Large Intestine, Rectum, and Anus Flashcards
How is the large intestine different from the small intestine in regards to healing?
- higher bacterial count
- increased collagenase after surgery
- different blood supply
What is cecal inversion?
- cecal intussuseption
- causes obstruction of the ileocolic junction
What are the clinical signs associated with cecal inversion?
diarrhea
hematochezia
tenesmus
weight loss
How is cecal inversion diagnosed?
- radiographs
- contrast radiographs
- endoscopy
How is cecal inversion treated?
- manual reduction
- colotomy
- typhylectomy
What are the indications for typhylectomy?
- cecal impaction
- cecal inversion
- perforation
- neoplasia
What are the most common cecal neoplasms?
leiomyoma/sarcoma
What are the causes of megacolon?
- mostly idiopathic
- pelvic obstruction
- neurologic
- endocrine
Describe the pathophysiology of idiopathic megacolon
- feces retained in colon becomes dehydrated and solidifies
- leads to chronic colonic distension
- smooth muscle and nerve damage
- increased absorption of bacterial toxins
What are the clinical signs associated with megacolon?
- straining to defecate
- hard mass on abdominal palpation
- depression
- anorexia
- vomiting
- dehydration
What is the medical treatment for megacolon?
- correct dehydration
- deopstipate
- increased fiber diet
- stool softeners
- osmotic laxatives
- prokinetics (Cisapride)
What is the surgical treatment for megacolon?
subtotal colectomy
- remove as much colon as possible
- colocolostomy helps retain ileo-colic valve
- ileocolostomy may result in severe diarrhea
What is atresia ani?
How is it treated?
- congenital abnormality
- stenosis or membrane over the anal tissue
- unable to defecate
- transect/resect the membrane
What is rectovaginal fistula?
- congenital abnormality
- connection between the vaginal vault and rectum
- associated with UTIs
What is anogenital cleft?
- congenital abnormality
- common opening for anus and genital tract
- leads to UTI
What is anal prolapse?
How is it treated?
- incomplete prolapse
- anal mucosa protrudes from orifice
- manually reduce and place purse string
What is rectal prolapse?
- complete prolapse: all layers of rectum protrude through anal orifice
What are the predisposing factors for rectal prolapse?
- parasites
- colitis
- urogenital disease
- tumors
- younger animals
What are the treatments for rectal prolapse?
if viable
- manually reduce
- saline, lubricant, mannitol
- purse string
if non-viable
- resect 1-2 cm from anus
- reduce prolapse
What are the complications associated with surgical treatment of rectal prolapse?
- infection
- dehiscence
- stricture
- recurrence
What are the most common tumors of the rectum?
adenomatous polyps
adenocarcinoma
How are rectal tumors diagnosed?
- direct observation
- digital rectal palpation
- colonoscopy
- biopsy
When is the trans-anal approach used?
- excision of small, non-invasive, pedunculated polyps
- lesions in the caudal 4-6 cm of rectum
When is the dorsal approach used?
tumors of mid-rectum
When is the rectal pull through approach used?
lesions in mid/caudal rectum
When is the ventral approach used?
lesions at colorectal junction or more extensive lesions
What are the common causes of anal sac disease?
infection of duct obstruction
What is the medical management of anal sac disease?
- express gland
- cannulate and irrigate
- infuse antibiotics and steroids
- drain/flush abcesses
What is the surgical management for anal sac disease?
anal sacculectomy
What are the complications associated with anal sacculectomy?
- infection
- draining tracts
- fecal incontinence
What is the most common anal sac tumor?
- apocrine gland adenocarcinoma
- highly malignant
What is the treatment for anal sac adenocarcinoma?
surgical excision and chemotherapy
What is perianal fistula?
chronic suppurative ulcerative tracts
What is the possible etiology of perianal fistulas?
- broad base low carriage tail
- abscessed anal glands
- hair follicle infection
- immune-mediated
Who is predisposed to perianal fistulas?
middle-aged GSDs
What is the medical management for perianal fistulas?
- perianal cleansing
- antibiotics
- immunosuppressive therapy
What is the surgical management for perianal fistulas?
- surgical excision
- anal sacculectomy
- cryosurgery
- fulguration
- tail amputation
- laser excision
- anoplasty
