Surgery of the Anal and Perianal Regions Flashcards
What is the term to describe the junction between the rectum and anal canal?
Anorectal line
At the anus the mucocutaneous junction with the perianal skin is known as
Anocutaenuous line
What muscles is the anal canal surrounded by? (2)
Internal smooth muscles
Striated external anal sphincter muscle
The anal mucosa and the external anal sphincter muscle are supplied via (3)
The right and left caudal rectal arteries
Branches of the internal pudendal arteries
The cranial rectal artery in some individuals.
What are anal glands? Where do they sit?
circumanal glands that lie in the cutaneous tissue of the anus
What are anal sacs; where are they found?
These are spherical/conical sacs, found between the inner smooth muscle and outer straited muscle of the anus.
Where do anal sacs excrete in dogs?
level of the mucocutaneous junction at approximately 4 and 8 o’clock on the anus.
Where do anal sacs excrete in cats?
Lateral to the anus.
What is atresia ani?
Congenital abnormality; failure of the normal rectoanal canal and anal aperture to develop
Define Type I Atresia ani
stenosis of the anal canal
Define Type II Atresia ani
Persistence of an anal membrane with the rectum ending immediately proximal to this as a blind pouch
Define Type III Atresia ani
Closed anus with a more cranially positioned blind ending rectum
Define Type IV Atresia ani
Cranial rectum ends in a blind pouch within the pelvic canal.
Clinical signs of atresia ani type I.
Essentially normal until after weaning when constipation and/or tenesmus can develop.
Clinical signs of atresia ani type II-IV. (4)When does it develop?
A normal initially 2-4 weeks of life before developing abdominal enlargement,
Anorexia
Restlessness
Unable to defecate.
Some will have a perianal bulge indicating the anal membrane.
What can be used to assess the location and degree of anal stenosis? (2)
Physical exam
Abdominal radiographs
Treatment of type I atresia ani (2)
bougienage or balloon dilation of the stenosis/stricture, although repeated procedures may be necessary.
Treatment of type II/III atresia ani
small linear incision can be made over the location of the absent anal aperture, preserving the anal sphincter. The rectum can then be identified and brought caudally to then be opened and sutured to the surrounding subcutaneous tissues if necessary.
What tumour of the anal sacs accounts for 17% of all tumours in the perianal area?
Apocrine gland adenocarcinoma
The three most common non-neoplastic conditions that affect the anal sac are
impaction
sacculitis
abscessation
Why is it thought that cats are less likely to suffer anal sac issues?
secretion of the sebaceous glands within the anal sacs is more lipid based -a more fluid secretion which is less likely to occlude the duct
What is an impacted anal sac, and how do treat?
anal sacs become swollen/engorged but are typically not painful. Impacted anal sacs are easy to palpate but can be less easy to express.
Treatment by manual expression is common, although in some cases sedation and flushing of the duct is required.
True or false
Sacculitis can occur without impaction, in which case hypersecretion can occur.
True
Sacculitis
A) What is it like on palpation?
B) What other clinical findings might there be?
A) Painful
B) pyrexia
What can form with sacculitis which is similar on exam to an anal mass?
metaplastic ossification (formation of irregular foci of bone
What medication is appropriate with anal sacculitits?
ABx
anti-inflam
How to treat anal sac abscessation?
Abscessation of the anal gland can be treated with incision, drainage and lavage of the abscess cavity.
Antibiotics and or anti-inflammatory medication are appropriate.
Proposed theories leading to anal sac disease? (11)
Abnormal seborrheic glandular secretions in patients with generalised seborrhea
Activity level
Anatomic variation *
Anal/Perianal swelling
Diarrhoea
Diet
Inflammatory bowel disease
Obesity
Perianal fistulae
Prolonged retention of secretions
Pudendal nerve dysfunction.
Where are anal sac ducts located in GSD which pre-disposes them to dx?
More cranial