Disorders & surgery Flashcards
Where is free gas best identified on abdominal radiographs? What view can help identify free gas?
Best identified between liver or stomach and diaphragm
Can do a horizontal beam in left lateral and focus on least dependent area
What is the normal diameter of intestine in dogs ans cats? What diameter is suggestive of obstruction?
- Dogs: normal = 2-3 times width of a rib, less than the width of an intercostal space
Suggestive of obstruction = intestinal diameter > 1.6 * narrowest width of L5 (increased suspicion when > 2.4*L5) - Cats: normal = less than twice the height of L4 body or 12mm
Suggestive of obstruction = intestinal diameter > 2 * height of cranial endplate of L2
What spec cPLI / spec fPLI is suggestive of pancreatitis in dogs / cats
- Spec cPLI > 400 mcg/L (unlikely if < 200 mcg/L)
- Spec fPLI > 5.3 mcg/L (unlikely if < 3.5 mcg/L)
Name risk factors associated with pancreatitis in dogs
- Hypertriglyceridemia
- Surgery
- Hypercalcemia
- Endocrine disorders (DM, hyperadrenocorticism, hypothyroidism)
- Duct obstruction
- Biliary reflux
- Pancreatic trauma
- Drugs (azathioprine, pheno, potassium bromide, L-asparaginase)
- Diet (dietary indiscretion, high fat)
What is the most common cause of pancreatitis in cats
Idiopathic (> 95%)
(Associated with DM, enteropathy, cholangitis, hepatic lipidosis, IMHA - but no causative association proven)
- No association with hypertriglyceridemia in cats
Briefly describe the pathophysiology of pancreatitis
- Premature activation of trypsinogen to trypsin within the pancreas (unclear cause - possibly changes in intracellular pH / iCa, co-localization of zymogen granules and lysosomes) –> activation of other proenzymes and NF-kB pathway
- Neutrophil migration into pancreas -> ROS, NO, phospholipase A2
-> Pancreatic necrosis, increased capillary permeability
–> exacerbation of inflammation - Activation of complement, kallikrein-kinin system, phospholipase A2 -> systemic vasodilation, increased permeability, activation of coagulation
-> DIC, edema, fluid losses, SIRS, MODS
Which enzyme involved in the pathophysiology of pancreatitis can promote ARDS and how?
Phospholipase A2: degrades surfactant –> pulmonary edema & ARDS
What can cause increased lipase (apart from pancreatitis)
- Gastroenteritis
- Liver disease
- Renal failure
- Glucocorticoid administration
- Heart failure
-> due to extra-pancreatic lipases
Name different lipase assays that can be used for diagnosis of pancreatitis
- Immunological lipase assays (measure immunoreactivity):
- Pancreatic lipase immunoreactivity (cPLI / fPLI) -> most sensible and specific, not affected by renal disease or glucocorticoids
- Spec PL (Spec cPL, Spec fPL) -> similar clinical performance to PLI, indicates negative result / gray zone / positive result
- SNAP PL (SNAP cPL, SNAP fPL) -> Se 91-94%, Sp 71-78% in dogs (good rule-out test)
- Catalytic lipase assays (measure lipase activity with different substrates)
- 1,2-diglyceride lipase -> very low specificity for pancreatic lipase (also measures extra pancreatic lipases)
- DGGR lipase -> more specific but not considered as good as PLI
- Trioelin lipase (= v-LIP-P) ->also supposed to be more specific
- Main difference is that immunological assays are not affected by extra-pancreatic lipases
What would ideally be the diagnostic imaging modality of choice for suspicion of acute pancreatitis
Contrast-enhanced CT scan
What characterizes cytology of acute pancreatitis>
Degenerate acini cells and large numbers of neutrophils
What are the parameters assessed in the Canine Acute Pancreatitis Severity Score
- SIRS (at least 2 SIRS criteria)
- Coagulopathy (thrombocytopenia < 63000 and/or PT increased by > 25% and/or PTT increased by > 25%)
- Increased creatinine (> 140 umol/L)
- Ionized hypocalcemia (< 1.1 mmol/L)
What ultrasound findings can suggest pancreatitis? What is the sensitivity of ultrasound to diagnose pancreatitis?
- Hypoechoic pancreas
- Enlarged pancreas
- Peripancreatic fluid
- Peripancreatic steatitis (hyperechoic fat)
- Thrombosis
Sensitivity depends on operator and severity of disease but overall max 60-70%
What factors can lead to disruption of pancreatic microcirculation (one pf the primary reasons why mild pancreatitis can progress to severe pancreatitis)?
- Fluid loss
- Microthrombi
- Changes in vascular permeability
What fluid is recommended in treatment of acute pancreatitis and why?
LRS for its alkalinizing effect –> increased pH may result in less trypsin activation in the acing cells
Why is early (within 24h of hospitalization) enteral nutrition recommended in animals with acute pancreatitis?
- Catabolic disease with loss of albumin & electrolytes
- Fasting leads to intestinal mucosal atrophy, changes in mucin composition, decreased transport of glutamine and arginine
- Improves motility and decreases bacterial translocation
What are possible indications for surgical management in acute pancreatitis
- Infected necrosis
- Extra-hepatic biliary obstruction if non-responsive to medical therapy
Always recommended to try to delay surgery
What are some things to think of if a patient that initially improved after an episode of pancreatitis becomes ill again?
- Pancreatic pseudocyst?
- Walled-off necrosis?
- EHBO
3 long term complications of acute pancreatitis?
- Chronic pancreatitis
- DM
- Exocrine pancreatic insufficiency
Name 3 causes of bacterial gastro-enteritis
- Clostridium spp
- Salmonella spp
- E Coli
- Campylobacter spp
What bacteria has been suggested as having a role in AHDS (acute hemorrhagic diarrhea syndrome)
Clostridium perfringens
What are the mechanisms of action of maropitant and ondansetron
- Maropitant: neurokinin-1 inhibitor -> inhibits substance P
- Ondansetron -> serotonin (5-HT) antagonist
What is the most efficient antacid among pantoprazole, esomeprazole, famotidine
- Esomeprazole most efficient
- Pantoprazole > famotidine when used as boluses
- Famotidine CRI 8 mg/kg/d >pantoprazole boluses
Name risk factors for gastrointestinal ulceration and hemorrhage in dogs and cats
- Drugs
- NSAIDs
- Gluocorticoids
- 3% hydrogen peroxide - Systemic diseases
- Hepatic disease
- Uremia
- Hypoadrenocorticism
- Pancreatitis
- Systemic neoplasia (mastocytosis, gastrinoma) - Gastro-intestinal disease
- Ischemic events (GDV, mesenteric volvulus / thrombosis, intussusception)
- IBD
- Neoplasia (lymphoma, adenocarcinoma, leiomyoma / leiomyosarcoma)
- Infectious (Salmonella, Clostridium, Campylobacter, Hookworms, Whipworms, Coccidia, Roundworms, Parvovirus, Coronavirus)
- Polyps
- AHDS - Stress of critical illness
- Stress-related mucosal disease (SRMD) in dogs
- Strenuous exercise in dogs
- Major surgery
- Hypovolemia
- Sepsis
What are the 2 most common causes of GI ulceration in dogs?
NSAIDs and hepatic disease
Why is HGE now called AHDS?
Histopathological changes are exclusive to the intestine and the stomach is not affected
What can cause false-positive / false-negative results on fecal occult blood test
- False-positive
- Diet rich in meat
- Presence of peroxidase-producing bacteria in GI tract
- Diet rich in fish, fruits, vegetables - False-negative
- Diet rich in vitamin C
A patient presents with obvious GI hemorrhage. What is your diagnostic approach?
- Coagulation profile
- CBC - microcytic hypo chromic anemia (chronic GI hemorrhage)? Normocytic, normochromic (acute)?
- Biochemistry: high BUN to creat ratio? Evidence of liver disease? Proteins?
- Cortisol
- Fecal smears, culture, parvo
- Gastrin levels
- DI: rads, CT, ultrasound?
- Endoscopy - most sensitive test to evaluate upper GI hemorrhage and ulcers
- +/- biopsies
- Capsule endoscopy
- Ex lap, scintigraphy, arteriography
Sensitivity of ultrasonography for detection of GI ulceration
65% for non-perforated ulcers
86% for perforated ulcers
What is suggestive of pneumoperitoneum on POCUS / abdominal ultrasound
Enhanced peritoneal stripe sign - hyperechoic line at the level of the peritoneum with reverberation artifact arising from the peritoneal lining (usually in non-dependent areas)
What are options for endoscopic hemostasis of GI bleed
- Cautery (thermal, electric, or laser)
- Administration of hemostatic powder / spray
- Clips
What are 3 indications to consider surgery in GI bleed?
- Preexisting surgical disease (FB, tumor, septic abdomen)
- Risk of exsanguination or perforation
- Failure to respond to medical therapy
What dog and cats breeds are predisposed to myasthenia gravis and megaesophagus
- German Shepherds and Golden Retrievers
- Abyssinian, Somali, and Siamese
What are differentials for regurgitation
- Pharyngeal disease
- Cricopharyngeal achalasia
- Neoplasia
- FB - Esophageal disease
Hypomotility (megaesophagus):
- Congenital
- Idiopathic
- Myasthenia gravis
- Neuromuscular disease
- Hypoadrenocorticism
- Lead toxicity
- Hypothyroidism
- Dysautonomia
- Lower esophageal sphincter achalasia
- Australian Tiger Snake envenomation
- Organophosphate toxicity
Inflammation (esophagitis):
- Chemical-induced (doxycycline)
- Gastro-esophageal reflux
- Spirocerca lupi
- Lupus
Mechanical obstruction:
- FB
- Stricture
- Gastric dilatation
- Neoplasia
- Vascular ring anomalies
- Extraluminal compression
- Hiatal hernia
- Gastro-esophageal intussusception
Are pro-kinetics indicated in dogs with esophageal dysmotility
No - the canine esophagus is made of striated muscles only so prokinetics will have not benefit and can increase the lower esophageal sphincter tone (making it harder for the food to reach the stomach)
What drug that is not a pro kinetic has been proposed for management of megaoesophagus?
Sildenafil - PDE-5 inhibitor that causes relaxation of the lower oesophageal sphincter
Where is the vomiting center located? What influences does it receive
- Vomiting center in the medulla, receives stimuli from:
- Cerebral cortex (anxiety, anticipation)
- Chemoreceptor trigger zone (CTZ): drugs (opioids), uremic toxins, hepatotoxins, endotoxins, cardiac glycosides
- Vestibular system (directly in cats, via CTZ in dogs)
- Gut
What are the main receptors involved in vomiting
- Dopaminergic
- Histaminergic
- Serotoninergic
- Muscarininc
- Neurokininergic
- Alpha2-adrenergic
- Glutamate receptor (NMDA)
- Enkephalinergic opioid
- Motilin
What are the 4 mechanisms of diarrhea
- Osmotic diarrhea (presence of excess intra-luminal osmoles)
- Secretory diarrhea (increased intestinal secretion or decreased intestinal absorption)
- Altered permeability (damage to epithelial cells or inter-cellular junctions leading to loss of substances)
- Deranged motility (increased peristaltic contractions or decreased segmental contractions)
Name one cause of primary / spontaneous septic peritonitis
FIP
What is the reported dehiscence rate following an enterotomy or R&A
7-16%
What is the sensitivity of abdominal ultrasound to identify gallbladder rupture? What other imaging modality has 100% sensitivity?
Se 56% for ultrasound, 100% for CT
What are the 3 groups of ethologies of septic peritonitis
- Primary -> usually hematogenous spread (FIP, bacteria, Toxoplasma)
- Secondary: GI, hepatobiliary, urogenital, hemolymphatic (spleen, LN), penetrating trauma, foreign material
- Tertiary: persistent or recurrent after surgical and antimicrobial therapy (usually GI leakage)
What are the most common bacteria isolated in septic peritonitis
- E Coli
- Enterococcus
- Enterobacter
- Clostridium
What volume of abdominal lavage is recommended in surgery for septic peritonitis
200-300 mL/kg
What is the range of survival for septic peritonitis in cats and dogs
Cats: 40-70% survival
Dogs: 46-88% survival
What patient positioning is recommended for an abdominocentesis
Left lateral recumbency (to prevent puncture of the spleen)
In Silverstein recommend doing the abdominocentesis in the right cranial quadrant with the patient in that position (??)
What is a risk with administering PPIs to prevent gastric ulceration from NSAIDs
PPIs can lead to dysbiosis at the level of the intestine and predispose to ulceration in the duodenum / small intestine
What is the mechanism of action of misroprostol
PGE2 analogue:
- increases mucosal blood flow
- increases mucus production
- increases HCO3 secretion
- decreases pepsin secretion
- preserves tight junctions
- improves mucosal regenerative capacity
What are side effects of misoprostol
- Abdominal pain
- Diarrhea
- Abortion
What is the mechanism of action of sucralfate
Dissociates into sucrose sulfate and aluminum hydroxide.
Sucrose sulfate binds to exposed mucosal proteins and prevents digestion by pepsin
AlOH provides some buffering effect to increase pH
What is required for sucralfate to have a benefit in esophagitis
Acidic environment in the esophagus (gastric reflux)
What are indications for the use of gastroprotectants
- Gastroduodenal ulceration and erosion
- Intrahepatic shunt (even after correction)
- Potentially animals competing in strenuous events
- Esophagitis secondary to gastro-esophageal reflux
Are PPIs indicated in GI hemorrhage due to thrombocytopenia
Could have theoretical benefit to help stabilize gastric blood clots since platelet aggregation improves when pH>6.0
But PPIs rarely achieve a gastric pH>6 and there is no proven clinical benefit
What are the 4 sites of esophageal narrowing (where esophageal FB can get stuck)
- Upper esophageal sphincter
- Thoracic inlet
- Heart base
- Esophageal hiatus (most common site of FB - 50-75% of cases)
What are the 3 possible mechanisms causing protein-losing enteropathy
- Lymphatic obstruction (idiopathic / congenital, inflammatory, congenital)
- Altered mucosal permeability
- Structural / mechanical injury to intestinal wall
What is a common mineral disorder encountered with PLE? Why?
Marked hypocalcemia
- Ionized hypocalcemia due to decreased absorption of the fat-soluble vitamin D
- Total hypocalcemia can be even worse due to hypoalbuminemia
Name 2 risk factors of mesenteric torsion (apart from being a German Shepherd)
- IBD
- Exocrine pancreatic insufficiency
- Ileocolic carcinoma
- Gastrointestinal foreign bodies
- Recent gastrointestinal surgery
- Blunt abdominal trauma
- Gastric dilatation and volvulus
What is a “whirl sign” indicative of on CT or ultrasound
It indicates organ torsion or volvulus with the blood vessels (mesh of concentric organ eg. spleen or intestinal loops, blood vessels and fat)
Where should a gastrotomy incision be performed
On the ventral surface of the stomach midway between the greater and the lesser curvatures (less vascularized area)
What is the difference between torsion and volvulus
- Torsion = twisting around the long axis
- Volvulus = twisting of bowel around the mesenteric axis
How to suture a stomach (suture material and pattern)
- Double layer inverting pattern: first layer simple continuous taking full thickness or mucosa only / second layer inverting pattern (Cushing, Connell, or Lembert) taking muscularis + serosa or all layers except mucosa
- Material: monofilament that needs to degrade slowly in acidic environment -> polydioxanone (PDS), poligleparone (Monocryl)
Name different types of gastropexy
- Incisional gastropexy
- Incorporating gastropexy
- Belt-loop gastropexy
- Circumcostal gastropexy
Which layers of the stomach and abdominal wall are incised for an incisional gastropexy? Where is the incision made?
- Peritoneum and muscle of abdominal wall (transverse abdominis) / serosa and muscular layer of stomach
- Incision made on the antrum and 2-3 cm caudal to the last rib on the right side
Name one surgical procedure increasing the pyloric outflow tract diameter
Y-U advancement pyloroplasty
Describe the movement of the stomach in a GDV
The pylorus and proximal duodenum move ventrally and then cranially. Then the pylorus continues to move, migrating from right to left.
Most common rotation is 180-270 degrees
What layer needs to be perfectly apposed when closing an enterotomy? What suture pattern is used?
Submucosa ; the mucosa should not be taken full-thickness
Single layer simple interrupted or continuous pattern
Where should an enterotomy incision for FB removal be done
On the anti-mesenteric border immediately distal (aboral) to the FB
What are risk factors of dehiscence following GI surgery
- Hypoalbuminemia
- Preoperative peritonitis
- Use of blood products
- Delayed enteral feeding post-op
- Intestinal FB
What % of small bowel length needs to be resected to cause short bowel syndrome
~ 50% ; signs appear earlier if distal intestine is resected
Name diagnostics that can be used to diagnose pancreatitis
No diagnostic is perfect -> need to use combination of results associated with suggestive clinical signs and CBC / biochem
- Lipase assays:
- Pancreatic lipase immunoreactivity (cPLI / fPLI)
- Spec cPL
- SNAP cPL, VetScan cPL, Vcheck cPL
- DGGR lipase
- v-LIP - Diagnostic imaging:
- Abdominal radiographs (mostly to rule out other things)
- Abdominal ultrasound
- Contrast-enhanced ultrasonography
- CT angiography
- MRI - Pancreatic cytology / histopathology
What is the Se / Sp of cPLI / Spec cPL, SNAP cPL, lipase DGGR, and v-LIP in dogs
- cPLI / Spec cPL: Se 70-90% (54-100% in cats), Sp 74-88% (67-100% in cats)
- SNAP cPL: Se 74-100% (reported 80% in cats), Sp 59-78%
- Lipase DGGR: Se 86-94% (~50% in cats), Sp 53-74% (~63% in cats)
- v-LIP: Se 100%, Sp 89%
What is the reported Se / Sp of abdominal ultrasound to diagnose pancreatitis in cats and dogs
- Dogs: Se 68% (up to 89% if using only 1 criteria among pancreatic enlargement, altered pancreatic echogenicity, or hyperechoic mesenteric fat). Sp 43% when using only 1 criteria, 92% when using 3 criteria
- Cats: Se 62-80%, Sp 67-88%
What breeds are predisposed to acute / chronic pancreatitis
Acute: Terrier, Mini poodles, Cocker Spaniel, Alaskan Malamute, mini Schnauzer, Dachshunds
Chronic: Cavalier King Charles, Collies, Boxers
What is a new treatment for pancreatitis and its mechanism of action
Fuzapladib sodium
Prevents extravasation of neutrophils into tissues
What are the 3 most common sites for esophageal FB? Why?
- Thoracic inlet
- Heart base
- Caudal esophagus
These are the sites where extra- esophageal structures restrict esophageal dilatation
Describe an approach for closure of a gastric incision
Continuous double-layer inverting closure in which the first suture line is full thickness and the second line incorporates only the serosa and muscular layers.
Monofilament absorbable suture.
Name subjective and objective criteria to assess gastric wall viability
Subjective:
- Gastric wall thickness
- Serosal surface color
- Evidence of serial capillary perfusion
- Presence of peristatilsm
Objective:
- Fluorescein dye injection
- Scintigraphy
- laser Doppler flowmetry
Name 3 gastropexy techniques
Incisional
Belt- loop
Circumcostal
Endoscopically assisted
Laparoscopic gastropexy
Where is the body wall incision performed for gastropexy?
2-3 cm caudal to the last rib on the right side
What layers of the stomach and of the peritoneum are incised for an incisional gastropexy?
What suture pattern is used?
Peritoneum: transverse abdominis muscle
Seromuscular incision in the gastric antrum either parallel or perpendicular to the long axis of the stomach. Care should be taken to avoid penetration of the gastric mucosa
Simple continuous pattern beginning with the craniodorsal edges of the incision
Name one complication of gastropexy
Pneumothorax
What are the 4 types of hiatal hernia?
- Type I (sliding): gastroesophageal junction has moved cranial to the diaphragm
- Type II (paraesophageal): a portion of the stomach moves into the caudal thorax through the hiatus adjacent to the esophagus
- Type III: combines the movement of the gastroesophageal junction into the thorax as well as movement of a portion of the stomach into the thorax adjacent to the esophagus.
- Gastroesophageal intussusception
What are risk factors associated with GDV?
- Purebred large or giant breed
- Increased thoracic depth-to-width ratio
- History of gastric dilatation and volvulus in a first-degree relative
- Feeding fewer meals per day
- Eating rapidly
- Aggressive or fearful tempera- ment
- Decreased food particle size
- Increased hepatogastric ligament length
- Exercise or stress after a meal
What is the most common rotation degree of the stomach for GDV?
180-270 degrees
Clockwise
Describe the manoeuvre for de-rotation of the stomach during GDV surgery
After the stomach is decompressed (orogastric tube), the surgeon must identify the pylorus and retract it toward the right side of the abdomen while using the opposite hand to push the body of the stomach dorsally.
Name some negative prognostic indicators for GDV
- Duration of clinical signs for more than 6 hours
- Concurrent gastrectomy or splenectomy
- Presence of hypotension, gastric necrosis, preoperative cardiac arrhythmias, peritonitis, sepsis, DIC
- Pre-operative plasma lactate > 6 mmol/L
*An increased duration of time from presentation to surgery has been associated with an overall decrease in the mortality rate
When performing a resection & anastomosis, describe 3 ways that luminal disparity can be addressed
- Sutures on the larger lumen side can be spaced farther apart than those of the smaller side
- The intestine with the smaller lumen can be transected at an angle or spatulated to create a larger luminal diameter
- The lumen diameter of the larger segment can be reduced
What conditions are associated with intussusception?
- Enteritis secondary to parasites, viruses
- Linear foreign bodies
- Cecal inversion
- Previous abdominal surgery
- Neoplasia in older animals
How can you differentiate between a rectal prolapse and a prolapsed intussusception?
If an instrument can be placed between the prolapsed tissue and the anus, this is diagnostic for an intussusception
In cases of rectal prolapse that require colopexy, where on the abdominal wall is the sexy performed?
To the left ventral abdominal wall approximately 2.5 cm lateral to the linea alba
True or false: Frank blood always indicates lower GI hemorrhage and Helena, upper GI
False
Its is the amount of time the blood remains in the GI tract that determines its color, not necessarily the site of bleeding.
–> Delayed transit time could result in Helena from a lower GI lesion
–> Decreased transit time could result in hematochezia from an upper GI bleed
Why is aspiration pneumonia more common in R+ than V+?
Reflex closure of the glottis occurs in emesis
Name a few prognostic indicators for septic peritonitis in dogs and cats
- Degenerative left shift: 2 fold risk of death or euthanasia
- Leukopenia: 18 fold increased risk for septic peritonitis in dogs with pyometra
- Persistant ionized hypocalcemia: negative prognostic indicator in cats
- Hyperglycemia on presentation: worse prognosis
- Inability to normalize lactate within 6-12 hours, persistant post-op hyperlactatemia, increasing lactate concentration: associated with non survival in dogs
- Organ dysfunction: increases odds of death
- Cats with septic peritonitis that received appropriate antimicrobials at admission: 4.4 times more likely to survive
- Hypoalbuminemia: associated with poor outcome
- Nutrtional support within 24h post-op: shorter length of hospitalization by 1.6 days
Diagnostic tests for parvovirus
- ELISA - detects viral antigens
- False negative: low viral shedding, binding of antibodies with antigen in diarrhea, performing text > 10 days post infection, dilution of antigen in liquid faces - PCR - detects DNA in whole blood
- Better sensitivity
- Characterization of strain - Hemagglutination
- Virus isolation
- Electron microscopy
What is the pathophysiology of ileum in GI obstruction?
Orad to the obstruction: Myenteric stretch stimulates COX-2 expression –> increased prostaglandin production –> Stimulation of EP2 and EP3 receptors by prostaglandin E2 results in ileus
Aboral to the obstruction: lack of ingest and inhibition of motor activity –> generalized ileum
What are negative prognostic indicators in cats with pancreatitis
- Ionized hypocalcemia
- Hypoglycemia
- Azotemia
