Anal & rectal conditions Flashcards
1
Q
Common dz of the rectum and anus
A
- anal sac dz
- anal furunculosis
- anal adenomas
- other peri-anal neoplasia
- rectal prolapse
- rectal stricture
- rectal neoplasia
2
Q
General considerations
A
- infection risk
- haemorrhage
- faecal incontinence (risk)
3
Q
General considerations - infection risk
A
- bacteria & faeces
- large clip
- evacuate rectum & place
- pause string or pack with swabs
- don’t use enemas
- pre-op iv antibiotics e.g. cephalexin/metronidazole
4
Q
General considerations - haemorrhage
A
- very vascular
- lots of perineal branches of major vessels
- electrocautery/vessel sealing/harmonic scalpel useful
5
Q
General considerations - faecal incontinence (risk)
A
- external anal sphincter is important in faecal continence
- disruption by excision/damage to nerve supply
- 50% of sphincter can be safely resected??
6
Q
What are the anal sacs? Where are they? How do they discharge?
A
- scent glands
- located at 4 & 8 o’clock in between external and internal anal sphincters
- discharge through ducts at defection
7
Q
Anal sac disease - examples
A
- impaction or abscessation
- due to a change in consistency of secretion or interference with normal duct emptying e.g. d+, tapeworm, seborrhoea, oestrus, scar tissue
- neoplasia & bites in cats
8
Q
Anal sac disease - presentation
A
- perineal irritation: scooting
9
Q
Anal sac disease - diagnosis
A
- impaction/infection readily diagnosed on palpation
10
Q
Anal sac disease - tx
A
- manual expression of the gland
- address underlying cause - d+, skin allergy, etc
- inspissated content may need irrigation
- blood tinged material / pus indicates abscess
– requires lavage and packing with local antibiotic (cow mastitis tubes / ear drops normally under GA)
11
Q
Anal sacculectomy - indications
A
- recurrent impaction
- neoplasia
- on occasion, an additional component of the tx for perianal fistula (anal furunculosis)
Delay sx if recently ruptured abscess
12
Q
Anal sacculectomy - complications
A
- draining sinus (some gland left)
- infection
- dehiscence
- tenesmus
- faecal incontinence
13
Q
Anal furunculosis (perianal fistulae) - what is it?
A
- suppurative, progressive, deep ulcerating tracts in the perianal tissues
- immunological theory
14
Q
Anal furunculosis (perianal fistulae) - signalment
A
- GSD, but any breed inc. crossbreeds
15
Q
Anal furunculosis (perianal fistulae) - CS
A
- low tail carriage
- +++ density of apocrine glands in perineum
- start off looking like little pin heads around the anus itself
- when lift the tail it looks relatively innocent (as if the dog has scraped itself / minor irritation), but if you probe these tracts you find they go very deep into the perineum
16
Q
Anal furunculosis (perianal fistulae) - tx
A
Cyclosporin (Atopica)
- for 12w will resolve 60% but 70% of these will recur in 4-17m
- very expensive
- can have multiple adverse effects e.g. v+/d+, coat changes, nephrotoxicity or hepatotoxicity, gingival hyperplasia
Hypoallergenic diet & immunosuppressive doses of preds
- only helped in 1/3 of very mild cases
- based on theory that there’s an association between IBD and fistulae
If a failure to respond to cyclosporin then check no anal sac involvement
- if there is, then the dog will need anal sacculectomy
17
Q
Anal adenocarcinoma - what is it?
A
- malignant lesion of perianal sebaceous glands
18
Q
Anal adenocarcinoma - where do they occur?
A
- in the same areas as adenomas
- can diffusely infiltrate anal areas
- often adherent to deeper tissues
19
Q
Anal adenocarcinoma - characteristics, CS & mets
A
- rapidly growing
- 13% have signs of sublumbar LN enlargement on presentation
- CS of dyschezia & pain
- rare to mets to other organs
20
Q
Anal adenocarcinoma - tx
A
- do not respond to castration
- aggressive surgical removal with adequate margins is indicated
- adjunctive radiotherapy but rarely curative
- regional LN excision
- poor prognosis due to local recurrence and mets
- distant mets can take many years to develop, repeat palliative local surgeries justified
21
Q
Anal sac adenocarcinoma - signalment
A
- generally older female dogs (over 10y)
22
Q
Anal sac adenocarcinoma - paraneoplastic syndrome
A
- paraneoplastic syndrome often accompanies
- tumour secrete PTH-like substance
- hypercalcaemia causes PUPD, depression, weakness, weight loss
- aggressive, 50% mets at presentation
- prolonged hypercalcaemia can produce irreversible renal damage
23
Q
Anal sac adenocarcinoma - what is it?
A
- small discrete nodules in the wall of either sac i.e. tumour within the anal sac itself
24
Q
Anal sac adenocarcinoma - diagnosis
A
Based on
- palpation
- biochem findings
- abdominal/thoracic rads
- abdominal/thoracic CT
- US of sublumbar LN
25
Anal sac adenocarcinoma - tx
Treat hypercalcaemia prior to surgery
Treatment
- excision of primary mass
- metastectomy
- adjunctive chemo
26
Perianal adenoma - what is it?
- perianal sebaceous gland adenoma
- testosterone dependent benign masses
27
Perianal adenoma - prevalence & tx
- 3rd most common tumour in male dog
- rare in castrated dogs, should resolve with castration
- normally seen in older pts
- don't see in cats as they don't have perianal glands
28
Perianal adenoma - characteristics
- well circumscribed hairless area of anal ring most common location, can see at tail base, prepuce & ventrum
- slow growing
- 0.5-3cm diameter
- can ulcerate if traumatised
- rarely adherent to surrounding structures
29
Perianal adenoma - diagnosis
- must differentiate from malignant adenocarcinoma
- biopsy
30
Perineal rupture - prevalence
- not uncommon
31
Perineal rupture - signalment
- normally entire older male
- occasionally in bitch/cat
32
Perineal rupture - prevalence
- can be spectacular
- bulging perineal area
- faecal tenesmus/dysuria
33
Perineal rupture - cause
- progressive weakening of pelvic diaphragm
- hormonal influence
- tenesmus
- congenital/acquired weakness
- colitis/prostatomegaly
34
What muscles support the anus? What is the relevance of this re perineal rupture?
- levator ani, coccygeus and external anal sphincter muscles provide lateral support to the anus
- disruption to this causes rectal enlargement, faecal impaction and tenesmus
- can be bilateral
- pelvic fat, peritoneal fat, prostate and bladder can herniate
35
Perineal rupture - diagnosis
- reducible perineal swelling
- on rectal, absence of pelvic diaphragm (lateral absence of muscle support)
- always check for bilateral dz
- asses sphincter tone -> chronic case can remain faecally incontinent despite sx due to neurological damage due to stretching
- US hernia / contrast urethrography will highlight bladder
36
Perineal rupture - bladder retroflexion
- emergency
- stranguria
- hyperkalaemia
- azotaemia
- avascular necrosis
37
Perineal rupture - tx
- cystocentesis through perineum if bladder retroflexed and can't pass urethral catheter
- IVFT (check K levels if urinary obstruction)
- hemiorrhaphy ± colopexy + castration
38
Perineal rupture - tx complications
- faecal incontinence
-- suture placement
-- duration of problem
- urinary problems
- infection
- rectal prolapse
- sciatic nerve entrapment
- recurrence
39
Rectal prolapse - what is associated with?
- ectoparasites/enteritis in young animals
- tumours or perineal hernias in middle aged/older animals
40
Rectal prolapse - incomplete vs complete prolapse
- incomplete prolapse = mucosa only
- complete prolapse = all layers of rectal wall in entire circumference
41
Rectal prolapse - Hx & CS
- everted tissue is oedematous, excoriated and can be bleeding
- recent straining, e.g. perineal surgery, constipation, urinary tract infection, dystocia, etc
42
Rectal prolapse - tx
Ensure not intussusception
Acute presentation
- lavage
- lubricate
- reduce and place purse string suture
Non-reducible or severely traumatised
- amputation
Recurrent
- colopexy
-- midline coeliotomy
-- identify the colon, draw it cranially and sexy the wall to the peritoneal wall
43
Rectal stricture - what is it normally secondary to?
- proctitis (inflammation of rectum lining)
- chronic anal sacculitis
- penetrating FB
- complication of anorectal sx
44
Rectal stricture - CS
- dyschezia
- constipation
- tenesmus
45
Rectal stricture - diagnosis
- digital rectal exam: narrowing of the bowel
- contrast radiography/colonoscopy are difficult as superficially located
- deep biopsy differentiates from neoplasia
46
Rectal stricture - tx
- superficial strictures tx by bougienage (well lubricated finger / blunt instrument)
- this may need to be repeated at regular intervals for many days
- corticosteroids then for 2-3w
- extensive strictures require resection by e.g. rectal pull-through
47
Rectal polyps - what are they?
- benign, adenomatous polpys
- little pedunculate/sessile/raised vascular lesions
- multiple or single
48
Rectal polyps - signalment
- male & female equally affected
- mean age 7y
49
Rectal polyps - cause
- unknown
50
Rectal polyps - clinical presentation
- blood/mucus in faeces
- tenesmus can occur
- polyp can occasionally prolapse from anus
- secondary rectal prolapse can occur
51
Rectal polyps - tx
- small pedunculate masses can be removed form distal rectum with electrocautery, or excision and suture placement
- larger polyps may need intestinal resection
52
Rectal adenocarcinoma - 3 types
- infiltrative
- ulcerative
- proliferative
53
Rectal adenocarcinoma - what do they do?
- invade the rectal wall causing fibrosis and stricture
54
Rectal adenocarcinoma - CS
- tenesmus
- dyschezia
- weight loss & lethargy with advanced malignancy
55
Rectal adenocarcinoma - diagnosis
- palpation
- radiography
- US
- endoscopy/protoscopy
56
Rectal adenocarcinoma - 3 sites
- colorectal junction and cranial 1/3 rectum
- middle 1/3 rectum
- caudal 1/3 rectum and anal canal
57
Rectal adenocarcinoma - surgical tx
- colorectal resection and anastomosis ± ischial pubic flap osteotomy
- dorsal perineal approach
- rectal pull-through
- pubic symphysiotomy
- consider and discuss continence with O
58
Rectal adenocarcinoma - pre-op considerations
- same as for anal sx
- care with enemas
- evacuate distal rectum
- large clip
- antibiotics effective against gram-ve aerobes and anaerobes
59
Atresia ani - what is it?
- absence of anus in neonate (as animal born with it)
60
Atresia ani - prevalence
- uncommon
61
Atresia ani - what can it be associated with?
- recto-vaginal or recto-urethral fistulae
- secondary megacolon
62
Atresia ani - CS
- tenesmus and bulging of perineum
63
Atresia ani - diagnosis
- confirmed on radiography
64
Atresia ani - tx
- involves created of an anus by excision of skin and terminal rectal mucosa and careful suturing
- subtotal colectomy?
