2. Toby O’Brien
2 Year Old Male Neutered Pug
History
6 week history of vomiting
Trial treatment with metronidazole, amoxicillin, maropitant and
omeprazole
Gastric and intestinal biopsies taken –NAD
Endoscopy – fluid in oesophagus
Further questioning: Toby had mostly been regurgitating. He was
bringing up food/fluid appeared frothy and contained undigested food
3. Differences between Vomiting and
Regurgitation
Vomiting Regurgitation
Prodromal Nausea Yes No
Retching Yes No
Substance of food Digested food or bile Often undigested/fliud
and froth. No bile
pH Acidic or Alkali Alkali
Time related to feeding Anytime Anytime but often related
to feeding
4. Common Ddx for Chronic Regurgitation
Megaoesophagus (Acquired or Congenital)
Vascular Ring Anomaly
Oesophagitis
Foreign Body
Stricture
5. Thoracic Radiographs
Patient should be preferably unsedated
Some sedative agents can cause dilation of the oesophagus and therefore can
imitate a megaoesophagus.
Can use contrast medium (barium) but care needs to be taken as if this is
aspirated difficult for lungs
11. Further Tests
Once ruled out Ring and presence of strictures
Start investigating for cause of megaoesophagus
Ach Antibodies to test for Myasthenia Gravis (takes several days to come back)
Basal Cortisol levels or an ACTH Stim Test to test for Addison’s
T4 and TSH levels to check for hypothyroidism
CK and AST levels (muscles damage)
12. Toby’s Results
Haematology
Mild leucocytosis with mild neutrophilia
Biochemistry
Mild hypoalbuminaemia
T4 26.1
TSH – 0.09
Basal Cortisol – 39
Because low did ACTH stim test
Pre – 33
Post – 271
NOT Addison’s
ACH receptor Antibodies: 072 – High therefor diagnosis of Myasthenia gravus made
13. Complications of Megaoesophagus
Aspiration Pneumonia
This should be checked for on the initial radiographs.
If present:
Treat with IV antibiotics
If not present:
Risk of developing AP in future thereforewater anf food must ge biven from a
height and dog must be monitored for signs of development of an aspiration
pneumonia (cough) and mucopurulent discharge
The most common reason for death in dogs with megaoespophagus
Approx 48% of dogs with megaoesopahgus will have aspiration pneumonia
14. Back To Toby….
Normal Basal Cortisol levels
ACTH Stim Test negative
But…
ACTH Antibodies above ref range
Therfore diagnosed with focal myasthenia gravis
15. Myasthenia Gravis
Can be Congenital or Acquired
Can be focal or diffuse
Congenital present less than a year old – caused by lack of Ch receptos
Acquired – An immue mediated disorder in which Autoantibodies form against the
nicotinic Acetylcholine receptors at the neuromuscular junctions
Dogs have striated muscle the entire length of the oesophagus and therefore it can
be focally affected
Diffuse causes exercise intolerance
Can be caused by Thyoma (mass in cranial mediastinum on thoracic radiograph)
Treatment: hhjhjhjhjh
16. Prognosis
Poor Prognostic Factors for Acquired Myasthenia Gravis
Over 13 months old
Aspiration Pneumonia present
Good
If responds to dietary
If the underlying cause can be treated
17. Management
Feed from height while waiting in test results
Uses gravity to aid food passing down oesophagus to stomach
Food consistency – Try meatballs or more liquid type food
18. Pyridostigmine bromide
Kept in for 24 hours to monitor for signs of side effects to treatment.
Famotidine
Plan
Recheck in 2 weeks to see how he is getting on (still regurg or no)
Reassess antibodies in a 3 months to look for evidence of remission
Re radiograph to look for signs that the oesophagus is less dilated
19. References
Shelton et al (1990) Acquired Myasthenia Gravis. Journal of Veterinary
Internal Medicine, 4: 281–284.
Webb et al (1997) Focal myasthenia gravis in a dog. Can Vet J 38: 493-495
Richardson (2011) Acquired myasthenia gravis in a poodle. Can Vet J.52(2):
169–172.
Foy et al (2011) Cholinergic crisis after neostigmine administration in a dog
with acquired focal myasthenia gravis. Journal of Veterinary Emergency and
Critical Care 21(5) , pp 547–551
McBrearty et al (2011) Clinical factors associated with death before
discharge and overall survival time in dogs with generalized
megaoesophagus. Journal of the American Veterinary Medical Association Vol.
238, No. 12, Pages 1622-1628
BSAVA Manual of neurology Chapter 7 pages 43-47
Elwood (2006) Diagnosis and management of canine oesophageal disease
and regurgitation In Practice 28: 14-21
Regurg = A passive process associated with return of ingesta from the oesophagus a
variable period after eating. Food is often returned in the form of a 'sausage'
covered in saliva. Saliva may be regurgitated, giving the appearance of 'whipped
egg whites'.
Vomiting=an active process with prodromal signs of nausea and hypersalivation. Active contractions of the abdominal muscles results in expulsion of stomach cotnents.
Can be Primary (Idiopathic) or Secondary
Idiopathic is either congenital or acquired
Secondary Megaoesophagus can be caused by:
Myasthenia Gravis (can be congenital or acquired)
Hypoadrenocorticism (Addison’s)
Canine Dysautonomia
Polyradiculoneuritis
Further diagnostics required
Impaired transmission of action potential from nerve to muscle
26% of dogs with megaoesophagus diagnosed with Myasthenia Gravis
Golden Retrievers, GSDs and Labradors
Bimodal age of onset (2-4) (9-13)
Side effects = cholinergic and can be muscarninc and nicotinic. These can include lacrimation, salivation, defecation, nystagmus, hypotension, bradycardia and arrhythmias. If these were to occur the muscarinic effects could be reversed by administration of Atropine
Other drugs such as immune-suppresives can be added
