Classification of portosystemic shunts entering the caudal vena cava at the omental foramen in dogs.

OBJECTIVE: To re-evaluate the anatomy and classification of congenital extrahepatic portosystemic shunts entering the caudal vena cava at the level of the omental foramen. MATERIAL AND METHODS: A retrospective review of a consecutive series of dogs undergoing CT angiography as part of the diagnostic work-up for a congenital extrahepatic portosystemic shunt. RESULTS: In total, 53 dogs met the inclusion criteria revealing four anatomically distinct omental foramen shunt types; one of which (32 of 53 dogs) showed no shunting blood flow through the right gastric vein and three of which (21 of 53 dogs) involved shunting flow through this vessel. The anatomy of these four distinct shunt types, as defined by CT angiography, was found to be highly consistent. In all cases, regardless of the tributary vessels, the left gastric vein was the final vessel that communicated with the caudal vena cava. Using these findings, a more accurate naming classification for congenital portosystemic shunts entering the caudal vena cava at the level of the omental foramen was proposed. CLINICAL SIGNIFICANCE: A precise pre-treatment anatomical classification of congenital extrahepatic portosystemic shunts entering the caudal vena cava at the level of the omental foramen is important for a more complete understanding of the severity of clinical signs and prognosis, and for the better communication between clinicians and researchers in this clinical field.

Implications of shunt morphology for the surgical management of extrahepatic portosystemic shunts.

OBJECTIVE: To describe the implications of extrahepatic portosystemic shunt morphology for the chosen site of shunt closure in dogs and cats. METHODS: A retrospective review of a consecutive series of dogs and cats managed for congenital extrahepatic portosystemic shunts. RESULTS: In total, 54 dogs and 10 cats met the inclusion criteria, revealing five distinct shunt types: left gastrophrenic, right gastrocaval (types Ai, Aii and Aiii), splenocaval, colocaval and left gastro-azygos. Without exception, findings of computed tomography angiography and direct gross observations at the time of surgery confirmed four consistent sites of communication between the anomalous shunting vessel and the systemic venous system: the caudal vena cava at the level of the epiploic foramen; the left phrenic vein at the level of the oesophageal hiatus; the azygos vein at the level of the aortic hiatus; and the caudal vena cava or iliac vein at the level of the 6th or 7th lumbar vertebrae. The use of intraoperative mesenteric portography was effective for confirming that at the time of surgery all portal tributary vessels were proximal to the point of shunt attenuation. CONCLUSIONS: Findings confirmed that for the common types of extrahepatic portosystemic shunts there were only four consistent sites of communication between the shunt and the systemic venous system. This information supports the use of a systematic approach for the location and attenuation of shunts in dogs and cats.

Post-temporary ligation intraoperative mesenteric portovenography: comparison with CT angiography for investigation of portosystemic shunts.

OBJECTIVES: Comparison of pre-operative CT angiography and post-temporary, full-ligation, intraoperative, mesenteric portovenography for the characterisation of intrahepatic portal vasculature in patients with single extrahepatic portosystemic shunts. METHODS: Descriptive analysis of previously collected images from 14 dogs and five cats. RESULTS: With the exception of shunts involving the right gastric vein, intrahepatic arborisation appeared similar on both modalities. Portovenography improved contrast enhancement and slightly enlarged the intrahepatic portal vasculature. CLINICAL SIGNIFICANCE: CT angiography cannot replace intraoperative mesenteric portovenography after temporary full ligation, which provides information on intrahepatic portal vascularity. It is a practical and dynamic procedure, providing results that are instantaneously available at the time of surgery. In addition, intraoperative post-temporary, full-ligation, mesenteric portography confirmed that the single shunting vessel had both been recognised and ligated.

New perspectives on the development of extrahepatic portosystemic shunts.

In this essay we use clinical evidence and knowledge of anatomy to examine the relationship between blood flow and formation of congenital extrahepatic portosystemic shunts in dogs and cats. First we report on the clinical findings in a series of 50 dogs and 10 cats and then systematically review peer-reviewed data on the detailed anatomy of shunts in dogs and cats. In dogs four types of shunt: spleno-caval, left gastro-phrenic, left gastro-azygos and those involving the right gastric vein account for 94% of extrahepatic shunts. Cats also exhibit four types of shunt: spleno-caval, left gastrophrenic, left gastro-caval and left gastro-azygos, and the first three of these account for 92% shunts in this species. Our findings lead us to propose that preferential blood flow influences the subsequent formation of one of a number of defined and consistent congenital extrahepatic portosystemic shunts in dogs and cats.

Comparison of computed tomographic angiography and intraoperative mesenteric portovenography for extrahepatic portosystemic shunts.

OBJECTIVES: Comparison of intra-operative mesenteric portovenography and computed tomographic angiography for the documentation of the portal vasculature in patients with single extrahepatic portosystemic shunts. METHODS: Retrospective study of patients with extrahepatic portosystemic shunts that underwent preoperative computed tomographic angiography and intra-operative mesenteric portography. Studies were compared for identification of the intra- and extrahepatic portal vasculature. RESULTS: Computed tomographic angiography demonstrated all four portal vein tributaries and sub-tributaries. Intra-operative mesenteric portography inconsistently demonstrated the cranial mesenteric vein, the gastroduodenal vein (12 of 49 dogs and 0 of 10 cats), splenic vein (46 of 49 dogs and 8 of 10 cats) and caudal mesenteric vein (3 of 49 dogs and 2 of 10 cats). Computed tomographic angiography showed the intrahepatic portal vein with shunts emanating from the left gastric vein, splenocaval shunts or shunts involving the left colic vein. It showed intrahepatic portal branching in 5 of 12 patients with shunts involving the right gastric vein. Intra-operative mesenteric portography showed the intrahepatic portal vein in 29 of 59 patients but was outperformed by computed tomographic angiography in all cases except those patients with a shunt involving the right gastric vein. CLINICAL SIGNIFICANCE: In cases that have undergone diagnostic preoperative computed tomographic angiography there is no indication for diagnostic intra-operative mesenteric portovenography before ligation. In contrast, portovenography performed "after" temporary full ligation of the shunt provides clinical useful information and might be considered an integral investigation during shunt attenuation surgery.

Morphology of congenital portosystemic shunts involving the left colic vein in dogs and cats.

OBJECTIVE: To describe the anatomy of congenital portosystemic shunts involving the left colic vein in dogs and cats. METHODS: Retrospective review of a consecutive series of dogs and cats managed for congenital portosystemic shunts. For inclusion a shunt involving the left colic vein with recorded intraoperative mesenteric portovenography or computed tomography angiography along with direct gross surgical observations at the time of surgery was required. RESULTS: Six dogs and three cats met the inclusion criteria. All cases had a shunt which involved a distended left colic vein. The final communication with a systemic vein was variable; in seven cases (five dogs, two cats) it was via the caudal vena cava, in one cat it was via the common iliac vein and in the remaining dog it was via the internal iliac vein. In addition, two cats showed caudal vena cava duplication. CLINICAL SIGNIFICANCE: The morphology of this shunt type appeared to be a result of an abnormal communication between either the left colic vein or the cranial rectal vein and a pelvic systemic vein (caudal vena cava, common iliac vein or internal iliac vein). This information may help with surgical planning in cases undergoing shunt closure surgery.

Morphology of splenocaval congenital portosystemic shunts in dogs and cats.

OBJECTIVE: To describe the anatomy of congenital portosystemic shunts involving the splenic vein communicating with the caudal vena cava at the level of the epiploic foramen. MATERIALS AND METHODS: A retrospective review of a consecutive series of dogs and cats managed for congenital portosystemic shunts. RESULTS: Ninety-eight dogs and eight cats met the inclusion criteria of a congenital portosystemic shunt involving the splenic vein communicating with the prehepatic caudal vena cava plus recorded intra-operative mesenteric portovenography or computed tomography angiography and gross observations at surgery. All cases (both dogs and cats) had a highly consistent shunt that involved a distended gastrosplenic vein that communicated with the caudal vena cava at the level of the epiploic foramen via an anomalous left gastric vein. CLINICAL SIGNIFICANCE: The morphology of the shunt type described appeared to be a result of an abnormal communication between the left gastric vein and the caudal vena cava and the subsequent development of preferential blood flow through an essentially normal portal venous system. The abnormal communication (shunt) was through the left gastric vein and not the splenic vein, as might have been expected. This information may help with surgical planning in cases undergoing shunt closure surgery.

Portal vein anatomy in the dog: comparison between computed tomographic angiography (CTA) and intraoperative mesenteric portovenography (IOMP).

OBJECTIVES: To compare and contrast the findings of intra-operative mesenteric portovenography (IOMP) and computed tomography angiography (CTA) for the visualisation and identification of the extrahepatic and intrahepatic portal venous system in the normal dog. METHODS: Retrospective study of dogs with raised post-prandial bile acids concentrations, normal portal venous pressures and grossly normal portal vasculature that had undergone both CTA and IOMP was performed. Images and video were compared with the published anatomic literature. RESULTS: Ten dogs met the inclusion criteria. CTA documented the portal vein and its tributaries in all 10 dogs. IOMP documented the portal vein and the cranial mesenteric vein in all 10 dogs and the splenic vein in 1 dog but failed to show the caudal mesenteric and gastroduodenal veins in any dog. CTA documented more extrahepatic portal venous tributaries than IOMP. Both techniques documented the intrahepatic portal vasculature completely with equal clarity. CLINICAL SIGNIFICANCE: There was a large difference between the ability of the two techniques to delineate the normal portal vasculature; CTA consistently visualised the extrahepatic portal vasculature more completely than the IOMP and, as such, might be considered the modality of choice for imaging the normal portal vasculature in the dog.

Morphology of congenital portosystemic shunts involving the right gastric vein in dogs.

OBJECTIVE: To describe the anatomy of congenital portosystemic shunts involving the right gastric vein in dogs. MATERIALS AND METHODS: Retrospective review of a consecutive series of dogs managed for congenital portosystemic shunt. RESULTS: Twenty-two dogs met the inclusion criteria of a congenital portosystemic shunt involving the right gastric vein with recorded intraoperative mesenteric portovenography or computed tomography angiography and gross observations at the time of surgery. Of these, 20 (91%) had a shunt that entered the pre-hepatic caudal vena cava at the level of the epiploic foramen and two (9%) had a shunt that entered the post-hepatic caudal vena cava at the level of the diaphragm. Shunts entering the pre-hepatic caudal vena cava could be further classified into three consistent subdivisions. CLINICAL SIGNIFICANCE: The morphology of each shunt type described appeared to be a result of an abnormal communication between the left gastric vein and the caudal vena cava, the presence or absence of an abnormal communication between the splenic, left gastric and portal veins and the subsequent development of preferential blood flow through essentially normal portal vessels within the portal venous system. The abnormal communication (shunt) was through the left gastric vein and not the right gastric vein, as might have been expected. This information may help with surgical planning in cases undergoing shunt closure surgery.

The use of rigid endoscopy in the management of acute oropharyngeal stick injuries.

OBJECTIVE: To evaluate the use of rigid endoscopy in the management of oropharyngeal stick injuries. METHODS: Retrospective analysis of case records between 2011 and 2013 from a large referral hospital. Data regarding signalment, clinical presentation, treatment options and final outcomes were recorded. RESULTS: Nine dogs were identified with acute oropharyngeal stick injuries. There were seven males and two females and the dogs were of various breeds, ages (1 · 5 to 9 years) and weights (11 · 9 to 38 · 4 kg). The time from injury to referral was between 1 and 3 days (median: 2 days). All dogs were anaesthetised and the tracts explored using a 30° forward-oblique, 2 · 7-mm-diameter, 18-cm-length rigid endoscope with corresponding 14 · 5 Fr sheath. The endoscopy was performed under saline irrigation. Foreign material (>1 mm in size) was removed using grasping forceps fed through the sheath. Subsequently, the tracts were re-inspected and flushed with further saline to confirm that all foreign material had been removed. All dogs recovered uneventfully and had excellent outcomes with no cases representing with chronic manifestations of oropharyngeal stick injuries. CLINICAL SIGNIFICANCE: Rigid endoscopy is an effective method for the diagnosis, assessment and, in certain cases, treatment of acute oropharyngeal stick injuries in dogs.

Morphology of congenital portosystemic shunts emanating from the left gastric vein in dogs and cats.

OBJECTIVE: To describe the anatomy of congenital portosystemic shunts emanating from the left gastric vein in dogs and cats. METHODS: A retrospective review of a consecutive series of dogs and cats managed for congenital portosystemic shunts. RESULTS: Forty-six dogs and 27 cats met the inclusion criteria of a congenital portosystemic shunt emanating from the left gastric vein. Of the 46 dogs, 28 (61%) had a shunt that entered the left phrenic vein, 10 (22%) had a shunt that entered the post hepatic caudal vena cava and in 8 (17%) the shunt entered the azygos vein. Of the 27 cats, 19 (70%) had a shunt that entered the left phrenic vein and 8 (30%) had a shunt that entered the post hepatic caudal vena cava. CLINICAL SIGNIFICANCE: The systemic vein into which the shunt entered was consistent showing three common presentations: left gastro-phrenic, left gastro-caval and left gastro-azygos. This information may help with surgical planning in cases undergoing shunt closure surgery.

Surgical management of laryngeal collapse associated with brachycephalic airway obstruction syndrome in dogs.

OBJECTIVE: To describe the use of cricoarytenoid lateralisation combined with thyroarytenoid caudo- lateralisation (arytenoid laryngoplasty) for the management of stage II and III laryngeal collapse in dogs. METHODS: A retrospective study of a consecutive series of 12 dogs suffering from life-threatening stage II or III laryngeal collapse associated with brachycephalic airway obstruction syndrome. RESULTS: Pre-operatively, either stage II collapse (2/12) or stage III collapse (10/12) was confirmed on visual examination. In all cases, a left-sided arytenoid laryngoplasty was performed. Two dogs were euthanased postoperatively as a result of persistent life-threatening respiratory compromise. The procedure resulted in subjective enlargement of the rima glottidis and an associated improvement in respiratory function in the remaining 10 dogs. Follow-up, long-term outcome (median, 3·5 years) in these dogs indicated that all owners considered that the surgery had resulted in marked improvements in their dog's respiratory function, tolerance to exercise, and quality of life. CLINICAL SIGNIFICANCE: Combined cricoarytenoid and thyroarytenoid caudo-lateralisation may be a useful procedure for treatment of stage II and III laryngeal collapse in the dog.

Penile amputation and scrotal urethrostomy in 18 dogs.

The objective of this study was to report the signalment, indications for surgery, postoperative complications and outcome in dogs undergoing penile amputation and scrotal urethrostomy. Medical records of three surgical referral facilities were reviewed for dogs undergoing penile amputation and scrotal urethrostomy between January 2003 and July 2010. Data collected included signalment, presenting signs, indication for penile amputation, surgical technique, postoperative complications and long-term outcome. Eighteen dogs were included in the study. Indications for surgery were treatment of neoplasia (n=6), external or unknown penile trauma (n=4), penile trauma or necrosis associated with urethral obstruction with calculi (n=3), priapism (n=4) and balanoposthitis (n=1). All dogs suffered mild postoperative haemorrhage (posturination and/or spontaneous) from the urethrostomy stoma for up to 21 days (mean 5.5 days). Four dogs had minor complications recorded at suture removal (minor dehiscence (n=1), mild bruising and swelling around the urethrostomy site and mild haemorrhage at suture removal (n=2), and granulation at the edge of stoma (n=1)). One dog had a major complication (wound dehiscence and subsequent stricture of the stoma). Long-term outcome was excellent in all dogs with non-neoplastic disease. Local tumour recurrence and/or metastatic disease occurred within five to 12 months of surgery in two dogs undergoing penile amputation for the treatment of neoplasia. Both dogs were euthanased.

Soft palate hypoplasia and concurrent middle ear pathology in six dogs.

This retrospective clinical study describes six consecutive cases of bilateral hypoplasia/malformation of the soft palate in dogs in which associated middle ear disease was investigated and the palatine defects were surgical repaired. Radiographic abnormalities of the tympanic bullae were seen in both ears of all six dogs (12 of 12). Negative tympanocentesis findings were recorded in 11 of 12 ears. A purulent otitis media was confirmed in one ear of one dog, and loss of hearing was also demonstrated in this ear on brainstem auditory evoked response hearing assessment. There was no evidence of hearing loss on brainstem auditory evoked response in any of the remaining ears. Surgical repair of the soft palate defect was undertaken in all six dogs. Long-term assessment of the clinical outcome was considered excellent in five dogs and reasonable in one dog (mean 18 months, range seven to 27 months). It would appear that surgical intervention for the treatment of bilateral palatine malformation/hypoplasia may be associated with a better prognosis than reported previously. The lack of middle ear effusion and associated hearing impairment suggests that the underlying aetiology of middle ear pathology in dogs suffering from congenital palatine defects may be different from that observed in human beings. The true nature of the radiographic bullae changes seen in dogs with soft palate defects remains unclear.

Modified functional end-to-end stapled intestinal anastomosis: technique and clinical results in 15 dogs.

OBJECTIVES: To evaluate the use of a gastrointestinal anastomosis (GIA) stapling device to perform small intestinal anastomosis in the dog. METHODS: A retrospective study to evaluate the use of a GIA stapling device to perform small intestinal anastomosis in 15 dogs. RESULTS: Reasons for intervention included dehiscence of a previous enterotomy (four of 15), intestinal neoplasia (five of 15), vascular compromise (three of 15), intussusception (two of 15) and foreign body (one of 15). The mean time taken to perform the anastomosis was 7.7 minutes (range five to 12 minutes). No operative complications were recorded and all dogs recovered from the surgery. Major (two dogs) and minor (six dogs) short-term complications of pyrexia and anorexia were recorded in six dogs. In five of these, the cause was considered to be related to a pre-existing peritonitis. One dog was euthanased five months postoperatively for a multi-centric recurrence of intestinal lymphoma. Six month follow-up confirmed an unremarkable and complete recovery in all remaining dogs. No major or minor long-term complications were recorded in any individual. CLINICAL SIGNIFICANCE: A modified stapled functional end-to-end intestinal anastomosis holds merit and should be considered a viable alternative to other stapled and sutured anastomosis techniques.

Improved survival in a retrospective cohort of 28 dogs with insulinoma.

OBJECTIVES: To determine the survival times for a cohort of dogs with insulinoma and to describe the impact of medical therapy both in non-surgical cases and in surgical cases following relapse. METHODS: A retrospective study of dogs with insulinoma is presented. The Kaplan-Meier method is used to evaluate the survival characteristics of this population. RESULTS: Twenty-eight dogs were included in the study. The median survival time for all dogs was 547 days. Nineteen patients underwent partial pancreatectomy. The median survival time for this group was 785 days and for those subsequently receiving prednisolone therapy on relapse it was 1316 days. Perioperative complications are discussed. CLINICAL SIGNIFICANCE: Survival times in this study exceed those in other studies published previously. In part, this is explained by an improved remission duration following surgery compared with previous reports. More striking though is the longevity of patients following institution of medical therapy. These data give strong objective support to the role of medical therapy in the management of canine insulinoma, including following relapse after surgically induced remission.

Caecal impaction and chronic intestinal pseudo-obstruction in a dog.

A 10-year-old female neutered cross-breed dog presented with a 4-month history of chronic intermittent diarrhoea and vomiting. Abdominal ultrasound showed dilated loops of small intestine and a suspected faecolith. Exploratory surgery revealed a caecal impaction and a typhlectomy was performed. Histopathological examination of caecal and full thickness small intestine sections demonstrated atrophy of smooth muscle fibres as well as an influx of plasma cells, lymphocytes and macrophages, and mild lymphoplasmacytic and eosinophilic enteritis. This combination of caecal impaction and chronic intestinal pseudo-obstruction has not been reported previously in the dog.

Vascular ring anomaly with coarctation of the aorta in a cat.

A 13-week-old, entire male domestic shorthaired cat was presented with a nine-week history of regurgitation following the ingestion of food. A diagnosis of a vascular ring anomaly with coarctation of the aorta was based on clinical signs, angiography and echocardiography. Surgical exploration via a right lateral thoracotomy confirmed the existence of a persistent right aortic arch with right ligamentum arteriosum, aortic coarctation and an aberrant left subclavian artery. Following the surgical transection of the aberrant left subclavian artery, the cat made an uneventful recovery, showing normal swallowing function with no evidence of regurgitation. Twelve months after surgery, the cat had no special dietary requirements and remained clinically normal.

Surgical management of constipation.

There are many recognised causes of constipation in the cat and the management of the condition depends on the clinician's ability to recognise the appropriate aetiology in each case. Most surgery therapies for constipation in the cat are related to the management of idiopathic megacolon, although causes such as pelvic outlet obstruction, complications of neutering surgery, perineal herniation, and malunion pelvic fractures may also require surgical intervention. Currently, the surgical management of megacolon consists of subtotal colectomy with the recommendation that the ileocolic junction be preserved. The procedure, in general, is associated with few life-threatening complications although the majority of individuals will experience a transient period of loose stool formation in the immediate post-operative period. In the majority of cases, the long-term outcome following subtotal colectomy is considered excellent.