Rodent Surgery Flashcards

1
Q

Rodents URT anatomy ?

A

Have sepratae urinary and vaginal openings - can determine if discharge is from urinary or reprod tract

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2
Q

Scent glands ?

A

Ventral scent gland dwarf hamsters and gerbils vs FLNAK in syrian hamsters

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3
Q

What patient factos to consider in rodent surgery?

A
  • Relatively small lung volume compared to body size
  • Ideally elevate head -> reduces abdominal contnts pushing against diaphragm
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4
Q

Wha surgical equipment/ haemostasis considerations?

A
  • Fine tipped equipment
  • sterile cotton tip applicatos
  • Artery forceps
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5
Q

HAEMOSTASIS in rodents?

A

in healthy animals total blood volume 7% of BW
- 10% of this can be drawn for blood sampling
- 0.5-0.7ml/100g max amount of blood loss
to calculate = each cotton tipped applicator holds 0.1ml blood

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6
Q

What initial assessment of rodents?

A
  • Full CE
  • Sabilise & get BW
  • Pre-op assess - RR & HR
  • Rodents don’t vomit => unnecessary to withold food &fasting inc risk of GI disturbanceds
  • Minimise stress
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7
Q

Pain in rodents?

A
  • Newcastle grimace scale - rats and mice
  • Hunched? hiding?
    -Belly pressing?
  • contracted abd muscles
  • loss of appetite
  • Chage of HR, RR and deph
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8
Q

surgical skin prep in rodents?

A

Iodine/chlorhex & good contact time
- Warm surgical scrub first
- Avoid excess alcohol due to evaporative losses

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9
Q

Iv placement where?

A
  • caphalic/saphenous in GP
  • Tail vein in rats
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10
Q

Intraosseous placement where?

A
  • Femur -> through trochanteric fossa
  • Tibia -> through tibial crest
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11
Q

What is fluid mainenance rate for most rodent species?

A

3-4ml/kg/hr

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12
Q

During surgery - considerations?

A
  • HYPOTHERMIA! - warm theatre, bubble wrap, warm fluids,
  • Prevent HYPOXIA! - oxygen admin
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13
Q

Post op considerations?

A

● Monitor & supportive care.
● Maintain body temperature
● Analgesia essential
○ Traumatising surgical site
● Fluid and nutritional support
○ Assist feeding ASAP.
● Therapeutic laser therapy
● Phovia

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14
Q

What reasons for skin surgery?

A
  • Lump removal - neoplastic /cystic
  • Absess surgery - thick, caseous material within a thick capsule
  • wound management
  • Scent gland hyperplasia/ neoplasia
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15
Q

Describe Trichofolliculoma in Guinea pigs

A
  • usually located over the dorsum, may ischarge keratinous or haemorrhagic material from a central pore
  • Surgical approach similar to lump removal
  • excision curative
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16
Q

Describe Ventral sent gland tumour surgery in gerbils and dwarf hamsters ?

A
  • In gerbils, neoplasia (SCC, adenomas, adenoCs)
  • wide excision aroudn scent gland
  • Most rodents have moderate to extensive amount of loose skin
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17
Q

Pregnancy prevention ?

A
  • Sexual maturity in mice/ rats/ gerbils = 6-8 weeks
  • sexual maturity in GP = 4-6 weeks (female) and 9-10 weeks (male)
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18
Q

Disease prevention for reproductive management ?

A
  • significant reduction in mammary tumours developing if ovariectomy performed in rats before 90 days
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19
Q

What non surgical options of reproductive management?

A
  • separation of sexes but welfare implications & fighting in same sex!
  • Medical management (implants -> NOT effective, CI in GPs) & Hormonal injections (not effective)
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20
Q

What surgical approaches to neutering?

A
  • Traditional, ventral abdominal midline
  • Flank (GP and rats) -> bilat or unilar
  • Combination approaches
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21
Q

What considerations for elective neutering ?

A
  • Small nodular ovaries
  • Ovaries locate dinf at
  • Confilcting advice in lit regarding type of uterus tat some rodents have - clinically no difference
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22
Q

What advantages of Flank approach?

A
  • Less invasive
  • Quick recovery time
  • Less risk of infection
  • Less risk of suture disruption and complications
  • Less risk of evisceration secondary to dehisence
  • Bilat or unilat
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23
Q

Flank (more lumbar) approach -> describe part 1

A
  • Find landmarks (spine, last rub, pelvis)
  • Incise bulge in midle
  • Blunt dissect trough muscles (external oblique & internal laminar muscles)
24
Q

Describe flank approach part 2

A
  • retract fat until you can see the distal uterine horn and ovary
  • Ligate the ovarian pedicle
  • Often a bilat flank approach
25
Q

Describe ventral midline approach

A
  • Similar to dog
  • Much fat on ovaries located at caudal pole of kidneys
  • BE CAREFUL WITH ADHESIONS! -> gentle handling, haemostasis, don’t use dry swabs, irrigate tissues & don’t use catgut sutures
26
Q

What signs of ovarian and uterine dx ?

A
  • Infertility
  • wbdo distention
  • Weight loss
  • Poor BCS
  • Vaginal discharge
  • on speicfic
  • Pain
27
Q

What signs of mammary dx?

A
  • Development opf masses
  • swollen glands
  • Discharge
  • Pyrexia
  • Non specific
28
Q

What ddx for surgical uterine dx?

A
  • Neoplasia
  • polyps
  • Infection
  • hydrometra
  • Endometrial hyperplasia
  • Torsion
  • Endometrial aneurysms
29
Q

What vaginal/vulval dx can be surgical ?

A
  • Congenital
    Neoplasia
  • Prolapse
  • vulvitis?
30
Q

What species specific considerations - gerbils ?

A
  • High incidence of ovarian dx -> cysts, neoP
    CLS: abd distention, bilat alopecia, weight loss, dec appetite, respiratory effort

Dx: cls, imaging
Ventral midline approach

31
Q

Pyometra or not - syrian hamsters?

A

Off-white, stringy discharge after ovulation on day 2 of oestrus cycle -> completely normal!

32
Q

Pyometra in hamsters/ gerbils?

A
  • Do not misinterpret in hamsters!
    Dx: cls, US, cytology
33
Q

What type of ammmary tumours do rats get?

A

Often benign fibroadenomatous mammary tumours

34
Q

What is thought to play a part in mammary tumours?

A

Prolactin

35
Q

Where an mammary tumours develop?

A

tissue extensive! -> from peri-anal to shoulder region!

36
Q

What prevention against mammary tumors?

A

Early age Ovariectomy (<90days)

37
Q

What charcateristics of male reprod tract ?

A

Histricomorphs (GPs) o not have a distinct scrotum
- Testicles located in inguinal region
- Testicles large for body size
- inguinal canals remian open -> funcitonal cremaster muscle to move in and out of abdo cavity

38
Q

Who’s inguinal ring closes?

A

Rabbits and rodents -> stays OPEN

39
Q

What approaches to ‘catsration’ do we have in rodents?

A
  • Scrotal -> open, closed, open/closed mix
  • Prescrotal - open, closed, open/closed mix
  • Abdominal approach

Vasectomy

40
Q

Describe Abdominal approach castration (GPs, and small rodents)

A
  • 1-2 cm incision between umbilicus and pubis
  • Start incision caudal to umbilicus
  • Incise Linea Alba
  • Exteriorise bladder & reflect caudally
  • Visualise testicle fat pad & exteriorise testicle
  • Break tunic attachment and place 1 clamp
  • Place encircling lig
  • Remove testicle and check stump for bleeding
41
Q

Describe Pre-scrotal/scrotal approach -> open-closed (modified open technique)

A
  • Dorsal recumbency - lidocaine block & prescrotal or scrotal incision
  • In cise tunica vaginalis & exteriorise testicle
  • Detach from lig of tail of the epididymis
  • Place lig proximal to incision in tunic to incorporate entier spermatic cord -> losing off tunic and external ring
42
Q

What are rodents prone to post-castration?

A

Incisional infections and scrotal abscessation

43
Q

How do we identify testicular dx?

A
  • Change in testicular shape/ texture
  • Change in libido
  • Inflammation / papules/ ulcers
44
Q

What kind of testicular dx do we see?

A
  • Testiular neoplasia
  • cryptochidism
  • Orchitis
  • Epididymitis
  • Preputial/ testicular trauma - sometimes surgical
45
Q

Describe fur ring in chinchillas and degus

A
  • Fur ting traps penis causing paraphimosis -> large areas of self trauma can be visible due to pain
46
Q

What GI dx are GPs prone to?

A

Bloat & GDV

(similar approach to dogs -> often see engorged gastric vessels and spleen)

47
Q

How do we deal with GDV/ Bloat in GPs?

A
  • Decompress stomach and careful reposition
  • Perform gastropexy using monofilament suture
  • Flush abdo with warmed steriel saline
  • Routine closure
48
Q

What GI (ish) dx do hamsters get?

A

Cheek pouch eversion -> bilat storage cheek pouches lined with a thin epithelium

49
Q

How to treat cheek pouch eversion?

A
  • Brief GA - clean pouch
  • 1ml syringe to reduce and reposition pouch in mough
    Place 1-2 mattress sutures, through the skin and cheek pouch and exit skin again - leave in for 2 weeks
  • Withhold normal diet for 3-5 days offer syringe soft feed to prevent use of pouch
50
Q

What urinary tract dx do GPs get?

A
  • Urinary calculi -> most common in males, urethral obstruction common
51
Q

How to treat urinary calculi?

A
  • Ventral midline incision caudal abdomen
  • Identify bladder & place soaked swabs
  • Place stay sutures at APEX of bladder & each side of proposed cystotomy incision
  • Enter bladder in avascular area
  • Remove uroliths (suction to prevent urine leakage)
  • Collect samples
  • lavage bladder
  • Close (one layer - monoF absorbable
52
Q

What orthopaedic surgery is routinely done in small rodents?

A

Degloving & Tail amputations

53
Q

Who prone ot degloving/ tail amp?

A

Gerbils and degus

54
Q

When is tail amputation recommended?

A

If loss of blood supply

55
Q

How to do a tail amp?

A
  • Make incision 1-2mm proximal to the location of skin loss
  • Incise the dorsal skin more proximal than the ventral skin
  • Tail incised between 2 vertebrae
  • Ensure haemostasis of ventral coccygeal vessels
  • Close via a Sc layer then intradermal suture layer or tissue adhesive