Stanley P. Snyder

Pathology of Campylobacter jejuni abortion in sheep.

Campylobacter jejuni was inoculated intravenously into pregnant ewes on gestation days 114 and 123 to reproduce ovine abortion. All ewes aborted 7–12 days post-inoculation. High numbers of C. jejuni were isolated from ewe tissues (caruncle, bile, cecal feces), fetal tissues, and placenta. C. jejuni colonies were identified in caruncles and placenta by light microscopy and immunoperoxidase techniques. Histologically, inoculated ewes had a severe purulent endometritis with vasculitis. Placentas from inoculated ewes and field cases showed necrosis and purulent inflammation; however, placentas from inoculated ewes had large numbers of bacterial colonies compared to few bacteria found in field cases. Histologically, only one fetus from the inoculated ewes showed lesions (purulent bronchopneumonia), whereas all fetuses from field cases had a distinct bronchopneumonia, and one fetus showed multifocal hepatic necrosis. These results suggest that C. jejuni (serotypes Penner 1 and Lior 2) is an important abortifacient organism for sheep.

Multifocal polioencephalomyelomalacia in Simmental calves with elevated tissue aluminum and decreased tissue copper and manganese

A spectrum of related malacic disorders called Simmental multifocal symmetrical encephalopathy have been reported in Simmental and Simmental crossbred cattle in Canada, Australia, and New Zealand. 3 The cause of this condition is unknown. We describe multifocal polioencephalomyelomalacia in Simmental calves reared in Oregon, USA, with morphologic lesions similar to those described in Simmental multifocal symmetrical encephalopathy. These calves also had elevated tissue concentrations of aluminum and deficient hepatic copper and manganese concentrations, which may be related to this condition. Four 7-month-old bull calves from a herd of 135 Simmental cows developed paresis, ataxia, and knuckling over of both hind limbs that progressed over a 2-month period to inability to rise. During the previous 2 years, 3 calves similarly affected died. Affected calves remained bright and alert and maintained the ability to suckle. Antibiotic therapy was not beneficial, and complete blood count and serum chemistry profiles were normal in the 3 calves evaluated. Two of the calves were presented to the Oregon State Veterinary Diagnostic Laboratory for postmortem examination. Significant lesions were limited to the central nervous system, with secondary mild symmetrical atrophy of the rear limb muscles. Grossly, oblong to circular foci of malacia of various sizes (up to 1 cm diameter) were seen throughout the gray matter of the brain. Similar gross lesions were within the gray matter of the lumbar spinal cord in 1 of the calves. Microscopically, these lesions were cavitated and were composed almost entirely of necrotic debris (Fig. 1). Scattered viable neuroglial cells were within these foci but neurons were not observed. Microgliosis, astrocytosis (including gemistocytes), active neuronal necrosis, ischemic neuronal changes, and vasculitis were not observed. Vessels were prominent within the lesions, principally because of hypertrophy of endothelial nuclei. Neurofibrillary tangles and/or extensive demyelination were not observed in multiple Bodain- and Luxol fast blue-stained histologic sections. The histopathologic changes were markedly uniform throughout the affected foci. The distribution of brain lesions was essentially identical in the 2 affected calves. The gray matter lesions of the brain involved numerous nuclei but invariably extended beyond nuclear boundaries. Individual lesions often involved more than 1 nucleus with some extension into the adjacent white

Dietary pyrrolizidine (Senecio) alkaloids and tissue distribution of copper and vitamin A in broiler chickens.

The effect of feeding a diet containing 5% tansy ragwort (TR) (Senecio jacobaea), a poisonous plant containing pyrrolizidine alkaloids (PA), on the blood and liver levels of copper, zinc, iron and vitamin A in broiler chicks was examined. Serum and liver copper and liver iron concentrations were increased in chicks fed a diet with 5% TR, while serum and liver zinc and vitamin A decreased. When PA were removed from the diet, partial restoration of normal serum vitamin A level occurred, indicating that the ability to mobilize liver vitamin A is not irreversibly inhibited by PA. The decline in serum vitamin A occurred by 8 days of TR feeding with a concurrent decline in growth rate. When chicks were fed a diet high in vitamin A (25,000 IU/kg), followed by a basal diet containing TR, serum vitamin A levels were significantly (P < 0.01) decreased, while liver vitamin A level increased. This indicates that mobilization of previously stored vitamin A from the liver is impaired by PA. Prior feeding of a high vitamin A level resulted in protective effects against PA toxicity, as assessed by histopathology. This study shows that a dietary source of PA modifies metabolism and tissue distribution of minerals and vitamin A.

Measurement of IgG Concentration in Ovine Fetal Fluids: A Useful Diagnostic Test

The Veterinary Diagnostic Laboratory at Oregon State University received 172 aborted ovine fetuses during the 1985–1987 lambing seasons; from 120 of these, body fluids were evaluated for IgG levels. Fifty-two (43%) of the fetal fluids had immunoglobulin G (IgG) levels greater than 15 mg/dl. Forty-five (87%) of the fluids with elevated IgG levels were confirmed or presumed toxoplasma or Chlamydia abortions. A mean fetal fluid IgG concentration of 111.5 ± 78 mg/dl was found for the 26 toxoplasma abortions; for the 19 Chlamydia abortions, a mean IgG concentration of 109 ± 91 mg/dl was found. Antibody titers equal to or greater than 1:40 against Toxoplasma gondii were detected in 23 fetal fluids. Fetal fluid IgG concentration less than 15 mg/dl was found to be associated with bacterial organisms (i.e., Campylobacter sp.) as the confirmed or presumed cause of abortion. These results suggest that measurement of fetal fluid IgG concentration is a useful, supportive diagnostic test in determining the cause of ovine abortion, and should be included as a routine laboratory procedure for ovine abortion diagnosis.