Samples of serum and urine were obtained simultaneously from 56 healthy lactating cows to determine ranges of fractional excretion (FE) of calcium (Ca), phosphate (PO4), magnesium (Mg), sodium (Na), potassium (K), and chloride (Cl). Samples were obtained at 3 stages of lactation: period 1 = 1 to 7 days, 2 = 83 to 112 days, and 3 = 175 to 197 days. The FE of electrolytes were significantly different among periods 1, 2, and 3 for Ca (P < 0.001), PO4 (P < 0.025) and Mg (P < 0.025), but were not significantly different for Na, K, and Cl. Least squares mean FE of Ca was lowest in period 1 and not significantly different for periods 2 and 3, whereas mean FE values for PO4 and Mg were highest in period 2 and not significantly different for periods 1 and 3. The mean FE values of Na, K, and Cl did not change with stage of lactation. Age and category of milk production (high, medium, and low) did not influence the FE values of the electrolytes.

L-lactic acid and D,L-lactic acid infusion in ponies resulted in metabolic acidosis with high anion gap (AG). Increased AG was explained entirely by increased blood L- and D-lactate concentrations. Hydrochloric acid infusion caused metabolic acidosis with decreased AG. Saline (NaCl) infusion caused mild metabolic acidosis, with no significant change in AG. Plasma K+ concentration was decreased by all types of infusions, with a maximum of 0.50, 0.25, 0.40, 0.50 mmol/L below baseline at the end of infusion in the L-lactic acid-, D,L-lactic acid-, HCl-, and NaCl-infused ponies, respectively. Only hydrochloric acid had a tendency to increase plasma K+ concentration. Hypophosphatemia developed in NaCl- and HCl-infused ponies, but not in the D,L-lactic acid-infused ponies. Serum inorganic phosphate concentration in L-lactic acid-infused ponies increased initially, but was significantly (P < 0.05) lower than values in the other ponies at 4 hours after onset of infusion. In ponies, the effect of acidemia on plasma K+ and serum inorganic phosphate concentrations was similar to that reported for other species. Changes were small in magnitude and depended on the nature of the acid anion. Results indicate that large changes in plasma K+ and serum inorganic phosphate concentrations during acidosis are probably not a direct result of acidemia.

Mycoplasma bovis is known as a causative agent of many disorders in cattle. In Europe, there is still a lack of commercial vaccines against M. bovis infection. Acute phase response (APR) is a non-specific host reaction to infection, most seen in changes in production of acute phase proteins. The aim of this study was to analyse APR in calves administered with an experimental M. bovis vaccine. Twelve healthy female calves were divided into two equal groups: experimental and control. The experimental vaccine containing the field M. bovis strain and two adjuvants such as saponin and lysozyme dimer was subcutaneously administered to the experimental group. Phosphate buffered saline was taken as the placebo and given to the control group by the same route as the vaccine. Blood samples were collected prior to the study (day 0), then daily up to day 7, and then each seven days until day 84 post vaccination. The concentrations of serum amyloid A (SAA), haptoglobin (Hp), interferon-γ (IFN-γ), and inteleukin-4 (IL-4) were determined using commercial ELISA kits. Following the vaccination, a significant increase in SAA, Hp, and IFN-γ concentrations was observed when compared to the unvaccinated calves, whereas the IL-4 concentration was not detectable. The experimental saponin-based M. bovis vaccine containing lysozyme dimer adjuvant visibly stimulated the APR in the calves, and some specific cytokines (Th1-dependent) directly involved in this response.

Veterinarians use flumequine (FLU) widely but its toxicological effects are still unclear. FLU doses of 53, 200, or 750 mg/kg were administered orally for six weeks to pubertal male rats for evaluation of their toxicity. Weight gain was poorer after seven days of exposure to FLU 750, but relative weights of the brain, adrenal and thyroid glands, and testes were notably higher. Haematological and lipid profile parameters, cardiac markers, and inorganic phosphate significantly increased in the FLU 750 group. Blood glucose, oestradiol and serum concentrations of immunoglobulins G (IgG) and E (IgE) significantly decreased after treatment. The levels of interleukins 10 (IL-10) and 6 (IL-6) fell significantly in the FLU 200 and FLU 750 groups. Cytochrome P450, family 1, subfamily A, polypeptide 1 (CYP1A1) and cyclooxygenase-2 (Cox-2) expression amplified after treatment. Serum levels of free triiodothyronine (fT3) and free thyroxine (fT4) reduced in the FLU 200 and FLU 750 groups without changes in total T3 or T4 level. All doses of FLU significantly depressed concentrations of thyroid-stimulating hormone (TSH) and testosterone. Histopathology of thyroid glands from rats treated with FLU 750 showed degeneration and depletion of thyroid follicular epithelial cells. Expression of 8-hydroxydeoxyguanosine (8-OHdG) was increased in a dose-dependent manner in the brain, but decreased in the testes. Expression of CYP1A1 increased in the adrenal and pituitary glands. The results of this study suggest that the toxicity of FLU in rats is an effect of its disruptive influence on the pituitary-thyroid hormonal system and on the dysfunction of the immune system.

OBJECTIVE To evaluate the effects of drinking nutrient-enriched water (NW) on water intake and indices of hydration in healthy domestic cats fed a dry kibble diet ad libitum. ANIMALS 18 domestic shorthair cats. PROCEDURES Group-housed cats were assigned to tap water (TW; n = 9) or NW (9) groups. All cats received TW at baseline (days −7 to −1). No changes were made to the food-water regimen for the TW group. The NW group received NW instead of TW from days 0 through 10, then received TW and NW in separate bowls (days 11 through 56). Food intake was measured through day 10; liquid consumed by drinking was measured throughout the study. Blood and urine samples were collected at predetermined times for analyses; 48-hour urine collection (days 28 through 30 or 31 through 33) was performed to assess output volume and aid endogenous creatinine-based glomerular filtration rate (GFR) determination. Data were analyzed with linear mixed-effects models. RESULTS Baseline TW and calorie intake were similar between groups. The NW treatment was significantly associated with increased liquid consumption during the treatment phase. Mean urine output was significantly higher in the NW group (15.2 mL/kg/d) than in the TW group (10.3 mL/kg/d). Mean GFR (1.75 vs 1.87 mL/min/kg, respectively) did not differ between groups. Effects of treatment and time were each significant for urine specific gravity and osmolality and urine creatinine, phosphate, and urea nitrogen concentrations, with lower values for the NW group. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that consumption of the NW can increase liquid intake and improve measures of hydration in healthy cats. These effects may offer health benefits to some cats in need of greater water consumption.

OBJECTIVE To determine bactericidal effects of enrofloxacin, florfenicol, tilmicosin, and tulathromycin on clinical isolates of Mannheimia haemolytica at various bacterial densities and drug concentrations. SAMPLE 4 unique isolates of M haemolytica recovered from clinically infected cattle. PROCEDURES Minimum inhibitory concentration (MIC) and mutant prevention concentration (MPC) were determined for each drug and isolate. Mannheimia haemolytica suspensions (10(6) to 10(9) CFUs/mL) were exposed to the determined MIC and MPC and preestablished maximum serum and tissue concentrations of each drug. Log10 reduction in viable cells (percentage of cells killed) was measured at various points. RESULTS Bacterial killing at the MIC was slow and incomplete. After 2 hours of isolate exposure to the MPC and maximum serum and tissue concentrations of the tested drugs, 91% to almost 100% cell killing was achieved with enrofloxacin, compared with 8% growth to 93% cell killing with florfenicol, 199% growth to 63% cell killing with tilmicosin, and 128% growth to 43% cell killing with tulathromycin over the range of inoculum tested. For all drugs, killing of viable organisms was evident at all bacterial densities tested; however, killing was more substantial at the MPC and maximum serum and tissue drug concentrations than at the MIC and increased with duration of drug exposure. Rank order of drugs by killing potency was enrofloxacin, florfenicol, tilmicosin, and tulathromycin. CONCLUSIONS AND CLINICAL RELEVANCE Findings suggested that antimicrobial doses that equaled or exceeded the MPC provided rapid killing of M haemolytica by the tested drugs, decreasing opportunities for antimicrobial-resistant subpopulations of bacteria to develop during drug exposure.

Samples of serum and urine were obtained simultaneously from 56 healthy lactating cows to determine ranges of fractional excretion (FE) of calcium (Ca), phosphate (PO4), magnesium (Mg), sodium (Na), potassium (K), and chloride (Cl). Samples were obtained at 3 stages of lactation: period 1 = 1 to 7 days, 2 = 83 to 112 days, and 3 = 175 to 197 days. The FE of electrolytes were significantly different among periods 1, 2, and 3 for Ca (P < 0.001), PO4 (P < 0.025) and Mg (P < 0.025), but were not significantly different for Na, K, and Cl. Least squares mean FE of Ca was lowest in period 1 and not significantly different for periods 2 and 3, whereas mean FE values for PO4 and Mg were highest in period 2 and not significantly different for periods 1 and 3. The mean FE values of Na, K, and Cl did not change with stage of lactation. Age and category of milk production (high, medium, and low) did not influence the FE values of the electrolytes.

Wick catheters were used to measure intracompartmental pressures of the extensor carpi radialis muscles and long heads of the triceps brachii muscles of 7 horses maintained under halothane anesthesia during controlled ventilation. Horses were positioned in left lateral recumbency on a water bed for 4 hours. Using a crossover design, 6 of the 7 horses were subjected to normotensive and hypotensive anesthesia on separate occasions. Hypotension was achieved by increasing the inspired halothane concentration. Hematologic and biochemical measurements were determined at designated intervals before, during and for 7 days after each anesthetic episode. Under hypotensive conditions, 2 horses developed severe, generalized myositis and were euthanatized. Three of the 5 other horses developed swelling of the downside masseter muscle, 4 demonstrated mild extensor deficits of the downside forelimb, and 1 had a severe extensor deficit of the uppermost hind limb. As a group, the hypotensive horses had markedly increased activities of serum enzymes (creatine kinase, aspartate transaminase, and blood lactate) and abnormalities in calcium-phosphorus homeostasis. Lameness or enzyme alterations were not observed in normotensive horses. Altough the intracompartmental pressure values were markedly increased in the muscle bellies of the compressed limbs of all horses, there was a statistically significant difference in intracompartmental pressures between the downside or compressed muscle compartments of the extensor carpi radialis of hypotensive and normotensive horses. High concentrations of halothane may predispose anesthetized horses to postanesthetic myositis, even when protective padding is used. Intracompartmental muscle pressure, as measured by the wick catheter, may not be a reliable predictor of equine postanesthetic lameness.

Hypophosphatemia was induced in 2 cows by reducing phosphorus content in their feed after parturition. Serum inorganic phosphorus (Pi) values decreased to 1 mg/dl within 10 days after parturition; and RBC adenosine 5'-triphosphate (ATP) and reduced glutathione values decreased to 50 and 70% of baseline values, respectively. Methemoglobin concentration was moderately higher than normal. These changes preceded the onset of hemolysis, and anemia progressed with decreases in PCV, hemoglobin concentration, and RBC counts. Serum Pi resumed its normal value when anemia was most severe. This RBC disorder was confirmed to be characteristic of hemolytic anemia in cows resulting from hypophosphatemia. The RBC glycolytic intermediates, totaal trisoe phosphate (combined glyceraldehyde-3-phosphate and dihydroxyacetone phosphate content) and fructose-1, 6-diphosphate, greatly increased in vivo and in vitro with decreases in serum or plasma Pi and RBC ATP. From our results, we concluded that inadequate Pi in the plasma impairs the function and viability of RBC by hindering the production of ATP via disturbance of reactions at the glyceraldehyde-3-phosphate dehydrogenase step.

We characterized the clinicopathologic manifestations of experimentally induced endotoxin-induced mastitis. Responses to hypertonic fluid therapy also were assessed. Eight cows received 1 mg of endotoxin by in infusion in the left forequarter. Four hours after endotoxin administration, cows received 0.9% NaCl, 5 ml/kg of body weight (n = 4) or 7.5% NaCl, 5 ml/kg (n = 4) IV. Endotoxin-infused cows had expanded plasma volume, hyponatremia, transient hyperchloremia and hypophosphatemia, increased serum glucose concentration, and decreased serum activities of liver- and muscle-specific enzymes. Calculated plasma volume increased at 6 hours in cows receiving hypertonic NaCl, and at 12, 24, and 48 hours after endotoxin infusion in both groups. Concurrent observations of decreased serum protein concentration, erythrocyte count, and hematocrit supported observations of increased plasma volume. Relative plasma volume was greater in cows receiving hypertonic NaCl (124.3%) than in cows receiving isotonic NaCl (106.6%) at 6 hours after endotoxin infusion. Cattle receiving hypertonic NaCl had increased voluntary water intake after IV fluid administration. Increased water consumption was not accompanied by increased body weight, indicating probable occurrence of offsetting body water loss. Serum sodium concentration in cows receiving hypertonic NaCl was increased 2 hours after fluid administration, but the magnitude of the change was minimal (< 4 mmol/L) and transient, indicating rapid equilibration with either interstitial or intracellular spaces. Serum sodium concentration was decreased in cows receiving isotonic NaCl at 12, 24, and 48 hours after endotoxin administration, compared with concentration prior to endotoxin administration, indicating selective loss of sodium.