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Abstract

Objective

To determine the effects of cisapride on feline colonic smooth muscle function.

Design

In vitro smooth muscle mechanical measurements.

Animals

Intact colon was obtained from healthy 2- or 3-year-old cats.

Procedure

Longitudinal smooth muscle strips from proximal and distal portions of feline colon were suspended in physiologic buffer solution (37 C, 100% O2, pH 7.4), attached to isometric force transducers, and stretched to optimal muscle length. Control responses were obtained at each muscle site with acetylcholine (10−8 to 10−4 M), cholecystokinin (10−11 to 10−7 M), substance P (10−11 to 10−7 M), or neurotensin (10−11 to 10−7 M). Muscles were then stimulated with cumulative (10−9 to 10−6 M) or bolus (10−6 M) doses of cisapride in the absence or presence of tetrodotoxin (10−6 M) and atropine (10−6 M), nifedipine (10−6 M), or calcium-free buffer solution.

Results

Cisapride stimulated contractions of longitudinal smooth muscle from proximal and distal portions of feline colon that were similar in magnitude to contractions induced by substance P and neurotensin. Cisapride contractions were only partially inhibited by tetrodotoxin (10−6 M) and atropine (10−6 M). suggesting that cisapride responses are only partially dependent on enteric cholinergic nerves. Nifedipine (10−6 M) inhibited the maximal contraction to cisapride (10−6 M) by approximately 80%. Removal of extracellular calcium did not inhibit cisapride contractions to a greater extent than did inhibition by nifedipine, indicating that calcium influx through voltage dependent calcium channels was predominantly responsible for the dependence of the cisapride contraction on extracellular calcium.

Conclusions

Cisapride-induced contractions of feline colonic smooth muscle are largely smooth muscle-mediated and dependent on calcium influx, and are only partially dependent on enteric cholinergic nerves.

Clinical Relevance

Cisapride may be useful in the treatment of feline colonic motility disorders. (Am J Vet Res 1996;57:541–546)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine whether colonic smooth muscle dysfunction is involved in the pathogenesis of idiopathic megacolon in cats.

Design

In vitro smooth muscle mechanical measurements.

Animals

Colon from healthy cats and cats with idiopathic megacolon.

Procedure

Colonic smooth muscle strips were suspended in physiologic buffer solution, attached to isometric force transducers, and contracted with acetylcholine (ACh; 10−9 to 10−4 M), substance P (SP; 10−10 to W−6 M), cholecystokinin (CCK; 10−11 to 10−6 M), potassium chloride (KCI; 10 to 80 mM), or electrical field stimulation (EFS; 25 V, 1 to 30 Hz, 0.5-millisecond duration). Isometric stress responses were compared with those obtained from healthy controls. Colonic smooth muscle strips were also evaluated histologically for neuronal and smooth muscle cell morphology.

Results

Passive isometric stress was not altered, but the active isometric stress responses of megacolon smooth muscle to ACh, SP, CCK, KCI, and EFS were significantly (P < 0.05) diminished, compared with healthy controls. Differences were observed in longitudinal and circular smooth muscle from proximal and distal portions of the colon. Histologic evaluation revealed few abnormalities of smooth muscle cells or of myenteric or submucosal plexus neurons. The contractile response of megacolon smooth muscle to EFS, and the inhibition of this response by tetrodotoxin, suggest that myenteric and submucosal plexus neurons in megacolon smooth muscle are functional.

Conclusions

Idiopathic megacolon is a generalized dysfunction of colonic smooth muscle in cats. The diminished isometric stress responses to receptor occupancy (ACh, SP, and CCK) and membrane depolarization (KCI) further suggest that the disorder involves disturbance in the activation of smooth muscle myofilaments. (Am J Vet Res 1996;57:580-587)

Free access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association

Summary

Two hundred ninety-five case records were included in an analysis of dogs treated by a standardized protocol for gastric dilatation/volvulus syndrome between 1986 and 1992. A breed predisposition was demonstrated for Great Danes, German Shepherd Dogs, large mixed-breed dogs, and Standard Poodles. One hundred and ninety-three dogs had gastric dilatation and volvulus (gdv) confirmed at surgery, 66 had simple gastric dilatation (gd), and 36 others had gastric dilatation but volvulus could not be proved or disproved (gd ± v). Among dogs with gdv, the fatality rate was 15% (29/193). Twenty-six (13.5%) dogs with gdv underwent partial gastrectomy, and 8 (31%) died or were subsequently euthanatized. In comparing the group of dogs with gdv that survived to those that died, there were no statistical differences in the age of dog, time between onset of clinical signs and admission, time from admission to surgery, or duration of anesthesia. Cardiac arrhythmias were detected in 40% (78/193) of the dogs with gdv. There also was no statistical correlation between development of a cardiac arrhythmia and outcome in dogs with gdv. The causes of death in dogs with gdv were multiple and varied; presumed gastric necrosis was a common reason for intraoperative euthanasia (11 dogs). Among dogs with gd or gd ± v, the fatality rate was 0.9% (1/102).

Free access
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)

Full access
in American Journal of Veterinary Research

Summary

Granulomatous hepatitis (gh) is an uncommon histopathologic diagnosis in dogs. On the basis of clinical reports, fungal infections appear to be the most common cause of gh in dogs, but many other potential causes have been identified. The medical records and histopathologic findings for 9 dogs with gh were reviewed to identify additional specific causes of gh in dogs. Diseases associated with gh included intestinal lymphangiectasia (n = 2), lymphosarcoma (n = 1), histiocytosis (n = 1), dirofilariasis(n = 1), and histoplasmosis (n = 1). In 1 dog, no other disease process was identified. Of the remaining 2 dogs, 1 had concurrent granulomatous pneumonitis of unknown cause, and the other had periportal hepatitis and temporal muscle wasting. All 9 dogs with gh had clinical evidence of liver disease, such as hepatomegaly, icterus, and ascites, or had high serum alkaline phosphatase and alanine aminotransferase activity. Because of the wide variety of potential causes of gh in dogs, an accurate diagnosis should be sought so that appropriate treatment can be chosen and an accurate prognosis given.

Free access
in Journal of the American Veterinary Medical Association

Objectives—

To determine typical clinical signs and clin-icopathologic findings in dogs with hepatic abscesses, to assess outcome of treatment, and to evaluate the role that abdominal ultrasonography has in the diagnosis of hepatic abscesses in dogs and in monitoring response to treatment.

Design—

Retrospective case series.

Animals—

14 dogs with hepatic abscesses.

Results—

Anorexia and lethargy were the most common historical complaints, followed by vomiting and diarrhea. Physical abnormalities included fever, dehydration, signs of abdominal pain, hepatomegaly, and mucosal bleeding. Hematologic abnormalities included leukocytosis with neutrophilia, mild to moderate thrombocytopenia, and mild anemia. Serum biochemical abnormalities included high alkaline phosphatase and alanine aminotransferase activities and high bilirubin concentration; hypoalbuminemia and prolonged coagulation values were also reported. Abdominal radiography revealed hepatomegaly, poor abdominal detail, a hepatic mass, or splenomegaly in 9 dogs. Thoracic radiography revealed alveolar consolidation or mixed bronchial/interstitial pulmonary patterns in 6 dogs. Hypoechoic, heteroechoic, or hyperechoic masses were identified in all dogs in which ultrasonography was performed. Escherichia coli, Clostridium sp, Klebsiella pneumoniae, Enterococcus sp, Staphylococcus epidermidis, and S intermedius were the most common bacteria isolated from hepatic abscesses. Concurrent infections were identified in the biliary tract, spleen, blood, endocardium, lung, prostate gland, peritoneum, lymph nodes, salivary gland, or brain of several dogs.

Seven dogs died or were euthanatized before definitive treatment could be initiated. One dog was successfully treated with antibiotics and was alive 12 months after medical treatment. Six dogs were treated surgically (ie, full or partial liver lobectomy, drainage, abdominal lavage) and medically (ie, antibiotic administration). Five of these dogs survived and were alive 12 months after surgery. Ultrasonography was used to monitor response to treatment in several dogs.

Clinical Implications—

Hepatic abscesses are rare in dogs, but the clinical signs and clinicopathologic findings are similar to other inflammatory hepatic diseases. Ultrasonography revealed abnormalities in all animals in which imaging studies were performed, and was successfully used to monitor response to treatment in several dogs. Medical and surgical treatments were used successfully to treat hepatic abscesses in dogs. (J Am Vet Med Assoc 1996;208:243-247)

Free access
in Journal of the American Veterinary Medical Association

Objective

To identify risk factors associated with acquired megaesophagus in dogs.

Design

Case-control study.

Animals

136 dogs with acquired megaesophagus (case dogs); 272 dogs from the general hospital population and 151 dogs that underwent thyroid-stimulating hormone response tests (control dogs). All dogs were more than 6 months old.

Procedure

Medical records of dogs in which megaesophagus was diagnosed during a 10-year period were reviewed. Inclusion criteria included regurgitation or vomiting, onset of clinical signs at more than 6 months of age, and radiographic evidence of generalized esophageal dilatation. Dogs with intra- or extraesophageal obstructive disease, brain stem disease, or neck trauma were excluded from analyses. Statistical analyses included odds ratios, 95% confidence intervals, and two-tailed t-tests. Control dogs were frequency matched to case dogs on the basis of year of diagnosis.

Results

Dogs with megaesophagus ranged from 0.75 to 18 years old (mean, 8.1 years) and were significantly older and heavier than control dogs. More males than females were affected, but sex and reproductive status were not associated with megaesophagus. German Shepherd Dogs, Golden Retrievers, and Irish Setters were at increased risk for developing megaesophagus. Peripheral neuropathies, laryngeal paralysis, acquired myasthenia gravis, esophagitis, and chronic or recurrent gastric dilatation with or without volvulus were associated with an increased risk of developing megaesophagus. Hypothyroidism was not associated with megaesophagus.

Clinical Implications

Dogs with acquired megaesophagus should be evaluated for peripheral neuropathies, laryngeal paralysis, acquired myasthenia gravis, esophagitis, and chronic or recurrent gastric dilatation with or without volvulus. These dogs may be evaluated for hypothyroidism; however, this study did not reveal a clear association between hypothyroidism and acquired megaesophagus. (J Am Vet Med Assoc 1997;211:1406–1412)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the incidence and prognostic significance of low plasma ionized calcium concentration in cats with clinical signs of acute pancreatitis (AP).

Design—Retrospective study.

Animals—46 cats with AP and 92 control cats with nonpancreatic diseases.

Procedure—Medical records were reviewed, and results of clinicopathologic testing, including plasma ionized and total calcium concentrations, acid-base values, and electrolyte concentrations, were recorded. Cats with AP were grouped on the basis of outcome (survived vs died or were euthanatized), and plasma ionized calcium concentrations, acid-base values, and electrolyte concentrations were compared between groups.

Results—Serum total calcium concentration was low in 19 (41%) cats with AP, and plasma ionized calcium concentration was low in 28 (61%). Cats with AP had a significantly lower median plasma ionized calcium concentration (1.07 mmol/L) than did control cats (1.12 mmol/L). Nineteen (41%) cats with AP died or were euthanatized; these cats had a significantly lower median plasma ionized calcium concentration (1.00 mmol/L) than did cats that survived (1.12 mmol/L). Ten of the 13 cats with AP that had plasma ionized calcium concentrations ≤ 1.00 mmol/L died or were euthanatized.

Conclusions and Clinical Relevance—Results suggest that low plasma ionized calcium concentration is common in cats with AP and is associated with a poorer outcome. A grave prognosis and aggressive medical treatment are warranted for cats with AP that have a plasma ionized calcium concentration ≤ 1.00 mmol/L. (J Am Vet Med Assoc 2001;219:1105–1109)

Full access
in Journal of the American Veterinary Medical Association

Objective

To characterize imaging findings in cats with confirmed inflammatory bowel disease (IBD) of the upper gastrointestinal tract (ie, stomach and small intestine) and relate these findings to clinical signs and histologic changes.

Design

Retrospective study.

Animals

33 cats with clinical and histopathologic diagnoses of IBD.

Procedure

Medical records were reviewed for signalment, clinical signs, clinicopathologic findings, radiographic and ultrasonographic findings, and results of endoscopic examination. Histologic findings were reviewed and characterized by severity and type of inflammatory infiltrate.

Results

All cats had 1 or more clinical signs (eg, vomiting, diarrhea, weight loss, and anorexia) consistent with IBD. Lymphocytic and plasmacytic infiltrates were observed in histologic sections of gastrointestinal tissue. Crypt distortion, villous blunting and fusion, and fibrosis were most commonly seen in cats with moderate or severe IBD. Clinicopathologic findings of some cats included anemia, leukocytosis or leukopenia, hypocholesterolemia, and hyper- or hypoproteinemia. Abnormalities were not found on abdominal radiographic views in 9 of 9 cats. However, contrast studies using barium revealed radiographic abnormalities in 1 of 3 cats. In 13 of 17 cats, abdominal ultrasonography revealed several intestinal abnormalities (eg, poor intestinal wall layer definition, focal thickening) and large mesenteric lymph nodes with hypoechoic changes consistent with IBD. Endoscopic observation revealed findings (eg, erythema, plaques, mucosal friability) consistent with inflammation in 9 of 18 cats.

Conclusions and Clinical Relevance

Compared with endoscopy of the gastrointestinal tract or abdominal radiography, clinical signs and ultrasonographic findings appear to have the best association with histologic grade of IBD in cats. (J Am Vet Med Assoc 1999;215:349–354)

Free access
in Journal of the American Veterinary Medical Association