Dog Abdominal Anatomy: A Surgeon's Guide to the Canine Abdomen
External landmarks, linea alba layers, abdominal vasculature, and organ relationships — the surgical anatomy every small-animal surgeon must know before incising the canine abdomen.
- The linea alba is a midline fibrous raphe formed by the aponeuroses of the external abdominal oblique, internal abdominal oblique, and transversus abdominis muscles. It is the avascular, relatively weak entry point for a ventral midline celiotomy — and the most common site of incisional herniation.
- The abdominal aorta gives off three major unpaired branches immediately caudal to the diaphragm: the celiac artery (hepatic, splenic, left gastric), cranial mesenteric artery (jejunal, ileocolic, middle colic), and caudal mesenteric artery (left colic, cranial rectal). The caudal vena cava runs to the right of the aorta — do not mistake it for a dilated ureter.
- The canine liver has six lobes (left lateral, left medial, quadrate, right medial, right lateral, caudate) divided by fossae and fissures. The gallbladder sits between the right medial and quadrate lobes. The caudate lobe has a papillary process that extends to the left of the esophagus — a normal finding on radiographs, not a mass.
- The dog's spleen is mobile (gastrosplenic ligament), and its tail can extend to the pelvic inlet or fold over to the right side. A 'splenic torsion' is a surgical emergency: the spleen twists around its gastrosplenic pedicle, causing venous occlusion before arterial, leading to massive splenomegaly.
- The ureters cross the external iliac arteries ventrally at the pelvic brim — this is the 'ureteric pinch point' where ureteroliths most commonly obstruct, and where you must identify and retract the ureters during ovarian pedicle ligation in a deep-chested bitch.
- Free abdominal gas on a preoperative radiograph in a dog that has NOT had a recent celiotomy is a perforated viscus until proven otherwise — explore immediately.
- A dog with a tense, tympanic, painful abdomen and a 'double bubble' sign on radiographs (gas in the stomach and proximal duodenum) has a gastric dilatation-volvulus (GDV) until proven otherwise — decompress and operate within the hour.
- Serosanguineous abdominal effusion in a dog with a palpable mid-abdominal mass and a history of collapse is a bleeding splenic hemangiosarcoma until proven otherwise.
- Green-tinged peritoneal fluid during celiotomy is bile peritonitis — find the gallbladder rupture or bile duct laceration before lavaging.
External Landmarks and Surface Topography
Every abdominal surgery begins with surface anatomy. Before you pick up a scalpel, you must know what lies beneath your landmarks — because you cannot see through the skin, but you can (and must) visualise through it.
| Landmark | Palpation | Underlying Structure | Surgical Significance |
|---|---|---|---|
| Xiphoid process | Palpable at the caudal sternebra | Cranial extent of the linea alba; the diaphragm attaches to the xiphoid | Cranial landmark for ventral midline celiotomy; incision starts 1–2 cm caudal to xiphoid |
| Umbilicus | Midline scar; variable location (mid-abdomen in adults) | Linea alba; falciform ligament attaches from umbilicus to diaphragm | The skin incision can curve around the umbilicus; the linea alba incision goes through it (umbilical scar is the weakest point of the linea alba) |
| Pubic brim / prepubic tendon | Palpable at the cranial pelvic inlet | The linea alba ends at the prepubic tendon; the pelvic canal begins immediately caudal | Caudal landmark for ventral midline celiotomy; do not incise the prepubic tendon — it is the origin of the pectineus and abdominal muscles |
| Costal arch (ribs 9–13) | Palpable dorsolaterally | The diaphragm attaches to the costal arch; the liver lies immediately caudal | The costal arch limits lateral retraction during cranial abdominal surgery. A paracostal ('gridiron') approach enters the abdomen just caudal to the last rib — through the abdominal obliques, not the linea alba |
| Flank | The soft tissue between the last rib, lumbar transverse processes, and tuber coxae | Three muscle layers: external abdominal oblique (superficial), internal abdominal oblique (middle), transversus abdominis (deep) | Flank laparotomy (grid approach) is used for unilateral procedures (e.g., nephrectomy, adrenalectomy) — avoids the ventral midline and its healing complications |
The abdominal cavity extends from the diaphragm (at the level of the 6th–7th intercostal space — surprisingly cranial) to the pelvic inlet. In a medium-sized dog, this is a volume of approximately 1–2 litres, housing the entire gastrointestinal tract, liver, spleen, pancreas, urogenital system, and major vessels. The cavity is lined by peritoneum — a single layer of mesothelial cells that is exquisitely sensitive to desiccation. Keep it moist: every laparotomy sponge that touches peritoneum should be warm and wet.
The Ventral Midline Approach: Layer-by-Layer Anatomy
The ventral midline celiotomy is the workhorse incision of small-animal surgery. Its advantage is that it goes through the linea alba — a fibrous, relatively avascular midline raphe. Its disadvantage is that the linea alba heals slowly (fibrous tissue, poor blood supply relative to muscle) and is the most common site of incisional herniation.
The layers, from superficial to deep:
- Skin: Incise with a #10 scalpel blade. The skin in the ventral abdomen is thin and mobile. In male dogs, extend the incision lateral to the prepuce — do not incise through the prepuce, as the preputial cavity contamination will seed the celiotomy with bacteria.
- Subcutaneous tissue (hypodermis): Variable thickness — in a lean dog it is a few millimetres; in an obese dog it can be 5–10 cm. The subcutaneous tissue contains the ventral branches of the superficial epigastric arteries and veins — ligate or cauterise these if they cross the incision line.
- External rectus sheath (external abdominal oblique aponeurosis): The first fibrous layer. The external rectus sheath is continuous across the midline as part of the linea alba. The subcutaneous tissue is loosely attached to it — bluntly separate with a gauze sponge.
- Linea alba: The midline fibrous raphe formed by the decussation of the aponeuroses of the external abdominal oblique, internal abdominal oblique, and transversus abdominis muscles. It is a pearly white band, 2–5 mm wide in a medium-sized dog, running from the xiphoid to the prepubic tendon. Incise it with a #15 scalpel blade, lifting it with forceps to avoid cutting the underlying structures — in a dog, the falciform fat sits immediately deep to the linea alba cranially, and the greater omentum covers the intestines caudally.
- Transversalis fascia / peritoneum: A thin, transparent layer that is pierced as you complete the celiotomy incision. The falciform fat sits within the falciform ligament, which is a peritoneal fold extending from the umbilicus to the diaphragm, containing the round ligament of the liver (the remnant of the umbilical vein).
| Linea Alba Layer | Composition | Healing Timeline | Risk of Herniation |
|---|---|---|---|
| External rectus sheath | External abdominal oblique aponeurosis; collagen type I fibers oriented cranioventrally | Regains ~50 % tensile strength by 14 days | Low — if closed with proper suture (slow-absorbable monofilament, e.g., polydioxanone) |
| Linea alba proper | Decussation of aponeuroses; primarily collagen type I; relatively avascular | Regains ~50 % tensile strength by 21–28 days (slower than muscle) | Moderate — this is the weakest point; dehiscence occurs at the suture line, not the tissue |
| Internal rectus sheath | Internal abdominal oblique + transversus abdominis aponeuroses; present only in the cranial third of the abdomen (absent caudal to the umbilicus) | Same as external sheath | Low — but rectus abdominis muscle can herniate through a defect in the internal sheath (rare) |
Closure of the linea alba is performed with a simple continuous or interrupted pattern using a slow-absorbable monofilament suture (polydioxanone, polyglyconate). The suture should bite 5–10 mm from the incised edge and be placed 5 mm apart. The goal is to approximate the edges without strangulation — over-tightening causes tissue necrosis and dehiscence.
The Abdominal Vasculature: A Roadmap
The abdominal vascular tree is remarkably consistent across dogs — and when you know the major branches, you can find any organ, control any haemorrhage, and avoid the catastrophic error of ligating the wrong vessel.
| Vessel | Origin | Course | Key Branches | Clinical Note |
|---|---|---|---|---|
| Celiac artery | Abdominal aorta (T13–L1) | Short trunk (1–2 cm); trifurcates | Hepatic a. → liver, gallbladder, proximal duodenum; Splenic a. → spleen, left limb of pancreas, greater curvature of stomach; Left gastric a. → lesser curvature of stomach, distal esophagus | The celiac artery is the first major unpaired branch. Ligate it incorrectly and you devascularise the liver, spleen, and stomach simultaneously. It is NOT ligated during splenectomy — only the splenic branches are. |
| Cranial mesenteric artery | Abdominal aorta (L1–2), immediately caudal to celiac | Caudoventral into the root of the mesentery | Jejunal aa. (8–12 arcades); Ileocolic a. → cecum, ileum, ascending colon; Middle colic a. → transverse colon; Right colic a. → ascending colon; Caudal pancreaticoduodenal a. → right limb of pancreas + duodenum | The cranial mesenteric artery is the largest unpaired branch. Mesenteric volvulus occludes this vessel at its origin → ischaemic necrosis of the entire jejunoileum, cecum, and colon. This is a catastrophic surgical emergency with a grave prognosis. |
| Caudal mesenteric artery | Abdominal aorta (L4–5) | Caudoventrally to the descending colon | Left colic a. → descending colon; Cranial rectal a. → cranial rectum | Smaller than the cranial mesenteric artery. The caudal mesenteric artery territory is less prone to infarction because of collateral supply from the middle rectal artery (from the internal iliac). |
| Renal arteries | Abdominal aorta (L2–3) | Paired; right renal a. is longer (aorta is left of midline) | Each gives off an adrenal branch and then enters the renal hilus | The right renal artery passes DORSAL to the caudal vena cava. If you are dissecting the right kidney, identify the artery before the vein — the artery is dorsal. Do not mistake the right renal artery for the right adrenal artery. |
| Caudal vena cava | Confluence of common iliac veins (L6) | Runs to the right of the abdominal aorta; passes through the diaphragm at the caval foramen | Receives renal veins, hepatic veins, phrenicoabdominal veins | The CVC is thin-walled and easily torn. During adrenalectomy, the right adrenal gland is intimately adherent to the CVC — a CVC tear during right adrenalectomy is the most common cause of intraoperative mortality in this procedure. |
Organ-by-Organ Relationships: What Touches What
The abdomen is a crowded space. Every organ touches at least two others — and when one enlarges (neoplasia, torsion, obstruction), it displaces its neighbours in predictable patterns. Knowing these relationships allows you to identify abnormal positioning on radiographs and plan surgical approaches that avoid collateral damage.
| Organ | Normal Position | Contacts (Adjacent Structures) | Displacement Pattern | Surgical Approach |
|---|---|---|---|---|
| Liver | Cranial abdomen; spans from left (6th ICS) to right (9th rib); contacts diaphragm | Diaphragm (cranially), stomach (caudoventrally), right kidney (renal fossa of caudate lobe), duodenum (right), pancreas (dorsal) | Generalised hepatomegaly → stomach displaced caudally and to the left on VD radiograph; right-sided mass → duodenum displaced ventrally | Ventral midline; extend cranially to xiphoid. For right-sided liver masses, a paracostal approach or median sternotomy may be needed |
| Spleen | Left hemiabdomen; tail is mobile and can extend to right or pelvic inlet | Greater curvature of stomach (gastrosplenic ligament), left kidney (splenorenal ligament), left limb of pancreas, jejunum | Splenomegaly → tail extends caudoventrally on VD radiograph; splenic torsion → spleen assumes a 'C' or 'reverse C' shape, with the tail displaced to the right hemiabdomen | Ventral midline; the spleen is delivered by gently lifting it out of the left gutter. In splenic torsion, do not untwist the pedicle before ligating — release of ischaemic metabolites and bacterial endotoxin causes fatal reperfusion injury |
| Stomach | Cranial abdomen; fundus left, pylorus right, body midline | Liver (cranially), diaphragm (cranially), spleen (left), left limb of pancreas (dorsal), transverse colon (caudally) | GDV → stomach rotates clockwise (viewed from ventral) 180°–360°; pylorus moves from right to left and dorsal to the fundus on a right lateral radiograph | Ventral midline; identify the greater curvature (omentum) and rotate the stomach back to normal position by grasping the pylorus (if palpable) and pulling ventrally and to the right |
| Duodenum | Right hemiabdomen; descending duodenum runs caudally along the right body wall; ascending duodenum runs cranially to the duodenocolic ligament | Right kidney (medial), right limb of pancreas (within mesoduodenum), right abdominal wall (lateral), cecum and ascending colon (medial) | Duodenal foreign body → gas-distended duodenum on right lateral radiograph; the duodenum may be visibly enlarged on the right flank | Ventral midline; the descending duodenum is located by retracting the jejunum to the left and following the right body wall cranially. It is pinker and thicker-walled than the jejunum |
| Jejunoileum | Central and caudal abdomen; occupies most of the abdominal cavity; highly mobile (long mesentery) | All other organs — the jejunoileum fills the spaces between them | Linear foreign body → jejunoileum is 'pleated' along the foreign body, with characteristic gas patterns on radiographs | Ventral midline; exteriorise the jejunum by running it through your fingers from the duodenocolic ligament to the ileocecocolic junction. Count the loops to ensure none are left outside the abdomen at closure |
| Colon | Dorsal abdomen; ascending colon right, transverse colon midline (cranial to the root of mesentery), descending colon left (retroperitoneal) | Ascending: duodenum (right), right kidney (dorsal); Transverse: stomach (ventral), pancreas (dorsal); Descending: left kidney (lateral), left ureter (dorsal) | Megacolon → descending colon distends ventrally on lateral radiograph, displacing the urinary bladder caudally | Ventral midline; the descending colon is the most accessible part, lying retroperitoneally in the left dorsal abdomen. For colectomy, the descending colon is mobilised by incising the peritoneum along its left lateral attachment |
The Urinary Tract: Kidneys, Ureters, Bladder
The canine urinary tract is retroperitoneal except for the bladder neck (which is intraperitoneal at the pelvic brim or within the pelvic canal, depending on bladder distension). The kidneys are located in the dorsal abdomen: the right kidney is more cranial (T13–L2, in the renal fossa of the caudate liver lobe), and the left kidney is more caudal (L1–L3). Both are retroperitoneal and palpable in the live dog — the right kidney is more difficult to palpate because it sits under the costal arch.
| Structure | Location | Blood Supply | Innervation | Surgical Landmark |
|---|---|---|---|---|
| Right kidney | T13–L2; retroperitoneal in the renal fossa of the caudate liver lobe | Right renal a. (from aorta); right renal v. → CVC | Renal plexus (sympathetic from T12–L2; parasympathetic from vagus) | The right kidney is slightly more cranial than the left. For nephrectomy, incise the parietal peritoneum lateral to the kidney and retract the kidney medially to access the hilus |
| Left kidney | L1–L3; retroperitoneal; more mobile than the right | Left renal a. (from aorta); left renal v. → CVC (the left gonadal vein drains into the left renal vein — NOT into the CVC) | Same as right | The left kidney is more accessible for biopsy. The left gonadal vein (testicular/ovarian) drains into the left renal vein — during ovariectomy, do not extend traction on the ovarian pedicle too far cranially, or you will avulse the left renal vein |
| Ureters | Course retroperitoneally from renal hilus to dorsal bladder neck; cross the external iliac arteries VENTRALLY at the pelvic brim | Ureteral aa. from renal a., aorta, and internal iliac a. | Ureteric plexus (sympathetic and parasympathetic) — pain from ureteral distension is referred to the corresponding dermatome (T12–L2) | The ureters cross the external iliac arteries ventrally — this is the ureteric pinch point. During ovarian pedicle ligation in a deep-chested bitch, identify and retract the ureters before placing the clamp |
| Urinary bladder | Intraperitoneal (except the neck); position varies from mid-abdomen (full) to pelvic canal (empty) | Cranial vesical a. (from umbilical a.); caudal vesical a. (from internal pudendal/vaginal/prostatic a.) | Pelvic plexus (sympathetic from hypogastric n.; parasympathetic from pelvic n.) — parasympathetic stimulation detrusor contraction; sympathetic stimulation internal urethral sphincter contraction | The bladder apex (vertex) is the thickest, most vascular part — use it for cystotomy incision. The trigone is the triangular area between the ureteral orifices and the urethral orifice — avoid it during cystotomy |
Surgical Approaches: Beyond the Ventral Midline
The ventral midline celiotomy is the default, but four alternative approaches are essential for specific indications:
| Approach | Incision Site | Layers Incised | Best Indications | Contraindications |
|---|---|---|---|---|
| Paracostal (gridiron) | 3–5 cm caudal and parallel to the last rib, through the flank | External abdominal oblique, internal abdominal oblique, transversus abdominis (all bluntly separated along fiber direction — no muscle transection) | Unilateral nephrectomy, adrenalectomy, ovariectomy (single ovary), cryptorchidectomy (abdominal testis) | Bilateral disease; need for full abdominal exploration; poor visualisation of contralateral structures |
| Flank (grid) | Mid-flank, midway between last rib and tuber coxae, ventral to lumbar transverse processes | Same as paracostal but more dorsal — through the three muscle layers | Rumenotomy (cattle, analogous); unilateral renal/adrenal procedures in dogs where ventral midline is contraindicated | Same as paracostal; also, the flank incision is more painful than midline (muscle separation, not avascular linea alba) |
| Paramedian | 3–5 cm lateral and parallel to the linea alba, through the rectus abdominis muscle | Skin, subcutaneous tissue, external rectus sheath, rectus abdominis muscle (bluntly separated longitudinally), internal rectus sheath (if present), peritoneum | Unilateral procedures where midline is compromised (e.g., previous midline dehiscence, infected midline wound) | Need for bilateral exploration; risk of rectus muscle herniation through internal sheath defect |
| Transverse | Horizontal incision across one or both rectus abdominis muscles | Skin, subcutaneous tissue, external rectus sheath, rectus abdominis (transected), internal sheath, peritoneum | Extensive bilateral cranial abdominal exposure (e.g., large liver mass, bilateral adrenal masses) | Transection of rectus abdominis causes more postoperative pain than midline; longer healing time; not for routine use |
The paracostal approach deserves special attention for adrenalectomy. The right adrenal gland is intimately associated with the caudal vena cava, and the ventral midline approach provides poor visualisation of the right adrenal–CVC interface. A right paracostal approach (incision just caudal to the 13th rib) gives direct access to the right adrenal gland, allows the CVC to be visualised throughout the dissection, and reduces the risk of CVC laceration — the most feared intraoperative complication of adrenalectomy.
Clinical Decision Table: Acute Abdomen in the Dog
An 'acute abdomen' — sudden onset of abdominal pain, vomiting, and often cardiovascular compromise — demands rapid anatomical reasoning. The differential list is organised by the anatomical structure involved, because the treatment is governed by which organ is dying.
| Structure | Condition | Key Clinical Signs | Radiographic Finding | Treatment Window |
|---|---|---|---|---|
| Stomach | Gastric dilatation-volvulus (GDV) | Non-productive retching, tympanic cranial abdomen, cardiovascular collapse | 'Double bubble' sign (gas in stomach + proximal duodenum); stomach displaced caudally and to the right on VD view | Decompress immediately (orogastric tube or trochar); operate within 1–2 hours of presentation |
| Spleen | Splenic torsion | Acute abdominal pain, splenomegaly on palpation, ± hemoabdomen | Spleen displaced to right hemiabdomen; 'reverse C' shape; loss of the normal splenic head shadow | Operate immediately — splenic torsion causes venous infarction; the spleen can rupture within hours |
| Spleen | Splenic hemangiosarcoma with rupture | Collapse, pale mucous membranes, hemoabdomen | Mid-abdominal mass; loss of serosal detail (peritoneal effusion); ± splenic mass visible | Stabilise with IV fluids ± blood products; explore once cardiovascularly stable (within hours, not minutes — unlike torsion) |
| Small intestine | Intestinal foreign body with obstruction | Vomiting (may be projectile), anorexia, ± palpable intestinal loop | Dilated, gas-filled intestinal loops proximal to obstruction; 'gravel sign' (mineralised material) if the foreign body is radiopaque | Operate within 12–24 hours; prolonged obstruction → intestinal ischaemia and perforation |
| Small intestine | Linear foreign body | Vomiting, abdominal pain, 'pleating' of intestines on palpation | Pleated, bunched intestinal loops; gas in small bubbles (not linear) — the linear foreign body itself is rarely visible | Operate urgently — the linear foreign body saws through the mesenteric border of the intestine, causing perforation at multiple sites |
| Small intestine / mesentery | Mesenteric volvulus | Acute abdominal pain, cardiovascular collapse, bloody diarrhoea | Diffuse, severe small-intestinal distension; loss of serosal detail; ± portal venous gas (grave sign) | Operate within 1–2 hours — mesenteric volvulus causes infarction of the entire jejunoileum; mortality is >80 % even with surgery |
| Peritoneal cavity | Septic peritonitis | Fever, abdominal pain, ileus, cardiovascular collapse | Loss of serosal detail; 'ground-glass' appearance; ± free abdominal gas if perforated viscus | Explore immediately after stabilisation — the source of sepsis must be identified and controlled (resection, repair, or drainage) |
- When you cannot identify the linea alba through the subcutaneous fat of an obese dog, make a stab incision through the skin and subcutaneous tissues, then use the falciform fat as your guide — it sits in the falciform ligament, which is ventral and adherent to the linea alba.
- The spleen is the most commonly iatrogenically injured organ during celiotomy — it slides into the incision from the left side. Always sweep the spleen away from the incision with a moistened laparotomy sponge before entering the abdomen.
- The right kidney is more cranial than the left in the dog (it sits in the renal fossa of the caudate liver lobe). If you are performing a nephrectomy, the right kidney is deeper and requires more retraction of the duodenum.
- The pancreas has two lobes (right and left) connected by a central body. The right lobe sits in the mesoduodenum alongside the descending duodenum — if you are exploring for an insulinoma, start with the right lobe in the mesoduodenum.
Frequently asked questions
The linea alba is a narrow white line that can be invisible under 5–10 cm of subcutaneous fat. Technique: make a skin incision from the xiphoid to just cranial to the pubis. Bluntly dissect the subcutaneous tissue with a gauze sponge — it separates easily from the underlying external rectus sheath. Then, look for the falciform fat — it is a yellow, lobulated fat pad that sits in the falciform ligament, which is adherent to the deep surface of the linea alba in the cranial abdomen. Grasp this fat and lift — the linea alba is the white fibrous band attached to it. Alternatively, palpate the linea alba between your thumb and index finger as a taut midline band. In a truly massive dog, make a small stab incision at the cranial end, identify the linea alba, and extend it with scissors.
Splenic torsion occurs when the spleen rotates around its gastrosplenic ligament pedicle. It is most common in large- and giant-breed dogs (Great Danes, German Shepherds), and the rotation is typically clockwise (viewed from ventral). The exact cause is unclear — theories include laxity of the gastrosplenic ligament, prior gastric dilatation stretching the ligament, and vigorous exercise with a full stomach. The torsion causes venous occlusion first (thin-walled veins collapse under torsion pressure), while the thicker-walled splenic artery continues to pump blood in → rapid, massive splenomegaly. Arterial occlusion follows, leading to splenic infarction and necrosis. Untreated, the necrotic spleen can rupture, causing fatal hemoabdomen.
The canine small intestine is approximately 3.5× the body length — roughly 2.5–4.0 metres in a 20–30 kg dog. This matters for three reasons: (1) When you exteriorise the jejunum to check for foreign bodies, you must count the loops to ensure you have replaced all of them — a missed loop left outside the abdomen will strangulate. (2) You can resect up to 70 % of the small intestine and the dog can still maintain nutritional status (short bowel syndrome develops when >70–80 % is resected). (3) The jejunal arcade arteries (from the cranial mesenteric artery) form vascular arcades that allow a 5–7 cm intestinal segment to survive on a single intact arcade — useful when resecting a segment with marginal vasculature.
Ureteroliths in the dog obstruct at three predictable pinch points: (1) the ureteropelvic junction — where the renal pelvis narrows into the ureter, (2) the point where the ureter crosses the external iliac artery ventrally at the pelvic brim — this is the most common site because the artery acts as a sling that compresses the ureter, and (3) the ureterovesical junction — where the ureter enters the bladder wall obliquely. On an abdominal ultrasound, start at the kidney and trace the ureter caudally; a dilated ureter proximal to a hyperechoic shadowing focus at one of these three points confirms the diagnosis.
The six lobes are: left lateral, left medial, quadrate, right medial, right lateral, and caudate (which has a caudate process and a papillary process). The left lateral lobe is the most commonly affected by hepatocellular carcinoma and is the most amenable to lobectomy (it has a narrow base that can be ligated with a single mass ligature or stapling device). The right lateral and caudate lobes are more difficult to resect because of their proximity to the caudal vena cava and the hepatic veins. The quadrate lobe is small and is the site of the gallbladder fossa — gallbladder mucoceles are the most common indication for surgery on this lobe.
Green-tinged peritoneal fluid is bile — this is bile peritonitis. Your priorities: (1) Do NOT lavage yet — you will only spread the bile throughout the abdomen. (2) Suction the bile and locate the source — the most common sources are gallbladder rupture (blunt trauma, mucocele rupture) or bile duct laceration (surgical trauma during duodenal or pancreatic surgery). (3) If the gallbladder is ruptured, perform a cholecystectomy (not a cholecystotomy — a ruptured gallbladder wall is too friable to suture). (4) If the common bile duct is lacerated, options include primary repair (if a clean, small laceration), biliary diversion (cholecystoduodenostomy), or biliary stent placement. (5) After controlling the source, lavage the abdomen copiously with warm sterile saline (2–3 litres in a medium dog) and place a closed-suction drain. Bile peritonitis carries a guarded prognosis — bile is intensely irritating to the peritoneum and causes chemical peritonitis that predisposes to bacterial superinfection.
Self-check quiz
Test yourself. Answers are below each question — cover them first if you are studying.
- A) Greater omentum
- B) Falciform fat (in the falciform ligament)
- C) Mesenteric fat
- D) Retroperitoneal fat herniating through the linea alba
Show answer
Answer: B) Falciform fat (in the falciform ligament)
The falciform ligament is a peritoneal fold extending from the umbilicus to the diaphragm, containing the falciform fat and the round ligament of the liver. It is adherent to the deep surface of the cranial linea alba. Its presence confirms you are in the abdomen and at the midline. The greater omentum is caudal and covers the intestines.
- A) Gastric dilatation-volvulus
- B) Splenic hemangiosarcoma with rupture
- C) Splenic torsion
- D) Mesenteric volvulus
Show answer
Answer: B) Splenic hemangiosarcoma with rupture
The combination of hemoabdomen, a palpable mid-abdominal mass, and acute collapse in a large-breed older dog is classic for splenic hemangiosarcoma rupture. Splenic torsion also causes splenomegaly but typically does not cause hemoabdomen until the spleen actually ruptures (which is a late event). GDV presents with tympany and non-productive retching, not hemoabdomen. Mesenteric volvulus causes intestinal distension and bloody diarrhoea, not a mass.
- A) Left kidney
- B) Right kidney
- C) They are at the same craniocaudal level
- D) It depends on gastric distension
Show answer
Answer: B) Right kidney
The right kidney sits in the renal fossa of the caudate liver lobe (T13–L2) and is more cranial than the left kidney (L1–L3). The right kidney is also deeper and more difficult to palpate and to exteriorise during nephrectomy because of its position under the costal arch.
- A) Ureteropelvic junction
- B) Mid-ureter (level of L4)
- C) Where the ureter crosses the external iliac artery at the pelvic brim
- D) Ureterovesical junction
Show answer
Answer: C) Where the ureter crosses the external iliac artery at the pelvic brim
The ureter crosses the external iliac artery ventrally at the pelvic brim — this is the narrowest point of the ureteral course and the most common site of ureterolith obstruction. The ureteropelvic junction and ureterovesical junction are also potential obstruction sites, but the vascular crossing is the most common.
- A) Right renal artery
- B) Right phrenicoabdominal vein
- C) Caudal vena cava
- D) Celiac artery
Show answer
Answer: C) Caudal vena cava
The right adrenal gland is intimately associated with the dorsal wall of the caudal vena cava. A CVC tear during right adrenalectomy is the most common cause of intraoperative mortality in this procedure. This is why the paracostal approach (which gives better visualisation of the adrenal-CVC interface) is preferred by many surgeons for right adrenalectomy.
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