Exam 4 Flashcards
Lecture 32
Mechanics of airflow in the exercising horse
-Speed requires efficient gas exchange
-Horse’s respiratory tract is designed for incredibly efficient gas exchange
Anatomy Review - Name the structures
Blue arrows
-Soft palate
-Epiglottis
-Arytenoid cartilage
Black arrows
-Nasal septum
-Nostril
-Ventral Conchae
-Dorsal Conchae
-Ethmoidal Conchae
-Septum to Guttural Pouch
Anatomy - Endoscopy
From bottom left to upper right
-Soft palate
-Epiglottis
-Laryngeal Saccule (ventricle)
-Vocal cord (fold)
-Opening to airway
-Arytenoid Cartilage (left, right)
-Opening to esophagus
Respiratory Physiology Review & Upper airway flow mechanics
Resting respiratory rate: 8-20 bpm
Tidal volume: 5L
Minute ventilation: RR*TV = 40-100 L
Exercise: 80-100 bpm, ~1500 L minute ventilation
Obligate Nasal breather
Upper airway flow mechanics
Galloping horse
Exhales as forehand contacts the ground Extended Phase
Inhales while handlers are engaged Gathered phase
-Inhalation: negative pressure
-Exhalation: positive pressure
-Exercise increases pressure disparity Upper airway
Airway Diameter and Resistance
-Airway resistance is primarily determined by airway diameter
-Cutting the radius by half increases resistance by a factor of 16
Areas of resistance
- External nares
- Nasal Mucosa
- Pharynx (soft palate and pharyngeal walls)
- Larynx (epiglottis and arytenoids)
Airway resistance during exercise
-80% Upper respiratory tract pathology - Inspiration
-50% Upper respiratory tract pathology Expiration
- 66% Upper respiratory tract pathology - at rest
Laryngeal Collapse
-Epiglottis, arytenoids
Pharyngeal Collapse
-Soft palate and pharyngeal walls - Mucosa around arytenoids.
Upper Airway Stabilization & Flexing Neck
Muscular tone - major contributor
-Nervous innervation (CNs)
-Autonomic effects: adrenaline constricts blood vessels during exercise - Larger Lumen!
Effect of Flexing Neck
-Decreased Layngeal space
Evaluation of the URT
Nasal cavity endoscopy - Name the structures
- History
-Use
-Presenting complaint
-Nasal discharge
-Cough
-Exercise tolerance
-Respiratory noise
-Dysphagia
Respiratory noise and exercise intolerance are not synonymous - PE of URT
-Respiratory disease
-Lameness (not always a full exam)
-Myopathies
-Cardiac disease
-Neurologic disease
-Inspiration to expiration ratio 1:1
-Head: facial symmetry, deformities
-Nostrils: airflow, palpation, nasal discharge, odor
-Palpation: nasal bones, LNs, Laryngeal cartilages CAD muscle, scars
-Oral exam
-Percussion: nasal sinuses
- Ancillary Diagnostic Aids
A. Endoscopy
-At rest
-Dynamic: treadmill, regular work
B. Radiographs
C. CT or MRI
D. Ultrasound
E. Bloodwork: not always useful
F. LRT workup
Nasal Cavity Endoscopy
-Ventral nasal meatus
-Ethmoid Turbinates
Endoscopy Anatomy - Name the structures
Pharynx, larynx, or guttural pouch?
Pharynx
D: dorsal pharyngeal recess
R & L: right and left cartilaginous flaps covering the nasopharyngeal openings of the guttural pouch
SP: Soft palate
Endoscopy Anatomy - Name the structures
Pharynx, larynx, or guttural pouch?
Guttural Pouch
ST: Stylopharyngeus m.
LCM: Longus capitus m.
CN IX: Glossopharyngeal
CN XII: Hypoglossal
CN X: Vagus
IC: Internal Carotid artery
MC: Medial compartment
A: Articulation of the stylohyoid and Petrous temporal bone
LC: Lateral compartment
EC: External Carotid artery
SH: Stylohyoid Bone
Name the Structures
-soft palate
-Epiglottis
-Vocal fold
-Opening to the airway
-Left and right arytenoid cartilages
-Laryngeal saccule (ventricle)
Endoscopy at Rest
What two structures should always be scoped?
Why no sedation?
What is the benefit of Nasal occlusion during exam?
-No sedation: to be able to diagnose static lesions
-Sedation: can affect the function of the muscles and make it hard to Dx
-Some lesions only seen with dynamic endoscopy
Always scope trachea and GP
Nasal Occlusion
-Can get negative pharyngeal pressures that are similar to exercise
-Arytenoid abduction is better correlated with swallowing than nasal occlusion
Dynamic Endoscopy
When does dorsal displacement of soft palate usually occurs?
Where should you always start?
-Safety concerns
-High intensity HR: 220bpm
-Does not perfectly mimic real life, practice first!
-Important for dynamic conditions
DDSP: occurs during fatigue so they need to be exercised for a while
Always start with resting = baseline
-Common to use dynamic to make definitive diagnosis
-Many lesions are not apparent at rest
-Flexion of poll, effect of tack, experienced during maximal intensity
Radiographs, CT, MRI
Radiographs
-Challenging to interpret
CT
- Best option for sinuses, but expensive
Lecture 33
Diseases of the Equine Nasal passages and Paranasal Sinuses
Epistaxis = Nosebleed
Unilateral
-Dry mucous membranes (cold weather)
-Exertion
-Ethmoid hematoma
-Nasal polyps
-Guttural pouch mycosis (mild disease)
-Neoplasia
Bilateral
-EIPH (racehorses, barrel horses)
-Head trauma
-Clotting disorders
-Severe pleuropneumonia
External nares
-Cartilaginous support over nasoincisive notch (pic)
-Motor innervation: Facial n. Trigeminal n.
-First major site of upper respiratory airway resistance
False nostril
External Nares Atheroma or Epidermal Inclusion Cyst
Etiology
-Cyst in false nostril
-Unknown cause
Dx
-FNA and Cytology
-Mass (3-5cm) spherical nodule
Tx
-Surgical Removal
Prognosis
-Excellent
The Nasal Passages
Uncommon problems
Etiology
-Trauma
-Inflammation
-Infection: abscess, granuloma
-Neoplasia
-Congenital - Wry Nose
The Nasal Septum
C/S
-Respiratory noise
-Decreased airflow
-Nasal discharge
-Facial deformity
Dx
-Based on clinical signs
-Radiographs: DV view most useful
-CT
-Endoscopy not helpful
Tx
-Resection of the septum
-Need to leave the rostral section to prevent collapse
-Very BLOODY!!
Nasal Polyps & Ethmoid Hematoma
Nasal Polyp
C/S
-Inspiratory dyspnea
-Nasal discharge
-Odor
Etiology
-Pedunculated growths from the mucosa of the nasal cavity, septum, etc.
Dx
-No breed, age, sex, predilection
Tx
-Surgical excision
Ethmoid Hematoma - Unilateral
Etiology
-Slowly expanding
-Non-neoplastic mass
-Originates from submucosa of ethmoidal labyrinth or paranasal sinuses
-Usually unilateral
-Can expand into sinuses
Dx
-Based on C/S
C/S
-Epistaxis - dark red blood, serosanguinous discharge, mild intermittent. Can be chronic
-Dyspnea
-Respiratory nouse
-Head shaking
-Halitosis
-Facial deformity
Can extend into the horse’s nose, but rare
Dx
-Endoscopy: Greenish-yellow to purple-red mass.
-Smooth surface, may have fungal plaques
-Biopsy
-Radiographs
Tx
-Surgical excision
-Frontal bone flap
-Lots of hemorrhage, have a plan for it!!
-Transendoscopic: laser, intra-lesion formalin injection (4% formaldehyde, repeat at 3-4 weeks intervals)
Paranasal Sinuses
Anatomy Review
-All compartments communicate directly or indirectly
-All drain eventually through the nasomaxillary opening
-Tooth roots: PM4, M1, M2, M3
Sinusitis
Primary
C/S
-Unilateral nasal discharge
-Often following an URT infection
-Streptococcus sp.
Secondary
C/S
-Tooth root abscess ODOR
-Trauma (facial fracture)
-Neoplasia
C/S
+/- Epiphora, conjunctivitis, enlarged submandibular LNs, respiratory noise, facial deformity (more common with paranasal sinus cysts)
-Nasal dischage: ODOR, purulent, unilateral
Dx
-Radiographs: fluid lines
-Endoscopy: can see pus at the nasomaxillary opening. Can not see into the sinus!! only post-sinus flap
-Sinocentesis
-Cytology and culture
-Can lavage at the same time
-Sinoscopy
-CT: complicated cases
Tx
-Sinus Trephine
-Sinus Lavage
- Primary: Copious lavage, 5-10 L at the time
-Sterile Warm Seline
-Secondary: Correct underlying problem, otherwise same as primary
-Systemic antibiotics: ideally based on culture and sensitivity
Treatment failure is common, warn the client
-Ventral conchal sinus inspissated pus keeps coming back
Bilateral Nasal Discharge Origin
-Guttural pouches
-Nasopharynx
-Lungs
-Both paranasal sinuses - PRIMARY Sinusitis
Sinus Cysts
Etiology
-Fluid filled structure lined by epithelium
-Congenital possible
-Unknown
C/S
-Facial deformity
-Unilateral mumcoserous nasal discharge
-NO ODOR
-Reduced airflow on affected side
Dx
-Radiographs
-CT/MRI
Tx
-Remove
-Reoccur if lining not removed
Prognosis
-Good if fully removed
Sinus Neoplasia
-Squamous cell carcinoma: most common
-Typically malignant and invasive
C/S
-Nasal discharge
-Facial deformity
-Loose teeth
-Epiphora (overflow of tears)
Dx
-Aspirate fluid for cytology
-Biopsy
Tx
-Surgical margins difficult/impossible to get
-Typically euthanasia
Surgery of the Sinuses
Bone Flap Approaches
-Frontonasal
-Maxillary
-May be done standing or under GA
Bone flap
-Three sided hinged on the 4th side
-Created with: Osteotome, Oscillating Saw
Bevel the flap
-Similar to carving the top of a pumpkin
-Can secure the corners with wire, often left unsecured
Surgical Considerations
-Make large opening to facilitate drainage
-Post-op lavage may be needed: plan to place a foley catheter if needed
-Pack the sinus post-op: controls hemorrhage, remove 48-72 hrs
Case example
-Orosinus fistula was palpated during oral exam
-Tooth abscess did not heal properly
-Surgery and plugged the orosinus fistula
-Post-op: NSAID -Phenylbutazone
-Systemic antibiotics - penicillin/Gentamicin
-Hypertonic ophthalmic ointment
-Lavage the sinus with saline
-Plug management
Lecture 34
Diseases of Equine Respiratory tract
Dorsal Displacement of the Soft Palate
Etiology
-Intermittent of persistent malposition of caudal edge of soft palate dorsal to epiglottis
-Allows horse to mouth breath, but horse is obligate nasal breather
-Gurgling, choking, swallowing the tongue
-Idiopathic
-Inflammatory URT infection: affects nerve function pharyngeal branch of vagus
-Conformation: hypoplastic epiglottis
-Fatigue
-Pulling back the tongue predisposes (tongue ties common racing horses)
C/S
-Intermittent
-During racing: “chokes down” falters, usually towards the end of race
-Cheeks may bulge
-Coughing
-Salivation
-Max exertion
Only airway problem that creates EXPIRATORY noise
Dx
-History
-PE, rule out other URT impairment with resting endoscopy
-Dynamic endoscopy: some displacement normal, but it should stop as horse swallows
-Treadmill, overground: work horse until fatigue
-Radiograph
Endoscopy Tricks
-Make horse swallow (epiglottis should return to over soft palate position): Hit dorsal pharyngeal wall with the tip of endoscope, flush water through the scope, press on the larynx
-Once displaced pay attention to how quickly it returns to normal position
-Abnormal when they can’t fix it or takes them too long
Endoscopy Findings
-Ulceration of the soft palate: chronic displacement, turbulent airflow
-Inflammation in airway
-Determine when displacement occurs
Tx
-Treat underlying cause
-Anti-inflammatories throat sprays, steroids, DMSO
-Increase fitness level
-Noseband that keeps mouth closed
-Change bit
-Tongue ties: the tongue retracted in the mouth pushes up on the palate
-Cornell collar
Surgical Options
-Tie forward: best prognosis in literature
-Palatoplasty: creates scar tissue to make the palate more stiff. Laser, irritants, thermocautery
-Staphlectomy: resect caudal margin of the palate
-Strap muscle myectomy
-Permanent tracheostomy: last resort, non-athletic horses
DDSF - Tie forward procedure
Strap Muscle Myectomy
What cartilage and bone is the suture passed through?
-Goal: put larynx forward to allow the epiglottis to engage with the palate
-Suture passed from thyroid cartilage to the basihyoid bone
Strap muscle myectomy
-Sternohyoideus m.
-Sternothyroideus m.
-Can be done standing
-Llewelyn Procedure: transect the tendon of the sternohyoideus m. at the insertion of the thyroid cartilage
-Goal: reduction of caudal retraction of larynx
Prognosis
-Tie forward 80% success
-Based on TB racehorse data
-60% success other procedures
Laryngeal Hemiplegia - Cricoarytenoideus dorsalis m. ADDUCT
Unilateral or Bilateral
Etiology
-Arytenoid chondrites
-Damage to recurrent laryngeal nerve: perivascular injection, trauma, GP mycosis, Strangles abscess
-Organophosphate toxicity
-Hepatic encephalopathy
-Lead toxicity
-CNS disease
Left laryngeal hemiplegia
-Draft horses, TB, Racehorses
-Recurrent laryngeal neuropathy
-May have genetic component
C/S
-Inspiratory whistling or ROARING noise during EXERTION
-Paralyzed cartilage is pulled across to contralateral side due to negative airway pressure
Dx
-Endoscopy: at rest, no sedation. Dynamic for < grade 3
-C/S
-Palpate larynx: Atrophy of CAD mm.
-Slap test reflex: arytenoids abduct in response to slap on withers
-Ultrasonography
Progressive disease
1. Synchronous FULL abduction
2. Asynchronous FULL abduction
3. Asynchronous PARTIAL abduction
4. No appreciable abduction
Tx
-Prosthetic laryngoplasty: improves performance
+/- ventriculectomy, chordectomy, ventriculocordectomy: noise reduction
-Pedicle Nerve Graft: Young horses, 6-12 mts recovery
-Arytenoidectomy: salvage
Cordectomy & Prosthetic Laryngeoplasty
-Common to use laser via endoscope
-It is an “art” to know how much to take to keep a seal during swallowing
Laryngeoplasty
Complications
-Over-abduction: aspiration of feed
-Implant failure: almost all “relax”
-Infection
-Coughing
-Noise
Prognosis
-Prosthetic laryngeoplasty 70-80%
-Ventriculocordectomy: 80% noise reduction, but no change in function of airway
Dynamic Laryngeal Collapse
-Dorsal and/or lateral walls
-Displacement of palatopharyngeal arch
Etiology
-Idiopathic
-Guttural pouch distention - unilateral
-Neuromuscular dysfunction (CN IX, X)
-EPM, HYPP, Botulism
-Nasal obstruction
C/S
-Inspiratory noise
-Exercise intolerance
Dx
-Endoscopy
-Dynamic endoscopy
Tx
-Treat underlying cause
-No surgery option
-Anti-inflammatories
Prognosis
-Guarded for athletic function
Cleft Palate
Etiology
-Congenital defect
-Foal exam part important
C/S
-Milk draining from nose
-Coughing
Dx
-PE
-Endoscopy
Tx
-Surgical repair: complicated and prone to failure
-Treat pneumonia
Prognosis
-Guarded for life
-Most euthanized
-Worse if soft and hard palate involvement
Arytenoid Chondritis
-Inflammation or infection in arytenoid cartilage
Etiology
-Unknown
-Trauma
-Young TBs: secondary to URT infection?
C/S
-Roaring severe AT REST
Dx
-Endoscopy
-Granulation tissue axial surface of arytenoid
-Distorted corniculate process
-Hemiplegia - restricted movement
-Rostral displacement of the palatopharyngeal arch
-Ultrasound
Tx
-Conservative: antibiotics, anti-inflammatories, rest. Low success
-Surgical: Partial Arytenoidectomy
Arytenoidectomy
-Performed via laryngotomy
-Prognosis: 62%
-Complications: coughing, dyspnea, dysphagia, cartilage mineralization, webbing granulation tissue
Aryepiglottic Fold Entrapment
-Epiglottis is entrapped by aryepiglottic fold
Etiology
-Hypoplastic epiglottis
-Inflammation
-Subepiglottic cysts, Cleft palate, DDSP
C/S
-Exercise intolerance
-Sign from secondary DDSP: Gurgling, expiratory noise
-Coughing during eating
-Incidental finding
-Inspiratory or expiratory noise
Dx
-Endoscopy
-Can not see serrated border of epiglottis
-Can see back edge of fold
Tx
-resection via laryngotomy
-Requires GA, endoscopic guidance
-Axial division per nasum: standing, hooked history or laser
-Axial division per os: same as per nasum, but requires GA
Post-op
-Re-entrapment: 10% of cases
-DDSP: especially with a hypoplastic epiglottis, possible for all treatments
-Deformity of epiglottis caused by chronic entrapment, usually returns to correct shape
Lecture 37
Diseases and Disorders of the Guttural Pouch
Guttural Pouch Anatomy
What is the name of the area where endoscope is passed?
-Air filled Diverticulum of the auditory canal
-Extend from the roof of the pharynx to the base of the skull and from the Atlanta-occipital joint to the pharyngeal recess
-Pouches communicate with the nasopharynx and open routinely during swallowing
-Pharyngeal orifice: flaps where you pass the endoscope
Medial Components
-ICA: internal carotid artery
-Cranial cervical ganglion
-Cervical sympathetic trunk Vagus CNX
-Pharyngeal branch of Vagus n.
-CN IX, XII, CNXI,
-Cranial laryngeal n.
Lateral components
-External Carotid artery: Maxillary branch a.
-Facial nerve CNVII
Guttural Pouch Tympany
-Air distension in the guttural pouch
Etiology
-Congenital: seen shortly after birth to 1yr
-Idiopathic: no gross abnormality
-Typically unilateral
Arabian and Paint over-represented
-Fillies > Colts
C/S
-Air distended GP
-Swelling in parotid
-Non-painful, elastic, bilateral swelling despite unilateral lesion
-Possible: respiratory distress, interference with deglutition, aspiration pneumonia
Dx
-C/S
-Endoscopy
-Radiographs
Tx
-Needle decompression
-Make a permanent hole fo deflate: median septum, Salpingopharyngeal fistula
Prognosis
-Good with tx
Guttural Pouch Empyema
Etiology
-Sequel to URT infection: Strep equi (strangles)
-Horse becomes carrier
-Can occur secondary to rupture of a retropharyngeal LN abscess
-Submandibular LN inflammation
C/S
-Chondroids = Inspissated pus
-Chronic mucopurulent nasal discharge
-NO ODOR
-Swelling of adjacent LNs
-Extended head carriage
-Excessive respiratory noise
-Difficulty swallowing/breathing
-Typically no external swelling of the GP
-Usually UNILATERAL but may be Bilateral
Dx
-C/S
-Endoscopy: check both pouches
-Not clearing a Strep equi infection
-Culture and sensitivity
+/- Radiographs
Tx
-Can be a challenge
-Systemic antibiotics?
-Remove chondriods and pus: endoscopic and snare
-Acetylcystine to dissolve chondroids
Prognosis
-Good once resolved
-Neuro signs generally resolve
Guttural Pouch surgery
A. Hyovertebrotomy
B. Viborg’s triangle
-Tendon of the sternocephalicus m.
-Linguofacial vein
-Vertical ramus of the mandible
C. Modified Whitehouse
D. Whitehouse
Indications
-Chorioids
-Loss of potency of nasopharyngeal orifice
Guttural Pouch Mycosis
Etiology
-Aspergillus fumigateurs: most commonly
-Diphtheric membrane
-Necrosis of underlying structures: Carotid artery
C/S
-Epistaxis
-May be mild and intermittent initially
-Severe nose bleeding eventually
-Bleed to death rapidly
-Dysphagia
-Respiratory noise
-Horner’s syndrome
Dx
-Endoscopy
-C/S
Tx
-Antifungals: variable and slow results
-May need nutritional support
-May need esophagostomy tube if dysphagic
-Enilconazole
-Fluconazole
-Systemic anti fungal: Itraconazole
-Remove diphtheric membrane
-Months of treatment if no artery involvement, which requires surgical intervention
Surgical
-Semi-emergency if vessels are involved
-Occlude affected artery
-Coils or balloons
-Retrograde flow! occlude both sides of lesion
-Fluoroscopic guidance
Prognosis
-50% of horses bleed to death
-Neurologic deficits may not resolve or take months to recover
Temporohyoid Osteoarthropathy (THO)
-Progressive disease of middle ear
-Anatomy: affects temporohyoid joint
-Stylohyoid, tympanohyoid, squamous part of temporal bone
Etiology
-Inner or middle ear infection
-Joint fuses: possible fracture of petrous bone.
-CNVII, CNVIII damage
-Degenerative process
-Can also involve CNIX, CNX
C/S
-Variable
-Early: head shaking, ear rubbing, resistance under saddle
-Oral exams and teeth floating important
-Acute neurological deficits
-Vestibulocochlear, Facial nerve, Glossopharyngeal nerve.
-Asymmetric ataxia, head tilt towards affected side, spontaneous nystagmus - slow towards affected side.
-Facial paralysis, decreased tear production, inability to close eye
-Dysphagia
Dx
-Endoscopy of both sides
-C/S
-CT
-Radiographs
Tx
-Medical: mild cases. Systemic antibiotics, NSAIDs.
-Surgical advanced cases
Prognosis
-Fair: near signs may persist >1y to resolve
THO
THO Surgical treatment
-Goal: relieve pressure on temporal bone
-Partial stylohyoidectomy: bone tends to regrow
CERATOHYOIDECTOMY: remove ceratohcyoid bone
Trachea - Tracheotomy
Emergency procedure if complete airway obstruction
Procedure
- Junction of cranial and middle third of the neck (clip)
- Rough prep
- Local anesthetic
- Final prep (skip if horse can’t breath)
- 10 cm VERTICAL incision through skin (midline)
- Blunt dissection between bellies of sternothyrohyoideus
- Incise HORIZONTAL through annular ligament between rings (one cut)
- 1/2 -1/3 circumference. Caution with carotid artery.
Don’t cut cartilage, gets pissed off
Tracheotomy
Clean BID
Heal by second intention when no longer needed
Scar small
Lecture 42
Diseases of Equine Thorax
Thoracic Trauma
Penetratring wounds
C/S
-Shock: hypovolemic if blood loss
-Respiratory distress: quick, short, shallow breaths. Nostril flaring, increased effort, increased thoracic excursion
-Hypoventilation: cyanotic membranes
-Weakness
-Pain: stiff gait
Dx
-PE to determine extent of injury: rule out abdominal involvement = colic
-PE: thoracic auscultation
-Blood gas
-PCV/TS
Radiographs best
Ultrasound better
-Wound exploration
-Thoracocentesis (U/S guided)
-Thoracoscopy
Blood gas
pH normal: 7.35-7.45
PCO2: 35-45 mmHg
HCO3: 22-26 mEq/L
Steps
1. Look at the pH
2. Look at the PCO2
3. Look at the HCO3
Tx
Triage
-Treat and diagnose at the same time
-Don’t pull the object out until you are ready to deal with the pneumothorax
-Pack IMMEDIATELY and bandage to decrease air in the chest
-Treat shock: expand blood volume (IV catheter and IV fluids)
-Remove fluid and air from the thorax
-Supplemental O2
Pain control
-NSAIDs
-Multimodal (opioids, intercostal nerve block, etc)
Systemic antibiotics
-Penicillin or Naxcel
-Gentamicin
-Metronidazole
Wound Care
-Seal the wound
-Loban dressing works well
-Stent bandage: tie some loops with suture adjacent to the wound. Apply a sterile (or at least clean) suck towel over the wound
-Umbilical tape
Tetanus toxoid
Treat pneumothorax: can develop into sepsis
Treat hemothorax
Treat the development of sepsis: flush chest with saline, use chest tube.
Thoracic Trauma Tx & Px
- Jeckson Pratt Drain
-Closed suction drain. Empty bulb, negative pressure - Chest tube placed dorsally: removes air
- Chest tube placed ventrally: removes fluid
- Heimlich valve: one way valve
Prognosis
-Good without abdominal involvement
-Guarded if septic pleuritic (about 50% die or are euthanized)
Rib Fractures
Etiology
-Severe blunt trauma
-More common in foals
-Neonates: dystocia from foaling mare
C/S
-Possibly subclinical
-Increased Respiratory effort
-Pain: Colic
-Relunctant to move
-Grunting or groaning on palpation
-Crepitus
-Rarely penetrate lung
-Flail chest: multiple ribs broken dorsal and ventral
Dx
-Adult horses: ultrasound is best
-Foals: palpation standing or dorsal recumbency
Ultrasound better than radiographs
-Can see underlying pathology, fluid, pulmonary contusions, pericardial fluid, # ribs affected, degree of fragmentation
-Radiographs
-CT/MRI
Tx
-Pain control: multimodal, NSAIDs
-Restricted exercise
Indications for surgical repair (foals)
-Displaced fractures near heart
-Multiple fractures
-Internal injuries
Prognosis
-Good to excellent without internal injuries. Usually heal very well
Pneumothorax
Etiology
-Disruption of thoracic cavity
-Air infiltrating through tissues to thorax from outside structures: axillary wounds, tracheal wounds, esophageal wounds.
C/S
-Increased respiratory effort
-Tachypnea
-Dyspnea
-Cyanotic MMs
-Distress
Tx
-Supplement O2
-Seal the hole
-Remove the excess air to allow the lung to re-inflate
Dorsal
-Indwelling dorsal chest tube with Heimlich valve
-Be aware of re-expansion pulmonary edema!!
Prognosis
-Good with uncomplicated cases
-Poor with traumatic wounds: typically other confounding factors
Hemothorax
Etiology
-Trauma: often with penetrating wound: nice growth medium for microbes
C/S
-Increased respiratory effort
-Tachypnea
-Dyspnea
-Pale mucous membranes
-Stiff movement
-Hypovolemic shock
Dx
-Determine cause
-C/S
-Auscultation
Ultrasound
-Radiographs
-Thoracocentesis
Tx
-Treat cause
-Treat blood loss
-Drain blood: aseptic, intermittent drainage vs. indwelling drain
-Pain control
-Systemic antibiotics
Prognosis
-Fair to good if sepsis does not develop: risk of pleural adhesions
-Guarded if sepsis develops: commonly does
Subcutaneous Emphysema
Etiology
-Wound that sucks air
Axillary wounds
C/S
-Air under the skin
-Complicated: respiratory
-Can lead to pneumothorax or pneumomediastinum
Sequela
-Pneumomediastinum: air around the trachea (black arrows). Easier visualization of the aorta, pulmonary arteries, and pulmonary veins
Tx
-Prevent air sucking: bandaging, suture, restrict movement, remove air from thorax
Prognosis
-Excellent without complications
-Air absorbs 24-48 hours
Diaphragmatic Hernia
Dx?
Surgical Procedures in the Thorax
Thoracoscopy
Thoracotomy & Rib resection
Lung biopsy
Thoracoscopy Indications
-Exploration: penetrating wound, neoplasia, diaphragmatic hernia, pleural effusion of unknown origin, ID best approach for thoracotomy.
-Facilitate drain placement
-Transect pleural adhesions
-Guided pulmonary biopsy
-Window pericardectomy
Procedure
-Make portals between ribs
-Can potentially perform standing: do not have ventilation option, pressure seals incomplete mediastinum
-Unilateral pneumothorax
-Collapsed lung allows for easy exploration, remove air at end.
Complications
-Injury during trocar placement, lung diaphragm
-Laceration of intercostal vessel
-Pain at surgery site
-Residual pneumothorax
-Failure to expose and identify area of lesion
Rib resection and Thoracotomy
Indications
Refractory pleuropneumonia
-Lung abscess
-Chronic pleural effusion
Purpose
-Drainage
-Lavage
-Reduce adhesions
Procedure
-First make sure horse can tolerate pneumothorax
-Standing preferred
-Use of U/S to determine approach location
-For rib resection: remove 20-25 cm piece of at least one rib, elevate periosteum, OB wire or oscillating saw to cut bone
Lung Biopsy
Indications
-Mass: neoplasia, granuloma
Procedure
-Thoracoscopy-guided best
-Must seal lung to prevent closed pneumothorax . Ligature, laparoscopic staplers, pre-tie ligature
Lecture
General Evaluation of the Equine Lower Respiratory Tract
Anatomy Review
-Equine lungs lack deep interlobar fissures and are distinct lung lobes
-Left lung: cranial and caudal lobes
-Right lung: Cranial, intermediate, caudal lobes
-Bronchioles: lobar, segmental, subsegmental
Physiology
Vascular supplies
-Pulmonary circulation: low pressure, low resistance
-Bronchial circulation: high pressure. nutrient supply to lymphatics, vascular & airway components
Equine LRT - History, PE, Dx Tools
History
-Age
-Breed
-Environment
-“Job” (ex: exercise induced hemorrhage)
-Recent events
-Endemic diseases
-Trauma
-Vaccination history
-CHIEF COMPLAINT
-Prior medical problems
PE
-Inspection:
Demeanor, posture, mental status, movement, deformations, nasal discharge, cough, respiratory effort (dyspnea), RR. Nasal hematoma can block sinuses, fluid or mass can obstruct. Nostril flare = Increase respiratory effort.
-Auscultation:
Under quiet conditions
Crackles, wheezes, trachea, bronchi, lung. Rebreathing bag.
-Palpation & Percussion: nostrils (airflow, odor). Area over sinuses, lNs, larynx/pharynx. Trachea, jugular (see if it coughs). Neck, chest.
-LNs in the intermandibular space, diffuse
Vocabulary
Normal respiration
-RR and effort
-Small abdominal component during expiration
-Eupnea: normal respiration
-Dyspnea: difficult breathing
-Tachypnea: rapid, shallow breathing
-Hyperpnea: increased frequent and depth of breathing
-Apnea: no discernible breathing
-Hyper/hypoventilation: alveolar ventilation - PaCO2
-Nasal discharge: uni or bilateral. Serous, mucoid, purulent, epistaxis.
-Cough: dry, moist, frequency, productive, hemoptysis.
-MMs: cyanotic, injected, pale, icteric.
-Dyspnea: inspiratory, expiratory or mixed
Diagnostic tools
-Imaging
-Respiratory sample collection
-Pulmonary function resting
-Blood work
-Endoscopy
-Radiographs
-Ultrasound
-Thoracoscopy
-Scinctigraphy
-Imaging
Respiratory Endoscopy
- Visualization
- Determine additional exams
- URT
- LRT: trachea, bronchi
Trachea: 1-5
-Sensibility, general conformation.
-Presence of secretions: mucus, non specific sign of inflammation, scoring (1-5) None, little, moderate, marked, large, extreme
-Presence of blood: sign of hemorrhage (timing post exercise 30-120 mins post exercise = EIH). Scoring
Bronchi:
-Determine side to sample
-Septum score: age, inflammation, edema.
Pulmonary Radiographs & Ultrasound
-Maybe difficult to obtain
-Only laterals possible in the adult
-Four films needed to cover lung field
-Expensive equipment
-Chest movement restricts techniques
Indications:
-Infectious LRT Dz
-Non-infectious LRT Dz
-Pneumothorax
-Diaphragmatic hernias
-Others
Other imaging techniques
-Cardiac ultrasound
-Thoracoscopy (pleuropneumonia, exploratory)
-Pulmonary scintigraphy (very advanced)
Respiratory Sample Collection
Tracheal lavage/Wash
Not super specific
Collect secretions from LRT
Culture and cytology
Techniques:
-Trans-tracheal: sterile preparation, stab incision, clip, small incision. Cheap equipment, no contamination.
-Trans-endoscopic: fast, no outside sigs, visualization, equipment costly, 30 ml saline injected, contamination LRT. Specific kit to protect against contamination.
EDTA tube (cytology), red top tube. Transport media suitable (aerobic and anaerobic culture)
Variable Results
-Epithelial cells
-Neutrophils: infection
-Eosinophils
-Erythrophages/hemosiderophages.
Bleeders three types: Neut, eosin, and erythrophages
Bacteriology interpretation
-Cytology, Nb colonies not same as type of bacteria
Virology
-Clinical: nostrils
-Subclinical: trachea
-PCR for: EHV1-2, EHV-4,5, Influenza
Bronchoalveolar lavage
Foamy secretion, preferred method for non-infectious
Endoscope:
-Visualization
-Cost
-Maintenance of equipment
-Recovery volume, need 250-500 ml sterile fluid.
BAL tube
-No visualization
-Low cost
-Recovery time
-Sedation (alpha-2 agonist, butorphanol)
-Restraint, local anesthetic
-Wedged position
-Instill 250-300 ml of saline
-Recovery with syringe aspiration or vacuum
-Aspect: surfactant, mucus, hemorrhage.
-Cytology after centrifugation/processing
Thoracocentesis
-Verify the presence of pleural effusion
-Collect fluid for cytological evaluation: infection, inflammation, trauma, neoplasia.
-Collect fluid for bacterial culture & AM sensitivity
-Treat (pleural effusion, hemothorax, pneumothorax)
-For local therapy
-Collect different fractions of fluid
-Normal pleural fluid = <3mg/dl protein, <10,000 cells/uL (non-degenerative neutrophils; mononuclear and mesothelial cells), straw color, clear, and odorless, <10ml
-Septic pleural fluid = >10,000 cells/dL, presence of degenerate neutrophils, cloudy, fibrin clots often present, >3 mg/dL protein, glucose <40 mg/dL, lymphocytes = chyle effusion, abnormal lymphocytes = lymphosarcoma
Pulmonary biopsy
Indications: only in combination with other techniques
-Diffuse lung disease
Contraindications: respiratory distress, hemoptysis, hemorrhage, pneumothorax, infection. NOT if RESP DISTRESS
Transthoracic
Transbronchial
Pulmonary Function Testing
-Classic test
-Oscillometry
-Plethysmography
-Forced expiration
-Others
Arterial Blood gas
-Mid-neck jugular vein
-Base of neck
Careful with carotid artery can be poked
-Heparinized syringe
-Anaerobic conditions
-Cooling
-Correct sample temp
PaO2 = 95-100 mmHg, PaCO2 = 40-45 mmHg
-Endoscopy while exercising
-Blood work
Lecture
Diseases and Disorders of the LRT 1
Recurrent Airway Obstruction - Severe Equine Asthma (a.k.a Heaves, COPD)
-Naturally occurring respiratory disease characterized by periods of reversible airway obstruction caused by neutrophil accumulation, mucus production and bronchospasm
Etiology
-Bacteria: endotoxin, toxins
-Molds: allergens, mycotoxins
-Forage mites: allergens proteases
-Plant debris
-Inorganic dust components
-Noxious gases: ammonia, hydrogen sulfide, methane
Triggers
-Inflammatory factors: allergens, respiratory infections, work
-Irritants: temperature change, exercise, cold air, strong odors
-Others: pollutants, gastric reflux
C/S
-Cough
+/- nasal discharge
-Poor performance
-Dyspnea: Increased respiratory effort
-Nasal flare and abdominal push
-Normal to increased RR
-Exercise intolerance
Severe cases: weight loss, hypertrophy of external oblique and rectus abdominus mm. “heaves line” Pulmonary hypertension. Wheezing and severe distress.
-Triggers in environment
-Recurrent and reversible: eliminate triggers and it goes away
-Bronchoconstriction/hyperreactivity
-Mucus production
Dx
-PE, history, auscultation
-Endoscopy: mucus accumulation. Tracheal hyper-reactivity
-BALF cytology >15% neutrophils
-TW not reliable for diagnosis
-Hematology and serum biochemistry: normal
-Radiographs: limited value
-Skin test: limited value
-Pulmonary function testing: advanced test
Tx
-Environmental control
-Systemic or local corticosteroids
-Steam, soak the hay
-Bedding: low dust, paper, cardboard
-Hay: avoid hay, silage or pelleted better
Medical Tx
-Systemic Dexanethasone (laminitis risk)
-Prednisolone
-Inhale corticosteroids: Beclomethasone diproprionate, Fluticasone propionate
Circlesonide: $200 for 15 days only FDA approved bronchodilator for horses
Bronchodilators
-B-2 adrenergic agonist: Clenbuterol, Terbutaline sulfate, Fenoterol, albuterol, pirbuterol, salmeterol.
-Methylxanthines (theophylline, pentoxifylline)
-Anticholinergics: atropine, Ipratropium bromide
Prognosis
-Affected horses will always be susceptible
Hx
-Middle age horse with a cough
-Summer pasture equine asthma in the South
-Winter asthma too
SEA forms
- Recurrent airway obstruction
-Stabled horses
-Get better on pasture
-Middle aged
-Breed: no
-Family: yes - Summer pasture associated
-Pastured horses
-Stay sick on pasture
Wheezes due to obstruction in airway constricted, crackles due to accumulation of mucus
Pathophysiology
- Airway obstruction
- Airway inflammation
- Mucus accumulation
Metered dose Inhalers Delivery System
Aeromask
Aerohippus
Equine Haler
Nebulizers & Jet Ultrasonic Mesh
Nebul from Agritronics
FlexiNeb
Jet Ultrasonic
Aservo Equihaler
-Adapted to the horse
-Gets activated in the respiratory system
-Soft mist technology
-Prodrug Ciclesonide = Des-ciclesonide (airway epithelium)
-SEVERE asthma
-Day 1-5 : 8 puffs BID, Day 6-10 : 12 puffs SID
-10-15 day treatment $200
Inflammatory Airway Disease - Mild Equine Asthma - MEA
Definition
-Poor performance, exercise intolerance, or coughing with out without excess tracheal mucus
-No increased respiratory effort
-No septic LRT inflammation detected on BALF cytology
-Pulmonary dysfunction
Etiology and Epidemiology
-Not well understood yet
-Predominantly young horses
-20-80% of racehorses in training
C/S
-Poor performance
-Difficult recovery after exercise
-Accumulation of mucus
-Cough, nasal discharge (both variable)
-No dyspnea
-No systemic signs
-No CBC
-No clinpath
Dx
-History, C/S
-BALF cytology
-Pulmonary function, exercise testing, others?
Tx
-Environmental control
-Medical: corticosteroids, bronchodilators, omega 3 fatty acids (DHA), sodium cromoglycate, acetylcystein, antibacterial, others.
Hyperreactivity = horse coughs easily when endoscopy due to inflammation
Lect LRT - 2
Exercise Induced Pulmonary Hemorrhage
Etiology
-alveolo-capillary membrane rupture
-Source of blood: pulmonary circulation
Exercise
-Pulmonary artery 20 mmHg to 90 mmHg
-Pulmonary pleural space -5mmHg to -60 mmHg
Risk Factors
-Pulmonary capillary hypertension
-Rheological properties of blood
-Subatmospheric pleural space
-Coagulopathy
-Airway obstruction
-Locomotor forces
-Pulmonary fibrosis
-Bronchial neovascularization
C/S
-Epistaxis (bilateral)
-Poor performance
-Rule out other problems, difficult to asses
Dx
-History & PE
-Endoscopy
30-120 mins after intense exercise (up to 7 d)
-Grades 1-4 related to severity
-Cytology either TW or BALF: more sensitive than endoscopy
-RBC >/= 1 week
-Hemosiderophages >/= 21days
-Erythrophages the longest
-Pulmonary radiographs: limited torso-caudal opacification possible
-Ultrasound should be normal
-Blood work should be normal
Ddx
EIPH
-Pulmonary abscess
-Trauma
-Pneumonia
-Foreign body
-Neoplasia
Epistaxis
-All of the above
-Guttural pouch mycosis
-Progressive ethmoidal hematoma
-Thrombocytopenia
-Trauma
-Neoplasia
Tx
-Prevent stress rupture of capillaries
a. Decrease pressure in pulmonary capillaries - Furosamine
b. Increase alveolar inspiratory pressure (less negative)
URT: correct dynamic collapse, “Flare strips”
LRT: bronchodilators, corticosteroids, reduce environmental dust
-Decrease inflammation and angiogenesis
-Reduce bleeding
a. Coagulopathy
b. Platelet function
-Maintain capillary integrity
Other options: Vitamin K, Aspirin, Biflavinoid, Vitamin C, Aminocaproic acid.
Prognosis
-1 episode = more episodes, affects performance on carrier
Pneumonia in Adult horses
Bronchopneumonia and pleuropneumonia
Bacterial Diseases of LRT
Airways
1. Bacterial Bronchitis
2. Septic IAD
Parenchyma
1. Pneumonia usually secondary to URT infection
Extension
1. Bronchopneumonia
2. Pleuropneumonia
Aspiration of bacteria from nasa-pharynx and oral cavity hematogenous spread (rare in adult)
Pneumonia
Etiology
B-hemolytic streptococcus Gram (+)
-Streptococcus equi subs zooepidemicus (normal bacteria)
-Non-enteric Gram (-)
Pasteurella spp, Actinobacillus spp (Pseudomonas spp, Contaminant) Bordetella bronchiseptica
-Enteric Gram (-)
E. coli, Enterobacter, Salmonella, Klebsiella spp.
-Anaerobes Less favorable prognosis
Bacteroides spp, Clostridium spp. Peptostreptococcus etc.
Epidemiology
Any age or breed
-Young racehorses
Prolonged transportation
-General anesthesia, upper airway surgery
-Recent viral respiratory disease
-Aspiration after choke (obstructed esophagus)
Pathophysiology
-Colonization of lung by opportunistic bacteria
-Weakened immune defenses
-Massive number of bacteria
Lowered head posture is essential for much-cilliary clearance in horses
Head restraint may be the single most predisposing factor during long distance transport
- Infiltration with inflammatory cells
- Damage to epithelium and endothelium
- Flooding with inflammatory cells, debris, fibrin
- Exudative pleuropneumonia
- Fibropurulent pleuropneumonia
- Fibrin deposits
- Organizational stage (pleural peel)
Early intervention before fibrinous stage is crucial
C/S
-Exercise intolerance
-Cough
-Nasal discharge
-Fever, anorexia, depression
-Change in aspect of nasal discharge
-Tachypnea, dyspnea, shallow breathing.
-Pleurodynia (pleural spaces painful)
-Elbows tucked in
-Sternal edema
-Changes in pulmonary auscultation/percussion
-Endotoxemia
-High HR, increased CRT, dry MMs.
Decreased lung sound in lower lung muffled sounds on percussion
Dx
-Hematology and biochemistry: inflammation
-Endoscopy: secretions, location
-Respiratory samples: TTW NO BALF
-Tracheal wash: culture and cytology
-Ultrasound: peripheral lung, pleura
-Radiographs after draining of fluid
-Thoracocentesis
-Thoracoscopy
Tx
-Antimicrobial therapy
Penicillin, Gentemycin, Metronidazole
-Systemic: choose broad-spectrum, based on culture
-Minimum 10 days or > when signs resolve
-Pleural drainage (tube with one way valve)
-Ancillary treatments (NSAIDs, analgesics)
-Hydration
-Nutrition
-Oxygenation
-Complications
Pleural drainage Indications
-Volume sufficient to cause respiratory distress
-Emphysematous
-Fetid odor
-Evidence of sepsis
Do it early before fibrin
-Ultrasound guided
-Determine best location
-One or both sides (fenestrated mediastinum)
Pleural Lavage
-Use of fibrinolytic agents
-Thoracoscopy
-Thoracotomy
-Complications: Phlebitis, thrombosis, diarrhea, pneumothorax, cellulitis, endotoxemia, laminitis, abscess.
Prognosis
-90% survival
-60% athletic performance
-Low if hemorrhagic necrotizing pneumonia
Pneumonia in Foals
- Rhodococcus pneumonia
- Other causes of pneumonia in foals
Rhodococcus qui
-Rod shape, spherical, Gram (+) facultative intracellular bacterium
-Intracellular survical
-Ubiquitous in soil
-Sporadic or endemic
-Environment and management
Zoonosis for immunocompromised
Etiology
-< 6 mots
-Usually 1st few days of life
-Only foals seems susceptible
-Primary: inhalation
-Secondary: ingestion
-Inhalation (ingestion), lung, sputum swallowed, replication in intestinal tract, manure, inhalation, spread.
-Immunocompetency
-Outcomes: healthy or sick (regressor or progresso)
C/S
-Acute/subacute
-Mild fever
-Occasional cough
-Increased respiratory rate
-Decreased appetite, lethargy, fever
-Cough, tachypnea, dyspnea
-Acute respiratory distress, death
-Subclinical, abnormal auscultation
-Chronic suppurative bronchopneumonia
-Extensive pulmonary abscessation
Dx
-Difficult early diagnosis
-Slow progression, slow functional compensation
-History and PE
-Hematology and biochemistry: Hyperfibrinogenemia, SAA, neutrophilic leukocytosis. Serology? ELISA for Vap-specific Ig.
-Radiographs: alveolar pattern, ill defined regional consolidation. Nodular regions and mediastinal lymphadenopathy
-Ultrasound: irregularities, focal areas of consolidation
-Extrapulmonary locations
TTW
-PCR with amplification for Vap A
-Culture and sensitivity (increasing resistance)
-Always interpret in conjunction with: Clinical signs of LRT disease, cytologic evidence of septic airway inflammation, radiographs or ultrasound of bronchopneumonia
Tx
-Address respiratory distress
-AB: Macrolides and Rifampin
Erythromycin + Rifampin
Azithromycin + Rifampin
Clarithromycin + Rifampin
Erythromycin = hyperthermia and diarrhea in foals. Colitis in mares
Ancillary
-Nutrition
-Hydration
-Environment
-Oxygenation
-NSAIDs
-Guided by resolution of clinical signs (3-8 weeks)
-Normalization of fibrinogen
-Resolution of u/s and radiographic lesions
Adverse effects
-Enterocolitis in mares: Clostridium difficile
Prognosis
-70-90% survival
Control and prevention
-Ventilation, dust, density, isolation
-Address pasture contamination
-Screening: visual inspection, TPR (2x/week)
-Laboratory: hematology, fibrinogen, SAA etc.
-Imaging
-Passive immunization: hyperimmune plasma (HIP) 1L at < 48 hrs and 2-4 weeks of age
Other Causes of Pneumonia in Foals
Lect URT disease 2
Common Respiratory Viruses and Pathogens
Nasal secretion sent to lab in whole EDT tube herpes in the WBCs buffy coat
Equine Herpes-1
-Whole Blood EDT tube
Equine Rhinitis
-Urine
Equine Streptococcus equi subsp zooepidemicus
-Aspirate from draining lymph node
Equine Streptococcus equi subsp equi
-Aspirate from draining LNs
Equine Herpes Virus -2, 5
-Blood
-Bronchoalveolar lavage
EVH-4 most frequently Isolated, Sep-Oct
Comprehensive Equine Respiratory PCR
EHV-1
EHV-4
Equine Influenza Virus EIV
Streptococcus equi subs equi
Equine Rhinitis A virus
Equine Rhinitis B Virus
Similarities
C/S
-Fever
-Cough and nasal discharge
-Exercise intolerance
Tx
-Rest
-Low dust
-Supportive care
-Management: NSAIDs Benamide
-Rest 1 week/day of fever, 2 weeks after end of coughing
Dx
-Nasopharyngeal swab
-Nasal swab
Prevention
-Biosecurity
-Vaccination: recommended every 6 mts for horses that participate in events EIV and EHV
-Isolation for 28 days
-Sanitize equipment and only use yours
-Throughly wash your exposed skin
-Practice preventative hygiene
Equine Influenza Virus
EIV
-H3N8 (A/equine/2)
-RNA
-Antigenic drift
-Eurasian
-American: South American, Kentucky, Florida (clade 1 & 2)
Vax protects against both
Epidemiology
-Stress of shipping and mingling
-Age: young and old
-Naive or unvaccinated
-Transmission: direct, aerosol, breathing space. Indirect
-Incubation: 1-3 days
C/S
-Rapid spread in naive horses
-Severe clinical signs
-Fever
-Deep dry cough (may last)
-Serous to much-purulent nasal discharge
-Edema?
-Complications: secondary infections, myositis
-Recovery usually uneventful
Depends on immune status and virulence
Dx
-ELISA: nasopharyngeal swab
-PCR: nasopharyngeal swab
-Virus isolation: nasopharyngeal swab
Prevention
-Biosecurity
-Vaccination: risk based IM or intra-nasal (inactivated)
-Requirement every 6 months
EHV-1 & EHV-4
EHV-1
-Syndrome: respiratory, abortion, neurologic
-Viremia: cell-associated
-Translocation: from airways
EHV-4
-syndrome: respiratory (abortion)
-Viremia: rare
-Translocation: rare
Etiology
-Ubiquitous
-80-90% of horses infected before age 2
-Double stranded DNA virus
-Subfamily Alphaherpesvirinae
Epidemiology
- Respiratory Disease
- Abortion
- Neonatal death
- Myeloencephalopathy
- Pulmonary??
-Distribution: worldwide
-Incubation 2-10 days
-Target tissue: airway epithelia, local LN, viremia, vascular endothelium
-Latency: trigeminal ganglia, T-lymphocytes
-Pathogenesis: focal epithelium, erosion, inflammation, vasculitis.
-Pattern: infection, latency, reactivation, transmission
-Outbreaks
C/S
-URTD: submandibular LN adenopathy, transient pyrexia (bi-phasic), mild mucopurulent discharge, inappetence, lethargy, edema, epiphora.
-Abortions: last trimester, without impending signs. Fetus no evidence of autolysis. EHV-1 more frequent abortions than EHV-4
-Weak foals, unable to nurse = death
-Myeloencephalopathy
-Pulmonary vasculotropic infection
Dx
-Fluorescent Ab: NP swab
-PCR
-Virus isolation
-Serology
Tx and Prevention
-Supportive care
-Biosecurity
-Vaccination
-Adult non-breeding vaccinate every 6 mts
Arteritis Virus - Equine Arteritis Virus - EAV
Etiology
-Carrier Stallion natural reservoir
-Venereal transmission
-Contaminated frozen semen
Reportable
-Vertical transmission
-Persistance in male accessory sexual glands
Pathogenesis
-Focal epithelium erosion, inflammation, viremia, pan vasculitis, persistent infection
C/S
-Most infections are subclinical
-Fever, depression, anorexia
-Resemble other URTD
-Conjunctivitis, edema, stiffness of gait, rash
-Foals: interstitial pneumonia, pneumoenteritis
-Abortion: 3-10 mts following respiratory infection.
-Fetus partially autolyzed.
Dx
-PCR: semesn, fetal tissue, swab
-Virus isolation: nasal swab, EDTA, placenta, etc.
-Serology: blood or serum
Tx and prevention
-Supportive care
-Biosecurity
-Vaccination
Lect URTD -3
Strangles - Streptococcus equi subs equi
Guttural pouch swelling
-The guttural pouch is the out pouching of the Eustachian tube that connects the throat to the middle ear
-There is one guttural pouch on each side
-Each pouch has a lateral and medial compartment containing sensitive vascular and nervous structures
Etiology
-Streptococcus equi subs equi
-Horse might be shedding it
-Frequent, old disease
-Outbreak worldwide
Epidemiology
Factors
-Horse age and immune status
-Virulence
-Management
Transmission
-Direct and indirect inhalation
-Encubation: 10-14 days
Shedding
-1-4 days after fever - isolate
-Last 2-6 weeks after purulent discharge
Carrier: years
Environmental persistence
-Surface 1 week
-Water 1 month
Pathogenesis
-Submandibular LN and supra pharyngeal LN preference
-Attachment to cells of crypts of lingual and palatile tonsils
-Then Mandibular and supra pharyngeal LNs
Influx of neutrophils
-Failure of neutrophils to kill due to hyaluronic acid capsule, antiphagocytic SeM proteins, Mac proteins**
-Bacterial enzymes cause abscess formation
-Spread to other organs
-Abscess in LN, thoracic and abdominal organs
-Bastard Strangles
C/S
-Fever
-Lethargy
-Decreased appetite
-Abscess (LNs)
-Purulent nasal discharge
-Cough
Complications
-10% of horses will remain chronic carriers after an outbreak
-Respiratory distress
1. Bastard strangles: metastasis
2. Purpura hemorragia and myositis (immune mediated)
3. Carrier (GP, sinus, decreased clearance)
Dx
-Hematology and biochemistry
-Imaging: endoscopy, radiographs, ultrasound
-Specific: nasopharyngeal wash»_space;> swab for strangles
-Needle aspirate
-Serology: screening - not very useful
-Culture: takes longer and don’t have the time
PCR test kit
-Rapid results
Prevention
-Quarantine and screening: new horses, returning horses, temperature, serology
-Outbreak: isolation, stop movement
-Biosecurity measures, traffic light system
-Release: 3 weeks, 3 tests to be out of quarantine
-Carrier: serology, qPCR
Prevention
-Vaccination
-Risk based
-Intranasal vaccine: MLV, give last, transient clinical signs
-IM vax: killed hind quarters, local reaction
Treatment
-Supportive care: housing, food, water
-Topical treatments: abscess maturation and drainage
-NSAIDs
-Antimicrobials are controversial:
NO: not needed, delayed abscess maturation and immunity
Yes: respiratory distress, bastard strangles, purpura hemorragia, carriers, management.
-Preventative tracheotomies
Penicillin effective
Ceftiofur effective, 3-4 days, used exclusively during 2nd phase of outbreak
Guttural Pouch Complications
-Irritation
-Empyema
-Chondroids: pus stones
-Unilateral nasal discharge
Outbreaks - find the carriers
Guttural Pouch Empyema
C/S
-Pus in the guttural pouch (Strep equi equi)
-Guttural pouch: irritation, empyema, chondroids
-None or systemic signs, cranial nerve issues possible
Dx
-Endoscopy (qPCR)
-Radiographs
Tx
-Conservatice
-Lavage: saline, acetylcysteine, penicillin gel
-Surgery
Prognosis
-Good
