Staphylococcal bacterial contamination of portable electronic devices in a large veterinary hospital.

BACKGROUND: Portable electronic devices are used regularly within the veterinary and medical environments. Use of these in clinical areas may predispose them to bacterial contamination and they could act as fomites, transmitting infection between clinicians and patients. AIM: To determine the prevalence, origin and nature of Staphylococcal bacterial contamination on the surface of portable electronic devices used in a large small animal hospital. MATERIALS AND METHODS: Staff were surveyed on the frequency of portable electronic device use and device-cleaning routines. Portable electronic devices were swabbed for staphylococcus species. Cultured cocci were tested for antimicrobial resistance and identified at the species level to help determine the likely source (human or animal). FINDINGS: Forty one of 48 (85%) of staff used a portable electronic device every day within the hospital. Useable swabs were obtained from 47 portable electronic devices. Staphylococci were found on 68% of portable electronic devices. Vancomycin and Oxacillin resistance were seen in 17 of 46 (37%) and 1 of 46 (2%) isolated colonies respectively, including four vancomycin resistant, coagulase-positive staphylococci. 44% of staff never cleaned their device. CLINICAL SIGNIFICANCE: Portable electronic devices are commonly used in veterinary hospitals, but few staff routinely disinfect them. The use of disinfectant to reduce colony counts should be implemented when forming protocols for these devices in the hospital. The majority of staphylococci found were of likely human origin. It is suggested that contamination is therefore more likely to be originating from staff rather than patients.

Serological markers of gluten sensitivity in Border terriers with gall bladder mucocoeles.

OBJECTIVES: To evaluate serological markers of gluten sensitivity in conjunction with cholecystokinin measurement in Border terriers with gall bladder mucocoeles. MATERIALS AND METHODS: Medical records from two referral hospitals were obtained between 2011 and 2019 to identify Border terriers with gall bladder mucocoeles, non-Border terriers with gall bladder mucocoeles and control Border terriers with non-biliary diseases. Enzyme-linked immunosorbent assays were performed on stored fasted serum samples for anti-gliadin IgG, anti-canine transglutaminase-2-IgA autoantibodies and cholecystokinin. Statistical analysis was performed using the Kruskall-Wallis test to identify differences between the groups. RESULTS: Fifteen Border terriers with gall bladder mucocoeles, 17 non-Border terriers with gall bladder mucocoeles and 14 control Border terriers with non-biliary diseases were recruited. Median transglutaminase-2-IgA autoantibodies in Border terriers with gall bladder mucocoeles was 0.73 (range: 0.18 to 1.67), which was significantly greater than in control Border terriers at 0.41 (0.07 to 1.14). Median cholecystokinin concentration in Border terriers with gall bladder mucocoeles was 13 pg/mL (6 to 45 pg/mL), which was significantly lower than in control Border terriers at 103 pg/mL (9 to 397 pg/mL). There was no difference in the anti-gliadin IgG between these groups. There was no difference observed in the non-Border terriers with gall bladder mucocoeles with either of the other groups. CLINICAL SIGNIFICANCE: Reduced cholecystokinin and increased transglutaminase-2-IgA autoantibodies was detected in Border terriers with gall bladder mucocoeles; which is in part homologous to gall bladder disease identified in human coeliac disease. The results suggest an immunological disease with impaired cholecystokinin release may be affecting gall bladder motility and possibly contributing to mucocoele formation in Border terriers.

Infiltrative laryngeal disease in dogs.

OBJECTIVES: To describe the clinical features and outcome of neoplastic and inflammatory infiltrative laryngeal disease in dogs. MATERIALS AND METHODS: Medical records at a single referral centre were retrospectively reviewed for dogs diagnosed with infiltrative laryngeal disease by CT or laryngoscopy. RESULTS: Fifteen dogs were included, with a median age of 6 years (range 1-14 years). Thirteen dogs were diagnosed with inflammatory disease including granulation tissue (n = 4) and neutrophilic (n = 2), septic neutrophilic (n = 2), eosinophilic (n = 1) lymphocytic/plasmacytic (n = 1) and mixed/unclassified (n = 3) inflammation. One dog was diagnosed with large cell lymphoma and one dog was diagnosed with mast cell tumour. Twelve dogs survived to discharge. Follow-up was available for 10 dogs diagnosed with inflammatory disease. Four had fully recovered (7, 10, 23 and 32 months) and one dog developed acute leukaemia and was euthanased at 2 months. Five dogs had recurrence of clinical signs at 1, 1, 5, 17 and 26 months. The dog with lymphoma was euthanased at 8 months and the dog with mast cell tumour died at 5 months. CLINICAL SIGNIFICANCE: In this cohort, infiltrative inflammatory lesions of the larynx were more common than neoplastic infiltration. For dogs that survived to discharge, outcome was fair although relapse was common.

Staff attitudes to and compliance with the use of a surgical safety checklist.

OBJECTIVES: To investigate staff attitudes to the use of a surgical safety checklist in a small animal operating room and to gain insight into barriers to use. MATERIALS AND METHODS: A questionnaire was designed and used to assess attitudes of 36 operating room personnel to the checklist. The checklist was retrospectively audited on 984 patients over an 8-month period to investigate compliance. RESULTS: Responses were obtained from 100% of operating room personnel. Attitudes to the checklist were positive, with 83.4% agreeing that it improved teamwork and 100% agreed that the checklist improved patient safety, reduced error and was best practice. Most personnel (94%) believed that a completed checklist was used for every procedure. Several barriers were highlighted, including issues of hierarchy and team-working and lack of training. 984 checklists were used during the study period with 83 (8.4%) being fully completed. CLINICAL SIGNIFICANCE: Surgical safety checklists have potential to improve patient safety in veterinary operating rooms. However, appropriate design and implementation are critical and surgeons should endeavour to support checklist use.

Health-related quality of life following surgical attenuation of congenital portosystemic shunts versus healthy controls.

OBJECTIVES: To design a health-related quality of life questionnaire for dogs with congenital portosystemic shunts, use it in a cohort of dogs treated with suture attenuation and compare results with those obtained from a healthy control cohort. MATERIALS AND METHODS: Data were collected from the hospital records of dogs treated with suture ligation of an intrahepatic or extrahepatic congenital portosystemic shunt at two referral centres. Owners were asked to complete a questionnaire assessing their dog's health-related quality of life preoperatively (retrospectively) and at the time of follow-up. Owners of control dogs also completed the questionnaire. RESULTS: One hundred and twenty-eight dogs with congenital portosystemic shunts and 131 control dogs were recruited. Median follow-up time was 64 months (range 19.7 to 157.2). The median long-term health-related quality of life score was excellent for both intrahepatic and extrahpatic shunt cases and similar to that of control dogs. The long-term portosystemic shunt clinical sign scores for both intrahepatic and extrahepatic congenital portosystemic shunt dogs were significantly worse than the those of the control group. CLINICAL SIGNIFICANCE: Suture attenuation of congenitial portosystemic shunts is associated with an excellent health-related quality of life score at long-term follow-up.

Gall bladder mucoceles in Border terriers.

BACKGROUND: Gall bladder mucoceles (GBM) are a leading cause of biliary disease in dogs with several breeds, including the Shetland Sheepdog, American Cocker Spaniel, Chihuahua, Pomeranian, and Miniature Schnauzer apparently predisposed. OBJECTIVE: To determine risk factors, clinical features, and response to treatment of GBM in Border terriers (BT). ANIMALS: Medical records of 99 dogs (including 51 BT) with an ultrasonographic (±histopathologic) diagnosis of GBM from three referral centers in the United Kingdom were collected. A control group of 87 similar-aged BT with no ultrasonographic evidence of gall bladder disease was selected for comparison. METHOD: Retrospective case-control study. Odds ratios were calculated to establish breed predisposition. Signalment, presence of endocrine disease, clinicopathologic results, and outcome were compared between the BT, other breeds, and control BTs. RESULTS: The odds of identifying a GBM in a BT in this hospital population was 85 times that of all other breeds (95% confidence interval 56.9-126.8). BT had similar clinical signs and clinicopathologic changes to other breeds with GBM. There was no evidence that endocrinopathies were associated with GBM in BT. CLINICAL SIGNIFICANCE: A robust breed predisposition to GBM is established for the BT.

Intrahepatic congenital portosystemic shunts in dogs: short- and long-term outcome of suture attenuation.

OBJECTIVES: To report the short- and long-term outcomes of one- or two-staged suture attenuation for complete closure of intrahepatic congenital portosystemic shunts in dogs. MATERIALS AND METHODS: Retrospective cohort study of dogs surgically treated for intrahepatic congenital portosystemic shunts between February 2000 and March 2015. Long-term follow-up was conducted by telephone conversations with the referring veterinary surgeon, owner, or both. RESULTS: In total, 55 dogs had suture attenuation of their intrahepatic congenital portosystemic shunt; 10 dogs (18·2%) tolerated complete attenuation, whilst 45 dogs (81·8%) tolerated partial attenuation. Postoperative complications occurred in 24 dogs (43·6%), and six dogs (10·9%) died. Repeat surgery was performed in 33 of 39 dogs (84·6%) that had previously undergone partial attenuation, and 27 of these (84·9%) ultimately achieved complete shunt attenuation. One dog (3·0%) died following second surgery, resulting in an overall postoperative mortality of seven of 55 (12·7%). Detailed follow-up was available for 22 dogs that were still alive at a median of 29 months after surgery (7·4 to 103·1) with a subjectively good quality of life. Of 17 dogs (82·4%), 14 with complete attenuation in one or two surgeries had an excellent outcome compared with one of five dogs (20%) with persistent shunting. CLINICAL SIGNIFICANCE: Staged suture ligation resulted in a high proportion of complete attenuation and reduced persistent shunting compared with a single surgery. Repeat surgery was associated with fewer complications than the first surgery. The proportion of dogs with an excellent outcome was greater for those that had complete attenuation in one or two surgeries compared with those with persistent shunting.

The incidence of surgical site dehiscence following full-thickness gastrointestinal biopsy in dogs and cats and associated risk factors.

OBJECTIVES: The objectives of this study were to: (1) document the incidence of surgical site dehiscence after full-thickness gastrointestinal biopsy in dogs and cats and (2) identify potential risk factors. METHODS: Data relating to dogs and cats undergoing full-thickness gastrointestinal biopsy were reviewed retrospectively following submission of a completed questionnaire by 12 referral institutions. Outcome measures were definite dehiscence, possible dehiscence (clinical records suggestive of dehiscence but not confirmed), suspected dehiscence (definite and possible combined) and death within 14 days. Logistic regression was planned for analysis of association of dehiscence with low preoperative serum albumin, biopsy through neoplastic tissue, biopsy alongside another major abdominal surgical procedure and biopsy of the colon. RESULTS: Of 172 cats, two (1·2%) had definite dehiscence, and four (2·3%) had possible dehiscence. Low preoperative serum albumin was significantly associated with definite dehiscence in univariable analysis and with suspected dehiscence and death within 14 days in univariable analysis, but all odds ratios had wide 95% confidence intervals. A histopathological diagnosis of neoplasia was significantly associated with death within 14 days in univariable analysis. Of 195 dogs, two (1·0%) had definite dehiscence, and three (1·5%) had possible dehiscence. In dogs, there was no association between any outcome measure and the putative risk factors. CLINICAL SIGNIFICANCE: Incidence of dehiscence following full-thickness gastrointestinal biopsy was low in this study. When determining the appropriateness of biopsy in individual cases, this information should be balanced against the potentially life-threatening consequences of dehiscence.

Treatment of intrahepatic congenital portosystemic shunts in dogs: a systematic review.

The aim of this study was to establish the evidence base for the treatment of intrahepatic congenital portosystemic shunts in dogs through a systematic review of the pertinent literature. Studies were filtered for evidence to answer the question "Which of the treatment options for intrahepatic CPSS in dogs offers the best short- and long-term outcome?" Studies were assigned a level of evidence based on a system published by the Oxford Centre for Evidence-Based Medicine. Thirty-two studies were included in the review. Twenty-six provided level 4 evidence and six provided level 5 evidence. There were no level 1, 2 or 3 studies. One study compared surgical treatment with medical management and one study compared suture ligation with ameroid constrictor placement. The remaining studies were case series describing the outcome for one treatment method alone. Methods and timings of assessments of short- and long-term outcomes were highly varied, making direct comparisons challenging. The evidence regarding the treatment of intrahepatic congenital portosystemic shunts in dogs is weak, with only two studies directly comparing treatments. There is a lack of evidence regarding short- and long-term outcomes on which to base clinical decisions.

Long-term serum bile acid concentrations in 51 dogs after complete extrahepatic congenital portosystemic shunt ligation.

OBJECTIVES: To report the long-term bile acid stimulation test results for dogs that have undergone complete suture ligation of a single congenital extrahepatic portosystemic shunt. MATERIALS AND METHODS: Data were collected from the hospital records of all dogs that had undergone a complete suture ligation of a single congenital extrahepatic portosystemic shunt. Owners were invited to return to the referral centre or their local veterinarian for repeat serum bile acid measurement. Dogs diagnosed with idiopathic epilepsy and undergoing bile acid stimulation tests were used as a comparison population. RESULTS: Fifty-one study dogs were included, with a mean follow-up time of 62 months. 48 dogs had no evidence of multiple acquired shunts and a significant reduction in the pre- and post-prandial serum bile acid concentrations at long-term follow-up compared with pre-operative measurements. Pre- and post-prandial serum bile acids were statistically significantly greater for dogs that had undergone a full ligation (with no evidence of multiple acquired shunts) at all time points compared to the control dogs (P<0·001 for all comparisons). CLINICAL SIGNIFICANCE: The results suggest that in dogs treated with complete suture ligation mild increases in serum bile acids are not clinically relevant if there are no physical examination abnormalities, a normal body condition score and no relapse in clinical signs.

Lipopolysaccharide and toll-like receptor 4 in dogs with congenital portosystemic shunts.

Surgical attenuation of a congenital portosystemic shunt (CPSS) results in increased portal vein perfusion, liver growth and clinical improvement. Portal lipopolysaccharide (LPS) is implicated in liver regeneration via toll-like receptor (TLR) 4 mediated cytokine activation. The aim of this study was to investigate factors associated with LPS in dogs with CPSS. Plasma LPS concentrations were measured in the peripheral and portal blood using a limulus amoebocyte lysate (LAL) assay. LPS concentration was significantly greater in the portal blood compared to peripheral blood in dogs with CPSS (P = 0.046) and control dogs (P = 0.002). LPS concentrations in the peripheral (P = 0.012) and portal (P = 0.005) blood of dogs with CPSS were significantly greater than those of control dogs. The relative mRNA expression of cytokines and TLRs was measured in liver biopsies from dogs with CPSS using quantitative PCR. TLR4 expression significantly increased following partial CPSS attenuation (P = 0.020). TLR4 expression was significantly greater in dogs that tolerated complete CPSS attenuation (P = 0.011) and those with good portal blood flow on pre-attenuation (P = 0.004) and post-attenuation (P = 0.015) portovenography. Serum interleukin (IL)-6 concentration was measured using a canine specific ELISA and significantly increased 24 h following CPSS attenuation (P < 0.001). Portal LPS was increased in dogs with CPSS, consistent with decreased hepatic clearance. TLR4 mRNA expression was significantly associated with portal blood flow and increased following surgery. These findings support the concept that portal LPS delivery is important in the hepatic response to surgical attenuation. Serum IL-6 significantly increased following surgery, consistent with LPS stimulation via TLR4, although this increase might be non-specific.

Markers of angiogenesis associated with surgical attenuation of congenital portosystemic shunts in dogs.

BACKGROUND: Dogs with congenital portosystemic shunts (CPSS) have hypoplasia of the intrahepatic portal veins. Surgical CPSS attenuation results in the development of the intrahepatic portal vasculature, the precise mechanism for which is unknown, although new vessel formation by angiogenesis is suspected. HYPOTHESIS: That the degree of portal vascular development and the increase in portal vascularization after CPSS attenuation is significantly associated with hepatic vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2) gene expression and serum VEGF concentration. ANIMALS: Client-owned dogs with CPSS undergoing surgical treatment. Forty-nine dogs were included in the gene expression data and 35 in the serum VEGF data. MATERIALS AND METHODS: Dogs surgically treated by partial or complete CPSS attenuation were prospectively recruited. Relative gene expression of VEGF and VEGFR2 was measured in liver biopsy samples taken at initial and follow-up surgery using quantitative polymerase chain reaction. Serum VEGF concentration was measured before and after CPSS attenuation using a canine specific ELISA. Statistical significance was set at the 5% level (P ≤ .05). RESULTS: There was a significant increase in the mRNA expression of VEGFR2 after partial attenuation (P = .006). Dogs that could tolerate complete attenuation had significantly greater VEGFR2 mRNA expression than those that only tolerated partial attenuation (P = .037). Serum VEGF concentration was significantly increased at 24 (P < .001) and 48 (P = .003) hours after attenuation. CONCLUSIONS AND CLINICAL IMPORTANCE: These findings suggest that intrahepatic angiogenesis is likely to occur after the surgical attenuation of CPSS in dogs, and contributes to the development of the intrahepatic vasculature postoperatively.

Hepatic hepcidin gene expression in dogs with a congenital portosystemic shunt.

BACKGROUND: Microcytic anemia is common in dogs with a congenital portosystemic shunt (cPSS) and typically resolves after surgical attenuation of the anomalous vessel. However, the pathophysiology of the microcytic anemia remains poorly understood. Hepcidin has been a key role in controlling iron transport in both humans and animals and in mediating anemia of inflammatory disease in humans. The role of hepcidin in the development of microcytic anemia in dogs with a cPSS has not been examined. HYPOTHESIS: To determine whether hepatic hepcidin mRNA expression decreases, while red blood cell count (RBC) and mean corpuscular volume (MCV) increase in dogs after surgical attenuation of a cPSS. ANIMALS: Eighteen client-owned dogs with confirmed cPSS undergoing surgical attenuation. METHOD: Prospective study. Red blood cell count (RBC) and mean corpuscular volume (MCV), together with hepatic gene expression of hepcidin, were measured in dogs before and after partial attenuation of a cPSS. RESULTS: There was a significant increase in both RBC (median pre 6.17 × 10(12) /L, median post 7.08 × 10(12) /L, P < .001) and MCV (median pre 61.5fl, median post 65.5fl, P = .006) after partial surgical attenuation of the cPSS. Despite the increase in both measured red blood cell parameters, hepatic gene expression of hepcidin remained unchanged. CONCLUSIONS AND CLINICAL IMPORTANCE: This study found no evidence that dysregulated production of hepcidin was associated with anemia in dogs with a cPSS.

Clinical assessment of a shaft screw for stabilization of the humeral condyle in dogs.

OBJECTIVE: To report the use of a 4.5 mm shaft screw for the management of humeral condylar fractures (HCF) and incomplete ossification of the humeral condyle (IOHC) in dogs, and to assess risk factors for complications. METHODS: Dogs with HCF or IOHC that were managed with a 4.5 mm shaft screw with a minimum follow-up of six months from surgery were included. Data from the case records were used to identify risk factors for complications. Long-term follow-up was provided by an owner questionnaire and veterinary re-examination. RESULTS: Forty-three elbows were treated in 40 dogs (14 IOHC, 29 HCF). Minor complications were seen in four cases (9%) and major complications in 10 cases (23%). There were no statistically significant risk factors for major complication. Infection resulted in shaft screw removal from three IOHC cases. Four of eight IOHC cases that had a lateral approach had a major complication compared with zero out of six dogs that had a medial approach, but this difference was not significant (p = 0.085). Nine of 12 IOHC cases and 20/23 HCF cases had excellent or good limb use at the time of long-term follow-up (median of 106 weeks, range 26-227 weeks). All fractures healed but IOHC fissure healing was inconsistent. Fatigue failure of shaft screws was not seen. CLINICAL SIGNIFICANCE: The use of shaft screws for the management of IOHC and HCF is associated with a relatively low rate of complications (compared to previous reports) and a good long-term outcome.

Magnetic resonance imaging for detection of late meniscal tears in dogs following tibial tuberosity advancement for treatment of cranial cruciate ligament injury.

OBJECTIVES: To document the use of and to estimate the accuracy of magnetic resonance (MR) imaging for detection of late meniscal tears in dogs with cranial cruciate ligament injury treated with tibial tuberosity advancement (TTA). METHODS: Medical records of dogs that had TTA followed by stifle MR imaging for suspected meniscal tear and subsequent arthrotomy were reviewed retrospectively. Magnetic resonance images were reviewed independently by an observer blinded to clinical information who classified menisci as torn, abnormal but intact, or normal. Magnetic resonance and surgical findings were compared. RESULTS: Eight stifles from large breed dogs were included. Six stifles had a medial meniscal tear identified in MR images and later confirmed surgically. In the remaining two stifles, the menisci appeared intact in MR images and no tear was identified at subsequent arthrotomy. Lateral menisci in all stifles appeared intact in MR images and were considered normal at surgery. Susceptibility artefacts associated with TTA implants were present in all images but did not adversely affect interpretation of intra-articular structures. CLINICAL SIGNIFICANCE: Magnetic resonance imaging appears to be accurate for diagnosis of late meniscal tears. Artefacts associated with TTA implants did not prevent evaluation of critical intra-articular structures. Further investigation with MR imaging should be considered when late meniscal tear is suspected following TTA.

Histopathological findings in the livers of cats with a congenital portosystemic shunt before and after surgical attenuation.

Histopathological changes are reported in the livers of cats with congenital portosystemic shunts (CPSS) before and after surgical attenuation. Medical records, portovenograms and liver biopsies from cats treated surgically for CPSS were reviewed. Biopsies were graded for histopathological features characteristic of CPSS. Of 40 cats with CPSS included in the study, all had portal vein hypoplasia and arteriolar hyperplasia at initial surgery, 20 (50 per cent) had hepatocyte swelling with microvesicular vacuolar change, 17 (42.5 per cent) had fibrosis, 12 (30 per cent) had hepatocyte swelling with macrovesicular vacuolar change, 8 (20 per cent) had biliary hyperplasia and 2 (5 per cent) had haemosiderin within Küpffer cells. Cats with macrovesicular vacuolar change were significantly older than cats without (P = 0.001), with median ages of 18.5 months and 8.5 months, respectively. Twenty-five cats had partial attenuation of the CPSS at initial surgery, and 16 of these had follow-up biopsy samples. There were no significant differences in the histopathological features of biopsies before and after partial attenuation. From first to second surgery, there was a significant improvement in intrahepatic vasculature on portovenography both before (P = 0.001) and after (P = 0.039) temporary complete attenuation. Following partial CPSS attenuation, there was no significant change in histopathological features despite an improvement in intrahepatic vasculature on portovenography.

Airway injury associated with cervical bite wounds in dogs and cats: 56 cases.

OBJECTIVE: To investigate the frequency of airway injury and damage to other vital structures associated with cervical bite wounds in dogs and cats and the implications for management and outcome. METHODS: A retrospective search of electronic patient records was used to identify dogs and cats suffering cervical bite wounds that were presented to a large multidisciplinary veterinary hospital over a four year period. RESULTS: Complete records were available for 55 animals, with one animal suffering two separate injuries. Fourteen animals (25%) had injuries to vital structures, including airway injury in nine (17%) which was surgically confirmed and treated in six (11%). Airway injuries were associated with either subcutaneous or mediastinal emphysema in all affected animals. Other structures injured included the jugular vein, pharynx, oesophagus and spine. Airway injuries were treated with primary repair in five animals and a fasciomuscular patch in one. Temporary tracheostomy was performed in three animals. Median duration of hospitalisation was one day (0-19) with 53 animals (54 cases) (96%) surviving to discharge. Long-term follow-up (16-114 months) revealed that 43 of 49 animals were alive with six that died due to unrelated reasons. CLINICAL SIGNIFICANCE: Cervical bite wounds are associated with significant injury to vital structures. Up to 17% of animals may have injury to their airway. Identification and treatment of airway injury is vital and was associated with an excellent outcome in six animals.

Vascular endothelial growth factor (VEGF) and VEGF receptor expression in biopsy samples of liver from dogs with congenital portosystemic shunts.

Surgical attenuation of a congenital portosystemic shunt (CPSS) results in increased liver mass, development of intrahepatic portal vasculature and improved liver function. Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis. The aim of this study was to investigate the role of VEGF and its receptor in the hepatic response to CPSS surgery. The study included 99 dogs with CPSS treated with either partial or complete suture attenuation. Forty-four dogs with partial attenuation underwent a second surgery for complete attenuation. The expression of VEGF and VEGF receptor 2 (VEGFR2) in biopsy samples of liver was assessed by immunohistochemistry with rabbit anti-human VEGF polyclonal antibody and mouse anti-human VEGFR2 monoclonal antibody. Expression of these molecules was graded. The proportion of samples expressing VEGF was significantly greater in samples from dogs with CPSS compared with control samples (P=0.04) and the proportion of samples expressing VEGFR2 was significantly greater in control samples compared with samples from dogs with CPSS (P=0.04). VEGF labelling grade decreased significantly (P=0.038) and VEGFR2 increased significantly (P=0.046) between first and second surgery. The decrease in VEGF may reflect transient expression, preferential expression of other factors, reperfusion of existing vessels and/or increased angiogenesis before surgery in the form of arterialization and subsequent reduction due to improved portal blood flow. Partial suture attenuation was associated with a degree of 'normalization' of VEGF and VEGFR2 expression when compared with the control samples. Further investigation is needed to provide more information on the hepatic response to CPSS surgery.