Epidemiology of Mycoplasma bovis in Pennsylvania veal calves.

The objective of the study was to estimate the prevalence and incidence of Mycoplasma bovis, a common cause of pneumonia, in veal calves. Using simple random sampling, 252 calves from 4 veal herds located in central Pennsylvania were selected and longitudinally followed for monthly collection of nasal swabs. Bronchial swabs and lung lesions were collected at the slaughterhouse. Nasal, bronchial, and lung lesion swabs were cultured for bacterial respiratory pathogens. Ninety lung lesions were identified, of which 41.1, 1.1, 1.1, 7.8, and 4.4% were culture positive for M. bovis alone, Pasteurella multocida alone, Mannheimia haemolytica alone, M. bovis and P. multocida co-infection, and M. bovis and M. haemolytica co-infection, respectively. The data indicate that potential interventions, such as therapeutics, vaccines, or management control measures, would be most effective before 50 d of age based upon the cumulative incidence of colonization.

Neosporosis-associated bovine abortion in Pennsylvania.

Neospora caninum was found in fetal tissues of 34 of 688 cases of bovine abortion submitted to the Pennsylvania Animal Diagnostic Laboratory System during the period from May 1994 to November 1996. The aborted fetuses ranged in gestational age from 3 to 8 months. Microscopic lesions consisted primarily of encephalitis and myocarditis. A labeled (strept) avidin-biotin staining procedure using anti-N. caninum polyclonal rabbit serum revealed N. caninum organisms within the fetal brain (27 of 27), heart (10 of 13), placenta (5 of 6), kidney (2 of 2), liver (1 of 4) and skeletal muscle (1 of 1).

Use of a hypobaric chamber as a model system for investigating ascites in broilers.

In a series of experiments, broilers were reared at simulated altitudes of 3000, 3500, and 5000 meters utilizing a hypobaric chamber. The purpose was to evaluate the chamber as a model for ascites syndrome and to further study the pathophysiology of this disease. Results show that this model can effectively reproduce the disease as it is seen in the field. Birds reared at the simulated altitude of 5000 meters had a statistically significant increase in EKG amplitude, packed cell volume, and heart-to-body-weight and lung-to-body-weight ratios when compared with controls reared at 366 meters. Additionally, there was a trend for birds dying of ascites to have larger-amplitude EKGs than survivors when reared at 5000 meters.

Ureteral fibropapilloma in a dog.

A fibropapilloma was found to involve the left ureter in a 7-year-old castrated male Doberman Pinscher dog. Severe unilateral hydronephrosis and hydroureter were associated with the ureteral mass. Treatment consisted of unilateral nephrectomy and ureterectomy. This case represents an additional type of primary ureteral neoplasm found in the dog.

Pulmonary aspergillosis associated with acute enteritis in a horse.

Invasive pulmonary aspergillosis was detected at postmortem examination of an 8-year-old Quarter Horse mare that had a history of diarrhea, laminitis, and bilateral nasal discharge. A diagnosis of Ehrlichia risticii infection was made on the basis of clinical signs of diarrhea and pyrexia, high serum antibody titer to E risticii (1:2,560), and multiple Salmonella-negative cultures obtained from fecal and colonic specimens. Possible pathogenic mechanisms contributing to the development of pulmonary aspergillosis secondary to enteric disease include mycotic invasion of the intestinal tract or immunocompromise and tissue devitalization secondary to severe enterocolitis. Exposure of the mare to large numbers of Aspergillus organisms may have been important in this case.

Neonatal Neospora caninum infection in dogs: isolation of the causative agent and experimental transmission.

Neospora caninum infection was diagnosed in 5 young dogs from 2 litters with a common parentage. The pups were born healthy, but developed hind limb paresis 5 to 8 weeks after birth. The predominant lesions were polyradiculoneuritis and granulomatous polymyositis. Neospora caninum was seen microscopically in sections of naturally infected pups, and was isolated in cell cultures, mice, and dogs inoculated with infected canine tissues. Antibodies to N caninum were detected in sera of infected dogs by indirect fluorescent antibody test.

Results of using histologic examination and acid-fast staining to confirm a diagnosis of swine mycobacteriosis made on the basis of gross examination.

Overall, 74% of the tissue specimens that meat inspectors at a large Pennsylvania packing plant identified as lesions of swine mycobacteriosis yielded Mycobacterium avium on bacteriologic culture. Histopathologic lesions compatible with mycobacteriosis were identified in 83% of the specimens; only 12% of the specimens had acid-fast staining organisms.

Clostridium piliforme infection in two farm-raised white-tailed deer fawns (Odocoileus virginianus) and association with copper toxicosis.

Necropsy of 2 white-tailed deer fawns who died acutely revealed diarrhea and melena in case No. 1 and no gross changes in case No. 2. Histologically, the livers of both deer displayed multifocal coagulative necrosis, with infiltrations of neutrophils, macrophages, and lymphocytes. By Warthin-Starry staining, bundles of filamentous bacteria were identified within hepatocytes at the periphery of the necrotic foci in case No. 1. There was multifocal myocardiocyte necrosis in case No. 1 and multifocal lymphoid necrosis of the Peyer's patches in case No. 2. Clostridium piliforme 16S ribosomal ribonucleic acid gene was detected in both livers by polymerase chain reaction (PCR) with C. piliforme-specific primers. The liver copper levels in both cases were normal to slightly elevated. The kidney copper level in case No. 2 was elevated. This represents the first published cases of Tyzzer's disease in deer, a novel use of PCR for the diagnosis of C. piliforme infection, and a possible association between copper toxicosis and Tyzzer's disease.

Echocardiographic detection of tetralogy of Fallot and myocardial abscesses in a calf.

A 4-month-old Holstein bull was examined because of a loud heart murmur and recurring fever. The calf was polycythemic and became cyanotic following and mild exercise. A tetralogy of Fallot was diagnosed echocardiographically. Echo-free spaces were delineated in the left ventricle and interventricular septum. These fluid filled spaces were documented as myocardial abscesses on post-mortem examination.

Morphometric and histologic changes in the pulmonary system of broilers raised at simulated high altitude.

Broilers were reared in conditions of hypobaric hypoxia (3500 m altitude) to investigate the development of pulmonary nodules in birds reared in hypobaric hypoxia and judged by clinical observation to be developing broiler pulmonary hypertension syndrome (BPHS); in unaffected birds reared in hypobaric hypoxia; and in birds reared at ambient atmospheric pressure. Gross pulmonary morphometric measurements, packed cell volume, electrocardiogram QRS amplitude and body weight also were compared among the three experimental groups. Results indicate that hypobaric hypoxia alone exercised little influence on the development of pulmonary nodules. Nodule numbers per section and nodule area per section were numerically greater in birds reared in hypobaric hypoxia, but there were no consistent significant differences in nodule numbers in birds which developed BPHS. As expected, absolute lung length, inter-rib distance and lung volume increased significantly with increasing age and size; but when these parameters were expressed as a function of body weight, they decreased with increasing age. Again, intergroup differences were inconsistent. Packed cell volume and electrocardiogram QRS amplitude were significantly increased in birds reared in hypobaric hypoxia.

Detection of viral antigen following exposure of one-day-old chickens to the Holland 52 strain of infectious bronchitis virus.

One-day-old specific-pathogen-free single comb White Leghorn chickens were inoculated by eyedrop with either 0.1 ml of phosphate buffered saline containing 10(4.3) EID50 of the Holland 52 strain of infectious bronchitis virus or normal allantoic fluid. Trachea, caecal tonsils and kidneys were removed from randomly selected birds at 0, 3, 5, 7 and 10 days post-inoculation (pi) and the presence or absence of viral antigen was detected utilizing virus isolation (VI), an indirect fluorescent antibody technique (IFA), or a streptavidin-biotin immunohistochemical (IH) technique. The presence of viral antigen as detected by the IH technique was also compared to histopathological changes in serial sections stained with haematoxylin and eosin. Detection of viral antigen occurred more frequently with VI than with IFA or IH. The IFA and IH techniques detected viral antigen with about the same frequency. Viral antigen was detected in the mucosa and submucosa of the trachea as early as 3 days pi, reached maximum levels at 5 days pi, and could still be detected in the mucosa at 10 days pi. In the kidney, viral antigen was not detectable by IFA or IH at 3 days pi, but could be visualized in distal convoluted tubules and collecting tubules at 5 days pi. At 7 days pi, antigen was detectable in the proximal convoluted tubules also. The presence of antigen in the caecal tonsils was sporadic, but it was detected in histiocytic cells and, occasionally, lymphoid cells of that organ.