Quantitative computed tomography has been used extensively to measure bone mineral density; particularly in the vertebral column and in the proximal portion of the femur in human beings with osteoporosis. Other potential applications of this technique include evaluation of bone adjacent to metallic endoprostheses and evaluation of fractures as they heal. Unfortunately, metal causes severe image degradation, principally seen as starburst streaking. One method used to decrease these artifacts is by imaging less-attenuating materials, such as titanium alloy. Titanium decreases image degradation sufficiently to allow accurate determination of the geometric properties of cadaveric bone. In our study, the effect of a titanium segmental endoprosthesis on bone mineral density measurement was determined by use of bone specimens from dogs and calibration standards. Titanium decreased the bone mineral density of calibration solutions from 6.8 (500 mg/cm3) to 17.7% (250 mg/cm3), and increased bone mineral density of cortical bone by 5.3%. Titanium did not affect the repeatability of these scans, indicating that the error caused by titanium was systematic and can be corrected. Our data were suggestive that quantitative computed tomography can be used to measure bone mineral density of cortical bone adjacent to titanium endoprostheses, with a predictable increase in density measurement.

Cerebrospinal fluid and serum were obtained from 16 clinically normal adult cows (11 dairy, 5 beef). Sodium, potassium, magnesium, total protein, and albumin concentrations, osmolality, and lactate dehydrogenase and creatine kinase activities, were quantified in CSF and serum. Total and differential cell counting, protein electrophoresis, and IgG quantification were performed on CSF. Statistical analyses of these variables, including mean, SEM, range, and 95% confidence intervals, were performed. Effects of blood contamination were evaluated, and were found to be negligible for all measured constituents. Correction factors for CSF creatine kinase and lactate dehydrogenase activities accounting for cellular contamination were developed. Total nucleated cell count was similar to counts in CSF of other species, but higher than values in healthy people. Differential leukocyte count in CSF was similar to that reported in CSF of other domestic animals: mostly lymphocytes, fewer monocytoid cells, and scant neutrophils. Cerebrospinal fluid protein concentration was higher than concentration reported for dogs, goats, and people, but was similar to values reported for horses. Beef cows had higher CSF total protein concentration than did dairy cows; also, beef cows had higher CSF gamma-globulin concentration. The concentration of sodium in CSF was slightly higher than the value in serum, and potassium concentration was lower than the value in serum. In contrast to studies of human beings, CSF osmolality was generally less than serum osmolality in the cows studied. Reference values for CSF electrolyte concentrations and osmolality are useful for diagnosis of salt poisoning and for assessment of the effects of fluid therapy. Magnesium concentration was lower in CSF, compared with serum. Reference values may be useful for diagnosis of grass tetany. Glucose concentration in CSF was variable, compared with serum concentration; sometimes, it was similar, lower, or even higher than serum glucose concentration. This variation reflects a more complete equilibration of glucose between CSF and blood, owing to the lower and more stable blood glucose concentration in cows. Creatine kinase activity in CSF was markedly less than, and was not correlated with, serum creatine kinase activity. Cerebrospinal fluid lactate dehydrogenase activity was markedly lower than serum lactate dehydrogenase activity. Compared with lactate dehydrogenase, creatine kinase activity had a wider range in these healthy cows; therefore, the former enzyme has higher specificity and sensitivity for diagnosis of diseases affecting the CNS.

Paraherquamide, an oxindole alkaloid metabolite of Penicillium paraherquei and P. charlesii, is a new anthelmintic with potential broad-spectrum use. In initial trials, it had an excellent safety profile in cattle and sheep at doses efficacious against a dozen or more helminths, but recently it produced unexpected and severe toxicosis in dogs at doses far below those that were safe in the ruminants. To provide data on which to build rational safety tests in the future, we tested the acute toxicity of paraherquamide administered PO to male CD-1 mice and compared its profile with the most potent anthelmintic known, ivermectin. The estimated doses lethal to 50% of a group of mice were 14.9 and 29.5 mg/kg of body weight for paraherquamide and ivermectin, respectively. The no-effect doses were 5.6 and 18.0 mg/kg for paraherquamide and ivermectin, respectively. Signs of intoxication in paraherquamide-treated mice, if they developed, emanated within 30 minutes of administration, irrespective of dose, and consisted of either mild depression with complete recovery or a 5- to 10-minute period of breathing difficulty followed by respiratory failure and death by 1 hour after treatment. Gross necropsy findings in paraherquamide-treated mice that died in the high-dose group were normal. Ivermectin-related toxicity was slower and more predictable, taking place over a 3-day period, with dose-dependent signs of intoxication consisting of tremors, ataxia, recumbency, coma, and death. Necropsy of ivermectin-treated mice that died in the high-dose group revealed dehydration, a condition most likely resulting from the coma-induced state. These observations are congruent with clinical data from dog studies and suggest that if broad-spectrum use of ivermectin (expected to be approx 0.2 mg/kg) is unlikely because of idiosyncratic toxic effects in certain dogs, then use of a compound for dogs with an acute safety factor half of ivermectin, such as paraherquamide, would be even more unlikely. These data are also coupled with observations from anthelmintic trials to suggest that ivermectin possesses a substantially greater therapeutic index than does paraherquamide as a broad-spectrum antiparasiticide for ruminants. Although paraherquamide has a lesser therapeutic index, a strategic use for it as an anthelmintic against ruminant parasites that have become resistant to any or all of the other modern broad-spectrum anthelmintics can be suggested.

Distribution of blood flow among various respiratory muscles was examined in 8 healthy ponies during submaximal exercise lasting 30 minutes, using radionuclide labeled 15-micrometers diameter microspheres injected into the left ventricle. From the resting values (40 +/- 2 beats/min; 37.3 +/- 0.2 C), heart rate and pulmonary arterial blood temperature increased significantly at 5 (152 +/- 8 beats/min; 38.6 +/- 0.2 C), 15 (169 +/- 6 beats/min; 39.8 +/- 0.2 C), and 26 (186 +/- 8 beats/min; 40.8 +/- 0.2 C) minutes of exertion, and the ponies sweated profusely. Mean aortic pressure also increased progressively as exercise duration increased. Blood flow increased significantly with exercise in all respiratory muscles. Among inspiratory muscles, perfusion was greatest in the diaphragm and ventral serratus, compared with external intercostal, dorsal serratus, and scalenus muscles. Among expiratory muscles, blood flow in the internal abdominal oblique muscle was greatest, followed by that in internal intercostal and transverse throacic muscles, in which the flow values remained similar. The remaining 3 abdominal muscles had similar blood flow, but these values were less than that in the internal intercostal, transverse thoracic, and internal abdominal oblique muscles. Blood How values for all inspiratory and expiratory muscles remained similar for the 5 and 15 minutes of exertion. However, at 26 minutes, blood flow had increased further in the diaphragm, external intercostal, internal intercostal, transverse thoracic, and the external abdominal oblique muscle as vascular resistance decreased. On the basis of our findings, all respiratory muscles were activated during submaximal exercise and their perfusion had marked heterogeneity. Also, blood flow in respiratory muscles was well maintained as exercise duration progressed; in fact, several muscles had a further increase in perfusion late during exercise.

Glomerular filtration rate (GFR) was measured in 12 clinically normal horses, using the standard inulin clearance method, and values were compared with values for 2 methods, using a single rapid IV injection of (99m)Tc-labeled diethylenetriaminepentaacetic acid ((99m)Tc-DTPA). The first (99m)Tc-DTPA method used a 2-compartment model to calculate GFR blood clearance of the tracer. The second method used sequential digital gamma camera images of the kidneys to determine fractional accumulation of the total dose of the tracer in the kidneys (percentage of injected dose, gamma camera) from 0 to 10 minutes after radionuclide administration. Linear correlation among the 3 methods was determined. Mean (+/- SD) GFR, using the inulin clearance method, was 154.67 +/- 42.28 ml/min/100 kg of body weight. Mean GFR, using the 2-compartment blood clearance curve, was 146.92 +/- 27.49 ml/min/100 kg. Mean GFR, using percentage of injected dose (gamma camera method) was 154.7 +/- 22.00 ml/min/100 kg. The percentage of injected dose (gamma camera method) did not correlate significantly to the inulin clearance results. However, a significant (r = 0.666, P < 0.018) correlation was observed between the inulin method and the (99m)Tc-DTPA blood clearance method. Significant (P < 0.0001) difference also was observed in the split function of the equine kidneys, with GFR of the right kidney contributing 60.1 +/- 9.12% of the total function, as determined by (99m)Tc-DTPA gamma camera imaging. Because the (99m)Tc-DTPA blood clearance method does not require urine collection, it may be a more practical procedure to measure GFR in the horse.

Cat foods containing propylene glycol (PG) induce Heinz body formation in feline erythrocytes. To further study the hematologic importance of dietary PG, 21 adult cats were allotted to 3 groups of 7 each and fed diets containing 0, 6, or 12% PG on a dry-weight basis. Cats fed PG had a dose-related increase in Heinz bodies within 2 weeks, and the increase persisted throughout the study. Although only slight changes occurred in PCV, hemoglobin concentration, and RBC count, punctate reticulocytes were significantly increased in the group fed 12% PG. Mean RBC survival was decreased in the groups fed 6 or 12% PG by 30 and 55%, respectively, compared with the control group. These data indicate that PG-containing diets cause a dose-dependent erythrocyte destruction, even when fed at concentrations as low as 6%.

The scavenging of superoxide radicals by endogenous and therapeutically administered superoxide dismutases may prevent superoxide-mediated oxidative stress leading to lipid peroxidation, membrane lysis, and cell death in a wide variety of normal and pathologic states. Simple inorganic manganous salts such as MnCl2 also have superoxide dismutase-like activity and are extremely inexpensive, compared with enzymatic superoxide dismutase preparations. In this study, we explored the use of Mn salts as antioxidant drugs. We used the percentage of inhibition of nitroblue tetrazolium reduction by superoxide as a measure of the amount of superoxide dismutase-like activity. We found concentration-related increases in superoxide scavenging activity in simple buffer solutions upon addition of 1.25, 2.5, and 5.0 microM MnSO4. To determine whether Mn salts can inhibit oxidative damage in tissues, we used an in vitro model of lipid peroxidation in ischemic and reoxygenated rat liver slices. Concentrations of 10, 100, and 1000 micromoles MnCl2/L of buffer significantly decreased indicators of lipid peroxidation believed to be initiated by intracellular superoxide. We then determined the effectiveness of MnCl2 as a superoxide scavenger in conscious horses by measuring the superoxide scavenging ability of equine plasma before and during intravenous infusions of 1.0 L volumes of 0.9% saline solution containing 0, 12.5, or 25 mM MnCl2. Plasma Mn concentrations, which were determined by atomic absorption spectrophotometry, increased as a function of time and dose. Intravenously administered MnCl2 concomitantly produced dose-related increases in superoxide scavenging ability of equine plasma at 15, 30, 45, and 60 minutes after the onset of infusion, compared with preinfusion control values. Heart rate and blood pressure of the treated horses, which were monitored to measure toxicity of MnCl2, gradually increased in both treatment groups. Clinical adverse effects of MnCl2 administration included defecation, pawing, hyperexcitability, flank watching, and sweating. The results of this study indicate that simple Mn salts may scavenge superoxide radicals in vivo with minimal adverse reactions and at a trivial cost.

Using radiopaque particles mixed with food, gastric emptying was assessed in healthy dogs not subjected to surgery, in healthy dogs 9 to 35 days after circumcostal gastropexy, and, in dogs 1 to 54 months after surgical treatment and recovery from gastric dilatation-volvulus (GDV). Circumcostal gastropexy surgery did not alter the 90% gastric emptying time for radiopaque particles in healthy dogs. However, 90% gastric emptying time was significantly (P < 0.05) increased after circumcostal gastropexy in dogs with GDV, compared with healthy dogs after the same surgical procedure and recovery period. These results imply that dogs with GDV have delayed gastric emptying of solid particles. Whether delayed gastric emptying of markers detected in affected dogs after surgical treatment and recovery was the result or the cause Of GDV was not determined. Results indicate that circumcostal gastropexy could be recommended as a prophylactic procedure for GDV in large breeds with deep thorax, because delayed gastric emptying of markers secondary to the surgical procedure is unlikely.

The abomasa of 1,949 slaughtered feedlot cattle, 45 necropsied feedlot cattle that died 2 to 45 days after arrival, and 45 necropsied pastured cattle were opened and examined. Of these organs, 484, 1, and none, respectively, contained erosions. The slaughtered cattle were fattened at 3 locations: 1,305 with 430 eroded abomasa were fed a ration of corn in northeastern Colorado; 144 cattle with 4 affected abomasa fed a ration of milo in south-central Arizona; and 500 cattle with 50 affected abomasa fed a ration of milo and corn in northwestern Texas. The redbrown lesions developed late during the second semester of fattening and were located mostly on fundic folds. Those on fold edges were linear and were 2 to 15 cm long, whereas those on fold sides were punctate and were 2 to 15 mm in diameter. Normal fold edges contained fewer goblet cells and less surface mucus than did fold sides. Eroded folds had disruption of surface epithelium, damage to endothelial cells, and dilated, thrombosed, congested, and ruptured capillaries. Mean pH values of 16 normal and 17 eroded abomasa were 4.7 and 3.9, respectively. Necrosis of all tissue toward the mucosal surface of erosions was extensive. The cause of gastric erosion in cattle is not known.

Using a newly formulated selective medium containing cefoperazone, we isolated 72 Campylobacter strains in fecal samples from 397 diarrheic dogs and cats. Of these, 39 were thermophilic catalase-negative Campylobacter species. We identified these Campylobacter strains by DNA:DNA hybridization, using digoxigenin-labeled total genomic DNA of 4 Campylobacter reference strains (C jejuni, C coli, C lari, and C upsaliensis) as a probe. The labeling was done with a commercially available kit. We could identify 66 of the 72 Campylobacter isolates to the species level with this method; identification with probes always agreed with conventional test results. Of the 66 identified strains, 33 were C upsaliensis and 33 were C jejuni. Six isolates could not be assigned to a known species with probes or conventional tests. On the basis of our findings, C upsaliensis is more resistant to cefoperazone than to cephalothin, thereby explaining the unexpected recovery of these campylobacters on cephalosporin-containing media.