---start---- medsurg3 11/2 brockman surgical diseases of the small intestine. first hour: clinical approach to patient presenting with signs referable to surgical small intestinal dz. slide: small intestinal anatomy. as usual, we can't afford to forget the anatomy; as surgeons we're constantly reminded how important it is to recognize the anatomy. physiology is less important during this discussion. remember it begins at the pylorus. there are important structures in proximal duodenum - common bile duct, accessory pancreatic duct join in major duodenal papilla usually 2 cm from pylorus. remember pancreaticoduodenal artery arising from celiac artery; rest of supply is via cranial mesenteric artery. pancreas has second duct - major duct in most animals - futher distant in dogs, not so in cats. ** dogs have usually two pancreatic ducts, cats typically have only one. proximal duodenal resection in cats, therefore, is problematic. descending, transverse, and ascending duodenum = 12-15 cm of intestine in most avg dogs; the rest is jejunum which festoons along mesentery supplied by cranial mesenteric artery. ileum has a prominent antimesenteric vessel as well. so you see nice long mesentery with obvious neurovascular bundles, and the antimesenteric side of the ileum has an atery on it. we do have to talk about intestinal obstruction. surgical conditions usually have some partial/complete obstruction. we tend to divide them into these categories: high/low (oral/proximal or low/distal obstruction) partial/complete simple/complicated (presence of venous or arterial compromise with the lumenal compromise) acute/chronic (chronic are always partial, acute are typically complete) complete simple proximal obstruction: pathophysiology is somewhat outlined in notes and is rather complex; we'll discuss a few simple things to remember that will help you dx and tx pet. -profuse vomiting will occur. most common presenting sign for animals with small intestinal dz is vomiting. of course, many things cause acute onset vomiting. but profuse vomiting will be seen with small intestinal obstruction. -proximal to common bile duct (b/w pylorus and CBD): alkalosis, hypochloremia, hypokalemia since vomit is mostly gastric acid -distal to CBD: acidosis, hypokalemia occur - due to lost of pancreatic bicarb as well. -rapid hypovolemia occurs - in emergency evaluation, you determine this and correct it - but if dealing with alkalotic hypochloremic animal you want to use different fluids than with acidotic animal. for alkalotic hypochloremic animal use normal saline replacement fluids - for acidotic hypokalemic patient use lactated ringers or normosol. so, acute complete proximal small intestinal obstruction typically would cause death within 48-72 hrs. complete obstruction is rare. usually is *almost* complete. mostly we see incomplete simple obstruction - this will cause: -same clinical presentation with acute onset vomiting -some things will pass obstruction -reduction of normal peristalsis proximal to obstruction -stasis of ingesta -bacterial overgrowth -maldigestion/malabsorption (associated with bacterial overgrowth) -diarrhea -chronic weight loss obstruction with vascular compromise: usually we think of pieces of bowel that get herniated through a small orifice like umbilical defect, or diaphragmatic defect, or in large animals we think of indirect and direct scrotal herniation - bowel passes through confining loops, gets dilated, twists - initially we compromise the venous return and cause blood pooling, hemorrhage, loss of fluid (hypovolemia); then we have added arterial occlusion resulting in bowel death, perforation, peritonitis, plasma loss, toxemia. most often we see that with entrapped bowel in hernias. complete simple distal obstruction: -vomiting -aerophagia -fluid/gas distension of bowel -bacterial overgrowth, translocation of bacterial toxins -toxemia (toxaemia) clinical diagnostic features of small intestinal obstruction: -vomiting -anorexia/inappetance -abdominal tenderness (strangulation, perforation...) -dehydration -depression -diarrhea - from partial obstructions, malabsorption, maldigestion -decreased defecation or no defecation slide: skinny, hunched dog. chronic partial intestinal obstruction in otherwise healthy dog. has maldigestion/malabsorption due to chronic obstruction.looks like EPI dog. small reality check: the acutely vomiting dog is not a rarity. there are many infective systemic diseases or other organ diseases that cause acute vomiting. you fall into the same diagnostic pit dr b does many times - young puppy, acute vomiting, just moved into new home, new toys, one is missing, they think puppy ate it...remmeber, distemper, parvo, lepto, all these diseases can cause acute vomiting, dehydration, etc. you can't dispense with careful history, careful vaccine history evaluation, full physical exam. don't ignore other possibilities. it really sucks when you take a dog to surgery and find out there is no obstruction. you really want to minimize the number of useless exploratories. radiographic features: plain film rads and contrast rads are the mainstay. historical features and signs are somewhat helpful - we'll go over each condition and discuss age, signalment, etc - but if you have a history suggestive of obstruction, you need imaging study to confirm. proximal complete obstruction: almost all have some fluid/gas distension of bowel. if you are lucky you will have radiodense foreign body but these are hardest to see distal complete: fluid/gas distension of bowel partial: distended bowel, fluid/ingesta, gravel sign - particulate material accumulating on oral side of obstruction - contrast study helpful loss of contrast - local or generalized - you do not want to see this, might indicate peritoneal effusion or peritonitis abdominal free gas - you really do not want to see this, it indicates a surgical emergency (perforation of bowel). slides: drawings of dog guts. remember topographic/radiographic anatomy of abdomen. most of the small intestine on the right lateral will occupy the central abdomen - caudal to stomach, dorsal to spleen, cranial to bladder. large bowel is usually seen in pelvic canal extending cranially, cecum is just cranial to bladder. remember where that stuff is b/c we will discuss diameter of bowel loops. if any part of small intestine is double the diameter of an adjacent piece of small intestine, that is a dx of ileus secondary to obstruction. but large bowel will always be 2x diameter of small intestine, and cecum could also be mistaken for dilated small intestine so be careflu with that. lat and vd abdominal rads: these are plain films. they appear somewhat fuzzy to me, but that may just be me. we see several loops of small intestine. we do not see the colon because this rad didn't reproduce well, but trust him. so we do see dilated small bowel on this radiograph. consistent with obstruction. on VD we see some dilated intestinal loops - one could be large, but the caudal one is obviously small bowel, and is dilated. lat rads: plain films - again demonstrating - feces are in colon, then cranially we see a very dilated loop in the ventral abdomen, definitely double diameter of small bowel seen more cranially. in the slide on the right, again we see feces in the colon, superimposed small and large intestine dorsally, and ventrally we see the gravel sign - a piece of small bowel full of ingesta and fluid, very dilated. this thickness is twice the thickness of a more cranial piece. lat and vd rads: more plain films - two rads of cat - presented with chronic vomiting. we see this cat is in good condition with large amounts of fat around the kidneys, we see dilated bowel loop and we also see ventrally we have lost serosal detail. there is a huge wad of falciform fat so there shoudl be good detail, but it is lost b/c of ruptured bowel and focal peritonitis - there is also a little free peritoneal gas in the area. this was an old cat with tumor and spontaneous bowel rupture. often we use contrast studies to dx obstruction: the most frequently used contrast study is oral administration of a barium suspension. people worry about using it in animals with suspected perforations. if you truly suspect perforation, switch to iodinated contrast. but if you find perforation you will go to sx, so barium is ok. lat rads: we see a lot of barium in the stomach, we see proximal duodenum full of barium, a bit distended - then we see a filling defect, and then there is some barium distal to the defect, but the outline is very thin distal to defect. another rad of a patient looks as though it has had a contrast study but has not! we see wonderful detail of dilated loops of bowel - not only do we see inner mucosa, we also see serosal surface very well. this is because there is so much free air in the abodmen, creating wonderful contrast b/w soft tissue serosa and air. this is bad. lat and vd post oral administration of barium - skipping this one. lat rad - an old dog with intestinal tumor demonstrating very nicely the dilated loop of small intestine with accumulation of particulate material on oral side of obstruction, and specks of radiodense material present - gravel sign. this indicates chronic partial obstruction. another rad demonstrating a barium study in animal with chronic, longstanding obstruction. we see dilation of small intestine suddenly tapering to a very narrow intestinal lumen - actually appears to be almost a complete obstruction. conditions: foreign body: may be simple, sharp, linear intusussception - telescoping of one piece of bowel into adjacent piece intestinal volvulus occurs occasionally strangulation of intestine through hernia neoplasia (LSA, adenoCA) probably most common cause in older animals abdominal trauma slide: it's almost impossible to discuss intestinal foreign bodies w/o discussing this stuff - corncobs. why people let dogs eat corncobs is unclear. probably dogs do it on their own. but these are notorious for getting stuck in intestines. this one was removed from a dog after about 2 weeks of obstruction. slide: rad showing evidence of small intestinal obstruction - dilated loops of small intestine. typically, dogs that have ingested something that is stuck in small intestine have acute, profuse vomiting, dehydration, metabolic derangement determined by level of obstruction. but sometimes do present with chronic condition. physically you will detect dehydration on PE. when you palpate abdomen you may feel the foreign body if you are lucky. however, do not rule out intestinal FB just b/c you can't feel it - that is dangerous - and do not be disappointed if you do not manage to palpate them - they are hard to palpate, animals are guarding abdomen. other types of FB are never palpated - linear types, strings, etc. do not rule out FB b/c you didn't palpate it. typically you do PE, you suspect FB or acute gastroenteritis, you do rads, and the rads will give you an idea of whether there is an obstructive pattern or not. may be some form of segmental ileus. if you are uncertain, other imaging technique may be used - gold standard being oral administration of barium. here, abdominal ultrasound is often used but Dr Brockman prefers positive contrast radiography with looking for filling defect. once you've made dx of intestinal obstruction with FB, tx must be surgical. cases: the rad we already saw - positive contrast showing filling defect in proximal duodenum - this turned out to be a surgical sponge, around which adhesions had started to form. had been extralumenal but eroded into the lumen! string/linear FB - have unique diagnostic challenges. very commonly seen in inquisitive playful cats. anyone with a kitten will understand this. they love to play with things hanging from strings. do not not play, but don't let them play unsupervised. they will swallow a needle with thread, and stuff like that. linear FB are only a problem if anchored in oral position. his dog had septic peritonitis from swallowing a pair of nylon stockings. he eats anything not nailed down. he often finds socks and stuff that have gone all the way through the dog. but socks and other linear FB do not cause problems if they do not get anchored - most commonly under the tongue esp in cats - always open mouth of a vomiting cat, and look carefully under the tongue - realizing sometimes something lodges under there and then skin heals over it! also may get anchored at the pylorus, causing intestines to squeeze and squeeze trying to move it, causing a plicated appearance of the intestine around the linear FB. the plication (folding) of the bowel is seen on contrast rads. as bowel gets plicated, the linear FB can cut through the bowel, typically at the mesenteric border. rad: linear fb with positive contrast - these plications would be full of air without the contrast, so you'd see multiple teardrop shaped areas of gas. slide: two intraoperative photos showing intestinal FBs - this dog ate a Led Zeppelin tape, and the cat ate a string FB - needle and thread. string FB probably less common than simple toy type FB, but they do require you to free anchoring point prior to removing the rest of the FB. how do you decide where to do the enterotomy? if you found the anchoring point around the tongue and released that, simply pick a spot somewhere in the middle so you can gently feed the end through. often, though, you need to do more than one enterotomy - you may have to do one proximally, one in the middle, one distally. do not worry about doing multiple enterotomies. a technique for one single proximal enterotomy has been described - using red rubber catheter to milk FB down to rectum for retrieval. that's not really used here. one of Dr B's colleagues removed something from a dog's intestine - a sexual aid. she removed it, dog did fine, but when owner came to pick up dog they asked what was in the dog, and she said it was a corn cob. ---break--- so - we discussed anatomy, pathophysiology of obstruction such as hypovolemia, metabolic derangements to address prior to sx, value of plain films/contrast rads to make dx, and intestinal fb such as linear and nonlinear types. next thing to discuss - intusussception: this is the condition where a smaller diameter piece telescopes into a larger diameter adjacent piece. we see it typically in animals with a concurrent condition resulting in hypermotility. diarrhea secondary to hypermotility, young animals with lots of parasites, or post acute viral enteritis. most common site is ileocecocolic junction, where distal ilium goes into colon. the mesentery going through into the intususscipiens will set limit of how much can telescope in. sometimes the intususscuceptum will pass out the rectum. you need to tell that apart from rectal prolapse. this example looks like a hot dog sticking out of the butt. simple test is to place a well lubricated, clean, blunt tipped probe such as old glass thermometer in between structure and anal orifice. if it is rectal prolapse, can only go in about 5 mm. if an intususcuception, can go way in. clinically, these dogs may have had some antecedent acute v/d episode, be recovering from GI disease, often are young animals. if they've had some episode of diarrhea, or vomiting, and you get persistence of diarrhea, wt loss, intermittent vomiting - you may suspect this. if you have telescoped bowel in abdomen you might palpate it as a sausage shaped mass in the mid-dorsal abdomen. that is a finding very significant - do not get it confused with a large full colon. you can rule out full colon b/c these animals generally have diarrhea. a large sausage mass is typical. slide: little terrier who presented with chronic diarrhea, painful abdomen. rads of his abdomen show us a dilated loop of small intestine, and whole ventral abdomen is occupied by a small intestine with gravel sign - full of particulate material. so we suspect some kind of obstruction. how can we further dx this dog? well, barium orally is probably the best option. but u/s was used here. and u/s is a good diagnostic tool for intususscuception. you will see multiple echogenic borders b/w bowel loops. it helps a lot when it is labelled intussusception. hey, i fixed my spelling to match his, now they are spelling it the way i wanted to spell it. not fair. i'll have to look this up. if you give barium orally, you expect to see that as the barium reaches the telescoped area it starts to creep down the inside of the intussuscipiens, and when it gets to the end of the telescoped bowel, creeps back around the outside - so you see this caterpillar type thing. another thing to try is to give a barium enema - then you see the classic sign of coiled watchspring appearance to the bowel. so you treat this surgically. correct fluid and electrolyte derangements first. you see small diameter bowel going into larger piece - hopefully you can just pull it out, reduce it manually, without any further surgery. more often, as with this little jack russell...you find a hugely dilated intestine, and as you try to reduce it you start to tear the piece you are pulling on, since it is damaged. so you then have to resect affected area and anastomose the good ends. resection and anastomosis will be covered soon. a word of caution: preexisting disease is often at the root of the intussusception. this slide shows a piece of small bowel in a cat that has been partially reduced - there was a true intussusception...after resection, this was opened to find a tumor within the small intestine. so in old animals who develop intussusception, submit resected bowel for biopsy. slide: intussuscipiens inside intussusceptum - really ugly. once you have removed the intussusceptic portion of bowel and done your anastomosis, you should also perform an enteroplication. this may seem rather aggressive...but you want to intentionally create adhesions b/w loops of bowel to prevent further intussusceptions while treating underlying causes. so you place sutures b/w serosal surfaces of small intestines. this reduces the recurrence rate to zero from about 15-20%. one concern with intussusception is that it does occur at iliocolic junction, and this often needs to be resected. the physiologic derangements resulting from resection of this area are concerning. animals will typically respond well, but may have diarrhea for 3-5 mos as a result of rapid dumping of SI contents into colon, creating osmotic diarrhea. typically dogs will respond nicely over time, though, and accomodate to this. Intestinal volvulus: fortunately, rare. this is something GSD are predisposed to, esp if they already have EPI. most dogs we see - one to two cases/yr - present to ES with acute vomiting, retching, abdominal retching, abdominal tympany. this mimics GDV. these dogs are going to have severe circulatory compromise and severe acid/base/electrolyte disturbances. acidotic, etc. when you do abdominal rads, you see not a dilated stomach but a dilated intestine. the whole small intestinal mass is severely dilated. when you take them to surgery no matter how rapidly, you find gray/green loops of bowel -totally dead. also some dark purple stuff - on the way out. very little healthy bowel will remain. how much can you remove and have a functional animal left? short bowel syndrome - maldigestion/malabsorption. we can remove 75-80% of small intestine and have a functional pet, but these animals often do not even have 10% of functional small intestine remaining, so it's a problem. successful surgical therapy has occured only in cases where dog was going to surgery anyway for a chronic problem, and they found an acute intestinal torsion. but if you find an existing intestinal torsion and you find dead bowel you really can't help the dog. it's very rare, but very disastrous. sometimes you do see smaller segments affected - if a small segment passes through a little hole in mesentery and gets strangulated, and dies - you can resect that as long as it is less than 80% of existing small intestine. intestinal volvulus is rare. much more common is the foreign body, and intestinal neoplasia. intestinal neoplasia is more often seen in middle aged to older animals, most likely presenting with signs of chronic partial intestinal obstruction. sometimes the dx is not made until the tumor perforates the bowel, causing septic peritonitis, but more often they present with signs of chronic partial obstruction. rads: partial obstruction in distal small intestine - these rads are from a 12 yr old french bassett, presented w/6 month history of intermittent vomiting and chronic diarrhea, with significant weight loss. we see massive loops of dilated small intestine, dilated small intestine filled with particulate material making the gravel sign. abdominal ultrasound can be very useful to dx intestinal tumor, and also important in evaluating for metastatic disease. recall , these met via portal system to liver.needless to say, if you suspect neoplasm, also radiograph the thorax. this dog had negative chest rads and liver u/s - you can see nicely on these slides that there is a hugely distended small intestine on the oral side of the tumor. tx - resection of tumor, anastomosis. Dr B likes to empty oral bowel as much as possible because it reduces diameter, and reduces amount of ingesta that will go past anastomosis site in first 24 hrs. carefully evaluate liver at time of sx and bx if needed. also bx LN associated with area of mass. slide: cat at surgery - 12 yr old cat with chronic vomiting and intermittent vomiting and diarrhea. it has an intussusception which, once reduced, contained a tumor. the area was resected and biopsied. most common tumors: adenocarcinoma of secretory structures of intestinal mucosa/submucosa. in cats, most common is LSA followed by adenocarcinoma. occasionally we see smooth muscle tumors - leiomyoma/leiomyosarcoma; more rarely we see other tumors. but adenocarcinoma most common in dogs, LSA in cats, then adenoCA. ** mast cell tumors rarely seen, other CT tumors rarely seen. cats with intestinal LSA often have very subtle lesions such as simple thickening of the intestinal wall, or a small erythematous area on antimesenteric border, or slight thickening of one area or whatever. after resection/anastomosis - LSA can be txd with chemotherapy, but has a variable response in intestinal form. Dr B is unaware of any reliable, reproducible results using chemotherapy for adenocarcinoma of the intestine. if you make a dx early and use surgical tx you can get prolonged dz free intervals - some have gone 2-3 yrs before mets appeared. slide: this isn't small intestine per se, it is a leiomyosarcoma in the cecum. these dogs that have cecal leiomyosarcoma often present for whole blood in feces. so that's intestinal neoplasia...again, make your dx based typically on rads in animals we suspect of having it. u/s can be helpful to dx it in intestine, but more so for screening the liver, and chest rads are important to take prior to resectino of these tumors. resection can afford prolonged dz free interval if no mets are present. chemo only for LSA. briefly - intestinal obstruction with vascular compromise: to illustrate this, we look at this young male dog with scrotal herniation. a piece of intestine passing through the inguinal ring. but this can happen with any small hole through which bowel passes. we see indirect inguinal hernias in old, multiparous female dogs with loose inguinal rings who typically pass either a gravid or infected uterus through the ring (b/c inguinal rings are so lax, almost whole abdominal contents can go through w/o entrapment or strangulation), and in young, sexually active males. these dogs do develop strangulation. typically they present b/c of acute onset vomiting, they have an apparent acute testicular enlargement, scrotal enlargement, palpably enlarged spermatic cord, palpable bulge in inguinal area. don't ignore this. can u/s and see loops of bowel in subcu tissue. the bowel may undergo arterial and venous compromise when it strangulates. can become totally incarcerated: one specific case was brought in b/c it had an inguinal abscess - pus was coming out after local vet lanced it. this was 3 weeks ago. owner remarked that when dog ate, pus was more voluminous. see, dog had had an inguinal hernia, which the local vet lanced, creating an enterocutaneous fistula. gross. note to self: don't do that. traumatic lesions of small intestine: these are rare in the UK, more common here. he suspects although he doesn't know that we see more of these in West Philly than any other school. Gunshot wounds, stab wounds are most common. any penetrating abdominal trauma is cause for exploratory abdominal surgery once patient is stable enough. BDLD interactions with biting can cause this, too. slide: minor damage following gunshot wound - simple debridement and suturing or resection and anastomosis. slide: more extensive damage from gunshot wound - lots of liquefactive necrosis of GI tract, not compatible with life. blunt abdominal trauma that is nonpenetrating - such as HBC - these dogs may present initially doing great, then gradually getting abdominal distension, pain, vomiting, or diarrhea - due to avulsion of mesenteric attachement from 3-5 cm of intestine, which is then going to undergo necrosis due to loss of blood supply. this requires resection and anastomosis. so penetrating abdominal trauma is cause of damage for many organ systems and requires exploratory. degree of damage is variable, tx with local suturing or resection/anastomosis. sometimes not compatible with life. if you treat a hit by car, and it gets a distended animal and vomiting after a few days, realize it could have this mesenteric avulsion. Ok - how do you do a resection and anastomosis or linear enterotomy? good question, I was wondering myself, frankly. Intestinal Resection and Anastomosis: as discussed with bladder surgery...the most important layer when suturing intestine is the submucosa. ideal suture placement for suturing intestines would be to pass suture from 3-5 mm away from cut edge, through the muscle, through submucosa, but not through mucosa into the lumen. this is very hard to do. it is more important to ensure you get the submucosa than to avoid entering the lumen. entering the lumen is more acceptable than missing the submucosa entirely. in small animals, full thickness sutures are unavoidable. if you can avoid going through mucosa, great, if not, it's not the end of the world, just make sure you do get the submucosa ** most people use PDS, you can use any synthetic absorbable - vicryl, maxon, dexon - not chromic gut, not monocryl. to do this surgery - identify your lesion. identify reasonable margins of healthy tissue on either side. note blood supply. one vascular branch turns into an arcuate arcade of anastomosing arterioles - there is a great collateral system. so look at the piece of bowel and its blood supply. ligate supply at base and divide it b/w ligatures. you will see a color change in affected bowel. then go to the mesenteric border and ligate the arcuate arcade at the edge of affected area. now, place crushing clamps on the side of the bowel to be removed, and gentle occlusal clamps some 2-3 cm away from where you will cut, on healthy bowel. you will cut the mesojejunum, as closely as possible to piece you are removing. cut along the clamp, and remove the clamped, devitalized segment, leaving healthy edges in the doyenne clamps. the cut edges will evert - you can ignore this and work around it or take metzenbaums and trim back so you can see muscularis and submucosa. now, place sutures - 3-5 mm away from cut edge, and 3-5 mm apart - appositional sutures through muscularis and submucosa hopefully avoiding mucosa. tension is appositional, not strangulating. as with bladder surgery - as tight as a kiss with a little passion (what the hell does that mean?) do not strangulate the tissue, do not leave big gaps. gentle apposition only. once you've done that, close the mesenteric defect as well. times have changed. there are other ways to do this mechanically. surgical staplers - GIA or TA stapler - GIA creates V shape with open lumen, TA seals cut ends. this is a functional end to end anastomosis - but not really used b/c few people have these in practice. it goes without saying that once done your anastomosis, you will protect it with the omentum - place an omental patch over it. that is all there is to it. there are situations where you are not thrilled with quality of bowel you are suturing. if in doubt, take it out. although there are things you can do to try and support questionable areas - suture serosa all around the healing piece and compromised piece. same principles apply to linear enterotomy. if you make a linear incision to remove foreign material, you do it in antimesenteric border. suturing is the same. protect with omentum or serosa. ----end-----