Dysautonomias- grass sickness and DPJ Flashcards
what is grass sickness
a generalised dysautonomia affecting primarily the enteric nervous system - causes a decrease in GI motility and secretions
Cause unknown
what age range is most affected by grass sickness
2-7 years
which months of the year is grass sickness most common
april- july
peak in may
List 6 risk factors for grass sickness
Horses on pasture
Stress
Domesticated birds in the same field
Good-fat BCS
Cool, dry weather between 7-11 degrees
Frequent worming
How does grass sickness cause disease
Decrease in GI motility from mouth to anus with a decrease in GI secretions
List the 3 types of grass sickness and what are the survival times associated with them
Acute - die rapidly/found dead- >2 days
Sub acute - > 7 days
Chronic - some survive
List 7 clinical signs associated with acute grass sickness
Severe gut paralysis - colic
Dysphagia
Nasogastric reflux
Mucous coated droppings
Muscle tremours
Sweating
Tachycardia (60-80bpm)
List 6 clinical signs associated with sub-acute grass sickness
Similar to acute but less severe
Dysphagia
Mild-moderate colic
sweating
Muscle tremors
Rapid weight loss
tucked up appearance
What is the prognosis for a horse with acute grass sickness
prognosis for recovery= hopeless
Usually die or are euthanised within 2 days of clinical signs
what is the prognosis for a horse with sub-acute grass sickness
May die or be euthanised within 1 week of clinical signs- still bad prognosis
List 4 clinical sign associated with chronic grass sickness
Mild/intermittent colic
Reduced appetite
Difficulty eating
Rapid/severe weight loss/emaciation
Describe the prognosis of chronic grass sickness
some may recover
What are the diagnositic tests for grass sickness
Ileal biopsy- best
rectal biopsy- not used as much as lower sensitivity
what do you require to do an ileal biopsy
requires a laparotomy - which decreases the likelihood of survival
where is the pathology found in acute and chronic grass sickness
chronic= localized to ileum
acute= generalized intestinal pathology
Describe what will you see on histology on an ileal biopsy
Neuronal degeneration within ganglia
Depletion of ganglia
Vacuolation
What is the phenylephrine test
Topical application of 0.5% phenylephrine to one eye
examination 30 minutes later
used to help diagnose grass sickness
what is a positive result to the phenylephrine test
reversal of the ptosis in that eye, increase in angle between the corneal surface and the eyelash
list a disadvantage of phenylephrine test for using to diagnose grass sickness
false positives seen
What can you see on oesophageal endoscopy which can help confirm diagnosis of grass sicknesss
Linear oesophageal ulcers
Many don’t have these though
Describe how to treat grass sickness
Intensive and prolonged Nursing
Symptomatic therapy
Analgesia
Feeding
Appetite stimulation - diezepam
prokinetics- neostigmine
why is giving analgesia important to treat grass sickness
Promotes voluntary feeding – reduces pain associated with swallowing and abdominal pain
describe how to feed a horse with grass sickness
small feeds every 30-60mins
hand grazing
varied diets
hand feeding (don’t leave horse to eat)
How is a diagnosis of grass sickness fully confirmed
At post-mortem
samples from cranial cervical ganglion and tested
List 3 ways to prevent grass sickness
Cause unknown
Stabling the animals during the spring and early summer
Stable during prolonged dry weather around 7-11 degrees
Don’t use “bad” pastures where cases have occurred before
