Rectum

Question 1

Atresia coli

Answer 1

Absence of myenteric ganglia (ileum, cecum and large colon)
Recessive lethal white gene

Question 2

Dominant lethal white gene

Answer 2

Homozygous breeding
Early embryonic death

Question 3

Recessive lethal white gene

Answer 3

Breeding 2 overo paints
s or s’ alleles responsible for white foals
Homo allele affects migration of cells from neural crest

Question 4

Blind end atresia

Answer 4

Congenital loss of blood supply’Absent large, transverse or small colon
Gaps in the mesentary

Question 5

CS of atresia coli

Answer 5

Pink skin and pale mm
Fail to pass meconium → colic
No feces on rectal and bulge in anus if colon intact
Euthanize first 24 hrs
Feces present through vaginal wall

Question 6

Dx atresia coli

Answer 6

CS
Barium enema, endoscopy, exploratory sx

Question 7

Associated lesions of atresia coli

Answer 7

Cleft palate
Renal hypoplasia
Rectovaginal or rectourethral fistulae

Question 8

Tx for atresia ani

Answer 8

Membrane or skin removed
Rectal wall sutured to skin
Midline in severe cases

Question 9

Tx for atresia coli (fistulae)

Answer 9

Rectal pull through excision of stenosed agent
Closure of anobullar fistulae
Bowel incontinence not a problem

Question 10

Rectal tears

Answer 10

Quarter horses and arabians
77% in mares urogenital tract
Thromboembolic disorders (ischemic necrosis, thrombosis of cd. mesenteric and branches)

Question 11

Dorsal rectal tears

Answer 11

25-30 cm from anus (intraperitoneal portion)
↓ circular wall thickness
↑ in longitudinal taenial band

Question 12

CS of rectal tears

Answer 12

Fresh blood in rectal sleeve
↓ resistance on palpation
Sweat in 2-3 hrs due to peritonitis (↑ HR, fever, abdominal pain, splinted abdomen and endotoxic shock)

Question 13

Graded rectal tears

Answer 13

1: mucosa and submucosa
2: muscular walls only
3: a- full thickness but serosa intact, b- full thickness into mesocolon (G3 seen clinically)
4: complete tear into the abdomen

Question 14

Rectal tear evaluation

Answer 14

Epidural anesthesia
Sedation
Bare finger palpation (position, distance form anal sphincter, depth of tear)
Remove feces from around tear

Question 15

How to tx grade 1 rectal tears

Answer 15

Broad spectrum ab
Mineral oil and IV fluids
Optional direct suturing of tear
Peritoneal fluid evaluation and serial hemograms

Question 16

How to tx grade 2 rectal tears

Answer 16

Dietary control and soften feces

Question 17

How to tx grade 3 rectal tears

Answer 17

Sedation
Epidural anesthesia (fecal removal and eval, prevents straining against)
Rectal packing (prevents G4 lesions, 10 cm cr. to tear → clamp/ purse-string anus)

Question 18

Medical tx for grade 3 rectal tears

Answer 18

Atropine
Broad abx, tetanus toxoid, mineral oil and IV fluids

Question 19

Surgical options for grade 3 tumors

Answer 19

Direct suture though rectal lumen or from prolapse
Diverting colostomy
Rectal liner
Suture through celiotomy

Question 20

Direct closure of rectal tears

Answer 20

Less than 15 cm from anus and easily dilated rectum
Patient horse
Blind suture 1 or 2 hand method
Expandable rectal basket

Question 21

Temporary rectal liner

Answer 21

Passed and sutured proximal to lesion
Pelvic flexure colotomy
Direct suture of tear: reduces lesion size and prevents ostomy and further leakage
Passed in 10-14d

Question 22

Ventral midline approach to rectal tears

Answer 22

Best fro cr. lesion forward to the pelvic brim
Elevate hindquarters with traction
Suture through colotomy on antimesenteric side

Question 23

Postoperative care for rectal tears

Answer 23

Broad abx
Pellets and mineral oil diet
Warm water enema of stoma
Local stoma abscesses
Heparin v methylcellulose
Heal: 4-6w

Question 24

Postoperative complications with rectal tears

Answer 24

Stomal abscesses
Peristomal herniation v. stricture

Question 25

Reanastomosis (rectal tears)

Answer 25

4-6w
Ventral midline celiotomy (evaluate and correct adhesions, remove stoma in infected)