Rabbits 1 Flashcards
Lifespan
5-10 years
Normal heart rate
150-300 bpm
Resp rate
30-60 bpm
Rectal temperature
38.5-40 deg cel
Water intake
50-150ml/ kg
Sexual maturity
16 weeks
gestation
30-33 days
Urine pH
8-9
Taxonomy of rabbit
- Kingdom: Animalia
- Phylum: Chordata
- Class: Mammalia
- ORDER: Lagomorpha
- Family: Leporidae
Head features
- Large erect (hear sound better) (or floppy) pinnae
- Large protuberant eyes, laterally wild field of view
- Cleft lip
- Twitchy nose
- Vibrissae thicker whiskers sensitive to touch and vibrations
- Specialised dentition
Are ears sensitive?
VERY sensitive, easily damaged. MUST never pick up from ears!
How are ears useful for the rabbit?
- Thermoregulation – thin skin, lots of blood vessels, good for retaining or losing heat
- Funnelling sound – can rotate 270 degs help locate predators
How are ears useful for us?
- Administering medications/fluids
- Blood sampling (Marginal earn vein) ONLY use Central auricular Artery if marginal blown or if need large blood samples or sampling arteriole gases
Rabbits eyes
- Large and protuberant
- Positioned laterally
- Blind spot - tip of nose and right behind, like horse
- third eyelid
- Harderian gland
- SINGLE ventral lacrimal punctum (c and d have 2)
What does protuberant eyes mean to the rabbit?
higher risk of trauma
• Corneal ulceration and laceration (cut) common
Harderian gland role
- Produces very stable tear film due to lipid component
* Rabbits able to go long periods without blinking and still have well lubricated eyes
Where does the single ventral lacrimal punctum drain?
into nasolacrimal duct
If a rabbit presents with eye disease - lymph from eyes, tear overflow what should you think
ALWAYS look at teeth
If a rabbit presents with eye disease why should you check the teeth?
- Nasal lacrimal duct
- Sharp bends that cross root of cheek teeth
- Root of cheek tooth comes right up almost into eye socket which is why has to bend
- Also has to bend at root of incisor
- So any dental disease causing teeth to elongate or push up into canal occlusion of duct, often get problems from this.
What type of retina do rabbits have? and describe
- Merangiotic Retina
- Blood vessels not spread across retina like in D and C
- out of optic disc and run side to side
- when using ophthalmoscope must look UPWARDS to find optic disc
- No tapetum lucidum so can’t see too well in dark therefore diurnal!
What causes rabbits eyes to become more protuberant when inc Blood pressure?
Large retrobulbar venous plexus (orbital venous sinus) behind eye. BV behind eye)
• Important to note during enucleation
• Retrobulbar abscessation common
Technique used to remove rabbit eye?
- Transpalpebral technique to remove eye
* Transconjunctival technique less likely to cause haemorrhage
Which extraocular muscle shuts eye?
• Depressor palpebrae (shuts eyelid)
Rabbit dentition formula
• I 2/1, C 0/0, P 3/2, M 3/3 = 28
What type of teeth do rabbits have?
Hypsodont - like horses •Aradicular/ elodont - open rooted
• Reserve crown, enamel extends below the gumline (teeth continually erupting)
• Reliant on calcium as produce lot of teeth material per month
Rabbit Peg teeth
• Second upper incisor lies behind the first maxillary incisor
Rate of incisor and cheek teeth growth
I = 3mm/ week CT = 3mm/ month
Main cause of dental disease
- Inappropriate diet e.g. high carbo and low fibre
What is usually the case with dental disease?
- Disease in cheek teeth leads to incisor overgrowth - very rate I is the primary problem
- At rest cheek teeth should NOT touch
How does dental disease progress?
Tongue and cheek ulceration causes pain - rather than grind teeth, go up and down, forms buccal spurs (on buccal aspect of maxilla), lingual spurs (lingual aspect of mandible).
Reduced attrition:
1. Reduced tooth wear
2. Elongation of crowns of teeth
3. Occlusion of cheek teeth at rest
4. pressure on crowns
5. Forces jaws apart, pushes root backwards into jaw bone
As this continues pressure on corwns forces reserve crowns further into bony socket
- Enamel spurs
- Jaw forced apart, I stop meeting as should.
- I also start to wear incorrectly = elongation of incisor teeth. Often lower I pushed forward
Abnormal anatomy alters chewing motion and sharp spurs develop. Incisor anatomy is also altered and these star to overgrow too
Tongue
- Hard to examine a conscious rabbit because:
- Really mobile
- Fleshy cheeks, small gape (can’t open wide) and muscular tongue torus at back of tongue
NOSE
Remember twitching is normal • ~150/min Very sensitive to touch on nares • Resent this Blind spot on very tip of nose only • Sensitive pads on nares, and presence of vibrissae compensate for this • Make touch at end of nose unbearable
Lungs
7 lobes: Left lung • Cranial, middle, caudal Right lung • Cranial, middle, caudal and accessory lobe
Why is intubating a rabbit tricky?
- Like cats and have sensitive larynx so to stop laryngospasm must numb it with local anaesthetic
- Long tongue,
- Small glottis
- Narrow Oropharynx = big fleshy cheeks often get in way
Respiratory system
- Obligate nasal breathers (like rodents)
- Respiratory rate 30-60 bpm
- Enormous abdominal cavity
- Small thoracic cavity – tidal volume only 4-6ml/kg
- Very sensitive to respiratory irritants – air freshener causes issue
What do you have to think about with regards to the diaphragm and surgery?
• Diaphragmatic contraction drives breathing rely more strongly on D than intercostal. So don’t put pressure on diaphragm during surgery – guts out, legs lower than head so not putting lot of weight against Diaphragm
Rabbit thymus
persists in the adult, found in cranial mediastinum
Heart rate
Systolic blood pressure
Total blood volume, and what % take
- HR high - 150-300bpm
- SBP - 90-135mmHg
- TBV - 50-75 ml/kg Don not take more than 10% total blood volume.
Where do we take blood from? and issues
- Marginal ear vein – fragile and only really get small amount
- Jugular- exophthalmos for short period of time. Avoid if taking lots over period of time. Really good if need to take lot. Tricky to find, position to take can compromise building
- Lateral saphenous - runs over side of hock, reasonable volumes, haemotosis – easy site to compress
- Cephalic
- Marginal ear vein
- Central AA - only really for arteriole blood gases or large volumes. But easily causes haematoma or haemorrhage
What system is the reason why we mostly see rabbits in practise?
DIGESTIVE SYSTEM
Digestive system broadly
- Hindgut fermenters
- Have a gall bladder (unlike horse) - Large stomach , HUGE caecum
- Starts at the mouth
- Grinding action of the cheek teeth
- Strong tongue ensures all food is masticated prior to swallowing
- Oesophagus
- Stomach
- SI
- Hindgut which consists of the caecum, proximal and distal colon
- diarrhoea is highly uncommon
Name the 4 pairs of salivary glands
- Parotid,
- Sublingual,
- Zygomatic,
- Mandibular
Describe oesophagus
three layers of striated muscle, extending all the way to the cardia of the stomach
Can Rabbits vomit?
NOPE - Well developed cardia sphincter 56 mins meaning no vomiting!
Hindgut fermentation
- In caecum
- microorganisms perform fermentation
- produce VFA which absorb across caecal wall
- . Bacteria replicate in caecum forming vital protein source
- Caecal pellet protected from stomach pH by mucous covering
- Caecal contents expelled as caecotrophs - eated directly from anus
- Digestion of caecal delivers protein to animal
Which VFA
• VFA seen is acetate followed by butyrate, then proprionate 1.2 mins
Main bacteria in hindgut fermentation
Bacteriodes spp
What does dental disease tend to occur as result of
occur secondary to:
• Poor diet
Fibre is ESSENTIAL
AS rabbit is a herbivore what does this mean about its saliva?
- AMylase rich
Stomach
- thin walled (often ruptures when death
- Lies left of midline
- Well developed cardiac sphincter
- pH 1-2 = and SI practically sterile
- J shaped and cardia in curve, contributes to difficulty vomiting
Why are neonates difficult to hand rear?
- Neonates have pH of 5-6.5, means difficult to hand rear
* Milk oil produced from 0-6 weeks reacts with milk from mother and protects against bacterial infection
Small intestine
- Relatively long (12% digestive volume)
- Secretes enzyme called MOTILIN which stimulates molility in SI, colon and rectun. NO affect on caecum
- Released in response to fat, inhibited by carbohydrate
- Terminal ileum ends in the SACCULUS ROTUNDUS (composed of lymphoid tissue to provide immune defence. Lot of bacteria in caecum) at the junction with colon and caecum
- Sometimes called the caecal tonsil at end of ileum at junction of colon and caecum. Composed of lymphoid tissue
Hindgut anatomy
- consists of caecum and proximal colon
- Caecum, 40% GI volume, ends in vermiform appendage (composed of lymph tissue, acts as defense against bacteria)
- Proximal colon -50cm
Proximal colon anatomy
- 3 subsections – 3 haustra/sacculations, single haustra, fusus coli
- Terminal portion is FUSUS COLI – regulates passage of food 1 hr mins
- Regulates passage of ingesta into distal colon
- Separates hard from soft faeces
Distal colon
• No sacculations
• No tenial bands
• Long!
90 cm
Caecotrophs
- Produced about 8 hrs post feeding
- eaten directly from anus
- Provides source of vit B, K and Protein
- HIGH fibre LOW protein encourages consumption - WE WANT. opposite discourages
As moves through colon faeces is either…
- HARD or SOFT
Hard faeces
- Contractions in proximal colon separate indigestible particles from liquid component
- Indigestible contents move to centre of lumen, further water absorbed
- Hard pellets produced
Soft faeces
- Smaller particles and liquid content move into peripheral lumen
- Antiperistalysis returns them to caecum for further fermentation
- Cecum contracts to expel soft contents into proximal colon, which then move rapidly through distal colon with no further water absorption
Why use marginal vein for blood sampling vs auricular artery?
• Vein rather than artery so less likely to cause haemotomas or extensive bleeding
How does a rabbit cope with small thoracic cavity?
• Adaptations:
o High chest wall compliance
o Low functional residual capacity
o Diaphragmatic contraction drives breathing
