover from acute disease strangles
most abscesses rupture followed by a full recovery
what is the chronic strangles disease
carrier state
retropharyngeal nodes can rupture pus into guttural pouch –> fails to clear and become carriers
what are the complications of chronic strangles disease
guttural pouch empyema
pneumonia
abdominal abscess
purpura hemorrhagica
how do you sample for strangles for diagnosis
aspiration and culture from abscess lymph nodes
nasopharyngeal swab or lavage
guttural pouch lavage
serology
what type of virus is equine influenza A
orthomyxoviridae (RNA) with two subtypes
1 = H7N7 equine 1 influenza
2 = H3N8 equine 2 influenza
what is the pathogenesis of equine influenza (6)
- neuroaminidase (NA) glycoproteins break down mucociliary protection giving access to underlying epithelial cells
- hemagglutinin (HA) glycoproteins are responsible for viral attachment to host cells
- replicate in resp epithelium
- cell necrosis and desquamation: irritant receptors exposed and cause excess mucus production and inflammation with massive lymphocyte infiltration and edema which causes cough
- impaired ciliated clearance system
- normal architecture takes 6 weeks to recover
what is the morbidity of equine influenza
high
what is the mortality of equine influenza
low
what are the clinical signs of equine influenza (8)
- extreme pyrexia: 39-41C
- upper resp tract signs: serous or mucopurulent nasal discharge
- lymphadenopathy
- pharyngitis
- tracheitis
- harsh cough for several weeks
- anorexia
- depression
what is the incubation period for equine influenza
3-5 days
how long does uncomplicated equine influenza last
2-10 days
how long are horses infected after clinical signs with equine influenza
3-6 days
how is equine influenza diagnosed
- history and clinical signs
- viral detection (PCR, ELISA)
- serology
how is equine influenza treated
- prompt isolation of affected and all contacts
- symptomatic: hydration & NSAIDs (pyrexia)
- minimize stress and prolonged rest
- antibiotics if suspect secondary bacterial infection
- vaccination
what is the vaccination schedule of equine influenza
- first vaccine: influenza + tetanus at 1 month
- second: influenza + tetanus at 6 months
- third: influenza at 1 year
- yearly boosters of influenza and every 2-3 years tetanus
what equine herpes virus causes resp disease
1 & 4
how long does immunity to equine herpes virus last
short
prone to repeat infections
how is a latent infection of equine herpes virus established
lymph nodes and ganglia
what are the clinical signs to EHV 1 & 4
similar to EI (less severe)
less marked cough
what does the severity of clinical signs of EHV depend on
age
immune status
strain
dose
what is endoscopy used for
visualize normal/anatomical abnormalities
what can be seen on endoscopy of URT (7)
- nasal passage
- ethmoid turbinates
- sinus drainage angle
- pharynx and larynx
- guttural pouches
- trachea and carina
- proximal bronchi
how does endoscopy help assess trachea secretions
secretions accumulate due to impaired mucociliary clearance mechansim
graded from 0-5
