A simple and humane model of inflammation, induced by the intradermal injection of 0.3 mL of sterile 2% carrageenan, was characterized in calves by measuring the volume of skin swelling plus histological analysis of skin biopsies. Carrageenan produced a biphasic increase in skin swelling, with an early edematous response followed by a more chronic cellular infiltrate. The swelling and sensitivity to pressure observed in the early response were suitable for testing the antiedematous and analgesic activity of a new nonsteroidal anti-inflammatory drug (NSAID), oxindanac. Pretreatment with intravenous oxindanac at doses from 0.5 to 8.0 mg/kg reduced the volume of swelling and this reached statistical significance (p < 0.05) at 2 mg/kg. The ED50 and ED90 values for inhibition of the peak swelling volume (4 h) were estimated to be 1 mg/kg and 2 mg/kg, respectively. These compare with an ED90 of 2.0 mg/kg for inhibition of serum TxB2 production, an index of platelet cyclo-oxygenase activity. The dose of oxindanac required for antiedematous activity correlated, therefore, with maximal inhibition of serum TxB2. The analgesic activity of oxindanac reached no clear maximum response, but statistically significant difference (p < 0.05) from placebo was reached with doses of 2 mg/kg and above. It is concluded that intradermal carrageenan produced a simple, humane and useful model for dose estimation of a new NSAID in calves.

Using a force plate, ground reaction force (GRF) patterns at take-off and landing between the hooves and the ground were recorded for all limbs of 5 Dutch Warmbloods jumping a 0.8-m vertical fence from the right-leading canter. Distribution of the GRF and force impulses over the 4 limbs at take-off and landing were considerably different from those recorded at the normal canter. At take-off, the propulsory GRF of the hind limbs were 3 to 5 times higher than at the normal canter, depending on the jumping technique of the horse. At landing, the propulsory GRF were mainly increased in the trailing forelimb and in both hind limbs. The vertical GRF amplitudes and force impulses were of similar magnitude to those at the canter, although increases up to 160% were found in the hind limbs of the horse with the worst jumping technique. The trailing forelimb carried the highest loads, up to twice the animal's body weight; GRF amplitudes tended to increase when higher fences were used. However, the jumping technique of the horse may have more influence, because an easily jumping horse could clear a 1.3-m-high fence with similar loads on the limbs.

To investigate the feasibility of using changes in body or mammary temperature to detect mastitis, radiotransmitters were implanted midway between rear udder quarters and in the peritoneal cavity of 5 Holstein cows (1 to 3 months in lactation) housed in an environmental chamber (16 +/- 2 C; lights on 7:00 AM to 11:00 PM). After a 6-week control period, Escherichia coli endotoxin (0.5 mg) was injected after the morning milking into left rear teat cisterns via the teat canal. Wisconsin mastitis test score and somatic cell count in all quarters increased significantly (P < 0.01) by the next milking. Effects were greatest in the endotoxin-exposed quarters. Milk yields for all quarters decreased significantly (P < 0.01) by the first milking after endotoxin injection. Udder and body temperatures at milkings were similar and were not affected by treatment. When temperatures were averaged for the 5 cows for each of 120 time points/d, average temperatures, relative to time of injection of endotoxin, were increased by 0.5 C above baseline at 2.75 hours, peaked at + 2.9 C at 6.50 hours, and remained high through 9.25 hours after injection. Power spectra calculated for individual cows on a daily basis universally indicated an increase in power at low frequencies on the day of injection. Subsequently, Streptococcus agalactiae (200 colony-forming units) was injected into right rear teat cisterns. Wisconsin mastitis test score increased at the second milking after injection. Cell count and quarter milk yield decreased by the third milking. As with endotoxin, injection of S agalactiae could not be detected via a change in temperature at milkings. Of the 5 cows, 3 had a peak in temperature after injection of S agalactiae. Average temperatures for these 3 cows relative to time of injection, were increased by 0.5 C above baseline at 24.25 hours, peaked at + 1.4 C at 26.25 hours, and remained high through 28.75 hours after injection. Power spectra calculated for the day in which a temperature peak was detected for these 3 cows indicated an increase in power at low frequencies, compared with spectra for all other days. Similar increases in power were also detected for the 2 cows that did not have temperature peaks. When clinical signs of mastitis are obvious at milking, there is little advantage of using body temperature for detection of infection. When clinical signs are not obvious, body temperature is often only minimally increased. Thus, monitoring body temperature at milkings adds little to the ability to detect mastitis. Of more interest is the ability to detect transient temperature increases that often develop in association with less-severe infections. Also, as early treatment increases the likelihood of successful treatment, detection of the onset of temperature increases would be advantageous for treatment of severe infections. Detection of a transient temperature peak requires taking temperature readings every 2 hours. To detect mastitis when a temperature peak does not occur requires measurement every 15 minutes to calculate power spectra. The ability to detect the onset of acute clinical infections and subclinical infections, using frequent temperature readings, indicates that development of a practical radiotelemetry system for use on farms may be warranted, depending on cost. The added potential of using body temperature to monitor general health and to detect estrus enhances the economic feasibility of developing such a system.

A protocol was developed for preparation of platelet concentrates (PC) to support thrombocytopenic dogs. Four clinically normal dogs with platelet counts that ranged from 200 to 330 X 10(9) platelets/L were used as donors. One unit (450 ml) of blood was collected by venipuncture into a double blood bag. Whole blood (WB) was centrifuged for 4 minutes at 1,000 X g (braking time = 2 minutes, 30 seconds) to prepare platelet-rich plasma (PRP). The PRP was expressed into the satellite bag and was centrifuged for 10 minutes at 2,000 X g (braking time = 2 minutes, 36 seconds). The platelet-poor plasma was expressed, leaving 40 to 70 ml of plasma and the pelleted platelets in the satellite bag. The resulting PC was left undisturbed for 60 minutes to promote disaggregation, and the platelets were then resuspended by gentle manual agitation. Forty-eight PC were prepared. Mean (+/- SD) platelet yield from WB to PRP was 78 +/- 13)% (range, 35 to 97%); yield from PRP to PC was 94 (+/- 6) % (range, 75 to 100%); and overall yield (PC from WB) was 74 (+/- 13) % (range, 36 to 91%). Mean PC platelet count was 8.0 (+/- 3.0) X 10(10) platelets/PC (range, 2.3 to 13.4 X 10(10) platelets/PC). The WBC content was 0.1 to 2.3 X 10(9) platelets/PC, representing 3 to 74% of WBC in the WB. Hematocrit was 0.1 to 26.2%. Results of bacterial and fungal culturing were negative.

The IgG and IgM classes of antibodies to a water-soluble antigen preparation derived from microsporum canis were determined by ELISA in the sera of 79 cats with dermatophytosis confirmed by results of fungal culture, and of 46 specific-pathogen-free-derived, barrier-maintained cats with no previous exposure to dermatophytes. Of the 79 cats with dermatophytosis, the species isolated were: M canis from 72, M gypseum from 6, and Trichophyton mentagrophytes from 1. Concentrations of soluble M canis antigen-specific IgG and IgM were significantly (P < 0.05) higher in the cats with dermatophytosis than in the control cats. The IgG concentration was larger than or equal to 2.0 ELISA units/ ml in 71% of the cats with dermatophytosis and in 9% of the control cats, whereas IgM concentration was greater than or equal to 4.0 ELISA units/ml in 38% of the cats with dermatophytosis and in 11% of control cats. There was no significant difference in either IgG or IgM values between the cats with M canis infection and those with other non-M canis dermatophyte infections.

Twelve mature (5 sexually intact males, 4 castrated males, and 3 females) mixed-breed dogs were surgically thyroidectomized and used in a Latin-square design pharmacokinetic study of orally administered L-thyroxine. The dogs were treated with 44, 22, and 11 Kg of L-thyroxine/kg as a single morning dose or in divided doses, morning and evening. Serum concentration of thyroxine (T4) was evaluated to determine a number of pharmacokinetic variables for comparison. Mean steady-state concentrations (C(SS)) were determined from the area under the curve. Variables were analyzed for comparisons between dosages by use of ANOVA. Concentration at steady state was highest for dogs of the 44-micrograms/kg of body weight once-daily group and was lowest for dogs of the group given 11 micrograms/kg in 2 daily doses. Single daily administration resulted in higher C(SS), except at the 22-micrograms/kg/d dosage. Clearance was faster for the 22- and 44-micrograms/kg/d dosages than for the 11-micrograms/kg/d dosage. The half-life (t(1/2)) and mean residence time (MRT) also were shorter for the 44-micrograms/kg/d dosage, possibly indicating more rapid elimination of the drug at higher doses and dose-dependent kinetics. Perhaps, as the dogs' metabolism increased with higher iodothyronine concentrations, hormone degradation was accelerated. Interval (divided vs single dose) caused some expected changes: maximal concentration was higher and minimal concentration was lower when single administration was used. These undulations resulted in iodothyronine concentrations above the physiologic range for a number of hours, whereas concentration closer to physiologic ranges was achieved by use of divided doses. Delayed absorption (lag time) was seen in 37 of the 72 data sets, but was generally short, about 0.25 hour. Mean time to maximal concentration was 3 to 4 hours. At the higher dosages, serum total T4 concentration was high normal or above normal during most of the time after L-thyroxine administration, but serum concentration of total 3,5,3'-triiodothyronine did not remain within the normal range until the 44-micrograms/kg/d dosage was used. The customary dosage of 22 micrograms/kg/d (0.1 mg/10 lb/d) may not be adequate for most dogs. Pharmacokinetic variables appear to be highly dependent on the individual dog. Those with rapid absorption and higher concentration tended to have these characteristics at each dosage in this study. The pharmacokinetic variables, therefore, appear to be highly individualized, and dosages recommended for treatment of hypothyroidism should be considered to be only a starting point for the average dog. To avoid underdosing or overdosing, monitoring of treatment to adjust dose for individual dog kinetic variables seems to be imperative.

Eight dogs were determined to be orthopedically normal on the basis of prelavage physical examination, stifle radiography, synovial fluid analysis, and force plate analysis (peak vertical force normalized for body weight, and time on the force plate). Each dog had 1 stifle randomly assigned to be lavaged with 100 ml of a commercially available 0.05% (w/v) chlorhexidine diacetate solution, and the contralateral stifle was lavaged with lactated Ringer's solution. Difference was not detected between the chlorhexidine diacetate and lactated Ringer's solution-treated joints, with regard to results of synovial fluid analysis and clinical lameness evaluations on days 4 and 8 after lavage. Chlorhexidine diacetate caused a more intense synovitis than did lactated Ringer's solution, as determined by histologic evaluation of synovial membrane specimens after necropsy on day 8; however, a difference in the intensity of toluidine blue staining of articular cartilage was not found between treatments. Chlorhexidine diacetate, as a 0.05% (w/v) solution, cannot be recommended as a joint lavage fluid until the duration of inflammatory changes in the synovial membrane are determined or until the chemical constituents of chlorhexidine diacetate causing the synovitis can be identified and removed.

A rebreathing method for measurement of pulmonary diffusing capacity for carbon monoxide (DL(CO)) and functional residual capacity (FRC) was evaluated in conscious horses. Horses were manually ventilated through an endotracheal tube, using a custom-made syringe filled with a gas mixture containing 18-carbon monoxide (18CO) and helium (He). The 18CO and He concentrations were continuously monitored by use of a mass spectrometer connected to the rebreathing circuit. Values for DL(CO), and FRC were calculated from changes in the concentration of these 2 gases. In 11 Thoroughbreds, mean (+/- SD) DL(CO) was 330.3 +/- 56.9 ml.min-1.mm of Hg-1, and FRC was 20.21 +/- 3.35 L. Body weight normalization yielded mean (+/- SD) values of 0.652 +/- 0.114 ml.min-1.mm of Hg-1.kg-1 for DL(CO), and 39.9 +/- 6.4 ml.kg-1 for FRC.

The hemodynamic effects of 2 dosages of ephedrine were studied in 6 dogs anesthetized with isoflurane only (end-tidal concentration equivalent to 1.5 times minimum alveolar concentration). Following instrumentation, baseline (time 0) measurements included heart rate (HR), respiratory rate, mean arterial blood pressure (MAP), cardiac output, and blood gas tensions. Cardiac index (CI), stroke volume (SV), systemic vascular resistance (SVR), arterial oxygen content (CaO2), and oxygen delivery and consumption (DO2 and VO2, respectively) were calculated. Three dogs were given ephedrine IV at a dosage of 0.1 mg/ kg of body weight, and 3 dogs were given ephedrine IV at a dosage of 0.25 mg/kg. Measurements were recorded at 5, 10, 15, 30, and 60 minutes. Each dog then received the alternate dosage of ephedrine, and measurements were again recorded at the same intervals. Effects of ephedrine varied with dosage. Neither dosage was associated with significant changes in pH, PaO2, PaCO2, VO2, or respiratory rate. Ephedrine at a dosage of 0.1 mg/kg caused transient significant increases in MAP, CI, SV, CaO2, and DO2, significant decreases in HR and SVR, and a late, slight decrease in CaO2. Ephedrine at a dosage of 0.25 mg/kg caused a greater and more prolonged increase in MAP, as well as increases in CI, SV, and SVR, and a decrease in HR. The higher dosage of ephedrine also caused a pronounced increase in hemoglobin concentration and CaO2, resulting in a 20 to 35% increase in DO2 throughout the 60-minute experiment.

Pyelonephritis was experimentally induced in 10 clinically normal dogs by nephropyelocentesis and introduction of Proteus mirabilis into the randomly chosen right or left renal pelvis. Dogs were examined by nephrosonography and excretory urography before and 2 weeks after infection. The major nephrosonographic findings of pyelonephritis were renal pelvic dilatation, usually with proximal ureteral dilatation, and a hyperechoic mucosal margin line within the renal pelvis, proximal portion of the ureter, or both. In addition, at least one or more of the following were observed: generalized hyperechoic renal cortex, focal hyperechoic areas within the medulla, and focal hyperechoic or hypoechoic cortical lesions. Interpretation of excretory urograms resulted in 3 false-negative and 1 false-positive conclusions, compared with the histologic findings. Interpretation of nephrosonograms resulted in 2 false-negative and no false-positive conclusions. Of the kidneys with histologic evidence of pyelonephritis, 73% were detected by excretory urography, whereas 82% were detected by nephrosonography. Nephrosonography appeared to be useful for detection of mild to moderate cases of acute pyelonephritis that may be be interpreted as such by excretory urography.