Magnesium Oxide Induced Metabolic Alkalosis in Cattle

A study was designed to compare the metabolic alkalosis produced in cattle from the use of an antacid (magnesium oxide) and a saline cathartic (magnesium sulphate). Six, mature, normal cattle were treated orally with a magnesium oxide (MgO) product and one week later given a comparable cathartic dose of magnesium sulphate (MgSO₄).

The mean percent dry matter content of the cattle feces changed significantly (P<0.001) following administration of both MgO (15.6-8.1) and MgSO₄ (17.0-8.7) but there was no significant difference between treatments. The mean rumen pH values changed significantly (P<0.001) following administration of both MgO (7.-8.7) and MgSO₄ (7.3-8.3) but there was no significant difference between treatments. However, use of the MgO product caused a more severe (P<0.001) metabolic alkalosis as determined by base excess values. The base excess values remained elevated for 24 hours in the MgO treated group compared to only 12 hours after MgSO₄ administration. Following MgO administration, mean hydrogen ion concentration (pH), bicarbonate ion concentration ([HCO₃-]) and base excess were 7.44, 33.3 mmol/L and +8.0 respectively compared to 7.38, 27 mmol/L and +3.0 after MgSO₄.

Since the oral use of MgO in normal cattle causes a greater and more prolonged metabolic alkalosis compared to MgSO₄, MgO is contraindicated as a cathartic in normal cattle or in cattle with abomasal abnormalities characterized by pyloric obstruction and metabolic alkalosis.

     

Exocrine Pancreatic Insufficiency in the Dog: Historical Background,Diagnosis, and Treatment

This overview summarizes research performed during the last decades that has had an impact on the diagnosis and management of exocrine pancreatic insufficiency (EPI) in dogs. Pancreatic acinar atrophy is by far the most common cause for the maldigestion signs of canine EPI. The ability to diagnose pancreatic acinar atrophy in the subclinical phase before the development of total acinar atrophy and manifestation of clinical signs has offered new possibilities to study the pathogenesis of the disease. Diagnosis of exocrine pancreatic dysfunction is based on typical findings in clinical histories and clinical signs and is confirmed with pancreatic function tests. In recent years, the measurement of serum canine trypsin-like immunoreactivity has become the most commonly used pancreatic function test to diagnose canine EPI. Serum trypsin-like immunoreactivity measurement is species- and pancreas-specific. When clinical maldigestion signs of EPI appear, enzyme replacement therapy is indicated. Despite accurate enzyme supplementation, only a small portion of orally administered enzymes are delivered functionally intact into the small intestine. In dogs, the highest enzyme activity in the duodenum has been obtained with nonenteric-coated supplements: raw chopped pancreas or powdered enzymes. Aside from dietary enzyme supplements, dietary changes are often made to improve clinical response, but sometimes weight gain and stool quality remain suboptimal. Other medications for treatment of gastrointestinal tract signs are often used in such dogs with EPI. Antibiotics are the most common adjunctive medication. Of the antibiotics administered, tylosin is used in Finland almost exclusively.     

The design and use of a device to detect deer pedicle growth

The design, construction and use of a device to detect changes in deer pedicle volume are described. The device is highly sensitive for detecting the initiation of pedicle growth. Between-sample differences of 170 mm3 in the pedicle volume of live deer were detected (triplicate measurements) using the detector; these correspond to a change in height of the pedicle of at most 0.67 mm. The within sample coefficient of variation was 1.4%. The pedicle growth detector enables more precise measurements to be obtained for identifying the onset of pedicle development to the nearest week than is currently possible with palpation.     

Experimental colibacillosis in gnotobiotic piglets exposed to 3 enterotoxigenic serotypes

Three strains of enterotoxigenic Escherichia coli (ETEC) (064:KSNT, K88ac; 020:KSNT, K88ac and 08:K85ab, K99) originally cultured from outbreaks of diarrhoea in piglets a few hours old, were administered orally to gnotobiotic piglets. There was a marked age-related difference in the clinical response to infection between the 3 strains although they all produced heat-stable toxin. All 3 strains produced severe clinical signs of depression, anorexia, vomiting, diarrhoea, followed by dehydration and death in one-day-old piglets. In piglets infected at 3 days of age the two K88+ ETEC caused diarrhoea and death but the K99+ ETEC induced moderate diarrhoea only. In piglets infected at 7 days of age, the 064 strain produced severe diarrhoea and death, and 020 strain caused mild diarrhoea in 3 of 6 piglets with one death while the 08 strain caused no illness. Pathological changes in the intestinal tract associated with these infections were minimal, or absent. Immunofluorescent staining with homologous hyperimmune sera demonstrated adherence of the 3 ETEC strains to the brush border of small intestinal epithelial cells. Fluorescing organisms were observed in all infected piglets irrespective of the severity of clinical signs but the degree and extent of colonisation varied with the age of the piglets and the infecting strain. This may explain the difference in clinical response between the 3 strains.     

A survey of the selenium status of beef cows in Alberta.

An epidemiological survey was conducted in Alberta to measure the selenium status in blood of beef cows during the fall and to determine the risk of selenium deficiency among specific geographic regions of Alberta. Three census divisions of Alberta based on the Statistics Canada Census of Agriculture were chosen as the study areas for the project. Soils and plants in area A (Edmonton area) and area B (Calgary area) were known to be deficient in selenium, while soils and plants in area C (southeast corner of Alberta) were known to have adequate levels of selenium. Blood samples were collected from 335 cows on 29 farms from the 3 study areas. These samples were collected from cows that had recently been removed from pasture in October and November 1992. Answers to a short questionnaire pertaining to various herd characteristics and management practices were also obtained for each herd. The average value of selenium for all cows sampled was 2.20 mumol/L. The average value of selenium of cows in areas A and B was 1.93 mumol/L. The average value of selenium of cows in area C was significantly (P < 0.05) higher at 2.70 mumol/L. Nine percent of the cows in the study were considered marginal or deficient in selenium (< 1.27 mumol/L selenium). Herds located in area C, herds that were provided with supplemental feed on pasture, and herds that were pregnancy checked had higher average herd selenium values than did other herds. Cow-calf producers located in areas with selenium-deficient soils should pay particular attention to selenium supplementation for their cows. Some of the negative "geographic" effects on selenium values can be overcome by more progressive management practices.