VET 405: GASTROINTESTINAL SYSTEM & METABOLISM
MODULE 1: COMPARATIVE GI ANATOMY
- Oral cavity: tooth anatomy (incisors, canines, premolars, molars), species variation, eruption times
- Esophagus: muscular tube, species differences in innervation
- Stomach: monogastric (carnivores, horses, pigs) vs ruminant forestomach
- Canine/feline stomach: simple pouch, gastric glands (parietal, chief, mucus-secreting)
- Equine stomach: small relative to body size, continuous gastric secretion
- Small intestine: duodenum (pancreatic/bile duct entry), jejunum, ileum; intestinal villi structure
- Colon/cecum: water absorption, fiber fermentation, species variation
- Ruminant GI: esophageal grooves, 4-chambered forestomach (rumen, reticulum, omasum, abomasum)
MODULE 2: RUMINANT FORESTOMACH ANATOMY & PHYSIOLOGY
- Rumen: fermentation vat (45-50 L in cattle), anaerobic fermentation by microbes
- Ruminant microbiota: bacteria (Firmicutes, Bacteroidetes), archaea (methanogens), ciliate protozoa
- Fermentation pathways: cellulose → volatile fatty acids (acetate, propionate, butyrate)
- Ruminant: cud chewing, salivary buffering (maintains pH 6-7), eructation (belching)
- Omasum: water absorption, particle sorting
- Abomasum: true stomach, gastric secretion (HCl, pepsin, renin in neonates)
- Ruminant intestinal anatomy: longer small intestine for microbial byproduct absorption
MODULE 3: GI PHYSIOLOGY & DIGESTION
- Saliva: amylase (minimal in carnivores), mucus lubrication, buffering; salivary glands (parotid, submandibular)
- Gastric secretion: parietal cells (HCl, intrinsic factor), chief cells (pepsinogen), G cells (gastrin)
- Gastric motility: fundic relaxation, antral grinding, pyloric sphincter control
- Pancreatic secretion: bicarbonate (buffer stomach acid), digestive enzymes (amylase, lipase, proteases)
- Bile: produced by liver, stored in gallbladder (except horses, no storage); emulsifies fats
- Small intestinal digestion: brush border enzymes (peptidases, disaccharidases), nutrient absorption
- Colonic function: water resorption, bacterial fermentation (fiber), short-chain fatty acid production
MODULE 4: METABOLIC DISORDERS
- Ketosis (acetonemia): excessive fat mobilization, inadequate carbohydrate intake
- Hypoglycemia: decreased blood glucose; causes (starvation, sepsis, liver disease, excessive insulin)
- Hyperglycemia: elevated glucose; causes (diabetes mellitus, stress, corticosteroids)
- Electrolyte imbalances: hypokalemia, hyponatremia, hypocalcemia (milk fever), hyperkalemia
- Hepatic lipidosis: fatty liver from lipid accumulation, common in obese/anorectic cats
- Protein-energy malnutrition: inadequate amino acids/calories, muscle catabolism, poor wound healing
MODULE 5: COLIC & GI EMERGENCIES
- Colic (equine): abdominal pain from GI disorder; types include impaction, displacement, torsion, strangulation
- Acute abdomen signs: severe pain, dark mucous membranes, prolonged capillary refill, shock
- Surgical vs medical colic: impaction (medical), large colon displacement (surgical), torsion (surgical)
- Peritonitis: abdominal inflammation from perforation/infection; diffuse pain, systemic toxemia
- GI foreign bodies: obstruction from non-digestible items; radiographic diagnosis, endoscopy or surgery