Changes in smooth muscle contractility of rainbow trout (Oncorhynchus mykiss Walbaum) intestine during acclimation to altered temperature

The effects of altered water temperature in vivo on in vitro smooth muscle contractility of rainbow trout intestine were investigated. Temperature has a significant effect on receptor-mediated intestinal smooth muscle contractility in the rainbow trout. The efficacy of 5-HT, carbachol, and transmural stimulation increased with temperatures above 10°C, with an optimal increase at 15°C. There was also a modest increase in the potency of 5-HT and carbachol within 2 days of establishing trout at 20°C. By day 8, most of these changes had either stabilized or were returning to control values, suggesting that acclimation changes in membranes and enzyme activities were taking effect. However, the contractile responses to carbachol and transmural stimulation were still increasing at this time. This may imply that the muscarinic receptors are more resistant to membrane acclimation changes and may take longer to adapt. Because these experiments were controlled for handling stress and seasonal changes that affect contractility, we have been able to demonstrate some early changes in smooth muscle contractility that occur during acclimation to altered temperature.     

The effects of acute temperature change on smooth muscle contractility of rainbow trout (Oncorhynchus mykiss Walbaum) intestine

The effects of altered temperature in vivo on in vitro smooth muscle contractility of rainbow trout intestine were investigated. Initial analysis of the data revealed a seasonal variation in the maximal tension of intestinal smooth muscle attainable with 5-hydroxytryptamine (serotonin), carbachol, KCl, and transmural stimulation in vitro. Peaks occurred in spring and troughs in autumn. There was no seasonal cycling of the potency of the stimulants. All data regarding the efficacy of the stimulants were subsequently corrected for seasonal variation. The response of smooth muscle depends on the temperature of the water in which the fish are placed (2°C−20°C). There was a marked linear increase in efficacy and a slight increase in potency of the stimulants with increasing temperature. Changes in responsiveness of the intestinal smooth muscle occurred within 30 min of moving the fish between tanks. Smooth muscle reactivity returned to pretreatment values by 48h. Any changes in responsiveness with regards to time were unlikely to be as a consequence of water temperature, but may have been a result of handling stress.     

Changes in serum glucose,sodium, and tonicity in cats treated for diabetic ketosis

Objective – To examine serum sodium, glucose, and tonicity in cats with diabetic ketosis. Design – Retrospective study. Setting – A university‐based referral hospital. Animals – Cats admitted to the ICU during the period 1998 to 2002 with a diagnosis of diabetic ketosis. Interventions – None. Routine clinical management of diabetes and associated conditions. Measurements – Serum biochemistry assessments. Main Results – Abnormalities of glucose, sodium and serum tonicity (ST) were common in the study group. Serum sodium but not glucose correlated closely with ST. A subset of cats treated with intravenous insulin and an isotonic sodium‐containing solution for 72 hours showed a significant decrease in glucose from admission values at 48 and 72 hours (but not at 24 hours). Serum sodium, potassium, and ST were not significantly different from admission values at any time over the 72‐hour period. However, the relative contribution of individual osmolytes varied over the course of treatment. Although glucose decreased >120% from admission values over the 72‐hour treatment period, the approximately 5% rise in serum sodium that occurred offset the osmotic effect of falling glucose and the overall ST change was <3%. Conclusions – The incidence of osmotic‐mediated neurologic complications during treatment of cats with diabetic ketosis is low in part because the minimal fluctuation in ST during treatment likely prevents the development of osmotic gradients between serum and central nervous system tissues. The use of isotonic sodium‐containing fluids in the treatment of feline diabetes acts to minimize large osmotic shifts by adding sodium to the serum compartment as the glucose concentration falls.     

Effects of irrigation sources on ammonia-oxidizing bacterial communities in a managed turf-covered aridisol

Ammonia-oxidizing bacteria (AOB) perform the rate-limiting step of nitrification, a key process in the global nitrogen cycle. In this study, chemical factors controlling AOB activity, diversity, and composition in a turfgrass-covered aridisol irrigated with groundwater, Colorado River water, or reclaimed wastewater were examined. Activity of AOB contributed an average of 96% of potential nitrification activity in four soils examined, and this activity correlated positively with ammonium concentration and negatively with salinity of the irrigation water. AOB abundance, as determined by quantitative polymerase chain reaction, also correlated positively with ammonium concentration in the irrigation water but negatively with soil salinity. Characterization of AOB communities by denaturing gradient gel electrophoresis showed the presence in every soil of AOB taxa, most commonly found in high-ammonia environments. The soil with the fewest years of management had the least diverse AOB population, compared to the other three soils, and much lower specific nitrification activity. This soil was irrigated with highly saline Colorado River water, which likely exerted acute negative effects on the activity of AOB. In summary, this study revealed that, although AOB activity and growth responded positively to ammonium availability in irrigation water, the salinity of the water and soil had strong negative effects on these aspects of the AOB community.     

Survey of the status of copper, interacting minerals, and vitamin E levels in the livers of sheep in Ontario

Livers from cull ewes and market lambs raised in Ontario were obtained to determine the status of specific minerals and vitamin E. Values for copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) obtained by atomic absorption and inductively coupled plasma--atomic emission spectroscopy (ICP-AES) were found to be statistically different but sufficiently biologically similar to allow the use of ICP-AES for screening groups of samples for deficient or toxic levels of those minerals. Toxic levels of cadmium were not found. Toxic levels of aluminum were found in 1 cull ewe and 1 market lamb. A significant proportion of both market lamb samples (40.0%) and cull ewe samples (50.0%) had high to toxic levels of Cu. In market lambs, Fe, Mn, molybdenum (Mo), selenium (Se), and Zn were not found to be important determinants of Cu level. In cull ewes, Fe, Mn, and Zn play a moderate role in the variability of liver Cu levels. Selenium was found to be present at marginal levels in 3.3% of cull ewe samples and in 42.6% of market lamb samples. Vitamin E was found to be low to deficient in 10.0% of cull ewe samples and in 90.0% of market lamb samples. In market lambs, only Mo was associated with Se levels, and no minerals were associated with vitamin E levels. In cull ewes, there was a strong association between Se and vitamin E. This survey demonstrates that marked nutritional imbalances of Cu, Se, and vitamin E exist in cull ewes and market lambs in Ontario.     

Effects of firocoxib, meloxicam, and tepoxalin on prostanoid and leukotriene production by duodenal mucosa and other tissues of osteoarthritic dogs

OBJECTIVE: To evaluate the in vivo effects of firocoxib, meloxicam, and tepoxalin on prostaglandin (PG) and leukotriene production in duodenal mucosa and other target tissues in dogs with chronic osteoarthritis (OA). ANIMALS: 8 dogs with chronic, unilateral OA of the stifle joint. PROCEDURES: In a crossover design, each dog received placebo (no treatment), firocoxib, meloxicam, or tepoxalin for 7 days, followed by a 21-day washout period. On the first day of treatment (day 0; baseline) and days 2, 4, and 7, samples of whole blood, synovial fluid, and gastric and duodenal mucosae were collected. Prostaglandin E2 concentrations were measured in synovial fluid of the stifle joint and after ex vivo stimulation of whole blood samples. Synthesis of PGE1 and PGE2 was measured in samples of gastric and duodenal mucosae. Concentrations of thromboxane B2 (TxB2) were measured in whole blood samples. Leukotriene B4 (LTB4) concentrations were measured in samples of whole blood (ex vivo stimulation) and gastric and duodenal mucosae. RESULTS: Firocoxib, meloxicam, and tepoxalin significantly suppressed whole blood concentrations of PGE2, compared with baseline and placebo concentrations, at days 2, 4, and 7. Tepoxalin significantly suppressed serum TxB2 concentrations, compared with baseline, firocoxib, meloxicam, and placebo, at all 3 time points. Production of PGE1 and PGE2 was significantly lower in duodenal versus gastric mucosa. Tepoxalin significantly decreased rates of PGE1 and PGE2 in duodenal and gastric mucosae, compared with baseline rates. CONCLUSIONS AND CLINICAL RELEVANCE: PG production was lower in the duodenum than in the stomach. Firocoxib had a COX-1-sparing effect in vivo.     

Disease prevalence among dogs and cats in the United States and Australia and proportions of dogs and cats that receive therapeutic diets or dietary supplements

OBJECTIVE: To estimate disease prevalence among dogs and cats in the United States and Australia and proportions of dogs and cats that receive therapeutic diets or dietary supplements. DESIGN: Telephone survey. Sample Population-Dog and cat owners located in 5 geographic areas. PROCEDURES: A telephone survey was administered to dog and cat owners. RESULTS: Of 18,194 telephone calls that were made, 1,104 (6%) were to individuals who owned at least 1 dog or cat and agreed to participate. Information was collected for 635 dogs and 469 cats. Only 14 (1%) respondents indicated that their pet was unhealthy, but 176 (16%) indicated that their pets had 1 or more diseases. The most common diseases were musculo-skeletal, dental, and gastrointestinal tract or hepatic disease. Many owners (n = 356) reported their pets were overweight or obese, but only 3 reported obesity as a health problem in their pets. Owners of 28 (2.5%) animals reported that they were feeding a therapeutic diet, with the most common being diets for animals with renal disease (n = 5), reduced-calorie diets (5), and reduced-fat diets (4). Owners of 107 of 1,076 (9.9%) animals reported administering dietary supplements to their pets. Multivitamins (n = 53 animals), chondroprotective agents (22), and fatty acids (13) were the most common dietary supplements used. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that most dogs and cats reported by their owners to have a health problem were not being fed a therapeutic diet. In addition, the rate of dietary supplement use was lower than that reported for people.     

Fanconi's Syndrome in a Dog With Primary Hypoparathyroidism

An 11 -year-old castrated male mixed breed dog was referred for evaluation of muscle twitching, polyuria, polydipsia, anorexia, and periocular alopecia. Primary hypoparathyroidism was diagnosed by documenting decreased serum concentrations of parathyroid hormone and ionized calcium. Neurological, gastrointestinal, and dermatological signs resolved after calcium repletion. Initially, 1,25-dihydroxycholecalcif erol PO was required to correct the hypocalcemia. Dihydrotachysterol, in combination with oral calcium supplementation, was used for long-term maintenance of normal serum calcium concentration. Aminoaciduria, glucosuria, and hyperchloremic metabolic acidosis were consistent with a diagnosis of Fanconi's syndrome. This diagnosis was further supported by the presence of hypokalemia and increased urinary fractional excretion of sodium, potassium, calcium, phosphorus, and magnesium. Renal tubular dysfunction resolved after oral supplementation with calcium and vitamin D₃. Fanconi's syndrome in this dog may have been caused by decreased serum concentration of 1,25-dihydroxycholecalciferol, which was secondary to decreased parathyroid hormone production.