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Biomedical subjects

M D Willard

Publications and source records attributed to M D Willard.

At least 19 recordsLinked to original sources
PubMed1995

Third degree atrioventricular block and acquired myasthenia gravis in four dogs.

Third degree atrioventricular block was diagnosed in 4 dogs with acquired myasthenia gravis (serum acetylcholine receptor antibody titer > 0.6 nmol/L). All 4 dogs had megaesophagus. Two dogs also had mediastinal thymomas, which were resected. One dog with thymoma received a permanent pacemaker at the same time that it underwent thymectomy; the other did not develop third degree atrioventricular block until 3 months after thymectomy. Both dogs with thymoma died of severe aspiration pneumonitis within 3 months after surgery. The third dog received a permanent pacemaker and was treated with pyridostigmine bromide, but also died of aspiration pneumonitis 1 month after the pacemaker was implanted. The fourth dog was treated with prednisolone and pyridostigmine bromide and improved, but did not become clinically normal. Because third degree atrioventricular block as well as myasthenia gravis can cause signs of weakness, acquired myasthenia gravis should be considered in dogs with idiopathic cardiac conduction disturbances. Likewise, an ECG should be evaluated in dogs with acquired myasthenia gravis.

Animals↗
PubMed1995

Changes in the intestinal mucosal cell populations of German shepherd dogs fed diets containing different protein sources.

Sixteen German Shepherd Dogs from 4 litters were IgA-deficient on the basis of at least 1 of 2 serum IgA determinations, and all had small intestinal bacterial overgrowth, as documented by quantitated small intestinal bacterial culture in another study. These dogs were fed 2 diets that differed principally in their protein source (chicken vs beef, milk, and wheat). All dogs were fed each diet for 2 weeks before the study began. Next, all dogs were fed the chicken-based diet for 2 months. Then, half the dogs (group 1) were randomly assigned to continue eating the chicken-based diet, while the other half (group 2) ate a diet containing beef, milk, and wheat proteins. The small intestine was biopsied at the beginning of the study and after dogs had eaten the assigned diet for 2 and 4 months. At 2 months, group-2 dogs had more colonic mucosal mast cells, but this difference did not persist at 4 months. At the end of the study (ie, 4 months), although all dogs were clinically normal, group-2 dogs had significantly (P = 0.010) decreased numbers of jejunal villus plasma cells. However, these histologic changes were not considered clinically important. There were no significant differences in blood eosinophil counts, serum trypsin-like immunoreactivity, or cobalamin, folate, or IgA concentration. Clinical differences were not detected between the 2 groups, before or after the study. Changes were seen in serum IgM and IgG concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Characterization of naturally developing small intestinal bacterial overgrowth in 16 German shepherd dogs.

Sixteen German Shepherd Dogs were found, via quantitative microbial culture of intestinal fluid samples, to have small intestinal bacterial overgrowth (IBO) over an 11-month period. All dogs were deficient in serum IgA. Consistent clinical signs suggestive of an alimentary tract disorder were not observed. Serum cobalamin determinations were not helpful in detecting IBO. Serum folate concentrations had variable sensitivity and specificity for detecting dogs from which we could culture > or = 1 x 10(5) bacterial/ml from intestinal fluid samples in the nonfed state. Histologic and intestinal mucosal cytologic examinations were not useful in detecting IBO. Substantial within-dog and between-dog variation was found in the numbers and species of bacteria in the intestines. The difficulty in diagnosing IBO, the variability in organisms found in individual dogs on repeated sampling, the likelihood that intestinal fluid microbial cultures failed to diagnose IBO in some dogs, and the potential of IBO to be clinically inapparent were the most important findings in this study.

Animals↗
PubMed1994

Comparison of species and numbers of bacteria in concurrently cultured samples of proximal small intestinal fluid and endoscopically obtained duodenal mucosa in dogs with intestinal bacterial overgrowth.

Concurrent bacterial culturing of duodenal/proximal jejunal fluid and duodenal mucosa was performed on 2 occasions in each of 16 IgA-deficient German Shepherd Dogs with small intestinal bacterial overgrowth. The interval between sample collections in each dog was 74 to 78 days. Species of bacteria and numbers of bacterial colony-forming units (CFU) per milliliter of fluid were compared with species and numbers found in the concurrent duodenal mucosa sample. There was inconsistent correlation for number of CFU and minimal correlation for species of bacteria isolated from the 2 sites. Fewer bacterial CFU usually were isolated from the mucosa than from the concurrent fluid sample. When the same numeric criteria used for diagnosing small intestinal bacterial overgrowth in samples of intestinal fluid (ie, > or = 10(5) bacterial or > or = 10(4) anaerobic CFU/ml) were used to interpret results of culturing duodenal mucosa, quantitations of bacterial CFU in duodenal mucosa was found to be a specific, but insensitive test.

Animals↗
PubMed1994

Effects of dietary supplementation of fructo-oligosaccharides on small intestinal bacterial overgrowth in dogs.

Sixteen IgA-deficient German Shepherd Dogs with small intestinal bacterial overgrowth were randomized into 2 groups. One group was fed a chicken-based kibble diet; the other was fed the same diet, but with 1% fructo-oligosaccharides supplemented at the expense of cornstarch. After being exposed to the diets for 46 to 51 days, the group that ate the supplemented diet had significantly (P = 0.04) fewer aerobic/facultative anaerobic bacterial colony-forming units in fluid from the duodenum/proximal part of the jejunum, as well as in the duodenal mucosa. We could not detect significant differences in the species of bacteria found in the intestine of these 2 groups of dogs. We conclude that at least some dietary carbohydrates can affect small intestinal bacterial populations in dogs with small intestinal bacterial overgrowth.

Animal Feed↗
PubMed1993

Left aortic arch and right ligamentum arteriosum causing esophageal obstruction in a dog.

A 10-week-old, mixed-breed dog was examined because of persistent regurgitation. Results of thoracic radiography and fluoroscopy of the esophagus, using a liquid suspension of barium sulfate, were suggestive of a vascular ring anomaly. During left lateral thoracotomy, a left aortic arch was identified, but the cause of the esophageal obstruction could not be determined. Results of endoscopic examination of the esophagus suggested a compressive lesion originating from the right side of the esophagus. An anomalous artery could not be identified on an aortogram. Post-mortem examination revealed a left aortic arch and right ligamentum arteriosum that were causing the esophageal obstruction.

Animals↗
PubMed1992

Chronic diarrhea associated with intestinal anomalies in a six-year-old dog.

A 6-year-old mixed-breed dog was referred because of chronic diarrhea, which had begun after antibiotic treatment for pulmonary disease. Intestinal bacterial overgrowth was presumptively diagnosed on the basis of intestinal mucosal cytologic examination and low serum cobalamin concentration. When the diarrhea did not respond to treatment, contrast radiography was performed and a short small intestine was found. The diarrhea could not be managed by medical treatment, and the dog was euthanatized. Necropsy revealed 2 blind intestinal pouches attached to a 46-cm length of small intestine connecting the stomach and colon. The dog's deteriorating condition was attributable to necrosis and rupture of 1 of the pouches.

Animals↗
PubMed1991

Toxoplasmosis in two cats with inflammatory intestinal disease.

Lymphocytic-plasmacytic enteritis, a chronic inflammatory intestinal disease, was diagnosed in 2 cats. In 1 cat, recurrence of clinical signs after initiating treatment was attributed to relapse of the inflammatory intestinal disease, but was found to be attributable to relapsing toxoplasmosis secondary to immunosuppressive drug therapy. Treatment with clindamycin resolved the recurrent toxoplasmosis. In the second cat, clinical signs of toxoplasmosis did not develop, but serologic testing yielded evidence of active toxoplasmosis. Treatment with clindamycin caused the titers to decrease. Relapsing toxoplasmosis may be responsible for apparent resistance to treatment in cats for inflammatory intestinal disease being treated with immunosuppressive drugs.

Animals↗
PubMed1991

Hyponatremia and hyperkalemia associated with idiopathic or experimentally induced chylothorax in four dogs.

Two dogs with idiopathic chylothorax and 2 dogs with experimentally induced (ie, ligation of the cranial vena cava) chylothorax were treated by intermittent thoracic drainage. Of these 4 dogs, 3 that did not have evidence of renal failure had normal or near-normal serum sodium and potassium concentrations before thoracic drainage began, and all 3 developed repeatedly marked hyponatremia and hyperkalemia during thoracic drainage. Another dog became weak and depressed, ostensibly because of hyperkalemia. Serum sodium and potassium concentrations in 1 dog with spontaneous chylothorax returned to normal after chylothorax resolved and thoracic drainage was stopped. The other 3 dogs died or were euthanatized, and the effect of stopping thoracic drainage could not be evaluated. In 3 dogs in which it was measured, normal-to-high plasma cortisol concentration was observed before and after adrenocorticotropin administration, and 2 dogs also had hyperaldosteronemia. Hyponatremia was hypothesized to be caused by sodium loss via thoracic drainage whereas hyperkalemia may have been multifactorial in origin, but probably was attributable, at least, in part to decreased renal potassium clearance.

Animals↗
PubMed1991

Panfibrinonecrotic colitis in a dog treated by subtotal colectomy.

A dog with signs of small intestinal disease developed signs of severe large intestinal disease after being treated with multiple agents. Endoscopy and biopsy revealed total destruction of the colonic mucosa, which necessitated total parenteral nutrition plus subtotal colectomy. It was hypothesized that the multiple prior treatments led to an overgrowth of toxigenic or cytotoxic bacteria, which caused this colonic mucosal destruction.

Animals↗
PubMed1991

Obesity: types and treatments.

Causes of obesity include a low resting metabolic rate, environmental factors, family behavior patterns, a poorly developed satiety response and reactive eating due to stress or anxiety. Morbid obesity is characterized by an increased number of adipocytes and a degree of irreversibility. Overeating increases the size of adipocytes; however, once adipocytes achieve their maximal size, proliferation is induced and massive, irreversible obesity may result. A syndrome of restrained eating produced by chronic dieting leads to hunger, frustration and rebound overeating. Treatment may be unsuccessful because of the failure to address specific causes of obesity in individual patients and the use of reducing regimens that are not designed to maintain weight loss. Recognition of the diverse clinical forms of obesity and their different etiologies permits treatment regimens to be more specific, increasing the likelihood of success. Even with this approach, treatment failure is common.

Adipose Tissue↗
PubMed1989

Obstructed portal venous flow and portal vein thrombus in a dog.

A young adult Doberman Pinscher had clinical signs and laboratory data consistent with the copper-associated hepatopathy commonly found in Doberman Pinschers. Hepatic biopsy and hepatic copper analysis did not support this diagnosis. Furthermore, changes seen in the hepatic biopsy specimen did not explain the acquired portosystemic shunting or the portal hypertension that the dog had. A mesentery venoportagram revealed markedly delayed filling of one portal vein, and necropsy revealed a small thrombus partially occluding that hepatic vein. It was not determined whether obstructed portal venous flow caused the portal vein thrombus or vice versa; however, it was theorized that the portal vein thrombus, once formed, contributed to further portal hypertension and/or delayed portal vein filling.

Animals↗
PubMed1989

Disorders of potassium homeostasis.

Hypokalemia and hyperkalemia are common problems that may be artifactual, iatrogenic, or due to altered body homeostatic mechanisms. ECG may help one to recognize hyperkalemia but not hypokalemia. Excessive K supplementation is a common iatrogenic cause of hyperkalemia whereas fluid therapy is a common cause of iatrogenic hypokalemia. The most common causes of spontaneous hyperkalemia are renal failure and hypoadrenocorticism whereas the most common causes of spontaneous hypokalemia are vomiting, diarrhea, and renal wasting. Symptomatic therapy is usually done until the underlying cause(s) is resolved.

Animals↗
PubMed1988

Diarrhea associated with myenteric ganglionitis in a dog.

Diarrhea in a Border Terrier was associated with inflammatory lesions of the myenteric plexus. This lesion has been documented rarely in dogs. It is speculated that the myenteric plexus lesions were responsible for an autonomic nervous system dysfunction, which resulted in extreme intestinal hypermotility and subsequent diarrhea. Suggested tests for dogs suspected to have autonomic dysfunction are given.

Animals↗