Spaying rabbits and rats (Proceedings)

Spaying rabbits

Indications:

o Intact females have a high rate of uterine adenocarcinoma

     • as high as 80% by age 3 years and older

          • very high incidence of systemic metastasis (mainly lung and liver)

o Intact females are impossible to keep together due to constant fighting

o High reproductive rate

     • Females can conceive within 24 hours post partum

Anatomy:

o The vaginal body is very long and more flaccid than in other species

o The vagina fills with urine during micturition

o Two cervices (bicornute cervix or cervix duplex) are present as normal anatomy

o The ovarian vessels are very well developed

o The bladder receives a branch from the uterine artery

o The uterine horns and the uterine blood vessels are often encased in large amounts of fat, especially in older females

o The large intestine, especially the cecum, is in close proximity to the surgery site

Preparation:

o All forms of stress should be avoided prior to surgery

     • House rabbit in a quiet ward

     • Avoid barking dogs

     • Try not to house a ferret directly next to a rabbit

     • Avoid olfactory or direct visual contact between the rabbit patient and prey species

o In older intact do perform radiographs and/or an ultrasound exam prior to surgery to check for subclinical uterine neoplasia or metastasis

o Ideally a CBC and a chemistry panel should be run prior to anesthesia

o Ensure doe is optimally hydrated

     • Maintenance fluids are approximately 120 ml/kg/day

Procedure:

o Generally very similar to a cat spay

o Approach by ventral midline incision

o Make a 1-2 inch incision between umbilicus and pubis

     • Make incision closer to umbilicus as ovarian ligaments are not 'stretchable'

o Cervices will be visible immediately in the incision

o Do NOT use spay hooks of any kind

o Avoid manipulation of GI tract at all costs.

o Follow uterine horn cranially to ovary

o Ovary is extremely small in relation to uterine horn, and yellow

     • Left ovary is close to kidney

o Identify ovarian artery and ligate immediately

     • Hemoclips will speed procedure up

o Bluntly dissect along uterine horn

     • Radiocauthery can be used on smaller uterine vessels

o Repeat procedure on other side

o In young animals transection of uterine horn can be made cranial to cervix

     • Will leave cervix behind and may provide an additional barrier against bacterial contamination from vagina

o In older animals remove cervices completely

o Transection is performed in vagina (ovario-vagino-hysterectomy)

     • Reduces the chance of a subclinical uterine cancer in remnant tissue

o Close incision in a 3 layer fashion

     • Use an intradermal suture pattern

Follow-up:

o make sure animal is eating, urinating and defecating

Possible complications:

o Intestinal adhesions

     • Fibrin clots

o Ligation of a ureter

o Leakage of urine from vaginal stump

     • If cervix is completely removed

o Uterine cancer in the residual tissue

     • If cervices are not removed

Spaying rats

Indications:

o Intact females have a high incidence of mammary cancer (adenoma/adenocarcinoma)

     • as high as 66% by about 2 years of age (21 months)

     • Spayed rats have a significantly lower rate of mammary cancer.

     • If mammary cancer develops it usually has a low incidence of systemic metastasis (e.g. lung and liver)

o High reproductive rate

     • Note: Intact female hamsters normally have a vaginal discharge

          • Often mistaken for pyometra

Anatomy:

o The ovaries are located caudal to the kidneys in a large fat pad

o The uterine horn wraps around the ovary

o The ovarian vessels are not well developed

o The ovarian ligament is very long and the ovary is easily exteriorized

Preparations:

o Evaluate patient thoroughly for sub-clinical forms of respiratory disease or heart disease in older animals (over 2 years old)

o Ideally a minimal screen (hematocrit, total solids, blood glucose and blood urea nitrogen) should be run prior to anesthesia

o Make sure animal is optimally hydrated

     • Maintenance is approximately 100 ml/kg/day

Procedure:

Ventral approach :

o Very similar to cat spay

o Approach by ventral midline incision

o Make a 1 inch incision between umbilicus and pubis

o The cervix will be immediately visible in the incision

o Follow uterine horn cranially to ovary

o Identify vessels in mesovarium and ligate

     • Hemoclips will speed procedure up, otherwise use 5-0 Maxon or PDS

o Bluntly dissect along uterine horn

     • Radiocauthery can be used on smaller uterine vessels

o Repeat procedure on other side

o In all animals transection of uterine horn can be made cranial to cervix

     • Will leave cervix behind and may provide an additional barrier against bacterial contamination from vagina

o Close in a 2 or 3 layer fashion

     • Use an intradermal suture pattern

     • Apply lidocain to suture site, this will decrease frequency of selfmutilation.

Dorsal approach:

o Developed in lab animal medicine where ovariectomy is a common procedure

o Ovaries and part of the uterine structures can be accessed dorsally

o A dorsal approach offers a number of advantages to the ventral approach

     • Less invasive

     • Less painful

     • Smaller incision

     • Less likely to see post-surgical incision complications due to self-mutilation or contamination with soiled bedding material

o Make a half-inch skin incision on midline, directly over the spinal column, between the last rib and pelvis.

o The skin incision can then be moved to the left or right side about 1 cm lateral to the spinal processes to access the body wall

o Move the skin incision laterally to one side and bluntly dissect through the body wall.

o A large fat deposit is usually seen when dissecting through the body wall and the ovary sits within this fatty tissue.

o Exteriorize the ovary and the uterine horn and place a hemoclip around the uterine horn prior to excising it

o The body wall can be closed with a 5-0 Maxon or PDS or can be left open

o Repeat the procedure on opposite site

o Close skin with an intradermal suture pattern

Follow-up:

o make sure animal is eating, urinating, and defecating

o recheck suture site frequently

o keep separate from other cage mates, as they sometimes 'groom' suture out

Common complications:

o suture removal by animal

o inadequate pain management often responsible for self mutilation.

Resource:

Capello, V. Surgical Techniques for Neutering the Female Pet Rabbit. ExoticDVM 7.5 page 15

Johnson-Delaney, C. Ovariohysterectomy in a Rat. ExoticDVM 4.4 page 17