1.1 Small animal vomiting and regurgitation

Receptors, sensory pathway, common final pathway, center of emetic reflex

• Stimulation - visceral receptors, CRTZ (no blood brain barrier to detect toxins), external fear and pain (higher CNS)

• Sensory - vagal, sympathetic peripheral, vestibular neurons

• Common final pathway - nucleus tractus sollitarius

• Vomiting center (reticular formation of medulla oblongata) - coordination

GI signs of nausea (3)

• Reduced gastric tone

• Increased duodenal + proximal jejunal tone

• Reflux of duodenal contents in stomach

Visible signs of nausea (4)

• Depression

• Hypersalivation

• Repeated swallowing

• Licking lips

3 stages of vomiting

• Nausea

• Retching (heaves)

• Vomiting

How does the body prevent aspiration pneumonia during vomiting (2)?

• Glottis closes

• Soft palate presses up against nasopharynx

Physical response to vomiting (4+2)

• Abdominal muscles + diaphragm contract (effort in abdomen)

• Cardia opens

• Pylorus contracts

• Reverse peristalsis

• (sometimes cardiac rhythm disturbances)

• (sometimes colonic motility changes → defecation)

What is regurgitation almost always due to and what 3 factors make it more likely?

• Something in the oesophagus

• Gravity → head + neck held down and extended

• Alterations in food consistency

• Exercise

Where is the movement in vomiting V regurgitation?

• Vomiting - abdominal

• Regurgitation - shoulder (gagging)

When is there bile in vomiting, regurgitation and reflux?

• Vomiting - only if from duodenum onwards (stomach e.g. pyloric obstruction - no bile)

• Regurgitation - no bile (oesophageal problem)

• Reflux - only if brachycephalics or oesophageal damage from prior vomiting

Appearance of food in vomiting V regurgitation

• Regurgitation - undigested (eg overeating cats), covered in mucus from oesophageal irritation

• Vomiting - usually digested unless straight after eating

What method is used for retrieving oesophageal foreign bodies and what is the exception?

• Endoscopy

• Spiculated (spiky) things eg bones require surgery

3 causes of megaoesophagus

• Idiopathic most common

• Congenital (fox terriers)

• Neuromuscular diseases (toxicity, myasthenia gravis, metabolic)

Why should exploratory laparotomy not be used in regurgitation?

Animal under anaesthetic

How does the position of the GIT problem affect vomiting from primary GIT problems? (2)

• More frequent upstream - duodenum highest conc of vomiting receptors

• Time between eating and vomiting increases when going deeper

List 5 causes of secondary GI disease.

1. Accessory digestive organ lesions (pancreatitis)

2. Electrolyte imbalance (Na/K/Ca) influence vomiting receptors

3. Endogenous toxins (liver, kidney, ketoacidosis, infection, neoplasia)

4. Exogenous toxins (cause gut inflammation, may interact with vomiting center in blood)

5. CNS lesions (increased intracranial pressure from brain inflammation, epilepsy)

List 5 ways to investigate primary GI disease.

• Ultrasound of intestinal wall thickness + layering

• Radiographing

• Endoscopy (+ biopsy)

• Surgery (diagnostic - biopsy, therapeutic - tumour removal)

• (bloods - clinical status of patient, rarely gives cause)

Clues for primary GI disease (5)

• Vomiting relates to eating time (except pancreatitis)

• Abnormality palpable in gut (foreign body, intussusception)

• Vomiting associated with large bowel diarrhoea or significant + concurrent small bowel diarrhoea

• Animal clinically and historically normal in all other aspects

• Vomiting began before signs of malaise

Clues for secondary GI disease (3)

• Vomiting began after signs of malaise

• Other clinical signs (jaundice, PU/PD)

• Metabolic illness (usually endogenous toxins or electrolytes)

4 ways to assess primary GI lesions

• Barium meal or enema

• Endoscopy

• Proctoscopy

• Laparotomy

5 causes of primary stomach GI diseases causing vomiting

STOMACH → NO DIARRHOEA

• Gastritis

• Gastric foreign bodies

• Gastric ulceration (cause can be secondary)

• Pyloric disorder

• Abnormal gastric motility

4 causes of primary intestinal diseases causing vomiting

• Enteritis (parvo, corona, rota, garbage)

• Intestinal obstruction

• CE (chronic inflammatory enteropathy)

• Neoplasia

List 3 endocrine diseases which can cause secondary GI vomiting.

• Diabetic ketoacidosis

• Addison’s

• Hypercalcaemia

List 6 types of causes of oesophageal disorders causing regurgitation.

• Anatomic (cricopharyngeal disease, hiatal hernia - stomach slips through diaphragm, diverticulum)

• Megaoesophagus

• External compression (neoplasia, vascular ring anomaly)

• Internal obstruction (strictures, foreign bodies)

• Oesophagitis

• Intramural lesions