Chap 32 - Soft Tissue Surgery: Rabbits

Question 1

Why would one remove the perineal skin folds or inguinal pouches of a rabbit?

Answer 1

To address urine/fecal scalding due to obesity, spinal disease, other. Also address primary cause and husbandry.

Question 2

Describe the inguinal scent glands.

Answer 2

Bilobed glands within skin folds or crypts. More superficial pale lobe and deeper dark brown lobe.

Question 3

Describe the removal of inguina pouches/skin folds?

Answer 3

Crescent shaped incision, dissect skin and remove glands, appose skin edges but prevent everting urethral opening. Start antibiotics.

Question 4

Do the two bony orbits communicate in the rabbit?

Answer 4

Yes - 5mm foramen

Question 5

Describe the location of the lacrimal glands in a rabbit.

Answer 5

1) Orbital - caudal-dorsal to globe
2) Accessory - has retrobulbar, orbital, & intraorbital lobes, is located caudal-ventrally with a lateral duct
3) Gland of the 3rd eyelid - superficial, convex side of the cartilage. Deep - Harderian, rostro-medial.

Question 6

What is traction injury during enucleation?

Answer 6

Can result in oculocardiac reflex and bradycardia, or damage to contralateral optic nerve.

Question 7

Transpalpebral or transconjunctival approach for enucleation in rabbits and rodents?

Answer 7

Transconjunctival easier/better to stay close to globe to prevent damage to orbital plexus/venous sinus.

Question 8

What are the differences between a TECA and PECA?

Answer 8

TECA - higher risk of pinna necrosis, takes entire canal and secretory epithelium.
PECA - leaves pinna & distal canal intact (new blind pouch)

Question 9

Describe the cartilage anatomy of the rabbit ear.

Answer 9

Annular cartilage, aka cartilaginous acoustic meatus.
Scutiform cartilage
Auricular cartilage - includes tragus that connects to annular cartilage and creates the diverticulum.

Question 10

Describe the tympanic membrane.

Answer 10

Elliptical shaped. Larger pars tensa ventrally and smaller pars flaccida dorsally.

Question 11

Describe the thickness of the tympanic bulla.

Answer 11

It is thicker laterally and rostrally, thinner ventrally, medially, caudally.

Question 12

Describe the location of the facial nerve in relation to the tympanic bulla.

Answer 12

Facial nerve exits via the stylomastoid foramen and courses medial and caudal to the bulla.

Question 13

Describe the LBO procedure.

Answer 13

First perform TECA/PECA. Ventral to acoustic meatus, remove lateral wall of bulla with rongeurs or burr. Curette to remove debris & epithelium. AVOID oval & round windows that are located dorso-medial within bulla. Close over or create stoma for flushing.

Question 14

Why perform a VBO and what is the approach?

Answer 14

Perform only if the bulla is affected. (GP?)
Ventral neck, 3-5 cm incision parallel and medial to mandible & mandibular salivary gland, through muscles. Avoid hypoglossal nerve.

Question 15

Complications to ear surgeries?

Answer 15

temporary or permanent vestibular signs, facial nerve paralysis, dehiscence, infection, necrotic pinna

Question 16

Complications of abdominal surgery/exploratory laparotomies?

Answer 16

Heat loss, stasis, adhesions, organ penetration, peritonitis, infection/abscess, seroma, dehiscence

Question 17

What is the difference between direct and indirect inguinal hernias?

Answer 17

Indirect: tissue herniates through inguinal canal via the vaginal process.
Direct: through the inguinal canal adjacent to the vaginal process.

Question 18

Causes for acquired inguinal hernias?

Answer 18

Trauma, surgery, pathologic change to collagen formation & metabolism that weaken neurovascular lacunae.

Question 19

Surgical considerations for repair of inguinal hernia?

Answer 19

Close rings. Castrate +/- scrotal ablation if intact. If bladder/tissue cannot be replaced within the abdomen, perform laparotomy and pexy bladder to lateral abdominal wall. Strict rest due to risk of repair breaking down and recurrence.

Question 20

Describe the closures of the rabbit stomach vs intestines.

Answer 20

Gastrotomy - 2 layers (appositional & inverting, Cushing/Lembert), 3 to 4-0 suture
Enterotomy - Full thickness, 5 to 6-0. Close longitudinally or transversely.

Question 21

Describe 2 different excisional techniques for RNAs.

Answer 21

1) Wedge section - Both sides are cut in short obliques with longer mesenteric side than antimesenteric side.
2) If different size lumens - transect at 45-60 deg on narrow side and 90 deg (transverse) on wider section, so that apposed tissue will be closer in length.

Question 22

Information about anorectal masses in rabbits.

Answer 22

Papillomatous, friable, stalk or broad based within mucosal layer. Sharply excise, may have some straining, inflammation, or edema but is self-limiting.

Question 23

Describe the liver lobe anatomy.

Answer 23

R (Medial & lateral, smaller), L (medial & lateral), Quadrate (smaller, central, dorsal to others/stomach, contains fossa for gallbladder), and Caudate (on a stalk, caudal-most, on right side).

Question 24

Contraindications for liver surgery.

Answer 24

Coagulopathy, anemia, thrombocytopenia, decreased renal function, poor candidate for anesthesia.

Question 25

What antibiotics are recommended before liver surgery?

Answer 25

Enrofloxacin and metronidazole

Question 26

Common diagnostic test abnormalities to confirm liver lobe torsion?

Answer 26

Anemia (from sequestration in torsed lobe as well as mild hemoabdomen), increased ALT/ALP, +/- increased BUN/Creat (common), changes in echogenicity to specific lobe.

Question 27

Which two liver lobes are most commonly affected by a torsion?

Answer 27

``` #1, 2, 3 - Caudate due to stalk from liver hilus. #4 - R lateral. #5 L lateral. ```

Question 28

Are there differences in nephrectomy between ferrets and rabbits?

Answer 28

No. But possible worse adhesions post-op if urine leakage.

Question 29

How much of the bladder can be resected and the animal still be okay?

Answer 29

About 2/3 of the bladder - as long as trigone and ureters are intact/unaffected.

Question 30

What can be performed if you cannot retropulse urethral stones back into the bladder?

Answer 30

Perineal urethrotomy (not stomy as in ferrets). Use catheter to find stone, cut over it. Close 5-0, leave u cath in due to potential luminal compromise/obstruction.

Question 31

3 reasons why rabbit OHE so highly recommended?

Answer 31

1) prevention of uterine adenocarcinoma (75% in rabbits by the age of 7) 2) population control 3) hormone/behavioral tempering

Question 32

Recommended age for spaying rabbits? How about ovariectomy?

Answer 32

Pink book says 6-9 mo for spay, but I do them as early as 4-6 mo pending size/breed. Much easier pre-sexual maturity and less fat. Pink book says 6-12 mo for ovariectomy but I suspect this is for laparoscopy? because why would one ONLY ever take the ovaries in a rabbit????

Question 33

Why perform a median sternotomy on a rabbit?

Answer 33

Thymoma - histologically benign and rarely met but tend to recur. However if thymic carcinoma, which is rare, but these met.

Question 34

What is the perioperative mortality for median sternotomy in a rabbit?

Answer 34

Of 9 cases, 5 died within 3 days of procedure (55%), but some got 955d survival time.

Question 35

How is closing a sternotomy or thoracotomy different than other surgeries?

Answer 35

1) Pre-place suture around sternabrae/ribs prior to tightening/closing. 2) Place chest drain along dorsal chest.

Question 36

How is a chest tube placed?

Answer 36

1) Dorsally, incise skin around rib 10-12. 2) Use trocar with tube to course under skin to 8th ICS. 3) Enter thorax, push drain over trocar but continue to feed it over the trocar too @ 2nd rib dorsally. 4) Clamp and place stop cock to monitor pressure.