Ch 94 Rectum, anus + perineum Flashcards
Anatomy
- colorectal junction is an arbitrary point;
- proposed landmarks: pubic brim, L7, or the point at which the cranial rectal artery penetrates the seromuscular layer of the intestinal tract
- The visceral peritoneum along the distal rectum reflects cranially to blend with the parietal peritoneum (pararectal fossa)
- Caudal to this, the rectum is retroperitoneal.
- rectum is bounded dorsally by ventral sacrocaudal muscles, laterally by the levator ani muscle, and ventrally by the vagina/urethra
- The retroperitoneal portion of the rectum lacks a serosal layer
- Rectal mucosa contains approximately 100 solitary lymph nodules
- cranial rectal artery provides the majority of the blood supply to the terminal colon and rectum
- ## The intrapelvic rectum has a poorer blood supply
Anal Canal and Anus
- 1 to 2 cm long and lies ventral to the fourth caudal vertebra
- lined by stratified squamous epithelium
- junction of this epithelium with the simple columnar epithelium of the rectum is known as the anorectal line.
- The mucosa of the anal canal is divided, from cranial to caudal, into columnar, intermediate, and cutaneous zones
- Anal canal mucosa and sphincter muscles receive their blood mainly from caudal rectal arteries (internal pudendal arteries)
Anal Sacs, perineum, glands and muscle
anal sacs
- located between the inner smooth and outer striated sphincter muscles of the anus
- anal sac and duct are lined by stratified squamous epithelium.
perineum
- dorsally by the tail, ventrally scrotum or vulva, and laterally by the skin over the superficial gluteal and internal obturator muscles and the tuber ischii.
- deep surface it is bounded by the third caudal vertebra dorsally, the sacrotuberous ligaments laterally, and the arch of the ischium ventrally
- perineal fascia: superfiical (vessels and nerves) and deep (attached to obturator, ischii, sacrtuberous, gluteals)
- pelvic diaphragm = pelvic fascia, paired coccygeus and levator ani muscles
- internal pudendal and caudal gluteal arteries.
Glands of the Anus and Perineum
- circumanal, anal, and paranal sinus glands
- apocrine and sweat glands
Specialized Muscles
- internal anal sphincter consists of smooth muscle and thus has an involuntary function
- external anal sphincter is a circular band of striated muscle: permits maximum distention of the rectum for fecal storage while maintaining anal control and thus fecal continence
- paired rectococcygeal muscles are smooth muscles
Innervation of the Rectum and Anus
- peritoneal reflection contains autonomic nerve fibers of the pelvic plexus that innervate the rectum, internal anal sphincter, and rectococcygeus muscle
- pelvic plexus = pelvic n (parasympathetic); sacral nerves; and hypogastric n (sympathetic)
- Parasympathetic > excitatory to the rectum and inhibitory to the internal anal sphincter
- Sympathetic > inhibitory to the rectum and excitatory to the internal anal sphincter.
- caudal rectal (pudendal nerve) supplies voluntary control
- Control of rectal function, including storage and defecation, is through intrinsic and extrinsic systems
What is unique about the resting membrance potential in GI smooth muscle cells?
The resting membrane potential is not constant. It oscillates in slow waves over time, generated by pacemaker cells called the interstitial cells of Cajal
Patient Preparation and Antibiotic Therapy
- terminal rectum should be evacuated digitally and the anal sacs expressed before surgery
human
- meta-analysis, there was no evidence to indicate that human patients benefitted from mechanical bowel preparation or use of rectal enemas.
- In a meta-analysis of preoperative antibiotics before colorectal surgery, risk of surgical wound infection was greatly reduced by the use of prophylactic broad-spectrum antibiotics
- There was no value in continuing antibiotic administration after surgery was completed
How many bacteria are there per gram of faeces?
10^9 bacteria per gram of faeces
- Up to 90% anaerobes
- Gram-positive anaerobes: Clostridium, Lactobacillus,
- Gram-negative anaerobes: Bacteroides, Fusobacterium, and Veillonella
- Gram-positive aerobes (Streptococcus, Staphylococcus, Bacillus, Corynebacterium),
- Gram-negative aerobes (Escherichia coli, Enterobacter, Klebsiella, Pseudomonas)
What periop ABx are suitable?
2nd gen cephalosporins
Aminoglycoside + Beta-lactam or clindamycin
List the approaches to the rectum
- Ventral +/- symphysiotomy or bilateral pubic and ischial osteotomy (cranial rectum and colorectal junction)
- Dorsal (caudal to mid-rectum)
- Lateral (small focal lesion, not commonly used)
- Caudal (eversion, trancutaneous rectal pull through, transanal rectal pullthrough, Swensons pullthrough)
- Combined abdominal transanal approach
Ventral Approach
- indicated: tumors in the cranial rectum and colorectal junction
- urethra is catheterized to facilitate its identificatio
- ventral midline abdominal incision is extended caudally
- exposure to the pelvic canal is necessary, pelvic symphysiotomy, pubic osteotomy, or bilateral pubic and ischial osteotomies can be performed
- 2-cm margin of grossly normal bowel on both sides of a malignant lesion
- individual vasa recta supplying area ligated to preserve blood supply
- A single layer of simple interrupted approximating sutures through all layers of the bowel is recommended (less stricture)
- 3-0 or 4-0 PDS or polyglyconate
- 3 mm apart and 2 to 4 mm from the incised rectal edge
- Alternatively, an end-to-end anastomosis (EEA) stapler
Pelvic symphysiotomy
- separation of the pubis and ischium along their ventral midlines
- Retraction is limited by the flexibility of the bone and size of the dog;
- excessive retraction may result in sacroiliac luxation
Pubic and Ischial Osteotomies
- procedures offer wide exposure, facilitating blunt dissection of the cranial peritoneal reflection and pelvic nerves and ligation of specific vessels
- Periosteum and soft tissues removed from only one side of the pubis, allowing it to hinge
- Complete detachment of the bone segment may increase susceptibility of the avascular bone to infection and sequestration
- Holes are predrilled
Dorsal Approach
indicated: resection of tumors of the caudal to mid rectum
- U-shaped incision
- aired rectococcygeus muscles are transected near their attachments at the ventral surface of the coccygeal vertebrae
- To improve exposure the levator ani muscles can also be transected.
- prevent damage to the pelvic nerve plexus that fans along the lateral surface of the rectum
lateral approach
indications: limited to one side of the rectum > rectal diverticulum, rectocutaneous fistula, or rectal laceration
- similar approach is used for perineal hernia repair
- fascia between the external anal sphincter and levator ani is dissected to expose the lateral surface of the rectum
- Preservation of the caudal rectal nerve to the external anal sphincter is essential
Caudal Approach
1. mucosal eversion
2. transcutaneous rectal pull-through
3. transanal rectal pull-through
4. Swenson’s pull-through and modifications.
Rectal Eversion
- indicated for small, single, superficial, benign tumors (e.g., polyps) located in the caudal to mid rectum
- If the lesion has a pedunculated attachment, the stalk can be ligated and transected. If the lesion is sessile, a submucosal or full-thickness excision is performed
Transcutaneous Rectal Pull-Through Procedure
- caudal to mid rectum
- If the tumor is present in the anal canal, the initial incision is made in the skin adjacent to the anal opening > anal sac openings included therefore bilateral anal sacculectomies
- save the external sphincter muscle, undermining inside the circumference
- rectum is mobilized using a combination of blunt and sharp dissection and retracted caudally with stay sutures.
- The rectococcygeus muscle is transected
- Resection and anastomosis proceeds in sections to prevent cranial retraction of the rectum
Transanal Rectal Pull-Through Procedure
- mid to caudal rectum not involving the external anal sphincter, the initial incision can be made 1 to 2 cm cranial (internal) to the anocutaneous junction, leaving a cuff of anal canal and rectum and avoiding the anal sac ducts.
- cranial rectum is sutured to the remaining caudal rectal cuff
- lesions in the mid to cranial rectum > preserve the distal rectal stump.
- sutures or EEA stapler
Combined Abdominal-Transanal Approach (Swenson’s pull-through)
- indicated: tumors of the mid to cranial rectum that extend to the distal colon
- caudal laparotomy is performed
- distal colon is transected proximal to the lesion.
- Each end of the transection is stapled/Parker-Kerr
- The two stumps are then connected
- Allis tissue forceps into the rectum and grasps and everts the distal stump
- Once the distal segment (bearing the tumor) is fully resected, end-to-end anastomosis is performed
Stool softeners can be administered for several weeks
Complications of Colorectal Resection (6)
- hematochezia and dyschezia up to 2 weeks after surgery.
- Tenesmus can last up to 1 to 2 months
stricture
- more common after rectal resection than colonic resection
- caused by excessive tension, inflammation, inadequate blood supply, dehiscence, luminal narrowing, poor suture material, and localized infection
- treated by bougienage, balloon dilation, surgical incision of the constricting band, or resection and anastomosis
- Anal stricture: radial incisional anoplasty (incisions divide scar and closed transversely) or Z-plasties
Infection
- intraoperative spillage of fecal material
- postoperative dehiscence
- prevention: sx technique, intraop antibiotics, lavage, change gloves and instruments
dehiscence
- may be fatal
- dt tension, inadequate blood supply, improper technique, poor suture placement or material.
- risk for dehiscence is greater with resections greater than 6 cm
- tissues should be debrided, lavaged, and repaired, and drainage
transient fecal incontinence
- Two important factors contributing:
- external anal sphincter function (provided by the muscule and caudal rectal nerve)
- reservoir continence (ability to distend and store feces) > a function of length and motility of the colon and rectum
- Iatrogenic damage to the caudal rectal nerve, external anal sphincter, or cranial rectal peritoneal reflection and resection of a large proportion of the rectum may result in incontinence.
- continence if distal 1cm rectum intact > a transanal pull-through may be preferred to a transcutaneous procedure
neurologic dysfunction
- after symphyseal retraction (dt sacroiliac subluxation)
Nonunion of the osteotomy sites
List Tx options for an anal stricture
Faecal softeners
Balloon dilatation or bougienage
Resection and anastomosis
Z-plasty
Radial incisional anoplasty (+/- transverse closure)
Circumferantial anoplasty
What has been shown to increase the risk of faecal incontinence?
Resection of 6cm of rectum
Removal of distal 1.5cm of rectum
Removal of more than half the circumference of external anal sphincter
Damage to perineal nerves
Resection of the peritoneal reflection
Congenital Abnormalities
- cloaca is the common opening for the gastrointestinal, urinary, and reproductive tracts in developing embryos
- abnormal embryonic development of the cloacal region is responsible for congenital abnormalities of the rectum and anus
- concurrent abnormalities: vaginal, tail malformations, a short colon, absence of anal sac ducts and an incomplete or absent external anal sphincter
List the 4 types of atresia ani
Type 1 - Stenosis of the anus
Type II - Persistance of anal membrane with rectum ending as blind sac immediately cranial to imperforate anus
Type III - Imperforate anus but the rectal sac is further cranial
Type IV - Anus and terminal rectum can develop normally but the cranial rectum ends as a blind pouch within pelvic canal
If surgery is planned, sphincter function can be evaluated with the perineal reflex preoperatively by applying an electrical stimulus to the perineum or by pinching the vulva.
atresia ani tx
- essentially normal until weaning, at which time clinical signs such as constipation and tenesmus develop.
- type I atresia ani are treated with gentle bougienage or balloon dilation
- type II and type III atresia ani, a vertical incision is made in the skin over the anal dimple, distal rectum is identified and mobilised, opened, and sutured to the surrounding subcutaneous tissues and skin
- temporary end-on colostomy has been used as an adjunct to the management of type II
- type IV abdominal approach may be necessary
What are potential complications associated wth atresia ani?
- Established megacolon, potentially requiring subtotal colectomy
- Inability to provide normal faecal continence
- Development of anal stricture
small cases reported, most have long-term survival with varying number of incontinence
What is rectovaginal/urethrorectal fistula?
What are they often associated with?
Failure of the developing urorectal septum to seperate the cloaca
Commonly assoc with atresia ani, particularly type II
Rectovaginal and Urethrorectal Fistula
- a rectovaginal fistula may remain undiagnosed for months. In patients with a urethrorectal fistula, the classic signs are leakage of urine from the rectum, or urination from the urethra and anus simultaneously, and leakage of feces from the vulva
- LRT signs eventually
- increases the risk for ascending urinary tract infection
dx
- Positive-contrast retrograde urethrography best method for diagnosing a urethrorectal fistula and determining its position
- voiding cystourethrography may also be performed with or without fluoroscopy
outcome
- could be poor
- review of urethrorectal fistulas in 10 dogs and 2 cats, the long-term prognosis was reported as excellent with successful excision of the fistulous tract.
What are the Tx options for a rectovaginal fistula?
- Transverse incision between anus and vulva to isolate the fistula to resect the fistula, close the assoc defects and correct the atresia ani
- Transection of the rectum cranial to the fistula, fistulous section resected and rectum sutured to anus (rectal pull-through)
- Transection of fistulous tract near the vagina and then use the distal rectal portion for reconstruction of the anus (fistula flap technique)
Prognosis is good :)
complications fistula
- fecal incontinence
- urinary tract signs (uroliths)
- wound dehiscence (tension or fecal contamination)
- tenesmus,
- obstipation,
- rectal prolapse,
- anal stenosis
What is an anogenital cleft?
Rare condition in which urine and faeces enter a common cavity and body opening (cloaca)
Treatment of anogenital cleft in females is often successful. The anus is reformed ventrally, and tissues between the anus and vulva are reconstructed
Anal and Rectal Prolapse
- partial or anal prolapse, only anal mucos
- complete or rectal prolapse, all layers of the rectum around the entire circumference protrude through the anal orifice as an elongated, cylindrical mass.
- tissues become edematous, and spontaneous resolution of the condition becomes unlikely.
- Prolapse usually occurs secondary to tenesmus from gastrointestinal (especially colorectal or anal) or urogenital disease
- self-mutilation and trauma may occur with time
Diagnosis
- underlying reason for its development may be less evident.
- distinguish rectal prolapse from a prolapsed intussusception > the instrument or finger can be passed easily (5 to 7 cm) between the rectal wall and prolapsed tissue
treatment
- manually with saline or lubricants. Topical 50% dextrose
- purse-string suture is inserted at the mucocutaneous junction and tied loosely, place for 3 to 5 days to prevent recurrence
- given laxatives such as lactulose.
- colopexy
- rectal resection and anastomosis
- epidural
comlications
- incontinence, dehiscence, leakage, recurrence of the prolapse, and anorectal strictures
Anal and Perianal Tumors
- Perianal gland tumors originate from the circumanal modified sebaceous glands
- Cytology can confirm the hepatoid nature of the tumor, but differentiation between hepatoid adenoma and adenocarcinoma may be difficult
- adenocarcinomas exhibit greater pleomorphism and staining characteristics. Invasion of tumor cells into the surrounding tissue is an important histologic criterion for malignancy
- Enlarged sublumbar lymph nodes can be aspirated during a digital rectal exploration or via transabdominal ultrasonographic-guided aspiration.
Perianal Adenoma
- perianal or circumanal region, but they may also be found on the tail, prepuce, scrotum, inguinal region, thighs, and trunk
- hormone dependent and can be stimulated by androgens or inhibited by estrogens. Therefore they regress after castration or following estrogen therapy
- older entire male
- Perianal adenomas are slow growing, may ulcerate and become infected, but they are not commonly fixed to the deeper tissue
Tx
- Castration may be the sole procedure required for intact males
- large or diffuse lesions may redcue in size with castration, making subequent excision easier
- Excision is curative in more than 90% (especailly in femles)
What other diseases may be seen concurrently with perianal adenoma?
Perineal hernia (10%)
Testicular tumours
Hyperadrenocorticism (source of androgen for females)
Perianal Adenocarcinoma
- more common in intact male dogs and dogs weighing more than 35 kg,
- often larger, firmer, locally invasive, fixed, and rapidly growing.
- benign and malignant tumors are indistinguishable; therefore histologic sampling
- Metastasis to the sublumbar lymph nodes occurs in 15% of cases
- only prognostic factor identified for perianal adenocarcinoma is clinical stage
- T3 and T4 (invasive tumor) have a median survival of 6 to 12.5 months. with metastasis is 7 months.
tx
- en bloc excision with or without anoplasty and excision of lymph nodes affected by metastasis
- margin of 1 to 3 cm
- tumor is reportedly relatively radioresistant
- Electrochemotherapy has been used successfully for perianal adenomas and adenocarcinomas, with an objective response rate of 94%
ddx SCC, MM
Rectal Tumors
- large intestine is most commonly affected, with 36% to 60% of intestinal tumors occurring there
- More than 50% of colorectal tumors are malignant,
- adenocarcinoma most common
- leiomyoma and leiomyosarcoma, plasmacytoma, and carcinoids.
Benign Rectal Tumors
- benign adenomatous polyps
- composed of branching lamina propria covered by an abnormal epithelial surface
- single or multiple, raised, sessile, or pedunculated
- rectum and anorectal junction
- ddx leiomyomas, fibromas, plasmacytomas, ganglioneuroma
- malignant transformation of benign lesions may occur
- Polyps that invade the intestinal lamina propria and submucosa but not the basement membrane = carcinoma in situ
- 41% of dogs developed recurrence of clinical signs, and 18% developed malignant transformation.
dx
- tenesmus, dyschezia, hematochezia, mucoid feces, painful defecation,
- Most rectal tumors are located 3 to 8 cm from the anus
- Abdominal and thoracic radiography, abdominal ultrasonography, and endoscopy
- more than 50% of tumors are located in the middle portion of the rectum,74 endoscopic examination should be continued orad
- biopsy? a superficial biopsy may not be able to differentiate between these tumor types
Tx
- 2-cm margin of excision to reduce recurrence
- Local excision of adenomatous polyps is associated with a survival of 5 to 24 months
- prolapse of the rectum through the anus
- larger polyps and leiomyomas may require resection and anastomosis
- Leiomyomas of the caudal rectum may be removed via a dorsal or lateral approach with submucosal resection.
Malignant Rectal Tumors
- adenocarcinoma is the most common malignant tumor of the rectum
- Metastatic rates vary from 0% to 80%.
- Leiomyosarcomas are locally invasive but slow to metastasize. Gastrointestinal stromal tumors (GISTs) are similar in histologic appearance > differentiated on IHC with CD117
- Lymphosarcoma, the most common rectal tumor in cats
- Rectal lymphoma has a favorable prognosis, with an overall mean survival time of 1697 days
tx
- anal, ventral, dorsal, or lateral approach or a rectal pull-through technique may be used
- Conservative resection of malignant lesions has been reported by multiple authors
What % of rectal tumours are incorrectly diagnosed based on endoscopic biopsy?
What it the most common colorectal tumour?
1/3 incorrectly diagnosed
Adenocarcinoma most common in dogs, LSA in cats
What are the three forms of rectal adenocarcinoma?
- Pedunculated
- Cobblestone
- Infiltrative (classic ‘napkin-ring’)
Pedunculated and cobblestone have a good prognosis with surgical resection. Infiltrative/annular poor prognosis
List some paraneoplastic syndromes which can be seen with rectal neoplasia?
- Adenomatous polyps - Leucocytosis
- Eosinophilic masses - eosinophilia, neutrophilia, hypocholesterolaemia, hypoalbuminaemia
- Leiomyosarcoma - hypoglycaemia
- Secretory plasmacytomas - Hyperproteinaemia, monoclonal gammopathy
List alternative therapies for anal and rectal tumours
- NSAIDs
- Immunosuppresive medications for inflammatory polyps
- Pred and ivermectin (eosinophilic masses)
- Chemotherapy (MST 2532d vs 70d for rectal lymphoma in dogs)
- Orthovoltage irradiation (perforation and subsequent peritonitis possible SE)
- Colostomy
prognosis
- rectal polyps, carcinoma in situ, and leiomyomas is good if complete excision: 2 years or longer for polyp, 17% recurrence
- malignant neoplasia is generally guarded
- after surgery vary from 6 to 22 months
- GIST 21 months
- cats with complete excision of large intestinal adenocarcinoma is 138 days
- mast cell tumors is 199 days
What is the MST of malignant rectal tumours according to morphology?
Pedunculated 32m
Nodular or cobblestone 12m
Annular 1.6m
What it the most common location for rectal perforation?
Within the caudal 4cm leading to focal retroperitoneal infection
Tx of rectal perforation
- asap sx associated with improved survival and is important in preventing rectocutaneous fistula development
- Placement of drains and administration of broad-spectrum antimicrobials are indicated
- caudal perforations and rectocutaneous fistula are explored from a perineal approach.
- surgical wound is managed open, eventually healing by second intention.
- temporary colostomy of rectal stenting (ETT) to provide fecal bypass of the rectum until local tissues heal
dx: identify free gas in the perirectal tissues on rads
Anorectal Strictures
- can occur dt surgery or secondary to proctitis, trauma, penetrating foreign bodies, perianal fistula, congenital malformations, or infiltrative or proliferative neoplastic lesions
- Contrast radiography or CT can be useful in determining the exact location +/- biopsy
- nonneoplastic cases may respond to bougienage or balloon dilation or intralesional triamcinolone
- resection and rectal anastomosis
What are surgical options for faecal incontinence?
Sphincter-enhancing procedures
- Semitendinosus muscle flap
- Rotation of rectum 225 degrees before anastomosis
- Implantation of polyester-impregnated silicone elastomer ring
- Sartorius muscle transposition
- Free neuromicrovascular transfer of latissimus dorsi
medical
- dietary change to a low-residue diet, use of opioids to slow transit time
due to reservoir incontinence or sphincter incontinence
Anal Sac Neoplasia in Dogs
- Apocrine gland adenocarcinoma is the most common tumor, represents 17% of all perianal tumors
- readily obliterate the anal sac and invade surrounding soft tissues.
- equal sex distribution
- Spaniel breeds, particularly English Cocker Spaniels appear to be predisposed
- higher frequency of certain major histocompatibility complex type II alleles in tumor-bearing dogs
- ddx squamous cell carcinoma arising from the epithelial lining
tumor biology
- Expression of KIT (2.6% of tumors) and platelet-derived growth factor (PDGF)-β (19.5% of tumors)
- cellular nucleus may help to predict biologic behavior: larger nuclei were seen in metastatic tumors as compared to nonmetastatic tumors
- Expression of COX-2 in 100% of primary tumors and metastatic lesions, providing a biologic basis for the use of COX-2 inhibitors in this tumor type
- lower expression of the adhesion molecule E-cadherin was associated with a shorter median survival time
- paraneoplastic pseudohyperparathyroidism: secretion of a substance with biologic activity similar to PTH, resulting in persistent hypercalcemia
What % of AGASACA express COX-2?
What molecule has been associated with a shorter survival?
What % of cases have paraneoplastic hypercalcaemia?
100%
Decreased expression of e-cadherin assoc with shorter survival
27% hypercalcaemia (20-90%)
diagnosis
- incidental finding on routine rectal in 7% to 39% of dogs
- bilateral tumors have been reported, with an incidence of up to 10.5% at same time (or develop later in other side)
- paraneoplastic: polyuria, polydipsia, lethargy, weight loss
- FNA: polyhedral cells with uniform round nuclei and granular, light blue-gray cytoplasm
- cytologic features of malignancy may be subtle
staging
- rectal examination, complete blood count, serum chemistry, urinalysis, and thoracic and abdominal imaging (radiography and ultrasonography, or CT)
mets
- metastatic sites: sublumbar lymph nodes, abdominal organs (particularly the liver and spleen), and lungs.
- Metastasis to the lungs or bones is rare in the absence of sublumbar lymph node metastasis
- metastasis at the time of presentation 36% to 96%.
- volume of metastatic disease in these lymph nodes may be greater than the primary tumor
- mets to lung 16-53%
imaging
- lymph node metastasis have more heterogeneous lymph nodes and bigger (>1cm suggest but not confirmed by histo)
- MRI more sensetive particularly the sacral lymph nodes
treatment
- Hypercalcemia can result in acute renal failure and therefore must be treated before surgery
- 0.9% saline promotes calciuresis and protects tubular epithelial cells, furosemide (2 mg/kg IV BID)
Surgery
- Surgical excision of the primary anal sac mass is currently the treatment of choice
- surgery alone survival time of 16 to 18 months
- multimodal tx offers better MST (sx, chemo, extirpation)
l.n. extirpation
- historically literature are conflicted
- recently, appears to offer survival advanatge, as repeat removal increase MST
- Complications after extirpation: severe hemorrhage, overflow urinary incontinence, and death
Chemotherapy
- theoretically indicated, given the high metastatic rate, but it is not clear which animals will benefit from this modality and what the most appropriate drugs and protocol
- conflicting resuts re if improve MST
- Excision of anal sac adenocarcinoma and metastatic lymph nodes is often marginal
- cisplatin, carboplatin, doxorubicin, mitoxantrone, melphalan, chlorambucil, actinomycin D, piroxicam, epirubicin, prednisolone
- chemo downstaged some dogs with large tumors to allow surgical excision, and palliated clinical signs of rectal obstruction in some dogs
- Electrochemotherapy of an incompletely excised tumor, complete remission for more than 18 months.
- toceranib resulted in a partial response in 25% and stable disease in 62.5%,
radiation
- may prolong survival and delay tumor regrowth
- irradiation of the pelvic region can result in gastrointestinal perforation and death
- sx chemo + raditation MST 956d
Overall, the optimum therapeutic plan for any given individual is not known, and many reports have variability in the clinical stage of patients and the treatment regimen
- The median survival times of dogs from three studies with a controlled treatment regimen (sx + expiration + chemo/radiation) were 17 to 31 months
Complications (7)
- infection, 7%
- tenesmus,
- fecal incontinence 19% to 33% (more likely if anoplasty performed)
- temporary urinary incontinence,
- anal stenosis or stricture
- local recurrence/lymph nodes 29% to 45%
- Recurrence of hypercalcemia 35% to 50% (metastasis or regrowth)
List the stages of AGASACA and their associated MST
Stage 1 - Tumour under 2.5cm, no mets. MST 40m
Stage 2 - Tumour over 2.5cm, no mets. MST 24m
Stage 3a - LN under 4.5cm. MST 15-16m
Stage 3b - LN over 4.5cm. MST 10-11m
Stage 4 - Distant mets. MST under 3m
Negative prognostic factors (6)
- larger tumor size (>2.5 cm poorer prognosis, >5cm mets present in 86%)
- lymph node metastasis,
- distant metastasis
- advanced clinical stage,
- E-cadherin expression,
- not performing surgery
Anal Sac Neoplasia in Cats
- domestic shorthair (81%), Siamese cats may be predisposed.
- hypercalcemia is rarely a feature
- ulceration, sinus, fistulas, and purulent or hemorrhagic discharge more common in cats
- mets only 15% of cats,
outcome
- 75% euthanized or died dt surgical complications (13%), clinical progression (15%), or local recurrence (35% to 41%) leading to impairment of defecation
- prognosis is poor, with a median survival time of 3 months and 1-year and 1-year survival rates of 19% and 0%
Anal Sacculectomy
- iatrogenic trauma to the external anal sphincter and caudal rectal artery and nerve should be avoided
- blade and scissors, although the carbon dioxide laser has also been described
- open, closed, modified
Closed Technique
- anal sac is excised without entering its lumen
- sacs can be filled with: tape, suture material, anal sac gel, paraffin, silicone sealant, resin, dental acrylic, haemostat or 5- or 6-Fr Foley catheter
- sac is tightly adhered to external anal sphincter muscle, necessitating elevation or transection
modified closed technique (prpich 2024)
- a circular incision was made around the anal sac duct,then extended in a caudolateral direction overlying the anal sac. The subcutaneous tissues were dissected away from thesac and duct, and the tumor, sac, and duct were excised enbloc in their entirety. The external anal sphincter was then
reconstructed,
open technique
- permits visualization of the secretory lining of the anal sac to help ensure its removal
- permits complete removal of the anal sac duct and orifice.
- grooved director is inserted into the duct and anal sac
- modification of the open technique, the incision over the sac is made only down to the haired area of the anus (less trauma to the external anal sphincter)
Disadvantages
- trauma to the external anal sphincter
- risk infection from contamination by anal sac contents
- risk of dissemination of tumor
complications
- incidence of major complications low.
- Minor complication 3.2% to 32.3%
- one study more with open tehcnique
Intraoperative complications
- hemorrhage,
- iatrogenic nerve trauma
- laceration of the rectum.
Short-term complications
- scooting,
- inflammation, bruising, seroma
- infection (open, debridement and lavage, and antibiotic)
- dehiscence
- tenesmus, dyschezia, and constipation.
- fecal incontinence 3.2% to 14.5% (bilateral sacculectomy, open technique, usually resolve within 10 days)
Long-term complications 1.1% to 14.7%
- licking of the surgery site,
- fecal incontinence
- sinus or fistula (anal sac or ductal remnants)
- stricture formation
incontinence is uncommon after unilateral surgery because reinnervation from the intact site will occur in a few weeks, but fecal incontinence that persists for more than 3 to 4 months after bilateral surgery is unlikely to resolve.
Perianal Fistula, furunculosis
- characterized by single or multiple ulcerated sinuses or fistulous tracts that can involve up to 360 degrees of the perianal skin and subcutaneous tissues
- middle-aged German Shepherd Dogs
pathophysiology
- cause of perianal fistula is not clear, theories including anatomic, endocrine, infectious, and immunologic causes.
- anal sacs may only be involved secondarily.
- bacterial contamination and infection may occur (E. coli, Staphylococcus aureus)
- broad-based tail with low tail carriage
- More recent evidence > immune-mediated cause of perianal fistula
- histologically similar to those in humans with Crohn’s disease
- characterized by infiltration of large numbers of CD3+ T-lymphocytes, IgA- and IgG-secreting B-lymphocytes, and macrophages
- responsive to various immunosuppressive drugs
- Cyclosporine can suppress T-cell activation by blocking interleukin-2 (IL-2) expression directly
Perianal Fistula, furunculosis Tx
Cyclosporine
- alone has resulted in resolution of lesions in 70% to 100% of dogs treated
- a mean duration of 8.8 weeks
- some patients may require low-dose cyclosporine as a lifelong treatment.
- regular blood level monitoring should be performed to maintain cyclosporine doses within an appropriate therapeutic range
- 5 mg/kg q12 hours, target range from 400 to 600 ng/mL
- Anal sacculectomy and tract resection are performed in patients for lesions that do not resolve completely with cyclosporine treatment.
- Ketoconazole is an antifungal agent that affects cyclosporine metabolism by inhibiting hepatic and intestinal cytochrome P-450 oxidase activity, resulting in increased blood cyclosporine concentrations
pred
- dietary management and a tapering dose of prednisone over 6 to 8 weeks resulted in complete resolution in one-third of dogs
Tacrolimus
- inhibitor of calcineurin, with immunosuppressive actions similar to cyclosporine but with 10 to 100 times the potency.
- 80% resolution or can be used together or for maintenance following oral meds
azathioprine-metronidazole
- not cause complete resolution of perianal fistulas, decreases the severity and extent of lesions
Perianal Fistula, furunculosis Sx
- Complete excision of all fistulous or sinus tracts in the perianal area
- concurrent bilateral anal sacculectomy is recommended.
- partial or complete anoplasty may be necessary > Complete anoplasty should be performed only if owners are willing to accept incontinence.
outcome
- en bloch sx + sacculectomy: resolution of visible lesions in 29 of 33 (87.9%) dogs and resolution of clinical signs in 79.3%
Complications
- dehiscence, anal stenosis, fecal incontinence, flatulence, and recurrence of lesions.
Perineal Hernia
- weakness and separation of the components of the pelvic diaphragm
- permits deviation and dilatation of the rectum and caudal protrusion of various abdominal organs
- evator ani is the most common muscle atrophied
- most common location is caudal perineal hernia
anatomy
sacrotuberous ligament is not present in cats
- pelvic diaphragm = principal structure of the perineum, including the levator ani, coccygeus muscles, perineal fascia, and the external anal sphincter.
- levator ani muscle: two portions, iliocaudalis and pubocaudalis
- coccygeus muscle: strap-like, lies lateral and cranial to the levator ani
- external anal sphincter: surrounds the anal canal
- internal obturator muscle,
- sacrotuberous ligament: fibrous band from ischiatic tuberosity > sacrum
- superficial gluteal muscle
internal pudendal artery, vein, and nerve course caudomedially over the dorsal surface of the internal obturator muscle
- caudal rectal nerve = innervate external anal sphincter.
Etiology (7)
- almost exclusively in older intact males, who constitute 83% to 93% of cases,
- Pekingese, Boston Terriers, Corgis, Boxer Dogs, Poodles
- cause of the condition still remains unclear and is likely to be multifactorial
- association between perineal hernia and nontraumatic inguinal hernia has also been identified, suggesting a common pathogenesis
- Rectal Abnormalities (deviation, dilatation, and diverticulum > likely consequence rather than cause, excessive straining may weaken pelvic diaphragm)
- Androgens (predisposition of intact males, castration may help prevent recurrence from 43% to 23%)
- Gender-Related Anatomic Differences (female have larger, broader, and stronger levator ani muscles, longer rectal attachment; larger sacrotuberous ligaments)
- Relaxin (alters connective tissue components, greater expression of relaxin receptors in hernai dogs, produced in prostate gland)
- Prostatic Disease (25% and 59% concurrent, may result in chronic straining and recurrence, castration may help)
- Neurogenic atrophy (levator ani and coccygeus muscles, suggestive of a neurogenic myopathy, unknown if primary or secondary condition)
primarily testicular neoplasia in 69.7% of dogs
How may benign prostatic hyperplasia be assoc with perineal hernias?
Prostate gland is the primary site of relaxin synthesis
Muscles of pelvic diaphragm with perineal hernia has higher expression of relaxin receptors
25-59% of dogs with perineal hernia have concurrent prostatic disease, 69.7% have testicular abnormalities
signs and diagnosis
- unilateral or bilateral perineal swelling, straining to defecate, and constipation
- associated with obstruction, incarceration, or strangulation of herniated organs (bladder, or intestine)
- Dysuria and stranguria with prostatic disease or bladder retroflexion
- unilateral (47% to 66%) or bilateral, with the right side being more commonly affected
Bladder Retroflexion
- unable to urinate > retroflexion into the hernia may have occurred.
- in 20% to 29%
- azotemia and metabolic derangements > relieve the obstruction is indicated (U-cath or centesis)
- FNA fluid can confirm urine (2x serum Ure/crea)
- positive contrast retrograde urethrocystogram may be required
- presence of urinary bladder retroflexion has no effect on the complication rate
- literature confincted weather pexy makes difference to recurrence
diagnosis
- digital rectal examination may reveal a loss of the normal pelvic diaphragm and the presence of pelvic or abdominal viscera within the hernia.
- ID unilateral or bilateral disease
- abdominal radiography and ultrasonography (prostate dz, intrapelvic mass etc)
what % unilaterally develop a hernia on the contralateral side
10%
Medical and Dietary Management
dietary management, stool softeners, periodic evacuation of feces by digital removal or with the use of warm soapy enemas
- lactulose (0.5 to 1.0 mL/kg q8-12h, adjusted so that the animal is producing two or three soft formed stools a day) or methylcellulose and psyllium preparations.
Surgical Treatment options (7)
- Traditional herniorrhaphy
- Internal obturator muscle transposition
- Superficial gluteal muscle transposition
- Semitendinosus muscle transposition
- Prosthetic implants
- Biomaterials (Porcine SIS, Porcine dermal collagen, autologous fascia)
- Organopexy (colopexy, cystopexy, vas deferensopexy)
pre-op
- Patients that present with incarcerated or strangulated small intestine, however, require emergency abdominal exploration
- catheterization or bladder decompression
- Broad-spectrum perioperative antibiotics
- Epidural analgesia
Sx
- With most herniorrhaphy techniques, an incision is made over the hernia
- Gentle, firm pressure is used to replace herniated organs through the muscular defect
- dog can either be repositioned for a standard approach or castrated from a perineal approach
Traditional Herniorrhaphy
-diaphragm is reconstructed by placement of sutures between the external anal sphincter and the levator ani or coccygeus muscles and internal obturator muscle ventrally
- If significant atrophy is present, the sacrotuberous ligament can be used as the lateral component
- Both absorbable and nonabsorbable suture have been advocated
- suture placement through the rectal wall is avoided.
- urethra lies just ventral to the rectum
- sutures placed through sacrotuberus ligament, rather than around it, to avoid inclusion of the caudal gluteal vessels and sciatic nerve.
Internal Obturator Muscle Transposition
Advantages over the traditional:
- reduces tension sutures (and distortion of the external anal sphincter)
- additional muscular tissue and blood supply that may help improve healing and prevent breakdown.
- internal obturator muscle incised caudal lateral border, elevated from the ischium
- prevent damage to the obturator nerve and artery
- internal obturator tendon can be transected to provide greater dorsal elevation (care damage to the sciatic nerve)
- muscle is then transposed dorsally and medially to fill in the hernial defect
- all herniorrhaphy sutures are preplaced before tying
- suture is placed from the muscle flap’s lateral edge and tendon to the coccygeus and external anal sphincter muscles.
Superficial Gluteal Muscle Transposition
- tendon of the superficial gluteal muscle is isolated below the biceps muscle and cut at its insertion on the trochanter
- still has attachments to the sacrum, sacrotuberous ligament, and gluteal fascia > reflected over and sutured to the external anal sphincter
- care preserve the nerve and blood supply of the superficial gluteal muscle
- modification > superficial gluteal tendon of insertion is transected, and the muscle is rotated 45 degrees. allows closure of the defect dorsolaterally, but closure of the ventral defect is more challenging.
- Simultaneous transposition of the internal obturator and superficial gluteal muscles
Semitendinosus Muscle Transposition
- salvage procedure when other techniques have failed or for repair of ventral hernias
- relatively superficial, has a consistent blood supply, is expendable because of synergistic muscles
- transposed dorsally 180 degrees to fill a hernia on the ipsilateral side
- transposed 90 degrees to fill a contralateral hernia with a ventral defect.
- semitendinosus muscle is exposed and isolated
- caudal gluteal artery and vein, which are the major blood vessels to the proximal half of the muscle
- transected at its midbelly69 or closer to the stifle if more length is needed
- longitudinally and bluntly split into two parts and the medial half used to repair contralateral side
- sutured to the sacrotuberous ligament, coccygeus, external anal sphincter, and internal obturator muscle
- When the entire muscle is used, physical bulk of the muscle in the perineal region may make closure of the skin difficult
Prosthetic Implants
- Polypropylene and polypropylene-poliglecaprone mesh
- accommodate a significantly higher load when longitudinal cords oriented parallel to the tension axis
- approach is similar to that described for a traditional herniorrhaphy
- preplaced sutures
- modification > secured to the ischium via three holes drilled
- suture sinuses the most significant complication
- recurrence rate of 9.1%, with no long-term complication
Biomaterials
porcine small intestinal submucosa (SIS)
- regeneration of site-specific tissues, is resistant to infection, and promotes tissue ingrowth
- sheet of four-ply SIS
- found to be as strong as normal pelvic diaphragm and internal obturator transposition
- few clinical reports
porcine dermal collagen
- used to augment a traditional herniorrhaphy.
- success rate was 59.3%
autogenous fascia lata
- Fascia lata and the vaginal tunic
- less risk for immunologic rejection, foreign body reaction, or formation of a nidus of infection
- as primary repair, produced a strong repair with no evidence of recurrence
- Lameness associated with the donor site
Organopexy
- mixed results: some studies not show cystopexy or colopexy results in a lower rate of complications
- may be performed laparoscopically.
Cystopexy
- to prevent bladder retroflexion
- performed at apex or between the right bladder neck and right lateral abdominal body wall
- use is contraversial
colopexy
- reduce the rectal diameter by reconstructing the normal tubular shape
- diminishing the accumulation of feces, and to prevent caudal migration
- adjunct to the management of complicated hernias
vas deferensopexy
- relocates the enlarged prostate gland and bladder from the pelvic canal and improves fixation of the colon via the coloprostatic fascia
- vas deferens is identified on each side and retrieved from the inguinal canal.
- craniocaudal tunnel created under the transversus abdominis muscle at the level of the bladder apex
- vas deferens is pulled in a caudal to cranial direction through the tunnel
- used successfully in conjunction with perineal herniorrhaphy
Complications
- Tenesmus with or without evidence of recurrence is the most common complication
Staged Procedures
- recommend for patients with bilateral or complicated perineal hernias.
- Complicated = rectal dilatation, prostatic disease, retroflexed bladder or those that are recurrent
- initial surgery: laparotomy > colopexy and/or cystopexy + castration.
- hernia repair is scheduled 2 to 7 days after
- (93%) had an improved quality of life.
complications
- urine dribbling (37%)
- tenesmus (44%)
- wound complications (17%)
- hernia recurrence (10%).
Uncommon Perineal Hernias
- most common = caudal hernia > tissue protrudes between external anal sphincter, levator ani, and internal obturator muscles.
sciatic perineal hernia
- sacrotuberous ligament can be sutured to the coccygeus and levator ani
dorsal perineal hernia
- coccygeus muscle should be sutured to the levator ani muscle.
ventral perineal hernia
- a new perineal body crated by suturing the two levator ani muscles together
- closed with a semitendinosus muscle transposition
- urinary catheter should be placed to avoid urethral damage
post-op
- rectal examination is performed to confirm the rectal wall is appropriately supported and that sutures have not been placed through it. - A low-residue diet and stool softener
List potential post-op complications after perineal hernia repair
overall complication rate 5% to 68%
- SSI 6-43% (dt poor aseptic technique, excessive dissection, fecal contamination, uture penetration)
- wound dehiscence 0-29%
- Faecal incontinence 0-33%, permanent 10-15% (unilateral should have reinnervation)
- Sciatic nerve injury - less than 5%. (injury is evident immediately after recovery. If permanent - talocrural arthrodesis, long digital extensor muscle transfer to vastus lateralis, amputation)
- Urinary tract complications - 0-15% (bladder atony, incontinence, inadvertent placement of sutures through the urethra > prolonged stretching of the detrusor muscle or damage to the nerve and blood, transient or permanent)
- Tenesmus 4-43% (colopexy worsen?)
- Rectal prolapse 0-17%
- Recurrence 0-70% (10-48 traditional, 0-36 internal obturator, 36 superficial glut)
comparison of techniques complications and recurrence
- difficult to compare the complication rates between studies
overall
- 29% to 61% traditional herniorrhaphy
- 19% to 45% internal obturator
- 15% to 58% superficial gluteal technique
recurrence
- 10-48% traditional
- 0-36% (11%) internal obturator
- 36% superficial glut
- 12.5% internal obturator + mesh
Factors affect recurrence include surgeon experience, surgical technique, previous surgical repairs, amount of tension, ongoing predisposing factors, and whether the animal is neutered or intact.
List some unique features of perineal hernias in cats
Larger proportion are female
Bilateral disease more common
Perineal swelling less common (22.5%)
- most unkpwn cause, some had recent perineal urethrostomy (25% of cats), megacolon, perineal masses
- no association between surgical failure and type of surgical technique,
- Complications following surgery are reported to be less common in the cat
Histopathological diagnosis and surgical complications following bilateral anal sacculectomy for the treatment of unilateral canine apocrine gland anal sac adenocarcinoma: 35 cases (2019-2023)
A. Franca 2024
retrospective
Non-neoplastic dz 23 of 35 (66%) dogs
bilateral AGASACA seven of 35 (20%) dogs
9% intraoperatively (tumour capsule disruption) and 14% postoperatively (SSI)
comparable to those reported for unilateral anal sacculectomy alone
liptak 2016 (not published)
8.4% incidence
of bilateral AGASACA with around half of those patients
presenting with the contralateral anal sac tumour at a later stage
prospective study would be beneficial in investigating the true
incidence of incidental bilateral AGASACA and determining the
consequences of this phenomenon
liptak 2016
Treatment of canine perineal hernia with a fascia lata graft is noninferior to the elevation of the internal obturator muscle: a prospective randomized trial of 66 dogs
Åhlberg 2024
finnish
prospective
compare the recurrence rate after herniorrhaphy of canine perineal hernia (PH) using elevation of the internal obturator muscle (EIOM) or fascia lata graft (FLG)
12-month follow-up, the recurrence rate was 8.8% (3/34) in the EIOM and 10.3% (3/29) in the FLG group
Fecal incontinence occurred in 3 dogs (EIOM = 1; FLG = 2) resolving before the 3-month follow-up. As a long-term complication, ie, not present before surgery, urinary incontinence occurred in 1 dog (FLG).
the rectum was assessed to be dilated in approximately 90% of dogs at the 12-month follow-up,
Dogs in this study received lactulose in approximately 70% of cases
we refrained from closing the remaining fascia after FLG harvest, which may have decreased tension and discomfort.
Urinary incontinence occurred in 6% of dogs at 12 months
Recurrence and survival in dogs with excised colorectal polyps:
A retrospective study of 58 cases
Méric 2023
Retrospective multicentric cohort study
West Highland White Terrier (WHWT) breed
The
overall median time to recurrence was not reached after 2000 days. The overall estimated
median survival time was 1640 days.
larger polyps were
significantly associated with a shorter time of polyp recurrence
The polyps were removed using the pull-out method in 45/58 dogs
(78%), endoscopic diathermy resection in 7/58 dogs (12%), and
colectomy in 6/58 dogs (10%).
nsaid
distant metastasis in 3 dogs
Recurrence might have been underestimated in our study
because half of dogs were monitored for recurrence using only clinical
sign
Sentinel lymph nodemapping of the canine anal sac using
lymphoscintigraphy: A pilot study
lympadenectomy and metastasis to the iliosacral lymphocentrum are negative
prognostics indicators.
There was concordance between intramual and perimural techniques for the sentinel
lymph node identified in 50% of cases. A sacral lymph node was identified as sentinel in three of eight dogs (37.5%)
Combined transposition of internal
obturator and superficial gluteal
muscles for perineal hernia treatment
in dogs: 17 cases (2017-2020)
Rosselló 2023
Retrospective case series
obturator muscle to cover the ventral aspect of the perineal hernia and the superficial gluteal muscle to cover the dorsal aspect of the hernia
No recurrence of clinical signs or
rectal deviation was observed (16mths). Five dogs developed a superficial minor partial necrosis of the T-shaped
incision and two had surgical site infections.
Short- and long-term outcomes associated
with anal sacculectomy in dogs with massive
apocrine gland anal sac adenocarcinoma
Griffin 2023
massive (> 5 cm), 28 dogs
A retrospective multi-institutional study
(68%) dogs underwent concurrent iliosacral lymph node extirpation, including 17 of 18 (94%) dogs with suspected nodal metastasis preoperatively. Five (18%) dogs experienced grade 2 intraoperative complications. Ten (36%) dogs experienced postoperative complications
No dogs had permanent fecal incontinence, tenesmus, or anal stenosis.
19 dogs received adjuvant chemotherapy, radiation, or both.
Local recurrence 37%
Dogs with lymph node metastasis at surgery were more likely to develop new/progressive lymph node metastasis and distant metastasis
MST was 671 days
Lymph node metastasis at the time of surgery was a negative prognostic indicator for PFI but not OS.
Rectal perforation was observed during surgery in 3 of 28 (10.7%) dogs
consistent with prior reports demonstrating a greater incidence of metastatic disease with larger primary tumors, nodal metastasis was common in this population and the majority of dogs (64.3%) had stage 3 disease at the time of surgery. In addition, the majority (53.6%) of dogs in this cohort were hypercalcemic preoperatively.
In addition, adjuvant therapy was not found to be associated with PFI or OS in these dogs
Outcome of surgical treatment of
perineal hernia in cats: 36 cases
(2013-2019)
Hubers 2022
with modified internal obturator muscle transposition
34 had bilateral
The complicationrate was low, however, one cat experienced a major postoperative complication: rectal prolapse
short-term postoperative tenesmus which resolved in nine of 12 (75%).
good outcome (74%)
(10%) had fair outcomes
five of 31 (16%) had a poor outcome.
Of the five cats with a poor outcome, two required subtotal colectomy to manage clinical signs related to megacolon
can result in good owner-assessed longterm
outcome.
Perineal hernia repair in dorsal recumbency in 23 dogs:
Description of technique, complications, and outcome
Tobias 2022
Retrospective case series.
Internal obturator muscle transposition (IOMT) was performed in
22 dogs, and polypropylene mesh repair was performed in one dog
Eighteen dogs underwent abdominal pexy procedures, castration, or both
No intraoperative complications were
noted.
Incisional infection/drainage and persistent urinary incontinence were reported in four and two dogs, respectively.
Hernias reoccurred in four dogs and tended to be more common in dogs previous
herniorrhaphies (p = .053).
Recurrence rates were lowest in dogs that had no prior hernia repair or organ pexy (p = .035).
(17.4%) were treated with
antibiotics for suspected incisional infection
Submucosal resection via a transanal approach for
treatment of epithelial rectal tumors – a multicenter study
Cantatore 2022
report complications and long-term outcomes after submucosal
resections of benign and malignant epithelial rectal masses.
Study design: Retrospective multicentric study.
Sample population: Medical records of 93 dogs
Recurrence was identified in 20/93 (21%),
12/20 recurrent masses treated with repeat submucosal resection.
Median
survival was not reached in any group. The 1-,2-, 5-year survival rates for carcinomas
were 95%, 89%, and 73% respectively. However, overall survival was
longer for benign tumors than carcinomas (P = .001). Recurrence was more
likely when complications (P = .032) or incomplete margins (P = .023) were
present. Recurrence was associated with an increased risk of death
Presurgical biopsies were performed in 42 (45.2%) dogs,
with results being consistent with definitive diagnosis in
27/42 (64.3%).
A novel technique to incorporate the sacrotuberous
ligament in perineal herniorrhaphy in 47 dogs
Filippo Cinti 2021
Retrospective single-center study.
No major complications or recurrence were reported.
The only factors associated with an increased risk of complications included
increasing age (P = .019) and surgical treatment of a recurrent PH (P = .043).
Owners consistently reported good long-term outcomes.
with the objective to place the sutures around only the proximal half of ligament, which is further away from nerve/vessels.
In the technique described here,
all sutures were placed around the sacrotuberous ligament
in one single maneuver,
In conclusion, placement of sutures around the proximal
half of the sacrotuberous ligament for PH repair
resulted in no increase in complication rate, with no evidence
of sciatic nerve or gluteal vessels injuries. No
Use of bilateral superficial gluteal muscle flaps
for the repair of ventral perineal hernia in dogs:
A cadaveric study and short case series
Bitton 2020
free the origin and insertion of the ipsilateral SGM
Flaps
were used successfully to repair ventral perineal hernias in three dogs.
Comparison of methods to determine primary tumour size in canine apocrine gland anal sac adenocarcinoma
A. N. Schlag 2020
One hundred sixteen tumours from 107 dogs were included. There was moderate agreement between maximal dimension of the primary tumour measured by CT compared to formalin-fixed tissue and digital palpation. There was no significant difference in median maximum dimension between the measurement methods.
primary tumour size (>2.5cm), tumour-stage and vascular invasion are strong predictors of metastasis at presentation.
Novel application of internal obturator and semitendinosus muscle flaps for rectal wall repair or reinforcement
J. Rigg 2019
3 dog and 1 cat
three dogs sustained compromise of the rectal wall during
excision of anal sac adenocarcinoma
Polydioxa none
(2 M) was used to suture the cranial, lateral and caudal mar gins of the internal obturator muscle to the seromuscular layer of
the rectum in a simple interrupted pattern
has the potential to promote rectal wall healing, reducing
the risk of pararectal abscess formation
Apocrine gland anal sac adenocarcinoma in cats:
30 cases (1994–2015)
Pierre M. Amsellem 2019
Eleven cats developed local recurrence at a median of 96 days
after AGASACA excision. Incomplete tumor margins and a high nuclear
pleomorphic score were risk factors for local recurrence. Nuclear pleomorphic
score was negatively associated with DFI. Local recurrence and a
high nuclear pleomorphic score were risk factors for death. Median DFI and
survival time were 234 and 260 days, respectively.
local recurrence following
surgical excision was the most common reason cats
with AGASACA were euthanized
suggesting that wide margins should be
obtained whenever possible during AGASACA excision. Efficacy of chemotherapy
and radiation therapy for treatment of cats with AGASACA requires
further investigation.
sugery offers longer MST (cf no sx 90d)
Outcome and clinical, pathological,
and immunohistochemical factors associated
with prognosis for dogs with early-stage anal sac
adenocarcinoma treated with surgery alone:
34 cases (2002–2013)
Skorupski 2018
Median survival time was 1,237 days. Seven dogs had tumor recurrence and
9 dogs developed metastatic disease
dogs with early-stage nonmetastatic ASACA generally had
a favorable outcome following surgical removal of the primary tumor alone.
Routine rectal examination may be a simple and useful method for detection
of dogs with early-stage ASACA.
Outcomes of dogs with apocrine gland anal sac
adenocarcinoma treated via modified closed anal
sacculectomy (2015–2022)
Emma L. Davey
Cassandra Y. Prpich 2024
Observational clinical retrospective study.
Animal population: Forty-seven
median of 364 days of follow-up (range 156–2156 days). Only one dog (2.2%) developed
local recurrence
concern that normal
anal gland secretions in a dog with AGASACA may seed the entire duct with neoplastic cells. This concern forms the basis of our hypothesis that complete excision of the sac and duct, which does not occur in the traditional closed technique, would result in a
lower local recurrence rate.
Postoperative complications
were reported in 15 dogs (31.9%) and were considered minor in 14 dogs
(93.3%) and major in one dog (6.7%). Mean survival time for the 20 dogs that
were deceased as of November 1, 2022 was 521 days (range 156–1409 days)
and the median survival time was 388 days.
Abdominal lymph node
extirpation was performed in five dogs (10.6%), though 11 suspected to have l.n. mets
Mayhew 2020 – transanal minimally invasive surgery for submucosal rectal resection in cadavers
- submucosal rectal resection successful by TAMIS in all cadavers
- no full thickness suture penetration observed
- applicable for: rectal polyps restricted to mucosa of rectal wall in mid- to orad- third
