Rabbits Flashcards

1
Q

What are the general anatomical characteristics of lagomorphs?

A
  • Herbivores
  • 2 pairs upper incisors and 28 teeth
  • Mandible united and narrower than maxilla
  • Plantigrade hindlimbs
  • No foot pads, toes and metatarsals hair covered
  • Fuses coli
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2
Q

What are the lagomorph classes?

A

Lepus = rabbits, hares

Sylvilagus = cottontails

Ochotona = pikas

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3
Q

What are the similarities between rodents and rabbits?

A
  • Herbivorous
  • Diastema, gnawing and grinding compartments separated by lip folds
  • Very large masticatory muscles
  • Fast metabolism, acute hearing, smell, touch, obligate nose breathers
  • Chisel like permanently sharp incisors for cutting
  • Continually growing molars in guinea pigs, chinchillas, rabbits
  • Loose jaw articulation, rotatory, forward and back jaw movements
  • Caecotrophy in herbivores
  • High fibre herbivorous diet absolutely necessary for dental health and gut mobility
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4
Q

Describe the anatomy of the head and neck.

A
  • Tactile vibrissae
  • Large ears – erect or floppy. Important for thermoregulation
  • Philtrum like rodents
  • Dewlap in doe. Unknown purpose, potentially for fat storage and does pull out fur from here to build nests
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5
Q

Describe the anatomy and importance of the ears.

A
  • Thermoregulation as they do not contain any brown fat, do not sweat or pant
  • 12% of body surface
  • Highly visible central artery and peripheral veins
  • Counter current arteriovenous shunt
  • Unlike rodents possess no brown fat retain heat by shunting blood from ears to core
  • Caudal auricular/marginal ear vein important venepuncture site or euthanasia site
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6
Q

What are the other venepuncture sites in the rabbit?

A

Jugular vein and saphenous vein (easier than jugular)

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7
Q

Describe the eyes.

A
  • Wide visual field, except for just in front of the nose
  • Upper lid is shorter and thicker than the lower
  • Well-developed third eyelid but only moves 2/3 across the glove
  • Low blinking 1-12 times per hours (Draize test)
  • Extensive orbital venous plexus – care with enucleation and must ligate
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8
Q

Describe the lacrimal duct and its clinical significance.

A
  • Only 1 lacrimal punctum situated on lower lid medial canthus
  • Short canaliculus leads to lacrimal sac
  • Lacrimal duct very tortuous, 2 sigmoid curves, encased in bone
  • Exists at tiny nasal punctum
  • Slow drainage due to lacrimal duct
  • Prone to inflammation/dacrocystitis and blockage
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9
Q

Describe the mouth.

A
  • Blind spot in front of the mouth
  • Use lips and vibrissae for food discrimination and prehension
  • Do not use incisor for prehension so can extract
  • Philtrum extends to either side nares/harelip
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10
Q

Describe the digits.

A
  • 5 digits front foot, 4 digits hindfoot
  • Fur covered so no pads
  • Pododermatitis, typically at the level of the hock
  • Swift hopping movements – hindlimbs longer than forelimbs
  • Plantigrade but digitigrade while running
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11
Q

Describe the mammary tissue.

A
  • 2-5 pairs (have 8) nipples on the ventral thorax, abdomen and inguinal region
  • Female only
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12
Q

Describe the scent glands.

A
  • Territorial
  • Submandibular scent glands, may be seen rubbing faces on surfaces
  • Inguinal glands in spaces either side of anus dorsal to urogenital opening, can build up with caseous material which is normal unless excessive
  • Anal glands
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13
Q

Describe the general osteology of rabbits.

A
  • Hooked shaped suprahamate process in rabbits. Blunted in cats.
  • Acetabulum of pelvis excludes pubis – ilium, ischium and os acetabulum
  • Skeletal system light compared to body mass
  • New Zealand white skeleton 6% while musculature 56% body mass
  • Prone to spinal injury particularly at lumbosacral junction
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14
Q

Describe the skull.

A

Rabbit skull is larger than rodent skull, nasal terminates are exposed in the rabbit skull, is more domed shaped, has a characteristic diastema and large tympanic bulla (smaller than chinchilla).

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15
Q

State the rabbit dental formula.

A

2/1 0/0 3/2 3/3

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16
Q

Describe the rabbit dentition.

A
  • 28 teeth
  • All teeth aradicular and hypsodont
  • 4 incisors: 2 pairs of upper incisors rudimentary incisors on lingual side – peg teeth
  • Lower incisors lie between 2 pairs of upper at rest
  • Enamel on labial side upper ad both sides lower incisors
  • Diphyodont/2 sets of teeth – deciduous teeth lost in gestation
  • Diastema
  • Mandible united string fibrous symphysis
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17
Q

Describe the musculature of the head.

A
  • Large masseter
  • Smaller temporalis
  • Masseter does not insert on rostral nose
  • Flexible temporomandibular joint allows rostral, caudal and lateral movement
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18
Q

Describe the oral cavity.

A
  • Oral cavity small
  • Long tongue – lingual torus
  • Narrow oropharynx
  • Small glottis
  • Intubation difficult
  • Diastema
  • Cheek folds separate incisor teeth from oropharynx
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19
Q

What may dental disease present as?

A

Dental disease can present as not eating/gut stasis or abscessation.

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20
Q

Why does dental disease in rabbits arise?

A
  • All teeth aradicular/open rooted so grow continually
  • Need to wear against each other to maintain shape
  • Alteration can lead to malocclusion and elongated crowns
  • Elongation of reserve crowns/roots penetrate bone and emerge through periosteum
  • Periapical abscesses occur at sites of root penetration
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21
Q

What are the consequences of dental disease?

A
  • Abscesses occur over sites of reserve crowns of molars in maxilla and mandible
  • Also cause epiphora and dacrocystitis – reserve crowns impinge on nasolacrimal duct
  • Digestive disorders
  • Poor grooming
  • Perianal matting
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22
Q

Describe the cardiorespiratory system.

A
  • Both lungs lobated
  • No septa dividing into lobules, so pneumonia is not localised
  • Obligate nasal breathers. Mouth breathing in rabbits is a sign of respiratory distress.
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23
Q

Why is a high fibre diet important?

A

High fibre stimulates gut motility. Where gut motility is low, there can be over-digestion of food, increasing lactic acid and decreasing pH as a result. Affects gut microbes, causing damage to gut wall, excessive gas build up and ultimately toxins are absorbed in the body, which may lead to shock

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24
Q

What are the similarities and differences between rabbit and horse/cow digestive systems?

A

Quick fibre excretion like horses and cows

Bacteroides is main bacteria unlike lactobacillus in horse and cows

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25
Q

Describe the liver.

A

4-6 lobes in liver. Gall bladder present. Caudal lobe is pedunculated (‘on a stalk’). This can be subject to torsion, affecting blood supply to the liver.

26
Q

What is the ileocaecocolic complex?

A
  • Occupies more than half of the abdomen
  • Mesenteric attachments between caecum, appendix, proximal colon, ileum, distal colon and descending duodenum
  • Huge caecum extending from left to right diagonally
27
Q

What is gut stasis?

A

Greatest emergency: can be caused by stress, change/inappropriate diet (low fibre, sugar rich). If a rabbit goes of its food it should be taken to the vets immediately.

28
Q

Describe the stomach.

A
  • Large, simple
  • Gastric distension common
  • Well-developed cardiac sphincter
  • Small non-glandular cardia
  • Fundus glandular
  • Hair common because grooming behaviour
29
Q

Describe the small intestine.

A
  • Relatively short
  • End of ileum expanded into sacculus rotundus (unique to rabbit)
  • Left caudal quadrant
  • Lymphoid tissue, may be called caecal tonsil
  • Opens into ampulla caecalis coli and junction ileum, colon and caecum
  • Weak ileocaecal valve
30
Q

Describe the large intestine.

A

Very large, occupies the ventral floor

31
Q

Describe the caecum.

A
  • Largest of all animals relative to size
  • Fermentation – bacteroides rather than lactobacillus
  • Thin walled and friable
  • Spiral constriction
  • 3 parts/gyri
  • Vermiform appendix in right flar
32
Q

Describe the colon.

A

Can be described anatomically as ascending, transverse and descending colon but more simply divided into proximal and distal colon, which are separated by fusus coli.

33
Q

Describe the taenia and haustra of the proximal colon.

A

First section = 3 taenia and wartzen (wart like structures that increase the surface area – equivalent to 1st part of ascending colon

Second section = 1 taenia – equivalent to 2nd part of ascending colon

34
Q

What is the fusus coli?

A
  • Smooth bean shaped structure, equivalent to 3rd part ascending colon
  • Thickened circular muscle, highly innervated
35
Q

What is the funtion of the fusus coli?

A
  • Regulates passage of ingesta into distal colon, ‘pacemaker’
  • 3 types of colonic motility – segmental (chopping up of ingesta), haustral (churning circulations in contraction), and peristaltic (move ingesta forwards towards rectum or reverse peristalsis backwards in digestive tract)
  • High fibre eliminated fast – fuses coli stimulated by fibre
  • Nutrient rich particles sent back to caecum to become caecotrophs
36
Q

Describe the distal colon.

A

No taenia or haustra. Equivalent to 4th short part of ascending colon, transverse and descending colon. Contains faecal pellets.

37
Q

What is the purpose of caecotrophy?

A
  • Bacterial fermentation used to synthesise nutrients and avoids the need to store large volumes food
  • Necessary for production of B and K vitamins
38
Q

What are caecotrophs?

A

Richly concentrated digestible fraction produced caecum and proximal colon

39
Q

What are the functions of the fusus coli, segmental and haustral contractions?

A

Fusus coli regulates colonic contraction

Segmental and haustral contractions separate ingesta mechanically into solid and liquid

40
Q

Describe the hard faeces phase of caecotrophy?

A
  • Solid particles/ingestible fibre pass down the middle of the lumen.
  • Water is absorbed and excreted as hard dry pellets
  • Liquid fraction pass to periphery of haustra then returned by anti-peristalsis to caecum for further fermentation and becomes more concentrated with nutrients.
41
Q

Describe the soft faecal phase of caecotrophy.

A
  • Periodic change in motility caecum and proximal colon
  • Caecum contracts to expel soft paste into proximal colon
  • Digesta pass into distal colon with no separation/water absorption
  • Decreases in motility of caecum and proximal colon, increases motility of the distal colon
42
Q

What happens when caecotrophs are ingested?

A
  • Mucus from fusus coli protects caecotrophs from acid digestion in stomach
  • Pass to fundus of stomach where microbial fermentation may continue within caecotroph
  • Absorption of nutrients in small intestine
43
Q

Give a full outline of the process of caecotrophy.

A
  1. Fusus coli causes segmental and haustral colonic contractions. Solid particles move through the middle of the lumen, water is absorbed and content is excreted as hard faeces. Liquid fraction thrown into periphery of haustra.
  2. Antiperistalsis contractions return liquid fraction to caecum for more fermentation.
  3. Caecum contracts forcing a soft paste through the proximal colon into the distal colon without water absorption. Mucus is added at the fusus coli.
  4. Motility decreases in caecum and proximal colon but increases in the distal colon to excrete soft faeces/caecotrophs.
  5. Caecotrophs are ingested from the anus and pass to the stomach where they are protected from acid digestion by the mucus. Fermentation continues within the caecotrophs.
  6. Nutrients absorbed in small intestine.
44
Q

Describe the urogenital system.

A
  • Kidneys unipapillate
  • Smooth bean shaped
  • Urinary porphyria or haematouria distinguished using dipstick test
45
Q

Describe the anogenitalia of rabbits.

A
  • Urethra opens into floor of the genital tract, does not have separate orifice
  • Preputial opening ventral to anus, penis easily extruded
  • Anogenital distance not helpful in sexing
46
Q

Describe the male internal genitalia.

A
  • Subcutaneous scrotal sacs communicate freely with abdomen
  • Always perform closed castration
  • Testes horizontal, long, retractable
  • Cranial fat body
  • No glans or os penis
  • Copulatory lock
  • Ampullae
  • Bilobed vesicular gland
  • Bilobed coagulating gland produces the copulatory plug
  • Prostate – lobes
47
Q

Describe the female internal genitalia.

A
  • Duplex uterus
  • Long suspensory ligaments
  • Accumulations of fat on the broad ligament
  • Induced ovulatory
  • Ovariohysterectomy common – avoid uterine adenocarcinoma, present in rabbits that are unmated
48
Q

Describe pregnancy in lagomorphs.

A
  • Gestation 31-32 days
  • Altricial young – not common to all lagomorphs
  • False pregnancy common
49
Q

What are the anatomical differences between rabbits and rodents?

A

Rabbits:
- 4 upper incisors
- Mandible fused/fibrous and narrower than maxilla
- Saccules rotundus
- Fusus coli
- Combined urethral and genital opening

Rodents:
- 2 upper incisors
- Mandible unfused and wider than maxilla
- Separate urethral and genital opening

50
Q

Are the vertical or horizontal grooves of the incisors apparent? Are these normal?

A

Vertical. These are normal.

51
Q

How does the dental formula differ from rodents?

A

Have 2 lower incisors and 4 upper incisors. Rodents have 2 upper and lower incisors.

52
Q

Are rabbits able to vomit? Why?

A

No. Strong cardiac sphincter.

53
Q

What type of kidneys do rabbits have?

A

Unipapillate (one papilla and one calyx entering into the ureter directly).

54
Q

Are the kidneys symmetrically placed?

A

Right lies cranial to the left and is associated with the caudate lobe of the liver.

55
Q

Why is intubation difficult in rabbits? What are the other options?

A

Difficult due to narrow oropharynx, long tongue and small glottis.

  • Placing an ET tube into the trachea is difficult to visualise the glottis and causes laryngeal spasm/trauma.
  • Placing a mask over the nares obscures the field of view and if the seal is not tight, it may leak gas.
  • V gel is an alternative to endotracheal and masked anaesthesia in rabbits. V gel sits over the entre larynx and epiglottis.
56
Q

What is the sacculus rotundus?

A

Ileum end is expanded into the sacculus rotundus. Found in the left caudal quadrant, which is not visible on this specimen. Sacculus rotundus contains lymphoid tissue and is sometimes called the caecal tonsil. This opens into the ampulla coli at the junction of the ileum, caecum and colon.

57
Q

What is the role of the vermiform appendix?

A

Appendix has unclear function but thought to have a role in immunity.

58
Q

What is the ampulla coli?

A

Ampulla coli is the region of the caecum where the ileum enters and proximal colon exits the caecum.

59
Q

Name the lobes of the rabbit liver.

A
  • Caudate lobe
  • Right later lobe
  • Right medial lobe
  • Quadrate lobe – difficult to appreciate this, as it lies between the right lobe and quadrate lobe.
  • Left medial lobe
  • Left lateral lobe
60
Q

What is the clinical significance of the caudate lobe?

A

Due to pendulous nature of the caudate lobe, this may twist and cause a liver lobe torsion. Rabbits present with an acute history of anorexia, abdominal pain, ileus and collapse. Prompt diagnosis and treatment is essential. Treatment includes surgical resection and medical management.

61
Q

What is the clinical significance of the rabbit bladder?

A

Common finding in rabbits is bladder sludge/sand. The accumulation of calcium sediment in the bladder, usually a result of inactivity, obesity and inappropriate diet.