Experimental pneumonia caused by Pasteurella haemolytica was induced in 2-week-old gnotobiotic (n = 4) and conventional (n = 6) calves by endobronchial inoculation into the right caudal lung lobe of 7.9 X 10(10) +/- 0.6 X 10(10) (mean +/- SD) colony-forming units of P haemolytica in the 6-hour log phase of growth. The calves were studied for 24 hours or less. Regression lines for the relationship between clinical index and time for the gnotobiotic group and conventional group of calves were compared, and the clinical index was found to be significantly (P less than or equal to 0.005) more rapid in the gnotobiotic group. There was also a significant difference in the preinoculation, absolute segmented neutrophil count (P less than or equal to 0.05), and in the total serum protein, albumin, and globulin values (P less than or equal to 0.05). Comparison of the preinoculation and post inoculation blood cell and blood chemical values revealed a significant increase (P less than or equal to 0.05) in the numbers of band neutrophils and fibrinogen in conventional calves, and a significant decrease (P less than or equal to 0.05) in the total WBC count in gnotobiotic calves. Necropsy of both groups of calves revealed a circular to oblong lesion that was congested, edematous, and firm, and which occupied 20% to 100% of the right caudal lung lobe and involved the remaining lung lobes to a more minor degree. When mean lesion scores of the 2 groups of calves were compared, no significant difference (P less than or equal to 0.05) was found. Microscopic examination of the lungs revealed edema of the perivascular and interlobular septa and hemorrhage in the alveoli of both groups, although the conventional group had more fibrinopurulent inflammation.

Healthy mature roosters (n = 10) were given gentamicin (5 mg/kg of body weight, IV) and, 30 days later, another dose IM. Serum concentrations of gentamicin were determined over 60 hours after each drug dosing, using a radioimmunoassay. Using nonlinear least-square regression methods, the combined data of IV and IM treatments were best fitted by a 2-compartment open model. The mean distribution phase half-life was 0.203 +/- 0.075 hours (mean +/- SD) and the terminal half-life was 3.38 +/- 0.62 hours. The volume of the central compartment was 0.0993 +/- 0.0097 L/kg, volume of distribution at steady state was 0.209 +/- 0.013 L/kg, and the total body clearance was 46.5 +/- 7.9 ml/h/kg. Intramuscular absorption was rapid, with a half-life for absorption of 0.281 +/- 0.081 hours. The extent of im absorption was 95 +/- 18%. Maximal serum concentration of 20.68 +/- 2.10 microgram/ml was detected at 0.62 +/- 0.18 hours after the dose. Kinetic calculations predicted that IM injection of gentamicin at a dosage of 4 mg/kg, q 12 h, and 1.5 mg/kg, q 8 h, would provide average steady-state serum concentrations of 6.82 and 3.83 microgram/ml, with minimal steady-state serum concentrations of 1.54 and 1.50 microgram/ml and maximal steady-state serum concentrations of 18.34 and 7.70 microgram/ml, respectively.

Light microscopy, morphometry, and scanning electron microscopy were used to examine the mucosal morphologic features of 7 intestinal specimens (3 from the small intestine; 4 from the large intestine) from each of 8 horses 1 year after sham operation (group 1; n = 3) or extensive large-colon resection (group 2; n = 5). Qualitative light microscopic examination did not reveal differences between groups, but morphometry revealed significantly (P < 0.05) greater intercrypt area and distance in horses with colon resection and this was most pronounced in the cecum and remaining right ventral and dorsal colon. Crypt area and depth were similar for horses with colon resection and sham operation (P > 0.05). Qualitative evaluation of the scanning electron micrographs revealed more prominent crypt orifices in the large intestine of horses with colon resection. The larger intercrypt distance in the colon of horses with resection was not an obvious feature of the qualitative evaluation of the surface with scanning electron microscopy. Small intestinal morphologic features were variable and significant differences were not detected between horses with sham operation and colon resection. Horses adapted to extensive large-colon resection within 1 year by increasing the absorptive (intercrypt) surface area of the remaining large intestine.

Clinicopathologic manifestations of induced infection of the feline lower urinary tract with bovid herpesvirus-4 (BHV-4, strain FCAHV) were characterized in 6 conventionally reared adult cats (2 sexually intact males, 2 castrated males, and 2 females). Two additional control cats were exposed with noninfected cell culture control inoculum. Clinical and radiographic signs of lower urinary tract disease were not observed in exposed or control cats. Microscopic hematuria was detected in urine samples collected by cystocentesis from 4 of 6 exposed cats and 1 of 2 control cats. Results of culture of urine for bacteria, mycoplasmas, ureaplasmas, and viruses were consistently negative. Low titer of serum BHV-4 (strain FCAHV)-neutralizing antibodies was detected in 4 of 6 exposed cats, but not in controls. Gross abnormalities of the urinary tract were not observed in any cat. Light microscopic examination of serial sections of the lower urinary tract revealed mild focal lymphoid cystitis in 2 of 6 exposed cats, one of which also had increased amounts of connective tissue and proliferation of blood vessels in the urinary bladder lamina propria. Ninety days after initial exposure, BHV-4 (strain FCAHV) was reisolated from explanted urinary bladder tissues of 5 of 6 exposed cats. Virus was not isolated from tissues of control cats. It was concluded that BHV-4 (strain FCAHV) establishes persistent urinary tract infection in conventionally reared adult male and female cats. However, persistent BHV-4 infection in cats may remain clinically inapparent.

The role of endotoxin in the pathogenesis of acute pneumonic pasteurellosis is uncertain. Recently, we reported that Escherichia coli-derived endotoxin given by airway inoculation fails to induce lung injury in calves. Because Pasteurella haemolytica-derived endotoxin may differ substantially from E coli in its pathogenicity, we repeated these studies with Pasteurella endotoxin. Intratracheal inoculation of P haemolytica endotoxin caused hypoxemia and increased the alveolar-arterial oxygen differences without causing hypercarbia or changes in lung mechanical properties and volumes. In contrast, IV inoculation of endotoxin caused systemic hypotension, leukopenia, gas exchange impairment, increased total pulmonary resistance, and decreased dynamic compliance. Both routes of inoculation increased serum endotoxin concentrations and were associated with areas of pulmonary hemorrhage, edema, and acute inflammation. We concluded that P haemolytica-derived endotoxin is pathogenic by IV and airway routes of inoculation, and therefore differs from E coli endotoxin in its ability to induce lung lesions in calves.

X-ray-computed tomography (CT), nephrotomography, and ultrasonography were performed in 10 clinically healthy dogs (weighing 14 to 33 kg) to visualize the adrenal glands. In all 10 dogs, CT enabled visualization of both adrenal glands. Cross-sectional diameter was measured accurately. The size and shape of CT sections of the adrenal glands varied widely because of individual differences in the actual size and shape of the adrenal glands and because of their position in the plane of the CT scans. In 5 dogs, nephrotomography enabled visualization of 1 or both adrenal glands as oblong craniocaudal-directed densities in the craniodorsal portion of the abdomen. In 7 dogs, transverse ultrasonography enabled visualization of 1 or both adrenal glands as round or oval hypoechoic structures in the surrounding hyperechoic fat.

An in vitro bioassay system was used to study the effects of cyclopiazonic acid (CPA) mycotoxin on cardiac muscle. Acute exposure to 6 microgram of CPA/ml of modified Krebs-Henseleit solution significantly (P < 0.05) decreased 5 in vitro turkey cardiac muscle performance criteria: maximal weight a muscle could lift; maximal contraction velocity; relaxation velocity; time to peak contraction; and total time for muscle contraction and relaxation. The effect on these 5 criteria appeared to result from intracellular changes partially associated with calcium availability and were irreversible, suggesting that physiologic changes had developed after acute exposure to CPA.

Fourteen ponies and 3 horses were inoculated with Ehrlichia risticii 2 to 20 months after a similar initial inoculation. Although all 17 had clinical signs of equine ehrlichial colitis after the first inoculation, 16 of 17 remained clinically normal following the second inoculation. The remaining pony had a transient fever and developed signs of depression. Before the initial inoculation, none of the animals had a detectable antibody titer to E risticii. All animals developed titers after the initial infection; however, a significant change of titer did not develop after reinoculation in most animals.

The efficacy of an ophthalmic ointment containing benzathine cloxacillin for treatment of infectious bovine keratoconjunctivitis was determined in 2 experiments. In the first experiment, Holstein calves (n = 6/group) were inoculated with Moraxella bovis and treated on postinoculation days 3 and 6 with either topically applied benzathine cloxacillin (250 mg/eye) or long-acting oxytetracycline formulation (20 mg/kg of body weight, IM). A third group of inoculated calves remained untreated as controls. For the second experiment, 4 groups of calves (n = 6/group) were inoculated and treated on postinoculation days 3 and 6 with 50, 125, 250, or 375 mg of benzathine cloxacillin; a fifth untreated group served as controls. Ocular specimens were obtained for microbiologic culture, and eyes were observed and assigned a clinical score daily. Eyes were photographed on alternate days. Ulcer surface area was measured, using a planimeter. In experiment 1, the week-2 ulcer surface area measurements for both groups of treated calves were smaller than those for controls. There was a greater frequency of M bovis isolation from the ocular secretions of controls than from those of benzathine cloxacillin-treated calves during postinoculation weeks 2 and 3. The number of M bovis isolations from the benzathine cloxacillin- and oxytetracycline-treated calves was not significantly different at any sample collection interval. On week 3, the scores of the benzathine cloxacillin-treated calves were smaller than those of controls. In experiment 2, calves of the 250- and 375-mg group had smaller scores than did controls. During postinoculation weeks 1 through 3, M bovis was isolated less frequently from the ocular secretions of calves of the 250- and 375-mg groups than from those of the control calves.

Thyroxine (T4), 3,5,3'-triiodothyronine (T3), and cortisol frequently are quantified in canine serum or plasma samples to aid in the diagnosis of hypothyroidism, hypoadrenocorticism, and hyperadrenocorticism. Many laboratories have established reliable references values for concentrations of these hormones in blood of clinically normal animals. However, nonpathologic factors that affect thyroidal and adrenocortical secretion may lead to misinterpretation of test results when values for individual animals are compared with reference values. The objective of the study reported here was to identify effects of age, sex, and body size (ie, breed) on serum concentrations of T3, T4, and cortisol in dogs. Blood samples were collected from 1,074 healthy dogs, and serum concentrations of the iodothyronines and cortisol were evaluated for effects of breed/size, sex, and age. Mean (+/- SEM) serum concentration of T4 was greater in small (2.45 +/- 0.06 microgram/dl)- than in medium (1.94 +/- 0.04 microgram/dl)- or large (2.03 +/- 0.03 microgram/dl)-breed dogs, the same in females (2.11 +/- 0.04 microgram/dl) and males (2.08 +/- 0.04 microgram/dl), and greater in nursing pups (3.04 +/- 0.05 microgram/dl) than in weanling pups (1.94 +/- 0.05 microgram/dl), rapidly growing dogs (1.95 +/- 0.04 microgram/dl), and young adult (1.90 +/- 0.06 microgram/dl), middle-aged adult (1.72 +/- 0.05 microgram/dl), or old adult (1.50 +/- 0.05 microgram/dl) dogs. Dogs > 6 years old had lower mean serum T4 concentration than did dogs of all other ages, except middle-aged adults. Mean serum T3 concentration in medium-sized dogs (1.00 +/- 0.01 ng/ml) was greater than that in small (0.90 +/- 0.01 ng/ml)- and large (0.88 +/- 0.01 ng/ml)-breed dogs. Serum T3 concentration was lowest in nursing (0.85 +/- 0.01 ng/ml) and weanling (0.77 +/- 0.02 ng/ml) pups, increased in rapidly growing dogs (0.99 +/- 0.01 ng/ml) and young adult dogs (1.10 +/- 0.04 ng/ml), and decreased slightly in middle-aged (0.98 +/- 0.02 ng/ml) and old (1.01 +/- 0.03 ng/ml) adult dogs. Serum T3 concentration was unaffected by sex. Mean serum cortisol concentration was greater in small (1.06 +/- 0.07 microgram/dl)- than in large (0.79 +/- 0.03 microgram/dl)-breed dogs. Serum from nursing pups 0.57 +/- 0.04 microgram/dl) contained less cortisol than did serum from older dogs (mean values greater than or equal to 0.92 microgram/dl). Serum cortisol concentration was not different between males and females. These effects of breed/size and age on serum T3, T4, and cortisol concentrations should be considered when evaluating thyroid and adrenocortical functions in dogs.