Lecture 5 2/4/25 Flashcards
What are the four components of the emetic reflex?
-visceral receptors
-vagal and sympathetic afferent neurons
-chemoreceptor trigger zone
-emetic/vomiting center
What are the two pathways that trigger the emetic center?
-humoral pathway
-neural pathway
What are the characteristics of the humoral pathway?
-involves bloodborne substances
-triggers emetic center indirectly via the chemoreceptor trigger zone
What are the characteristics of the neural pathway?
-involves inflammation, infection, malignancy, or toxicity of the GI tract
-triggers emetic center directly
What are the inputs to the emetic center?
-chemoreceptor trigger zone
-vestibular apparatus
-cerebral cortex
-abdominal viscera
What things act at the chemoreceptor trigger zone to trigger the emetic reflex?
-drugs, including chemo drugs, bacterial toxins, and opioids
-metabolic waste products, including uremic toxins, ammonia, and ketones
What things act at the vestibular apparatus to trigger the emetic reflex?
-motion sickness
-vestibular inflammation or trauma
How does the vestibular input path vary between dogs and cats?
-in cats, the vestibular input goes right to the emetic center
-in dogs, the vestibular input first goes to the chemoreceptor trigger zone
What things act at the cerebral cortex to trigger the emetic reflex?
-sight/smell/thoughts
-extreme fear
-anticipation of pain
What things act at the abdominal viscera to trigger the emetic reflex?
-gastric or intestinal distension
-inflammation/irritation of the viscera, peritoneum, or pharynx
What are the indications for antiemetic therapy?
-animal is NOT suffering from GI obstruction or toxicity
-vomiting is severe/persistent
What are the characteristics of maropitant/cerenia?
-prevents vomiting mediated via CRTZ and emetic center
-may be a better anti-emetic than anti-nausea drug
-well tolerated, but can see vomiting or hypersalivation
What are the characteristics of ondansetron?
-may better a better anti-nausea drug than maropitant
-better function when giving parenterally
-side effects include sedation, fecal incontinence, and p-glycoprotein substrate (caution in collies)
What are the characteristics of metoclopramide?
-not a great antiemetic or antinausea drug
-more often used for prokinetic effects
-side effects include restlessness, spasms, aggression, hyperactivity, and or sedation
-interacts with lots of drugs
What are the steps to approaching a vomiting patient?
-differentiate between vomiting, regurgitation, and dysphagia
-determine chronicity
-describe frequency
-describe severity
-generate differentials
-create diagnostic and therapeutic plans
What are the extra-GI differentials for vomiting?
-hepatic dz
-renal dz/azotemia
-pancreatitis
-endocrine dz
-CNS dz
-motion sickness
-pyometra
-drug-induced
What are the acute primary GI differentials for vomiting?
-obstructive
-nutritional
-neoplastic
-infectious
-iatrogenic
-toxic
What are the chronic primary GI differentials for vomiting?
-inflammatory
-infectious
-neoplastic
-anomalous
How does the work up/treatment approach differ between mild/acute/uncomplicated cases and severe/recurrent/chronic cases?
-mild/acute/uncomplicated cases can be approached symptomatically
-severe/recurrent/chronic cases warrant a diagnostic workup
Which diagnostics should be considered with mild/acute/uncomplicated cases of vomiting?
-PCV/TS
-zinc sulfate fecal float
-abdominal radiographs
What are the therapy options for mild/acute/uncomplicated vomiting?
*easily digestible, low residue diet
–small, frequent meals
–given for 3-5 days or until resolution and then transitioned back to regular diet
*antiemetic or antinausea medications
What is most important about monitoring a mild/acute/uncomplicated vomiting case?
if there is no improvement in 48 hours, additional diagnostics should be performed
What are the components of a diagnostic workup for severe/recurrent/chronic cases of vomiting, as well as unresolved acute cases?
-CBC
-chem + electrolytes
-UA
-zinc sulfate fecal float
-spec cPL/CPLI (dogs) or fPL/fPLI (cats)
-abdominal radiographs
-abdominal ultrasound
What are the indications for hospitalization of a patient with acute vomiting?
-fever
-dehydration
-abdominal pain
-hematemesis
-hemorrhagic diarrhea/melena
-continued vomiting despite outpatient supportive care
-known toxin exposure
-neonate or toy breed (hypoglycemia concerns)
