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  • Author or Editor: Daniel J. Brockman x
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in Journal of the American Veterinary Medical Association

Abstract

Objectives—To determine the role of myosin light chain phosphorylation in feline colonic smooth muscle contraction.

Sample Population—Colonic tissue was obtained from eight 12- to 24-month-old cats.

Procedure—Colonic longitudinal smooth muscle strips were attached to isometric force transducers for measurements of isometric stress. Myosin light chain phosphorylation was determined by isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Stress and phosphorylation were determined following stimulation with ACh or SP, in the absence or presence of a calmodulin antagonist (W-7; 0.1 to 1.0 mM), myosin light chain kinase inhibitor (ML-9; 1 to 10 µM), or extracellular calcium - free solutions.

Results—Unstimulated longitudinal colonic smooth muscle contained low amounts (6.9 ± 3.2%) of phosphorylated myosin light chain. Phosphorylation of the myosin light chains was dose and time dependent with maximal values of 58.5% at 30 seconds of stimulation with 100 µM Ach and 60.2% at 45 seconds of stimulation with 100 nM SP. Active isometric stress development closely paralleled phosphorylation of the myosin light chains in ACh- or SP-stimulated muscle. W-7 and ML-9 dose dependently inhibited myosin light chain phosphorylation and isometric stress development associated with ACh or SP stimulation. Removal of extracellular calcium inhibited myosin light chain phosphorylation and isometric stress development in ACh-stimulated smooth muscle.

Conclusions and Clinical Relevance—Feline longitudinal colonic smooth muscle contraction is calcium-, calmodulin-, and myosin light chain kinasedependent. Myosin light chain phosphorylation is necessary for the initiation of contraction in feline longitudinal colonic smooth muscle. These findings may prove useful in determining the biochemical and molecular defects that accompany feline colonic motility disorders. (Am J Vet Res 2002;63:695–702)

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in American Journal of Veterinary Research

Abstract

Objective—To identify breed disposition, postoperative complications, and outcome in dogs with lung lobe torsion.

Design—Retrospective study.

Animals—22 client-owned dogs.

Procedure—Information on signalment; history; clinical findings; results of clinicopathologic testing, diagnostic imaging, and pleural fluid analysis; surgical treatment; intra- and postoperative complications; histologic findings; and outcome were obtained from medical records.

Results—All 22 dogs had pleural effusion; dyspnea was the most common reason for examination. Fifteen dogs were large deep-chested breeds; 5 were toy breeds. Afghan Hounds were overrepresented, compared with the hospital population. One dog was euthanatized without treatment; the remaining dogs underwent exploratory thoracotomy and lung lobectomy. Eleven dogs recovered from surgery without complications, but 3 of these later died of thoracic disease. Four dogs survived to discharge but had clinically important complications within 2 months, including chylothorax, mediastinal mesothelioma, gastric dilatation, and a second lung lobe torsion. Six dogs died or were euthanatized within 2 weeks after surgery because of acute respiratory distress syndrome, pneumonia, septic shock, pneumothorax, or chylothorax. Chylothorax was diagnosed in 8 of the 22 dogs, including 4 Afghan Hounds.

Conclusion and Clinical Relevance—Results suggest that lung lobe torsion is rare in dogs and develops most frequently in large deep-chested dogs, particularly Afghan Hounds. Other predisposing causes were not identified, but an association with chylothorax was evident, especially in Afghan Hounds. Prognosis for dogs with lung lobe torsion was fair to guarded. (J Am Vet Med Assoc 2000;217:1041–1044)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether hepatic portal vascularity assessed via intraoperative mesenteric portovenography (IMP) is related to outcome in cats undergoing surgical attenuation of a congenital portosystemic shunt (CPSS).

Design—Retrospective case series.

Animals—25 cats, each with 1 CPSS, in which IMP was performed before and after temporary complete occlusion of the shunting vessel to provide complete (n = 9) or partial (16) shunt attenuation.

Procedures—Medical records were reviewed for signalment, clinical history, postoperative complications, clinical outcome, and results of bile acids stimulation testing. Portovenograms obtained before and after shunt occlusion were graded to determine whether degree of intrahepatic portal branching was correlated with degree of shunt attenuation, clinical or biochemical factors, postoperative complications, or outcome. In 12 of the 16 cats that had partial CPSS attenuation, procedures were later repeated to achieve complete (n = 9) and additional partial (1) CPSS attenuation.

Results—Degree of opacification of the intrahepatic portal vessels increased significantly (higher portovenogram grade) after CPSS attenuation. The median portovenogram grade assigned after temporary shunt occlusion at the first surgery was significantly higher in cats that did not have postattenuation neurologic complications or neurologic signs at follow-up than in cats that did. It was also higher in cats that had a better clinical response to surgery versus those that had a poor response and in cats with reduced preprandial and postprandial serum bile acids concentrations at follow-up versus those that did not.

Conclusions and Clinical Relevance—IMP may be used to help predict complications and outcome following surgical treatment of CPSS in cats.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To describe a modified Blalock-Taussig shunt (mBT) procedure and assess its use in dogs with clinical signs associated with tetralogy of Fallot (TOF).

Design—Descriptive report.

Animals—6 dogs with severe TOF-associated clinical signs.

Procedures—Each dog had TOF (confirmed echocardiographically or angiographically) and underwent an mBT shunt procedure for surgical palliation of signs. The surgery was performed through a left fourth rib resection or a left fifth intercostal thoracotomy. The left subclavian artery was dissected free from surrounding mediastinal tissue. The main pulmonary artery trunk was exposed through an incision in the overlying pericardium. A shunt comprised of a 6-mm-diameter tube of expanded polytetrafluoroethylene (5 dogs) or a segment of carotid artery (1 dog) was sutured end to side between the left subclavian artery and pulmonary artery trunk.

Results—5 of the 6 dogs survived the immediate postoperative period. The dog that died shortly after surgery was the smallest of the dogs (weight, 2.9 kg [6.38 lb]) and had received the carotid artery autograft. Three dogs survived long term and 2 dogs died of unknown causes 6 years after undergoing the mBT shunt procedure. In all dogs that survived the mBT procedure, shunt patency was confirmed and quality of life appeared improved.

Conclusions and Clinical Relevance—These findings have suggested that the mBT shunt procedure safely provides long-term palliation of TOF-associated clinical signs in dogs. In addition, it may offer an effective low-risk and lower-cost alternative to open heart repair of TOF.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare results of surgical versus nonsurgical treatment of spontaneous pneumothorax in dogs.

Design—Retrospective study.

Animals—64 dogs with pneumothorax without any history of antecedent trauma.

Procedure—Information on signalment, thoracic radiographic findings, treatment, histologic findings, and outcome was obtained from the medical records. Signalment of affected dogs was compared with signalment of a control population of 260 dogs examined by the emergency service for reasons other than pneumothorax during the study period.

Results—Siberian Huskies were overrepresented in the case population, compared with the control population of dogs examined by the emergency service for other reasons. Twenty-eight dogs were treated without surgery (ie, thoracocentesis or tube thoracostomy with or without cage rest), and 36 were treated with surgery. Information regarding final outcome was available for 33 dogs treated with surgery (median followup time, 485 days) and 15 dogs treated without surgery (median follow-up time, 366 days). Dogs that underwent surgery had significantly lower recurrence (1/30) and mortality (4/33) rates, compared with dogs treated without surgery (6/12 and 8/15, respectively). A definitive diagnosis was obtained for 38 dogs, including 34 of 36 dogs undergoing surgery; 26 had bullous emphysema and 4 had neoplasia. Two dogs developed spontaneous pneumothorax secondary to migration of plant foreign bodies.

Conclusions and Clinical Relevance—Results suggest that recurrence and mortality rates for dogs with spontaneous pneumothorax managed surgically were significantly lower than rates for dogs managed by nonsurgical means alone. Early surgical intervention is recommended for definitive diagnosis and treatment of dogs with spontaneous pneumothorax. (J Am Vet Med Assoc 2002;220:1670–1674)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine survival times of and prognostic indicators for dogs with heart base masses.

Design—Retrospective study.

Animals—25 dogs.

Procedure—Medical records were reviewed to obtain information regarding signalment; initial complaint; results of physical examination, radiography, electrocardiography, and echocardiography; surgical findings; medical and surgical treatment; outcome; necropsy findings; survival time; and cause of death.

Results—Survival time ranged from 0 to 1,096 days (mean, 213 days; median, 57 days). None of the variables examined, including initial complaints and results of physical examination, radiography, electrocardiography, and echocardiography, were associated with survival time. However, dogs that underwent pericardectomy had a significantly longer mean survival time (mean ± SD, 661 ± 170 days) than did dogs that were treated medically (129 ± 51 days).

Conclusions and Clinical Relevance—Results suggest that dogs with heart base masses that undergo pericardectomy may survive longer than those that receive medical treatment alone. (J Am Vet Med Assoc 2001;219:485–487)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine outcome associated with intramural ureteral ectopia treated with 1 of 2 surgical techniques (neoureterostomy with ligation of the distal ureteral segment vs neoureterostomy with resection of the distal ureteral segment) and compare results of these 2 techniques in dogs.

Design—Multicenter retrospective case series.

Animals—36 dogs (15 treated with the ligation technique and 21 treated with the resection technique).

Procedures—Information was obtained from medical records. Long-term follow-up information was obtained by owner questionnaire.

Results—15 of 21 (71%) dogs in the resection group and 7 of 14 (50%) dogs in the ligation group still had urinary incontinence after surgery. Three of 20 (15%) dogs in the resection group and 4 of 14 (29%) dogs in the ligation group reportedly had multiple episodes of urinary tract infection following surgery. The outcome of surgery was judged to be excellent by the owners of 10 of 18 (56%) dogs in the resection group and 9 of 14 (64%) dogs in the ligation group. No significant differences were found between surgery treatment groups.

Conclusions and Clinical Relevance—Results of the present study suggest that although most owners of dogs that undergo surgery for treatment of intramural ureteral ectopia consider the outcome of surgery to be excellent, substantial proportions of dogs will continue to have urinary incontinence and recurrent urinary tract infections after surgery. Findings do not provide any support to the hypothesis that the resection technique is superior to the ligation technique for management of dogs with intramural ureteral ectopia.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether hepatic portal vascularity, as assessed by intraoperative mesenteric portovenography (IMP), is related to outcome in dogs undergoing attenuation of single congenital portosystemic shunts (CPSSs).

Design—Retrospective case series.

Animals—45 dogs, each with a single CPSS, in which IMP was performed before and after temporary complete occlusion of the shunting vessel and that underwent complete (17 dogs) or partial (28 dogs) CPSS attenuation (surgery 1).

Procedures—Medical records were reviewed for signalment, clinical history, and bile acids stimulation test results. Intrahepatic portal vessel (IPV) opacification in pre- and postocclusion portovenograms was graded to determine whether the degree of opacification was correlated with the degree of shunt attenuation, clinical or biochemical factors, or long-term clinical outcome. In 17 of 28 dogs that had partial CPSS attenuation, these procedures were subsequently repeated (surgery 2) to achieve complete (14 dogs) or further partial (3 dogs) CPSS attenuation.

Results—Compared with preattenuation findings, IPV opacification increased significantly after partial or complete CPSS attenuation. The degree of IPV opacification before and after CPSS occlusion (surgery 1) was greater in dogs that tolerated complete versus partial CPSS attenuation and was correlated positively with age. The degree of IPV opacification following CPSS occlusion (surgery 1) was maximal in all dogs without encephalopathy and was correlated negatively with follow-up preprandial serum bile acids concentrations and positively with clinical improvement.

Conclusions and Clinical Relevance—Data suggest that IMP can be used to assess changes in IPV blood flow and help predict outcome following attenuation of single CPSSs in dogs.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To review hepatic histopathologic lesions in dogs undergoing surgical attenuation of a congenital portosystemic shunt (CPSS) in relation to clinical findings and tolerance of complete surgical attenuation.

Design—Retrospective case series.

Animals—38 dogs that underwent surgical attenuation of a CPSS.

Procedures—Hepatic histologic examination findings and medical records of dogs undergoing surgical attenuation of a single CPSS between August 2000 and July 2004 were reviewed. Liver biopsy specimens were obtained from 38 dogs during surgery prior to complete (n = 16) or partial (22) attenuation of a CPSS and from 13 of the same dogs a median of 3 months following surgical attenuation.

Results—Portal tracts were inadequate for interpretation in 2 liver biopsy specimens. Liver biopsy specimens obtained prior to surgical attenuation of a CPSS had a lack of identifiable portal veins (13/36 dogs), hepatic arteriolar proliferation (25/36), ductular reaction (5/36), steatosis (16/38), and iron accumulation (32/38). Lack of identifiable portal veins on histologic examination was associated with increased hepatic arteriolar proliferation, decreased tolerance to complete surgical CPSS attenuation, and decreased opacification of intrahepatic portal vessels on portovenography. Ductular reaction was always associated with failure to tolerate complete surgical attenuation of a CPSS. Surgical CPSS attenuation resulted in significant clinical, serum biochemical, and portovenographic changes indicative of improved liver function, but only subtle changes in hepatic histologic examination findings.

Conclusions and Clinical Relevance—Dogs without identifiable intrahepatic portal veins that had a ductular reaction on hepatic histologic examination were less likely to tolerate complete attenuation of a CPSS.

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in Journal of the American Veterinary Medical Association