What is the normal respiratory rate of the horse?
8-12 bpm
Define the following:
Epistaxis
Haemoptysis
Dyspnoea
Epistaxis = nose bleed Haemoptysis = coughing up blood Dyspnoea = difficulty breathing
What is the normal values for haemoglobin per L in the horse?
120g Hg/ L
What is normal PCV in the horse?
40
Which lymph nodes are normally palpable in a healthy horse?
Non maybe the Submandibular.
The retropharyngeal is NEVER palpable.
How many times will a normal horse cough when you perform a tracheal squeeze?
0 to 1 times.
More than 1 cough may indicate tracheal hypersensitivity.
What are the three landmarks for the lung field in horses?
Triceps muscle, 17th intercostal space, olecranon
How do you differentiate a crackle, wheezes, stridor and stertor?
Crackle - short discontinuous sound eg. oedema
Wheeze- continuous musical sound - reduced airway
Stridor - intense continuous wheezes
Stertor - low pitched sounds
List some ways of diagnosing respiratory problems?
Endoscopy Pulse oximetry Arterial blood gas analysis Ultrasound Tracheal aspirate Bronchoalveolar lavage Thoracocentesis
What is the plica salpingopharyngeus?
Guttural pouch access
What is the rima glottis?
Opening of the throat
How is oxygen carried in the blood?
3% dissolved in plasma
97% haemoglobin bound
What does arterial blood gas analysis analyse?
PaO2 and PaCO2 analysis
What does pulse oximetry measure?
Haemoglobin saturation (SaO2) and can use it to calculate PaO2. More than 90% of SaO2
What is the bright white line you can see on a normal thoracic ultrasound?
Pleural surface
What do comet tails indicate and where will you see them?
Comet tails indicate pleural roughening or pulmonary inflammation.
Look at the lungs below the pleural surface.
Describe what pleural effusion looks like on an ultrasound?
Wedge of lung tissue - black wedge.
Differentiate tracheal aspirate and bronchoalveolar lavage.
TA - all lung fields, for focal disease, taken sterile (bacterial culture).
BAL- needs sedation, caudodorsal lungs/lower lowers, NOT sterile
What are the normal cytological findings of a tracheal wash or bronchoalveolar lavage?
Ciliated columnar epithelium & lymphocytes
ANY squamous cells & extracellular bacteria are due ot contamination
What are the highest level of neutrophils for a TA or BAL that are acceptable?
Less than 20% TA
Less than 5% BAL
More than this indicates airway inflammation
Describe normal characteristics of a thoracocentesis?
Clear, light yellow.
Less than 10 x 10^9 cells/L WBC
Less than 20 g/L protein
What is alar fold stenosis?
Flaccidity of alar folds causing a continuous muffled rattling sound.
Can resect folds or use nasal strips
Campylorrhinus lateralis causes what nasal condition?
Wry nose
A congenital deviation of the nasal, maxilla, premaxillar and vomer bone.
What is choanal atresia?
One or both the nasal cavities doesn’t communicate with the nasopharynx.
How do nasal septum deformities occur?
Trauma.
Airflow obstruction.
You will get assymetric airflow and can palpate septum.
What is mycotic rhinitis?
Aspergillus fumigates usually secondary to tissue damage. Get a chronic smelly nasal discharge and lymphadenopathy.
Describe how the nasal sinuses communicate with teeth?
Caudal maxillary sinus communicates with 10, 11 teeth.
Rostral maxillary sinus communicates with 8, 9 teeth.
How do you get sinusitis?
Primary from previous respiratory tract infection usually Streptococcus.
Secondary to dental disease, facial fractures, cysts, neoplasia, ethmoid haematomas.
How do you diagnose sinusitis?
Percussion, endoscopy, sinoscopy, nuclear scintigraphy
What are some clinical signs of sinusitis?
Nasal discharge - mucopurulent, haemorrhagic
Facial swelling
Bad breath
Draining tracts
How do you treat sinusitis?
Treat underlying disease.
Antibiotics
Feed on ground, low dust environment
Trephination & sinus lavage (under GA)
What are the common signs of progressive ethmoid haematoma and how would you treat this?
Unilateral epistaxis
Common and idiopathic.
Treat with endoscopic intralesional formalin injections at 2-4 week intervals
What is the principle that decreases oxygen delivery in the horse?
Reduction in airway diameter causing increase in airway resistance.
What is pharyngeal lymphoid hyperplasia?
Pharyngitis. Usually in young horses from an immune response of antigens. Just rest. Does look like raised lymphoid nodules in pharynx.
What is the most common pharyngeal performance issue?
Dorsal displacement of soft palate
What will you see clinically with DDSP?
Can’t observe epiglottis in nasopharynx.
Soft palate flaps in airway.
Usually from a cyst!
Swallowing restores the normal position.
Horse will be ‘fading rapidly’ during exercise.
How would you deal with DDSP?
Rest & anti-inflammatories
Tongue tie
Laryngeal tie forwards
In what situation might you see retropharyngeal lymph node enlargement?
Streptococcus equi subsp. equi.
Get throat swelling, dyspnoea, respiratory distress, dysphagia. Also abscesses in these retropharyngeal LN.
How does recurrent laryngeal neuropathy cause respiratory issues?
Also called laryngeal hemiplegia from nerve loss or trauma.
Inspiratory issue where the corniculate process of arytenoid cartilage can’t abduct. Get roaring sound.
What may occur when laryngeal hemiplegia progresses?
Collapse of arytenoids
Vocal cord laxity
Collapse of other vocal cord
Which is the most appropriate treatment for laryngeal hemiplegia:
a) Prosthetic laryngoplasty
b) Tie back surgery
c) Ventriculocordectomy
d) Neuromuscular pedicle graft
Tricked you! They all are!
None are that great because there is poor prognosis.
Define arytenoid chondritis.
Arytenoid cartilage infection causing loss of cartilage abduction. Treat with rest for 1-3 months.
How would you differentiate dorsal displacement soft palate and epiglottic entrapment?
DDSP - epiglottis is hidden
EE - can still see the epiglottis
How would you deal with a dorsoventral tracheal prolapse?
Emergency situation give oxygen and do tracheostomy
How would you differentiate RAO and IAD? (And define both too please!) *****
Recurrent airway obstruction- more obvious clinical signs, cough at rest
Inflammatory airway disease- no clinical signs just reduced performance.
Define RAO and it’s clinical signs.
Recurrent airway obstruction. Get obvious clinical signs with coughing at rest, exercise intolerance and tachypnoea.
Describe the pathophysiology of RAO.
Get airway inflammation - bronchospasms - airway obstruction - oedema - chronic airway wall remodelling (metaplasia, hypertrophy, fibrosis)
How will you diagnose and treat RAO?
Diagnosis - abnormal lung sounds, do a tracheal aspirate or bronchoalveolar lavage
Treat - environment control, clenbuterol (bronchodilator), corticosteroids
Describe IAD.
Inflammatory airway disease. In lower airway of young racehorses. They will get clinical signs during exercise (coughing). See neutrophils on tracheal wash and BAL.
What are some normal clinical findings with a tracheal wash and BAL in a patient with inflammatory airway disease?
Normally you see lymphocytes and macrophages. If you see neutrophils this is abnormal!
Why do most horses get epistaxis during very intense exercise? How do you deal with it?
Exercise induced pulmonary haemorrhage.
From a stress failure of pulmonary capillaries during exercise. Give furosemide (decrease BP during exercise but NOT race approved), or just no treatment.
What is a major cause of pulmonary oedema?
Upper respiratory tract obstruction
When is upper respiratory tract obstruction likely to occur?
Anaesthetic recoveries when you intubate for example.
How would you treat pulmonary oedema?
Furosemide (1mg/kg)
What is the major predisposing factor for pneumonia development and why?
Transport - horse can’t lower head, contamination of airway, reduced mucociliary clearance.
What bacteria are the common culprits causing pneumonia?
Strep. zooepidemicus
Strep. pneumnia
Bacteriodes
List the clinical signs and clinical pathology you are likely to see with pneumonia.
Fever, lethargy, exercise intolerance, abnormal resp.
Leukocytosis, neutrophilia, increase acute phase protein (hyperfibrinogenaemia)
What’s your treatment choice for pneumonia?
Gentamycin or Penicillin (broad spectrum antibiotics) first doing a tracheal aspirate & pleural effusion culture & sensitivity.
Nebulisation
Pleural drainage
NSAIDs
What are the four disease presentations of Strangles?
Strangles = Streptococcus equi ss equi
Classic Upper Resp Tract Disease (LN localised)
Purpura haemorrhagica (immune mediated vasculitis)
Disseminated abscessation (bastard strangles)
Immune mediated myopathy
Explain the principles behind transmission of a classic URT Strangles and the clinical signs most likely to be seen.
Transmitted within nasal shedding. The infection persists in horses guttural pouch (can be subclinical).
Get acute fever, mucopurluent nasal discharge, LN swelling, dysphagia, anorexia.
What’s purpura haemorrhagica?
Immune mediated vasculitis from Strangles infection. Get distal limb oedema, haemorrhages, serum ooze and skin necrosis.
Briefly, what is disseminated strangles and what is immune mediated myopathy stranges?
Disseminated - strangles spreads to rest of body (look for rough coat, pyrexia, weight loss)
Myopathies - rhabdomyolysis and atrophy
You diagnose a case of Strangles in a horse in your clinic, how did you diagnose it and what will you do now?
Diagnosis via guttural pouch wash/nasal wash (Strep equi ss equi is NOT normal flora).
Quarantine affected
Treat with penicillin, NSAIDs and drainage with any LN abscessation. Corticosteroids for purpura haemorrhagica and myopathies forms.
How does agaltica get caused by a Strangles infection?
Absence of milk secretion/abnormal milk secretion.
Secondary to fever, anorexia and lethargy.
Fix with Domperidone (increases prolactin by interfering with dopamine).
How do you prevent strangles?
Vaccines are no good have to more rely on the horses natural immunity.
Which viral disease affected ciliated epithelial cells, doesn’t survive long outside the host and requires rest and NSAIDs for treatment?
Equine influenza (type A virus)
What do the following herpesviruses cause: EHV-1 EHV-4 EHV-2 EHV-5
EHV-1 - respiratory, abortion, neurological
EHV-4- respiratory
EHV-2 - ubiquitous
EHV-5 - equine multinodular pulmonary fibrosis
How does EHV-1 & 4 get transmitted and what age horses are most susceptible?
Transmission via aerosol/direct/indirect contact.
Most horses infected by 2 years old.
Get fever, cough, nasal discharge, abortions.
Neuro signs in more than 5 years old horses.
What is equine viral arteritis?
Severe endothelial destruction RNA virus causing vasculitis.
Sheds in nasal, oral secretions, urine, faeces, semen, aborted material!! AND survives in chilled/frozen semen *
NOTIFIABLE DISEASE
What is African horse sickness?
Exotic in Australia but notifiable disease spread by Culicoides. Get lung form or heart form. Both high mortality.