Small animal surgery The authors, lecturers at the University of Zaragoza and clinicians at the Veterinary Hospital of the Zaragoza Faculty of Veterinary Medicine (HCVZ), combine their expertise and extensive surgical experience to make this a book of undeniable value.
Surgery atlas, a step-by-step guide
With its high-quality images and clear instructive text, this is a reference book for all veterinary clinicians and undergraduates.
The cranial abdomen
This book, the third in the series ‘Small animal surgery’, concerns the cranial part of the abdomen and provides a step-by-step description of the most common surgical procedures as well as some of the latest techniques.
Small animal surgery José Rodríguez Gómez María José Martínez Sañudo Jaime Graus Morales
Hernias Ureters Kidneys Adrenal glands Ovaries Spleen Pancreas Stomach Liver Portosystemic shunt
Surgery atlas, a step-by-step guide
The cranial abdomen General techniques
The cranial abdomen
Ureters / Ureteral lithiasis The closure of the ureter is then completed with simple interrupted sutures using the same material (fig. 16). Once the upper side has been sutured, the ureter is rotated 180°, and the suturing of the lower side is completed.
Ureteral anastomosis If the ureter is injured during surgery, or if stenosis is present that might cause a future recurrence of obstruction, the affected area should be resected and an anastomosis performed.
See also the chapter ‘Ureters: Periureteral fibrosis. Ureteral resection and end-to-end anastomosis’ in The Caudal Abdomen.
Make sure that the ureteral ends are not twisted before starting anastomosis and place as few as sutures as possible, but enough to prevent leakage of urine into the abdominal cavity.
If the ureter is injured near the bladder, a ureterocystostomy can be performed. See the chapter ‘Ureters’ in The Caudal Abdomen.
Fig. 16. Ureteral anastomosis is performed using interrupted sutures with fine
absorbable material. This photograph shows the finished suture of the upper side.
Postoperative care
In these cases, as much peri-ureteral fat as possible should be preserved, and the sutures should not be under tension.
It is necessary to continue the antibiotic treatment started before the operation (amoxicillin-clavulanic acid 15 mg/kg/12h PO) for two weeks, or to adjust treatment according to the results of sensitivity testing of a urine sample taken during the operation. It is advisable to moderately stimulate diuresis to reduce the aggregation of crystals eliminated by the kidneys. Also, the diet should be changed, according to the composition of the crystals, to minimise the risk of recurrence.
Ureteral anastomosis can be performed directly or after spatulation. This is done by making a lengthwise incision in both ends of the ureter (fig. 13). 24
During the postoperative period, the patient should be checked regularly for a possible uroperitoneum due to leakage of urine through the sutures.
A possible complication of ureteral surgery is fibrosis of the ureter in the operated area. This stenosis may cause obstruction and urinary retention (fig. 17).
Absorbable suture material is used, with a size of 5/0 to 8/0, depending on the diameter of the ureter.
To simplify the anastomosis, and to prevent suturing the walls together, two stay sutures are placed at an angle of 160-180° (figs. 14 and 15).
Fig. 13. The ureter has been spatulated by a longitudinal incision on this side to
Fig. 14. Stay sutures are placed at each end of the spatulated incisions to facilitate
Fig. 15. Traction on these sutures apposes the ureteral ends, which facilitates
Fig. 17. This patient was diagnosed with a right hydroureter. Laparotomy revealed that the obstruction was due to peri-ureteral fibrosis (white arrows) as a result of earlier
suturing both sides of the anastomosis.
ureteral anastomosis.
surgery. Yellow arrows: distended proximal ureter. Blue arrows: normal distal ureter.
widen the lumen and facilitate the anastomosis.
25
The cranial abdomen
Ureters / Ureteral lithiasis The closure of the ureter is then completed with simple interrupted sutures using the same material (fig. 16). Once the upper side has been sutured, the ureter is rotated 180°, and the suturing of the lower side is completed.
Ureteral anastomosis If the ureter is injured during surgery, or if stenosis is present that might cause a future recurrence of obstruction, the affected area should be resected and an anastomosis performed.
See also the chapter ‘Ureters: Periureteral fibrosis. Ureteral resection and end-to-end anastomosis’ in The Caudal Abdomen.
Make sure that the ureteral ends are not twisted before starting anastomosis and place as few as sutures as possible, but enough to prevent leakage of urine into the abdominal cavity.
If the ureter is injured near the bladder, a ureterocystostomy can be performed. See the chapter ‘Ureters’ in The Caudal Abdomen.
Fig. 16. Ureteral anastomosis is performed using interrupted sutures with fine
absorbable material. This photograph shows the finished suture of the upper side.
Postoperative care
In these cases, as much peri-ureteral fat as possible should be preserved, and the sutures should not be under tension.
It is necessary to continue the antibiotic treatment started before the operation (amoxicillin-clavulanic acid 15 mg/kg/12h PO) for two weeks, or to adjust treatment according to the results of sensitivity testing of a urine sample taken during the operation. It is advisable to moderately stimulate diuresis to reduce the aggregation of crystals eliminated by the kidneys. Also, the diet should be changed, according to the composition of the crystals, to minimise the risk of recurrence.
Ureteral anastomosis can be performed directly or after spatulation. This is done by making a lengthwise incision in both ends of the ureter (fig. 13). 24
During the postoperative period, the patient should be checked regularly for a possible uroperitoneum due to leakage of urine through the sutures.
A possible complication of ureteral surgery is fibrosis of the ureter in the operated area. This stenosis may cause obstruction and urinary retention (fig. 17).
Absorbable suture material is used, with a size of 5/0 to 8/0, depending on the diameter of the ureter.
To simplify the anastomosis, and to prevent suturing the walls together, two stay sutures are placed at an angle of 160-180° (figs. 14 and 15).
Fig. 13. The ureter has been spatulated by a longitudinal incision on this side to
Fig. 14. Stay sutures are placed at each end of the spatulated incisions to facilitate
Fig. 15. Traction on these sutures apposes the ureteral ends, which facilitates
Fig. 17. This patient was diagnosed with a right hydroureter. Laparotomy revealed that the obstruction was due to peri-ureteral fibrosis (white arrows) as a result of earlier
suturing both sides of the anastomosis.
ureteral anastomosis.
surgery. Yellow arrows: distended proximal ureter. Blue arrows: normal distal ureter.
widen the lumen and facilitate the anastomosis.
25
The cranial abdomen
Kidney / Nephrolithiasis
The kidney is dissected from its sublumbar attachments, leaving sufficient perirenal tissue for easy handling and to be able to fix it in its anatomical position after the intervention. Next, the kidney is flipped over medially, exposing its dorsal side (fig. 6).
Surgical procedure Pyelotomy is a very complicated procedure if the urinary tract is not distended.
Midline laparotomy was performed and the gastrointestinal parcel was moved to the right of the patient and protected with compresses soaked in lukewarm saline (fig. 4). In order to increase the dilation of the proximal ureter and renal pelvis, a vessel loop is placed around the distal part of the ureter (fig. 5).
Fig. 4. Exposure of the left kidney after moving the gastrointestinal parcel to the right of the patient. Note the thick fat layer that “protects� the kidney.
Fig. 6. The peritoneum and perirenal fat are incised at a distance from the kidney, which is moved to expose its dorsal surface. Note the large amount of fat in this area (red arrow: artery, blue arrow: vein, grey arrow: ureter).
The renal vessels and the ureter are identified. Dissection should be performed with care and precision to prevent damage to any of these structures (figs. 6 and 7).
50
51
Fig. 7. Careful dissection of the proximal ureter next to the renal pelvis. Take great care not to damage the renal vessels.
The proximal ureter and the pelvis are incised with a n° 11 scalpel blade, and the uroliths are removed with forceps, aided by intraureteral flushing (figs. 8-11).
Fig. 8. After incision of the proximal ureter, the uroliths are removed with fine forceps. Fig. 5. A vessel loop is placed distally around the ureter to stop the passage of urine, further dilating the proximal ureter.
The cranial abdomen
Kidney / Nephrolithiasis
The kidney is dissected from its sublumbar attachments, leaving sufficient perirenal tissue for easy handling and to be able to fix it in its anatomical position after the intervention. Next, the kidney is flipped over medially, exposing its dorsal side (fig. 6).
Surgical procedure Pyelotomy is a very complicated procedure if the urinary tract is not distended.
Midline laparotomy was performed and the gastrointestinal parcel was moved to the right of the patient and protected with compresses soaked in lukewarm saline (fig. 4). In order to increase the dilation of the proximal ureter and renal pelvis, a vessel loop is placed around the distal part of the ureter (fig. 5).
Fig. 4. Exposure of the left kidney after moving the gastrointestinal parcel to the right of the patient. Note the thick fat layer that “protects� the kidney.
Fig. 6. The peritoneum and perirenal fat are incised at a distance from the kidney, which is moved to expose its dorsal surface. Note the large amount of fat in this area (red arrow: artery, blue arrow: vein, grey arrow: ureter).
The renal vessels and the ureter are identified. Dissection should be performed with care and precision to prevent damage to any of these structures (figs. 6 and 7).
50
51
Fig. 7. Careful dissection of the proximal ureter next to the renal pelvis. Take great care not to damage the renal vessels.
The proximal ureter and the pelvis are incised with a n° 11 scalpel blade, and the uroliths are removed with forceps, aided by intraureteral flushing (figs. 8-11).
Fig. 8. After incision of the proximal ureter, the uroliths are removed with fine forceps. Fig. 5. A vessel loop is placed distally around the ureter to stop the passage of urine, further dilating the proximal ureter.
The cranial abdomen
Overview
Portosystemic shunt / Overview JosĂŠ RodrĂguez
Prevalence
Vascular anomalies that connect the portal vein with other systemic veins divert the blood from the splanchnic area (intestines, spleen, stomach and pancreas) straight into the blood stream that flows towards the heart, bypassing the liver parenchyma.
Such portosystemic connections may be extrahepatic (most common) or intrahepatic.
If blood from the portal area does not pass through the liver, the toxins that are normally metabolised by this organ are not inactivated and pass into the general circulation. Hepatotrophic substances also fail to reach the liver, so that the organ cannot develop properly.
Portosystemic shunts may be intrahepatic or extrahepatic, and congenital or acquired. Most extrahepatic shunts are congenital and single, representing 75% of cases. Some 60% of these are due to a connection between the portal vein and the caudal vena cava (fig. 1), the rest are connections between the gastroduodenal vein and the caudal vena cava (fig. 2). Intrahepatic shunts are usually congenital and single, representing nearly 15% of cases (fig. 3). Extrahepatic abnormalities are mainly found in small breeds, especially in the Yorkshire Terrier, Maltese, Pekingese and Lhasa Apso. Intrahepatic abnormalities, on the other hand, are found in medium and large breeds such as the German Shepherd Dog, the Labrador Retriever and the Spanish Water Dog.
Laboratory findings
Clinical signs may be very variable. Owners are mainly concerned by the retarded growth and weight loss of their dog. The patient may also present with anorexia, vomiting, listlessness, polyuria/polydypsia, abnormal behaviour or blindness.
The following changes may be found in these patients (table I):
The most common signs are vomiting, listlessness and ascites.
The signs of hepatic encephalopathy, i.e. ataxia, head pressing, circling and seizures are intermittent and increases after the ingestion of a high-protein meal.
Not all patients with a portosystemic shunt will develop hepatic encephalopathy.
Urate calculi are radiolucent; contrast radiography is required to make them visible.
These patients develop hepatic insufficiency followed by secondary hepatic encephalopathy due to the insufficient breakdown of substances such as ammonia, short-chain fatty acids and branchedchain and aromatic amino acids.
Urate calculi are usually rounded or oval-shaped, greenishgrey in colour, with a soft texture and slaty structure.
Fig. 1. Large-diameter vascular anomaly connecting the portal vein to the caudal vena cava. This abnormal vein (arrow) carries blood from the intestine and spleen and bypasses the liver.
Diagnostic imaging Plain abdominal radiography will only reveal a small liver (fig. 4).
Fig. 2. This case concerned a gastroduodenal-caval shunt. The vascular abnormality is more cranial, collecting blood from the duodenum and the stomach diverting it directly to the vena cava. The silk thread was placed at the junction of the shunt with the vena cava.
Fig. 3. Intrahepatic shunts occur as a result of a failure to close of the ductus venosus after birth. The yellow arrow indicates the vena cava, the blue arrow the vascular anomaly.
Table I. Haematology
These patients often have signs of urinary disease associated with urate uroliths: haematuria, dysuria, stranguria, urethral obstruction...
Patients with a portosystemic shunt present with underdeveloped liver and hepatic insufficiency, which may lead to hepatic encephalopathy.
244
Clinical signs
Fig. 4. Plain radiograph of a patient with a portocaval shunt, showing only a small liver.
Serum albumin BUN ALT, AST, ALP Bilirubin Urinalysis
Mild non-regenerative anaemia Microcytosis Decreased (normal in some cases) Decreased Moderately increased Normal Urate crystals
The decrease in serum BUN is due to the lack of hepatic conversion of ammonia absorbed by the intestine into urea. The increase of uric acid and ammonia in the urine leads to crystalluria.
Liver function tests will confirm this type of hepatic insufficiency. The most widely used test is the measurement of bile acids.
Protocol for the serum bile acid test Withhold food for 12 hours. Take blood to determine the serum bile acid level. Feed. Two hours later, take blood again to determine the serum bile acid level.
245
The cranial abdomen
Overview
Portosystemic shunt / Overview JosĂŠ RodrĂguez
Prevalence
Vascular anomalies that connect the portal vein with other systemic veins divert the blood from the splanchnic area (intestines, spleen, stomach and pancreas) straight into the blood stream that flows towards the heart, bypassing the liver parenchyma.
Such portosystemic connections may be extrahepatic (most common) or intrahepatic.
If blood from the portal area does not pass through the liver, the toxins that are normally metabolised by this organ are not inactivated and pass into the general circulation. Hepatotrophic substances also fail to reach the liver, so that the organ cannot develop properly.
Portosystemic shunts may be intrahepatic or extrahepatic, and congenital or acquired. Most extrahepatic shunts are congenital and single, representing 75% of cases. Some 60% of these are due to a connection between the portal vein and the caudal vena cava (fig. 1), the rest are connections between the gastroduodenal vein and the caudal vena cava (fig. 2). Intrahepatic shunts are usually congenital and single, representing nearly 15% of cases (fig. 3). Extrahepatic abnormalities are mainly found in small breeds, especially in the Yorkshire Terrier, Maltese, Pekingese and Lhasa Apso. Intrahepatic abnormalities, on the other hand, are found in medium and large breeds such as the German Shepherd Dog, the Labrador Retriever and the Spanish Water Dog.
Laboratory findings
Clinical signs may be very variable. Owners are mainly concerned by the retarded growth and weight loss of their dog. The patient may also present with anorexia, vomiting, listlessness, polyuria/polydypsia, abnormal behaviour or blindness.
The following changes may be found in these patients (table I):
The most common signs are vomiting, listlessness and ascites.
The signs of hepatic encephalopathy, i.e. ataxia, head pressing, circling and seizures are intermittent and increases after the ingestion of a high-protein meal.
Not all patients with a portosystemic shunt will develop hepatic encephalopathy.
Urate calculi are radiolucent; contrast radiography is required to make them visible.
These patients develop hepatic insufficiency followed by secondary hepatic encephalopathy due to the insufficient breakdown of substances such as ammonia, short-chain fatty acids and branchedchain and aromatic amino acids.
Urate calculi are usually rounded or oval-shaped, greenishgrey in colour, with a soft texture and slaty structure.
Fig. 1. Large-diameter vascular anomaly connecting the portal vein to the caudal vena cava. This abnormal vein (arrow) carries blood from the intestine and spleen and bypasses the liver.
Diagnostic imaging Plain abdominal radiography will only reveal a small liver (fig. 4).
Fig. 2. This case concerned a gastroduodenal-caval shunt. The vascular abnormality is more cranial, collecting blood from the duodenum and the stomach diverting it directly to the vena cava. The silk thread was placed at the junction of the shunt with the vena cava.
Fig. 3. Intrahepatic shunts occur as a result of a failure to close of the ductus venosus after birth. The yellow arrow indicates the vena cava, the blue arrow the vascular anomaly.
Table I. Haematology
These patients often have signs of urinary disease associated with urate uroliths: haematuria, dysuria, stranguria, urethral obstruction...
Patients with a portosystemic shunt present with underdeveloped liver and hepatic insufficiency, which may lead to hepatic encephalopathy.
244
Clinical signs
Fig. 4. Plain radiograph of a patient with a portocaval shunt, showing only a small liver.
Serum albumin BUN ALT, AST, ALP Bilirubin Urinalysis
Mild non-regenerative anaemia Microcytosis Decreased (normal in some cases) Decreased Moderately increased Normal Urate crystals
The decrease in serum BUN is due to the lack of hepatic conversion of ammonia absorbed by the intestine into urea. The increase of uric acid and ammonia in the urine leads to crystalluria.
Liver function tests will confirm this type of hepatic insufficiency. The most widely used test is the measurement of bile acids.
Protocol for the serum bile acid test Withhold food for 12 hours. Take blood to determine the serum bile acid level. Feed. Two hours later, take blood again to determine the serum bile acid level.
245