Postattenuation neurologic signs after surgical attenuation of congenital portosystemic shunts in dogs: A review.

The development of postattenuation neurologic signs (PANS) is a poorly understood and potentially devastating complication after surgical attenuation of congenital portosystemic shunts in dogs. Postattenuation neurologic signs include seizures but also more subtle neurologic signs such as depression, behavioral changes, tremors, and twitching. They most commonly occur within 7 days postoperatively and are typically unrelated to hyperammonemia, hypoglycemia, or electrolyte disturbances. This narrative review summarizes the findings of 50 publications from 1988-2020 that report occurrence of PANS. While most published reports included only dogs affected by postattenuation seizures (PAS), others included dogs with any form of PANS. Overall, PANS (including PAS) affected 1.6%-27.3% of dogs, whereas incidence of PAS ranged from 0%-18.2%. The etiology of PANS remains unknown; however, several theories have been proposed. Risk factors include preoperative hepatic encephalopathy, increasing age, and possibly certain breeds and extrahepatic shunt morphology. There is increasing evidence that prophylactic antiepileptic drugs do not prevent PANS. Treatment is centered around controlling neurologic signs with antiepileptic drugs and providing supportive intensive care. The 30-day survival rate in studies that included a minimum of four dogs affected by PANS was 0%-100% (median, 50.0%) and 0%-75.0% (median, 37.5%) for those with PAS. Mortality associated with PANS was typically related to occurrence of generalized seizure activity. Prognostic factors positively associated with short-term survival included having a history of preoperative seizures and development of focal seizures only. If affected dogs survived to discharge, survival for several years was possible, and the majority of neurologic signs manifested as part of the phenomenon of PANS appeared to resolve.

Force Distribution in the Canine Proximal Radio-Ulnar Joint on Extension of the Carpal Joint: A Cadaveric Study.

OBJECTIVE: The aim of this study was to measure the load on the lateral and medial aspects of the proximal radio-ulnar joint during extension of the carpus. STUDY DESIGN: This was an ex vivo biomechanical study. SAMPLE POPULATION: Twenty-two cadaveric Greyhound thoracic limbs were used. METHODS: Twenty-two paired thoracic limbs were used. The olecranon was attached to a custom jig with the foot resting on a stationary anvil. Load sensors were inserted into the proximal radio-ulnar joint, between the radial head and the lateral coronoid process, and between the radial head and the medial coronoid process. Specimens were tested under compression with measurements taken at 0, 4, 9 and 13.5 mm of axial displacement. Data collected at each point included forces on the specimen and medial and lateral coronoid processes as well as the angle of carpal joint extension. RESULTS: A linear mixed effects model relating load on the specimen and carpal joint extension angle had an R-squared value of 0.66, and load at the level of the medial coronoid process and angle of carpal extension had an R-squared value of 0.61. There was a significant difference in the loads measured on the lateral and medial coronoid processes at all angles (p < 0.0001). CONCLUSION: Extension of the carpus results in asymmetric loading of the proximal radio-ulnar joint. CLINICAL SIGNIFICANCE: The findings of this study show that loading of the medial coronoid process may be more complex than originally thought and supports the future investigation of novel management and therapeutic options for affected patients.

Small vs. Large Suture Bite-to-Stitch Interval for Closure of Midline Celiotomy in Cats: A Biomechanical Study.

Objective: The objective of this study was to compare the bursting strength and characterize the mode of failure of cranial and caudal midline celiotomies closed with 2 suture patterns and an absorbable monofilament suture material. Design: Randomized, cadaveric, ex- vivo mechanical testing. Sample: Feline cadavers (n = 32). Methods: Specimens were randomized into two groups based on the closure technique (small 2 × 2 mm or large 5 × 5 mm suture-bite-stitch-interval [SBSI] groups). Cranial or caudal midline celiotomies, 7.5 cm long, were created. A custom-made polyurethane bladder was inserted into the abdomen, and the celiotomies were closed in a simple continuous pattern using 3-0 polydioxanone. The repair was loaded to failure by inflating the bladder with compressed air. Bursting strength and mode of failure were recorded. Effects of body weight, gender, thickness and width of linea alba, suture-bite-stitch-interval, and location of celiotomy were analyzed using a mixed model analysis and an independent t- test, with P < 0.05 considered statistically significant. Results: There was no difference in bursting strength between cranial and caudal celiotomies. Bursting strength was lower for celiotomies closed with a large SBSI (P = 0.003). Bursting strength was greater in males compared to females (P = 0.003). Twenty five specimens failed distant from celiotomy closure, while 4 failed by fascial tearing at the site of needle penetration. Failure by loosening of the suture line with intact knots only occurred in 3 caudal celiotomies closed with a large SBSI. Gender, body weight and SBSI accounted for 61.5% of variability in bursting strength (P = 0.005). Conclusions: Small SBSI technique was mechanically superior to large SBSI when tested under these loading conditions. Clinical relevance: Supraphysiological pressures were required to cause failure in all specimens. Both small and large SBSI may be clinically applicable for midline celiotomy closure in domestic cats.

Prognostic factors for short-term survival of dogs that experience postattenuation seizures after surgical correction of single congenital extrahepatic portosystemic shunts: 93 cases (2005-2018).

OBJECTIVE: To identify prognostic factors for short-term survival of dogs that experience seizures within 7 days after surgical correction of single congenital extrahepatic portosystemic shunts (cEHPSS). STUDY DESIGN: Multi-institutional retrospective study. SAMPLE POPULATION: Ninety-three client-owned dogs. METHODS: Medical records at 14 veterinary institutions were reviewed to identify dogs that underwent surgical attenuation of a single cEHPSS from January 1, 2005 through February 28, 2018 and experienced postattenuation seizures (PAS) within 7 days postoperatively. Logistic regression analysis was performed to identify factors associated with 1-month survival. Factors investigated included participating institution, signalment, shunt morphology, concurrent/historical conditions, presence of preoperative neurologic signs, presence of preoperative seizures, aspects of preoperative medical management, surgical details including method and degree of shunt attenuation, type of PAS (focal only or generalized ± focal), drugs administered as part of the treatment of PAS, and development of complications during treatment of PAS. RESULTS: Thirty (32.3%) dogs survived to 30 days. Seventy-six (81.7%) dogs experienced generalized PAS. Factors positively associated with short-term survival included having a history of preoperative seizures (P = .004) and development of focal PAS only (P = .0003). Most nonsurvivors were humanely euthanized because of uncontrolled or recurrent seizures. CONCLUSION: Dogs that experienced PAS that had a history of preoperative seizures and those that experienced focal PAS only had significantly improved short-term survival. CLINICAL SIGNIFICANCE: The results of this study provide information that will help in the counseling of owners who seek treatment for PAS after surgical correction of cEHPSS. © 2020 The American College of Veterinary Surgeons.

Outcomes of eight cats with oral neoplasia treated with radical mandibulectomy.

OBJECTIVE: To report outcomes after radical mandibulectomy in cats. STUDY DESIGN: Multi-institutional retrospective study. ANIMALS: Eight cats were included. METHODS: Medical records were searched for cats with confirmed oral neoplasia treated with radical mandibulectomy. Data collected included demographics, surgical procedure, histopathological diagnosis, postoperative management, and outcomes. RESULTS: Ages ranged from 8 to 17 years. All cats had 75% to 90% of the mandible removed and feeding tubes placed. Seven cats had squamous cell carcinoma, and one cat had a giant cell tumor. Six cats ate on their own postoperatively. Three cats had local recurrence and tumor-related died at 136 and 291 days. Six cats had no recurrence, with survival times of 156, 465, 608, and 1023 days, and two cats were still alive at 316 and 461 days after surgery. The three long-term survivors died of causes unrelated to oral neoplasia. One cat died at 156 days due to aspiration of food material. The overall estimated mean survival time was 712 days. CONCLUSION: After radical mandibulectomy, independent food intake was achieved in 6 of eight cats, and four cats lived longer than one year. CLINICAL SIGNIFICANCE: Radical mandibulectomy should be considered for the treatment of extensive oral neoplasia in cats. Successful long-term outcomes are possible with aggressive supportive care perioperatively.

Intraoperative and major postoperative complications and survival of dogs undergoing surgical management of epiglottic retroversion: 50 dogs (2003-2017).

OBJECTIVE: To report intraoperative and major postoperative complications in dogs treated surgically for epiglottic retroversion (ER), compare the incidence of major postoperative complications between procedures, and report survival of surgically treated dogs. STUDY DESIGN: Multi-institutional retrospective study. SAMPLE POPULATION: Fifty dogs treated with 78 procedures. METHODS: Medical records of dogs diagnosed and surgically treated for ER from 2003 to 2017 at 11 institutions were reviewed. Complications were divided into intraoperative and major postoperative complications. RESULTS: Intraoperative complications occurred during 2 of 78 (2.6%) procedures. Thirty-six major postoperative complications were documented in 22 dogs after 36 of 74 (48.7%) procedures. Postoperative complications occurred after 7 of 12 (58.3%) nonincisional epiglottopexy, 23 of 43 (53.5%) incisional epiglottopexy, 2 of 4 (50%) partial epiglottectomy, 2 of 12 (16.7%) subtotal epiglottectomy, and 2 of 3 (66.7%) other surgical procedures. Epiglottopexy failure was the most common major postoperative complication. The incidence of major postoperative complications did not differ between procedures (P = .1239), although, when combined, epiglottopexy procedures (30/55) had a higher incidence of complications than epiglottectomy procedures (4/16; P = .048). Thirty (60%) dogs were alive at a median of 928 days (range, 114-2805), 8 (16%) were lost to follow-up after 411 days (range, 43-1158), and 12 (24%) were dead/euthanized after 301.5 days (range, 3-1212). Median survival time was not reached after a median of 716 days. CONCLUSION: Although intraoperative complications were uncommon, major postoperative complications were common, especially after epiglottopexy procedures. CLINICAL SIGNIFICANCE: Although surgical treatment of ER is associated with a high rate of major postoperative complications, especially epiglottopexy procedures, long-term survival can be achieved.

Incorporation of a polydioxanone absorbable plate in the successful repair of an iatrogenic oronasal fistula in a dog.

CASE DESCRIPTION: A 10-year-old castrated male Siberian Husky that had undergone complete excision of an oral plasmacytoma was evaluated because of development of a large oronasal fistula following failure of primary defect repair. CLINICAL FINDINGS: Clinical examination findings for the dog were unremarkable. The dog was receiving nutrition via an esophagostomy tube, which had been placed at the time of mass excision. The dog was notably head shy. Intraoral examination following sedation revealed a large (approx 25 × 20-mm) oronasal fistula, which was oriented craniocaudally in the long axis and located at the rostral aspect of the soft palate. Maturation of tissues had been allowed following failure of the primary repair, and an epithelialized border was identified circumferentially. TREATMENT AND OUTCOME: 10 weeks after mass excision, revision surgery involving 2-layer closure augmented with a polydioxanone plate was performed. At a recheck examination 21 days after revision surgery, near-complete healing of the closure site with no repair compromise was evident, and the dog had returned to oral food intake. A follow-up evaluation 40 weeks later revealed complete healing, with a single 1-mm defect at the medial aspect of the left maxillary dental arcade, as a result of suspected repeated trauma at the level of teeth 209 and 210. This defect was not associated with any clinical abnormalities. CLINICAL RELEVANCE: The outcome for this dog indicated that use of a polydioxanone plate offers a means of robust, long-lasting, and absorbable augmentation of a traditional 2-layer repair of an oronasal fistula in this species.

Effect of prophylactic treatment with levetiracetam on the incidence of postattenuation seizures in dogs undergoing surgical management of single congenital extrahepatic portosystemic shunts.

OBJECTIVE: To report the incidence of postattenuation seizures (PAS) in dogs that underwent single congenital extrahepatic portosystemic shunt (cEHPSS) attenuation and to compare incidence of PAS in dogs that either did or did not receive prophylactic treatment with levetiracetam (LEV). STUDY DESIGN: Multi-institutional retrospective study. POPULATION: Nine hundred forty dogs. METHODS: Medical records were reviewed to identify dogs that underwent surgical attenuation of a single cEHPSS from January 2005 through July 2017 and developed PAS within 7 days postoperatively. Dogs were divided into 3 groups: no LEV (LEV-); LEV at ≥15 mg/kg every 8 hours for ≥24 hours preoperatively or a 60 mg/kg intravenous loading dose perioperatively, followed by ≥15 mg/kg every 8 hours postoperatively (LEV1); and LEV at <15 mg/kg every 8 hours, for <24 hours preoperatively, or continued at <15 mg/kg every 8 hours postoperatively (LEV2). RESULTS: Seventy-five (8.0%) dogs developed PAS. Incidence of PAS was 35 of 523 (6.7%), 21 of 188 (11.2%), and 19 of 228 (8.3%) in groups LEV-, LEV1, and LEV2, respectively. This difference was not statistically significant (P = .14). No differences between groups of dogs that seized with respect to investigated variables were identified. CONCLUSION: The overall incidence of PAS was low (8%). Prophylactic treatment with LEV according to the protocols that were investigated in our study was not associated with a reduced incidence of PAS. CLINICAL SIGNIFICANCE: Prophylactic treatment with LEV does not afford protection against development of PAS. Surgically treated dogs should continue to be monitored closely during the first 7 days postoperatively for seizures.

Biomechanical properties of feline ventral abdominal wall and celiotomy closure techniques.

OBJECTIVE: To compare biomechanical properties and mechanism of failure of 3 regions of ventral abdominal wall in cats by using 2 suture materials, 2 suture bite-to-stitch intervals (SBSI), and full-thickness versus fascia-only closure. STUDY DESIGN: Randomized, cadaveric, ex vivo mechanical testing. SAMPLE POPULATION: 16 adult cat cadavers, 3 samples per cat. METHODS: Three regions of ventral abdominal wall were mechanically tested (N = 48 samples). Preumbilical, umbilical (U), and postumbilical (POU) regions were harvested by using a template. The thickness of the linea alba was recorded. Six samples without celiotomy served as controls. Twenty-eight samples were randomized to SBSI (2 × 2 or 5 × 5 mm) and suture material (3-0 polyglactin 910 or 3-0 polydioxanone) for simple continuous celiotomy closure. Fourteen samples were randomized to full-thickness or fascia-only closure. Samples were tested by linear distraction; tensile strength and mechanism of failure were recorded. Effects of body weight, thickness of linea alba, anatomic region, SBSI, type of closure, and suture material were evaluated by mixed model linear analysis. Load to failure was compared between males and females, full-thickness and fascia-only closure by independent t test, with P < .05 considered statistically significant. RESULTS: The POU region achieved lower loads to failure. Load to failure was greater in males compared with females. No difference was detected between full-thickness and fascia-only closure. Failure most commonly occurred by tearing of suture through tissues. Tissue failure with suture line loosening occurred mainly in the 5 × 5-mm SBSI group. CONCLUSION: The POU region is biomechanically weak and may therefore be predisposed to incisional herniation.

Successful treatment of refractory seizures with phenobarbital, propofol, and medetomidine following congenital portosystemic shunt ligation in a dog.

OBJECTIVE: To report a case of refractory seizures following congenital portosystemic shunt (CPSS) ligation that regained normal neurologic and hepatic function with novel treatment. Medical care included constant rate infusions (CRI) of propofol and medetomidine in conjunction with phenobarbital and supportive intensive care. CASE SUMMARY: A 2-year-old neutered male Bichon Frise was diagnosed with a single extrahepatic CPSS based on typical clinical signs, laboratory data, abdominal ultrasound, and computed tomographic angiography. Following initiation of standard medical treatment, a complete surgical ligation of the CPSS was performed. Recovery was uneventful until postligation neurologic dysfunction developed 54 hours after surgery. Seizures were controlled with phenobarbital (6 mg/kg IM q 12 h) and propofol CRI (0.3-0.6 mg/kg/min). Attempts to wean the dog from the propofol CRI resulted in recurrence of seizure activity until the addition of medetomidine CRI (0.016 µg/kg/min) 76 hours after initiation of drug-induced coma allowed gradual discontinuation of the propofol CRI. The dog regained full neurologic and hepatic function and had no further seizure activity apart from a small number of seizure episodes 5 and 22 months later. Adjustments in antiepileptic treatment resulted in no further neurologic dysfunction at 27-month follow-up. NEW OR UNIQUE INFORMATION PROVIDED: This report highlights the potential benefit of medetomidine CRI for treatment of postattenuation refractory seizures, which to date have proven impossible to predict and difficult to treat with high mortality rates and persistent neurological deficits in surviving animals. Neuroprotective, drug-sparing, and anti-hypertensive features of medetomidine might improve outcome in postligation refractory seizures. Further investigation and clinical application of medetomidine CRI may improve outcome in this complication of CPSS attenuation.

Mechanical comparison of loop and crimp configurations for extracapsular stabilization of the cranial cruciate ligament-deficient stifle.

OBJECTIVE: To biomechanically compare different loop and crimp configurations used for extracapsular suture stabilization of the CCL-deficient stifle. STUDY DESIGN: In vitro study. SAMPLE POPULATION: Crimped loop constructs of 100 lb Ande type nylon leader line in 7 different configurations comprising single and double loops, single and double crimps, and the interlocking loop configuration. METHODS: Constructs premade on external skeletal fixator bars 60 mm apart and tested in tension with a custom-made split circular arm mounted on a table-top materials testing machine. Data were derived from force/displacement plots. In "load to failure" test (10/group) constructs were loaded to failure with distraction rates of 10 mm/min; ultimate load, tension at 2 mm elongation and failure were recorded. In "staircase" test (5/group) constructs cycled at 100 N/s from 75 N with incremental increases of 50 N/cycle; ultimate load, maximum tension before elongation at rest over 2 mm and failure were recorded. In "cycling and jumping" test (10/group) 3 of 7 constructs cycled at 100 N/s 100 times from 50 to 100 N, then 5 times from 50 to 600 N; failure and elongation at cycles 1, 50 and 100 and at jumps 1 to 5 recorded. RESULTS: Double-loop double-crimp configurations were statistically superior to all other configurations in ultimate load, and to single-loop and interlocking loop configurations in elongation in "load to failure" and "staircase" tests. In "cycling and jumping" test the interlocking loop configuration specimens elongated significantly more than the others and only in the double-loop double-crimp group did all constructs complete the test. CONCLUSIONS: Double-loop double-crimp configurations are mechanically superior to other previously described configurations.

Ventral surgical approach to the lumbosacral joint in the dog.

OBJECTIVE: To describe a ventral surgical approach to the lumbosacral (LS) junction, access to L7 and S1, and access to the LS disc. STUDY DESIGN: Cadaveric descriptive study. ANIMALS: Canine cadavers (n = 6). METHODS: A ventral surgical approach to the LS junction was made and local anatomic structures documented. Accessible ventral L7 and S1 vertebral bodies and LS disc were marked with India ink. Total and marked surface areas were calculated. The potential for bicortical and unicortical implant placement was determined in transverse slices of L7 and S1. Exposed ventral disc annulus relative to vertebral canal diameters were measured. RESULTS: Portions of L7 and S1 were accessible in all dogs, but shape and dimensions varied. Ventral access for implant placement was available in both L7 and S1 in every dog. The median sacral artery and vein were in contact with the ventral LS disc annulus in every dog. Accessible ventral annulus were greater than vertebral canal in all dogs. CONCLUSIONS: Ventral approach to the LS junction is possible, with LS discectomy, and implant placement in L7 and S1 vertebral bodies possible from this approach. Injury to, or sacrifice of, the median sacral artery and/or vein may occur in this approach.

Association of intestinal disorders in cats with findings of abdominal radiography.

OBJECTIVE: To compare the radiographic appearance of small and large intestines of cats with various medical conditions and create a quantitative index for interpretation of intestinal diameters on radiographic views of the abdomen. DESIGN: Retrospective cohort study. ANIMALS: 74 cats that underwent abdominal radiography. PROCEDURES: Cats were assigned to 1 of 4 diagnosis categories: no gastrointestinal tract disease (n = 20), nonobstructive gastrointestinal tract disease (32), linear foreign body (LFB; 11), and small intestinal mechanical obstruction not caused by an LFB (11). Abdominal radiographs were evaluated without knowledge of history or diagnosis. Maximum and minimum external small intestine diameter (SID) and colon diameter (CD) were compared; dorsoventral and mediolateral measurements of the cranial end plate of L2 (VEL2) and L5 vertebrae were compared. Dorsoventral height of VEL2 from lateral radiographic views was used to determine maximum-SID:VEL2 and maximum-CD:VEL2 ratios. Gas patterns were evaluated. RESULTS: Nonobstructive gastrointestinal tract disease was more likely than obstruction until a maximum-SID:VEL2 ratio > 2.0. At a maximum-SID:VEL2 ratio of 2.5, probability of a disease not related to the intestinal tract was < 4%. At a maximum-SID:VEL2 ratio of 3.0, probability of a mechanical intestinal obstruction was > 70%. When the maximum-CD:VEL2 ratio was 2.0, probability of LFB was 50%; as the maximum-CD:VEL2 ratio increased beyond 2.0, likelihood of LFB decreased. Both gas pattern and CD correlated with diagnosis category. CONCLUSIONS AND CLINICAL RELEVANCE: Normalizing ratios of maximum-SID:VEL2 and maximum-CD:VEL2 obtained from measurements on lateral radiographic views of the abdomen in cats were related to diagnosis category.

Biomechanical evaluation of different numbers, sizes and placement configurations of ligaclips required to secure cellophane bands.

OBJECTIVE: To determine the number, size, and configuration of ligaclips most resistant to tensile forces when applied to cellophane bands. STUDY DESIGN: In vitro mechanical evaluation. SAMPLE POPULATION: Single-layer and triple-layer cellophane bands, 9.0 and 11.5 mm ligaclips. METHODS: Triple-layer bands were secured with a different number (2-5), size (9.0 or 11.5 mm) or configuration (linear or alternating placement) of ligaclips and mechanically tested. Force-deformation curves were generated and yield load in Newtons (N) was determined for each variable. A 3-way analysis of variance with post hoc Tukey's tests was used for statistical comparisons. Yield load for single-layer and triple-layer bands secured with 4 alternating 11.5 mm ligaclips was compared using a paired-sample (independent) t-test with P<.05 considered significant. RESULTS: Mean yield load increased as the number of ligaclips applied increased, but this effect began to plateau after application of the 4th clip. Mean yield load for 11.5 mm ligaclips was significantly higher than for 9.0 mm ligaclips (P<.001) and for the alternating configuration compared with the linear configuration (P<.001). Yield load for 4 alternating 11.5 mm ligaclips applied to triple-layer cellophane bands was significantly greater than the same configuration applied to single-layer cellophane bands (P<.001). CONCLUSION: 11.5 mm ligaclips applied in an alternating configuration and on triple-layer cellophane provided most resistance to tensile forces. The resistance to tensile forces increased significantly as the number of ligaclips applied increased from 1 to 4/band. CLINICAL RELEVANCE: Surgeons should be aware that the number, size, and configuration of ligaclips and cellophane thickness affect their resistance to tensile forces.

The effect of two modifications of unilateral arytenoid lateralization on rima glottidis area in dogs.

OBJECTIVES: To evaluate the clinical outcome and percentage increase in rima glottidis area achieved using a combined technique of cricoarytenoid and thyroarytenoid cartilage lateralization compared with cricoarytenoid cartilage lateralization alone in live anesthetized dogs clinically affected with bilateral laryngeal paralysis. STUDY DESIGN: Randomized prospective clinical study. ANIMALS: Twenty dogs with bilateral laryngeal paralysis. Methods-Bilateral laryngeal paralysis was diagnosed by direct laryngoscopy. Each dog was allocated randomly to 1 of 2 surgical groups: CAL (cricoarytenoid lateralization) and CTAL (cricoarytenoid and thyroarytenoid lateralization). Photographs were taken of each larynx before and after surgery, the images were digitized, and the preoperative and postoperative areas of each rima glottidis were measured. The percentage increase in rima glottidis area produced by each of the arytenoid lateralization procedures was compared. Follow-up was obtained by telephone survey of owners and referring veterinarians. RESULTS: There was no significant difference in mean (+/- SD) percentage increase in rima glottidis area for the CAL group (241.5 +/- 42.9%) or the CTAL group (236.4 +/- 44.5%). Clinical follow-up (median, 18 months postoperatively) indicated 60% of the dogs were still alive and only 1 dog had died as a result of complications related to surgery. CONCLUSIONS: CTAL for the treatment of canine laryngeal paralysis does not significantly increase rima glottidis area compared with CAL alone. The mean percentage increase in rima glottidis area obtained with both procedures was comparable to previously reported mean increases with CAL in live anesthetized dogs. Both procedures resulted in good long-term clinical outcome. CLINICAL RELEVANCE: CTAL is as effective as CAL in providing an increased rima glottidis for the treatment of bilateral laryngeal paralysis in dogs.