Rabbit GI System

Question 1

What is the Digestive Physiology of Rabbits?

Answer 1

• Herbivorous
• GI system combines simple stomach w/ hindgut cecal fermentation
  
  • Transit time ~3-6hrs
• Dietary fiber stimulates gut motility
• Teeth developed for high-fiber diet
  
  • Chewing w/ 120 jaw movements/min w/ lateral motion
• Peristalsis propels high fiber particles through colon quickly ⇢ firm pellets
• Fine low fiber particles travel backwards from colon to cecum
• In the cecum, small particles and fluid ⇢ fermentation ⇢ volatile FA, etc
  
  • This fermentation vat is where millions of gut bacteria digest the indigestible

Question 2

Describe the GI anatomy of rabbits?

Answer 2

• Large abdominal cavity
• GI tract is long (10-20% BW)
• Stomach contains 15% of the ingesta
• Cardia and pylorus well developed
  
  • Unable to vomit
• Pylorus easily compressed by duodenum
• Small intestines are 12% of GI volume
• Ileum ends at cecum, where it is expanded (sacculus rotundus)
• Large, thin-walled cecum holds ≥40% of ingesta
  
  • Most prominent organ of abdominal cavity
  • Sacculations and bands
  • Contains Bacterioides, protozoa, and some Clostrium, etc

Question 3

What does the diet of a rabbit consist of

Answer 3

• Fiber (≥15-16% CF) promotes motility
  
  • Provides large particle size ⇢ lattice-like ball ⇢ permits gastric acid penetration and digestion
• Pelleted diet (13-18% crude protein)
• Feed:
  
  • Premium high fiber hay (>70%)
  • High fiver uniform pellet (<25%)
  • Fresh greens (<5%) daily
  • Treats (<5%) - low sugar, high fiber treats (several times a week)
  • Fresh clean water

Question 4

What are Cecotrophs?

Answer 4

• Specialized fecal pellets produced in cecum
• Contain 2x protein, ⇡ volatile FA, ⇡ B vitamins, and ⇣fiber of usual fecal pellets
• Cecotrophy is particularly important for efficient digestion of forage protiens
• pH of stomach is <2.0 which may neutralize bacterial ingested with cecotrophs

Question 5

What would High energy, low fiber diets lead to in rabbits?

Answer 5

• Increase susceptibility to mucoid enteropathy and other enteric diseases
• Low-fiber:
  
  • ⇣ intestinal motility
  • Prolong cecal retention time
  • Reduce feed intake
  • Predispose to diarrhea
  • May change normal flora

Question 6

What do high fiber diets do for rabbits?

Answer 6

• Stimulate normal digestion, absorption, peristalsis and excretion

Question 7

What are the problems High Carbohydrate diets may cause in rabbits?

Answer 7

• Excessive glucose allow Clostridium spp. and E. coli to proliferate
• Results in excess VFA’s ⇢ lower cecal pH ⇢ inhibits normal flora ⇢ proliferation of pathogens ⇢ production of gas and toxins
• High carb diets inhibit release of motilin ⇢ further slowing GI motility

Question 8

What changes occur in the GI pH when rabbits mature?

Answer 8

• Gastric pH changes from 5.0-6.5 in neonate to 1.0-1.9 weanling/adults
  
  • bunnies can take probiotics

Question 9

What are the functions of the gut microorganisms in rabbits?

Answer 9

• Contains bacteria, some yeast, fungi, and protazoa
• Provides capability to digest food items (energy)
• Some bacteria may confer some immunity
• Management can influence the multibiome
  
  • Need to know which external factors can have adverse affect on gut flora

Question 10

What Grass Hays are fed to rabbits

Answer 10

• Timothy
  
  • Most popular and readily available in pet stores
  • long strand fiber source
  • Low in protein, calcium, and energy
  • Harvested 2-3 times a year depending on climate
• Orchard
  
  • Nutritionally similar to timothy
  • Soft texture w/ sweet smell and taste
  • High palatability to many small herbivores
• Oat

Question 11

What is Alfalfa?

Answer 11

• Legume family, not a grass
• Higher protein, calcium, and energy
• Feeding Recommendations:
  
  • young, growing animals
  • Treat in adult animals
  • Appetite stimulant in senior animals

Question 12

What is hay fiber?

Answer 12

• Hays made up of 2 types of fiber:
  
  • Indigestible fiber (larger particles) for proper gut motility
  • Digestible (fermentable) fiber (smaller particles) provides essential nutrients for cecum and for normal bacterial flora

Question 13

What are the Psychological Benefits of Hay?

Answer 13

• Encourages natural behaviors
  
  • Stimulates foraging and grazing
• Mentally stimulating
  
  • Decreases boredom-based negative behaviors
• Increases activity
• Provides sense of security
• A Pet that lives an enriched life is healthier, happier pet

Question 14

What are causes of Rabbit Gastrointestinal Syndrome? (RGIS)

Answer 14

• Low-fiber diet
• Small pyloric sphincter
• Inability to vomit
• Myoelectrical initiation of peristalsis occurs in duodenum or jejunum
• Excessive grooming
• dehydration
• Stress
• Pain
• Disease
• GI blockage

Question 15

What are the clinical signs of RGIS

Answer 15

• Gut stasis
  
  • can be panful and potentially fatal
  • Interstitial fluid flows into gut ⇢ dehydration
  • Reduction in absorption of electrolytes ⇢ electrolyte derangement
• Anorexia
• Oligodipsia
• Production of very small (or no) fecal pellets (rarely diarrhea)
• Depression +/-
• Weight loss +/-
• Pain (hunched over, tooth grinding, abdominal tenderness)
• abnormal intestinal sounds
• Acute Pyloric obstruction ⇢ depression, bloating (intensely painful), dehydration, hypothermia, shock
• Death - accompanied by hepatic lipidosis +/- clostridial overgrowth

Question 16

How does RGIS progress?

Answer 16

1. Low fiber diet/stress/disease
2. ⇣ GI motility
3. Inappetence
4. Imbalance of cecal flora/dehydration
5. Overgrowth of Clostridium spp
6. Gas and toxin production
7. GI tract pain
8. ⇣⇣ motility/anorexia
9. Hepatic damage/lipidosis
10. Death

Question 17

How is RGIS diagnosed?

Answer 17

• History
• Clinical signs
• Physical examination
• Radiography
• CBC/serum chemistries
• Exploratory laparatomy (seldom indicated)

Question 18

What does the Body Temperature of a rabbit indicate during RGIS?

Answer 18

• With onset of shock, rabbits become hypothermic, bradycardic, and hypotensive
  
  • Always obtain a BT in suspect cases
• BT of 98-99F are in early stages of shock
• BT below 98F indicate severe life-threatening shock

Question 19

What is the treatment of RGIS?

Answer 19

• Most respond to aggressive medical management
• Rehydration (PO, SC, IV)
  
  • Maintenance fluids is ~ 100-120 ml/kg/day
  • Administering 50-60ml/kg/day SC generally adequate in combination w/PO fluids
    
    • 25-35 ml/kg warm fluids may be needed q8h
  • Oral electrolytes generally required as well
  • Critically ill patients will require IV fluids
  • Important to rehydrate gastric contents
  • Balanced electrolyte solutions (unsweetened Pedialyte), water
• Force-Feeding ~10-15ml/kg q6-8h of Critical Care for Herbivores or Blenderized rabbit pellets in electrolyte solution (Pedialyte)
  
  • or as much as they will comfortably take
  • NG tube may be indicated
  • Fresh greens and timothy or grass hay ad libitum
• Vitamin B Complex (0.02-0.4 ml/rabbit SC, IMq24h)
• Antibiotics, if indicated
  
  • Enrofloxacin (5-10 mg/kg PO, SC [if diluted] q12h)
  • TMS
  • Metronidazole (20mg/kg PO q12hr for 3-5days)
  • Use parenterally until stools are passed
• Analgesics
  
  • Meloxicam (1mg/kg SC, IM PO q24h)
  • Buprenorphine (0.01-0.05 mg/kg SC,, IM, IV q6-12h)
  • Butorphanol (0.1-0.5 mg/kg SC, IM IV q4h)
  • Simethicone (65-130 mg/animal PO q1h for 2-3 doses) for abdominal discomfort
• Gastrointestinal promotility agents
  
  • Metoclopramide (0.2-0.5 mg/kg PO, SC q6-8h)
  • Cisapride (0.5mg/kg PO q8-12hh) compounded
• Adsorbents - Cholestramine
• May need to prevent gastric ulceration
  
  • Cimetidine (5-10mg/kg PO, SC, IM, IV q6-12h)
  • Ranitidine (2mg/kg IV q24h or 2-5 mg/kg PO q12h)
• Midazolam (0,25-0.5mg/kg SC, IM, IV) to reduce anxiety
  
  • may also stimulate appetite
• Exercise and abdominal massage
• Thermal support if Temp ≤99F
• Grooming

Question 20

What surgical treatments are there for RGIS

Answer 20

• Decompression of the stomach w/ an 18-French red-rubber catheter as an orogastric tube
• Gastrotomy if unresponsive to medical therapy
• Guarded prognosis (hepatic lipidosis +/-)