From 2 to 4.5 months of age, 80 crossbred gilts were reared in a conventional grower unit where they were naturally exposed to mycoplasmal and bacterial pathogens that cause pneumonia and atrophic rhinitis. At 4.5 months of age, gilts were moved to environmentally regulated rooms (4.9 X 7.3 m) and assigned at random to 1 of 2 treatment groups: low aerial concentration of ammonia (4 to 12 ppm; mean, 7 ppm) or moderate aerial concentration of ammonia (26 to 45 ppm, mean, 35 ppm). Low concentration of ammonia was obtained by flushing of manure pits weekly, whereas moderate concentration of ammonia was maintained by adding anhydrous ammonia to manure pits that were not flushed. Gilts were weighed biweekly. Mean daily gain (MDG) was less (P < 0.01) for gilts exposed to moderate concentration of ammonia than for gilts exposed to low concentration of ammonia after 2 weeks in their respective environments. By 4 and 6 weeks, however, MDG was similar between the 2 treatment groups. After 6 weeks in these environments, 20 gilts from each treatment group were slaughtered, and prevalence and severity of lung lesions and snout grades were determined. At slaughter, body weight was greater (P < 0.01) in gilts exposed to low, rather than moderate, ammonia concentration (94.5 vs 86.8 kg; SEM, 3.3 kg). Percentage of lung tissue containing lesions (18 vs 12) and snout grade (2.8 vs 3.1) were similar between gilts exposed to low or moderate concentration of ammonia. The remaining 20 gilts in each treatment group were maintained in their respective environments, exposed daily to mature boars and bred at first estrus. Age at puberty was similar between gilts exposed to low or moderate concentration of ammonia (208 vs 205 days; SEM, 1.3 days), even though weight at puberty was less (P < 0.03) for gilts exposed to low concentration of ammonia than for gilts exposed to moderate concentration of ammonia (109.7 vs 118.2 kg; SEM, 4.5 kg).

Fifteen isolates of Escherichia coli obtained from the blood and tissues of septic foals had plasmid DNA of size ranging from 2.5 to 93 megadaltons. These isolates grew in normal equine serum (serum resistant), a trait previously documented to be expressed by isolates obtained from blood and tissues of septic foals, but not by isolates obtained from the feces of clinically normal horses. Of these isolates, 3 contained conjugal plasmids that encoded resistance to multiple antimicrobial agents linked to serum resistance and, in 1 isolate, to production of aerobactin as well. Serum resistance and production of aerobactin are related to virulence of septicemic E coli from non-equine sources.

The association between ocular squamous cell tumors and various measures of solar radiation was evaluated for 2,775 contemporaneous Hereford cattle. The animals were from 34 herds located in 21 states in the United States and in one Canadian province. Examinations and photographs were made of the eyes of all cows and heifers in a herd; 33 herds were examined between June and August 1957 and 1 herd was examined in 1958. Solar radiation was measured by altitude and mean annual hours of sunshine applying to an individual herd, and global radiation, a cloudiness index, and elevation of nearby National Weather Service stations. All measures of solar radiation provided evidence of a significant association between increasing risks of developing cancer eye and increasing levels of radiation; adjustments were made for possible confounding effects of age and corneoscleral pigmentation. Associations were evident whether affliction was defined as the occurrence of any type of tumor (ie, plaque, papilloma, or carcinoma), or as the occurrence of only papilloma or carcinoma. Average ages of affected cattle also tended to be lower at high radiation levels than at low levels, further supporting the hypothesis that solar radiation has an important role in the development of this disease. In view of the heritability of eye pigmentation and its inhibitory effect on lesions, cancer eye may be controlled by selective breeding for increased pigmentation in and around the eye to afford protection against the harmful effects of incident UV radiation.

Concentrations of total, free, and esterified carnitine were determined in plasma, liver, and skeletal muscle from cats with idiopathic hepatic lipidosis and compared with values from healthy cats. The mean concentrations of plasma, liver, and skeletal muscle total carnitine; plasma and skeletal muscle free carnitine; and plasma and liver esterified carnitine were greater (P < 0.05) in cats with idiopathic hepatic lipidosis than in control cats. The mean for the ratio of free/total carnitine in plasma and liver was lower (P < 0.05) in cats with idiopathic hepatic lipidosis than in control cats. These data suggest that carnitine deficiency does not contribute to the pathogenesis of feline idiopathic hepatic lipidosis.

Lumbar and thoracic vertebrae of the extinct horse, Equus occidentalis, were examined for gross and radiographic evidence of overriding spinous processes. Of 2,661 vertebrae examined, 580 had intact spinous processes. Thirty-six intact spinous processes, which appeared grossly similar to overriding spinous processes in the modern domestic horse, E caballus caballus, were radiographed. Of these 36 vertebrae, 2 had radiographic signs compatible with a radiographic diagnosis of overriding spinous processes, ie, radiographically observed lysis and/or sclerosis. Seemingly, weight bearing or other stresses imposed by human beings may not have induced the signs of overriding spinous processes.

The effect that topical administration of cyclosporine would have on the number and type of microorganisms isolated from the corneal surface of dogs with keratoconjunctivitis sicca was studied. Schirmer tear tests were performed on and corneal swab specimens were collected from 61 eyes of 31 dogs with keratoconjunctivitis sicca prior to and after 3, 6, and 12 months of treatment with cyclosporine. In eyes that responded to cyclosporine treatment (Schirmer tear test value increased by greater than or equal to 5 mm/min, compared with pretreatment value), the percentage of eyes from which bacteria were isolated after 3, 6, and 12 months of treatment was significantly (P < 0.001) less than the percentage from which bacteria were isolated prior to treatment. However, among eyes that did not respond to treatment, we did not detect a significant change over time in prevalence of bacteria or type of bacteria isolated. The percentage of eyes from which fungi were isolated decreased during treatment; however, the small number of eyes in which fungal culture results were initially positive precluded demonstration of a significant change. For all eyes, we did not detect any significant differences over time in the frequency with which specific bacterial genera were isolated, with the exception of beta-hemolytic Streptococcus spp. Opportunistic corneal infections were not detected even though none of the dogs received antibiotics. An increase in production of tears, which contain anti-infection proteins, was believed to be the primary factor responsible for the decrease in the percentage of eyes from which microorganisms could be isolated.

We studied the uptake and sequential transneuronal passage of pseudorabies virus (PRV) in rat CNS by use of a combination of immunohistochemistry and in situ hybridization. Protocols for rapid detection of PRV by immunohistochemistry and in situ hybridization in rats with PRV infection of the CNS after intranasal instillation of a wild-type strain of PRV were optimized in vitro, using porcine kidney-15 cells. Pseudorabies virus-specific hybridization signals appeared in the cytoplasm and nucleus of PRV-infected porcine kidney-15 cells by postinoculation (PI) hour 6. In tissue sections of PRV-infected rats, PRV nucleic acids were detected in areas of the rat brain in close proximity to the areas in which PRV antigens were evident. The PRV was initially found in the nucleus of trigeminal ganglion neurons at PI hour 24. At PI hour 72, PRV antigens were observed in the mid-brain, and 24 hours later, in the telencephalon. We also found evidence of specific progressive transsynaptic transmission of the virus, and, on the basis of that, we have constructed a map of the synaptic contacts and pathways in the brain. Therefore, combined use of immunohistochemistry and in situ hybridization was useful for characterizing the pathogenesis of PRV in the CNS of rats after intranasal inoculation, following a pattern that mimics PRV infection of the natural host.

Three laparoscopic procedures were performed on each of 6 adult jersey cows in the first trimester of gestation to describe normal laparoscopic anatomy of the bovine abdomen. Also, a technique for laparoscopy of the cranioventral portion of the abdomen was described. Right paralumbar fossa, left paralumbar fossa, and cranioventral midline laparoscopy were performed 72 hours apart on each cow. Physical examination findings, CBC, serum biochemical analysis, and peritoneal fluid analysis before and 72 hours after the first surgery were used to assess the effects of the procedures on the cows. Exploratory celiotomy was performed 2 weeks after the last laparoscopy. The cows were then reexamined 6 weeks after the last procedure. The t-test for paired data was used for statistical analysis; the level of significance was P < 0.05. Laparoscopy was performed without complication in all cows. Adverse effects of laparoscopy, individually or serially, were not observed. Significant differences were not found between CBC, serum biochemical, and peritoneal fluid variables taken before and 72 hours after surgery.

Lymphoscintigraphic evaluation of the thoracic duct (TD) was performed in 10 healthy and 12 dogs with experimentally created TD abnormalities (6 dogs with TD lacerations and 6 dogs with cranial vena ligations). Complete imaging took 4 hours and caused no adverse effects or complications. Lymphoscintigraphy of healthy dogs failed to image the TD; however, background activity in the abdomen and thorax, and radioactivity in the kidneys, bladder, liver, and heart were noticed. Lacerations and transections of the TD were experimentally created, in 6 dogs to ascertain whether TD rupture could be detected with lymphoscintigraphy. Lymphoscintigraphy was performed within 48 hours of creating the TD defect. There was no significant difference in the scintigraphic pattern of healthy dogs and those with experimentally created TD defects. Ligation of the cranial vena cava was performed in 6 dogs; 3 dogs developed chylothorax. In those 3 dogs, diffuse radioactivity was imaged in the thorax and was compatible with thoracic lymphangiectasia. In one of these dogs, linear activity consistent with the TD and localized regions of radioactivity cranial to the heart (compatible with the mediastina lymph nodes) were noticed. Lymphoscintigraphic findings in these dogs correlated with lymphangiographic findings.