The choking horse Flashcards
Approach to ptyalism/drooling & hypersalivation
- General history
- Focused history
- Physical exam
- Morphological abnormalities?
If no - Functional abnormalities
Focused history
Diet
- Legume contaminated with fungus (Rhizoctonia leguminicola?) -> hypersalivation due to transient increase in saliva production
- Oral PBTZ given with Clembuterol -> transient period of hypersalivation
Dental
- Speculum, good light source, gag
Obstructive morphological abnormalities
- Retropharyngeal lymphadenopathy
- Malformation, injury, oedema (pharynx, larynx, oesophagus)
- Pharyngeal disorders (abscess, cicatrix, inflammation)
- Laryngeal disorders (epyglottic cysts, RDP Arch)
- Palate disorders (DDSP, cleft palate)
- Guttural pouch disorders (tympany & empyema)
- Oesophageal problems (obstruction & diverticula)
Painful morphological abnormalities
- Teeth (root abscess, broken teeth, abnormal wear)
- Mandible/maxilla (fractures, trauma)
- Stomatitis/glossitis
- Temporohyoid OA (pain, may also cause functional)
- Temporo-mandibular osteopathy
Stomatitis/glossitis causing choke
FB most common (glossitis)
- desiccated plant material/awns
- metal/wire
Ulcerative stomatitis
- bute toxicity
- blester beetle poisoning
Vesicular stomatitis
- viral (Poxvirus & Rhabdovirus serotype: New Jersey, Indiana)
Bacterial
- Actinobacillus lignieresi
Functional abnormalities - neuro exam
Infectious
- rabies
- viral encephalitis
- verminous encephalitis & EPM
- botulism & tetanus
- meningitis
CNS trauma
- cerebral damage/oedema
- brainstem haemorrhage
CNS masses
- e.g. cholesteroloma
Toxic
- lead poisoning
- yellow star thistle
- hepatoencephalopathy
Other
- polyneuritis equi
- Grass sickness (dysautonomia)
- THOosteoarthropathy
- guttural pouch (mycosis, neoplasia, empyema)
- Petrous temporal bone fracture/osteomyelitis
Functional abnormalities - look for muscular aetiology
- HYPP
- NMD
- PSSM
- Masseter myositis
- Hypocalcaemic tetany/eclampsia
- Myotonia
- Rectus wapitis ventralis rupture
- White snake root toxicity
- Megaoesophagus
Choke - clinical presentation
- regurgitation of food/water/saliva
- ptyalism
- dysphagia
- coughing
- repeated head extensions or retching
- anxiety
Choke - other less common clinical signs
- distention
– left jugular furrow (right side in some horses) - crepitus
– oesophageal rupture - CS of complications
– dehydration
– rr/abnormal pattern
– fever
– other signs of systemic inflammation
Diagnosis
- General physical exam
- Palpate neck and thoracic inlet
– both sides but focus on left
– thoracic inlet a common site of obstructions - Oral exam
- Thoracic auscultation
– Some may have aspiration pneumonia, esp if have had the obstruction for some time - NG intubation
– Confirms diagnosis and locates the obstruction - Clinpath
– Hydration status (PCV/TP, urea/creatinine)
– CBC
-> further information re systemic inflammation
– Electrolytes
– Acid-base status - Radiography
- US
Radiography
- Survey plain films
- Determines extent and location of the obstruction
- Contrast radiography
– Barium (iodinated contrast for rupture)
–> barium paste PO
–> liquid barium (cuffed NG tube)
– Double contrast
–> liquid barium by cuffed NG tube under pressure
–> Gives best definition
– Additional information
–> Rupture
–> Aspiration pneumonia
Medical management (spontaneous resolution)
- remove all feed & water
– NPO (nothing per os) - IV fluids
- NSAIDs/analgesics
- sedation (for relaxation of the oesophagus)
- oxytocin (for proximal obstruction)
- ideally place in stall without bedding (at least for 24-48h)
Medical management (assisted resolution)
- oesophageal lavage & drainage
– sedation
– maintain head below the thoracic inlet
– pumping lots of water in via NG tube into oesophagus to try macerate and dissolve obstruction
– use a double lumen NG tube so can put water through 1 side, empty water and contents through the other lumen - aggressive oesophageal lavage
– cuffed nasotracheal and naso-oesophageal tube to prevent aspiration
– standing or under GA - GA
– minimises aspiration
– aids relaxation
– if impaction hard/difficult/very long
General considerations for medical management
Once relieved prevent re-obstruction
- repeat endoscopy to assess mucosal damage
- fusiform dilation predisposes to re-obstruction
- small quantities soft feed 48h post relief (almost liquid for 1st few days)
- provide electrolytes and fresh water
- anti-inflammatories
– care with NSAIDs as may exacerbate the
oesophageal ulcerations
– avoid oral, go IV
- broad spec antibiotics?
– if the obstruction has been there for quite a while, aspiration pneumonia is quite likely
– particularly if find there are signs that indicate systemic inflammation or abnormal thoracic auscultation or abnormal thoracic US -> consider broad spec AB
Surgical - Oesophagotomy (primary closure)
- Incision above/on obstruction
- Longitudinal oesophagotomy with primary closure
– standing with tube in place
– approach dictated by location of lesion
– laryngeal hemiplegia common complication
