Reproductive effects of fenoxycarb on sheep.

Fenoxycarb (ethyl [2-(4-phenoxyphenoxy)-ethyl] carbamate) is an insect growth regulator used for long-term fire ant control. Because of its effects on insect reproduction and its potential use on pasturage consumed by food animals, a reproductive study was conducted using Rambouillet sheep. The sheep were dosed daily with a placebo or with fenoxycarb at 0.69 or 1.38 mg/kg/day, representing ten (10x) and 20 times (20x) the maximum amounts of fenoxycarb in forage or hay treated at recommended levels for fire ant control. Parameters that were measured included rates of weight gain of adults, serum clinical chemistry profiles of adults, spermatozoal morphology and motility, estrus cycling, pregnancy rates, maintenance of pregnancies to term, numbers of live births, and rates of weight gain of lambs to 28 days. There were no statistically significant (P < or = 0.05) differences between the exposed and control groups of sheep in any of these facets of the study. No clinical signs associated with exposure to fenoxycarb were observed in any animal at any time, and no exposure-related pattern of pathologic lesions or reproductive organ histology was observed. Means of hepatic fenoxycarb residues in the rams followed a statistically significant (P < or = 0.05) dose-related pattern. No fenoxycarb was detected (detection limit of 5 ppb) in any neonatal liver, despite the presence of hepatic fenoxycarb residues in the treated ewes, indicating that transplacental transport of fenoxycarb was minimal. No fenoxycarb was detected in any lamb liver at 28 days, although both the colostrum and the milk of exposed ewes were found to contain fenoxycarb at levels proportional to the treatments. Based on the lack of significant findings in this study, it is unlikely that use of fenoxycarb, according to label instructions (currently applicable to homeowner and registered agricultural usage) for fire ant control in pasturage or hay fields, will affect ruminant reproduction.

Scrotal hydrocele secondary to ascites in 28 bulls.

Twenty-eight of 104 mature bulls in a herd were examined to determine the cause of scrotal enlargement. Ascites was determined as the source of a transudate that accumulated in and expanded the scrotal vaginal cavity to induce a scrotal hydrocele. In our experience, scrotal hydrocele in mature bulls usually is caused by the accumulation of fluids in the scrotal vaginal cavity without evidence of local inflammation or traumatic lesions. In the bulls reported here, ascites was associated with intestinal edema that was tentatively attributed to a hypersensitivity reaction to gastrointestinal nematodes. Ascites in mature bulls with scrotal hydrocele in which primary lesions of the scrotum and scrotal contents are not detected should induce practitioners to perform additional diagnostic procedures to determine the cause of the fluid.

Generalized lymphangiectasis in a dog with subcutaneous chyle and lymphangioma.

A 2 1/2-year-old spayed Great Dane was evaluated for large, fluctuant, chyle-containing swellings on the ventral portion of the left side of the abdomen. Multiple abnormalities of the lymphatic system were diagnosed, including thoracic duct obstruction, lymphangioma, subcutaneous chyle reflux, intestinal lymphangiectasia, and dilatation of hepatic, mesenteric, and pleural lymphatic vessels. Mesenteric lymphangiography revealed leakage of contrast medium into the subcutaneous tissues adjacent and to the left of the second lumbar vertebral body. Dietary and surgical management to control the chylous reflux were unsuccessful, and the dog died approximately one year after the skin lesions were first observed.

A toxicological investigation of the garden shrub Brunfelsia calcyina var. floribunda (yesterday-today-and-tomorrow) in three species.

Brunfelsia calcyina var. floribunda is an ornamental evergreen shrub found in the United States. A diagnosis of the fatal intoxication of a canine due to consumption of plant material (primarily berries) was made. The significant features of the clinical constellation were similar to those seen with substances interfering with the neurotransmission process, such as lathyrus or strychnine. Necropsy findings on the canine were unrevealing. Toxicologic studies performed on mice and rats with ground shrub material demonstrated that all parts of this plant are toxic, but unequally so. All plant preparations produced signs similar to those of a spinal convulsant. There were no distinguishing gross pathologic or histopathologic findings associated with the toxicoses induced in the laboratory animals with preparations from this plant. The toxic principles from this shrub are water soluble and very stable. The ability of aqueous extracts stored at 4 C to produce the clinical syndrome and subsequent lethality remained unchanged over a period of 4 months. Exposures are not always fatal. They most often occur in the canine and there is a significant hazard for small children.

Rhodococcus equi foal pneumonia: protective effects of immune plasma in experimentally infected foals.

The immunoprophylactic capacity of specific immune plasma was evaluated in pony foals infected experimentally with Rhodococcus equi. Immune plasma, produced by repeated parenteral administration of viable R. equi to adult horses, was harvested and frozen. Group I (six control foals) and Group II (six principal foals) received lactated Ringers solution and immune plasma respectively at three and five days of age. R. equi were aerosolised into a caudal lung lobe of all foals at seven days of age. Clinical signs, haematological alterations, immune responses, thoracic radiographs and technetium99m pulmonary perfusion scans were monitored. All foals were destroyed and complete post mortem examinations performed. All foals developed pneumonia as evidenced by clinical, radiographic and perfusion alterations, but the survival rate of principal foals was significantly (P less than 0.01) greater than that of control foals. Five control foals developed terminal disease, whereas all principal foals recovered. There was no significant (P greater than 0.05) difference in temperature response, or peripheral blood leucocyte, neutrophil or fibrinogen concentrations between groups. ELISA values for R. equi antibody were significantly (P less than 0.001) greater in principal foals following treatment, but there was no significant (P greater than 0.05) difference in IgG or IgM concentrations between groups. Results of the haemolysis inhibition assay indicated that equi factor neutralising antibodies were transferred by immune plasma to the principal foals. Post mortem examinations of five control foals destroyed at approximately three weeks post infection because of terminal disease, revealed severe pyogranulomatous pneumonia. One control and all principal foals were either free of lesions or had resolving lesions and/or minimal scar formation at three months post infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimentally induced photosensitization in cattle with Cooperia pedunculata.

Photosensitization was induced in 2 Charolais heifers following administration of a mixture of air-dried, ground, green (75%) and dead (25%) leaves of the south Texas forb, Cooperia pedunculata, and subsequent exposure to sunlight. Plant material used in this study was collected from a pasture where natural cases of primary bovine photosensitization were occurring. Signs of photosensitization were observed in one heifer after 2 doses of plant material--10 g/kg on day 1 and 5 g/kg on day 2. Continued administration of plant material at 5 g/kg/d on days 3, 4, 7, 8, and 9 resulted in severe signs and lesions of photosensitization and death on day 23. A second heifer developed signs of mild photosensitization following administration of plant material at 1.7 g/kg/d for 4 days. This heifer recovered by day 18. Clinical and pathologic findings of this trial were consistent with the primary form of photosensitization observed in natural cases seen in cattle of south Texas exposed to this plant.

Immune responsiveness and lymphoreticular morphology in cattle fed hypo- and hyperalimentative diets.

Immune responses and lymphoreticular morphology were studied in 3 groups of yearling Hereford steers fed hypoalimentative, maintenance and hyperalimentative diets for 142 days. Significant decreases in plasma protein levels and circulating lymphocyte levels occurred in low energy intake steers. Percent circulating lymphocytes bearing surface immunoglobulins and serum levels of IgG and IgM did not vary significantly within or between groups. Antibody responses to Brucella abortus bacterin inoculated on day 63 were similar in all 3 groups. Antibody responses to chicken erythrocytes inoculated on day 88 were significantly lower in hypoalimentated steers. Differences between groups in lymphocyte blastogenic responses to phytohemagglutinin (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM) were not significant. Hyperalimentated steers had significantly depressed PWM responses compared to a baseline value established for that group. In addition, hypoalimentated steers tended to have elevated responses to PHA, although differences were not significant. There were no significant differences between groups in dermal hypersensitivity responses to tuberculin following sensitization with viable Bacillus Calmette-Guerin (BCG). The thymuses of hypoalimentated steers were markedly atrophied but lymph nodes and splenic white pulp were normal. Thymus, lymph nodes and spleen were normal in hyperalimentated steers.

Catastrophic death losses in a dairy herd attributed to type D botulism.

Clostridium botulinum type D intoxication was diagnosed as the cause of death of 42 of 67 lactating cows in a southeast Texas dairy herd over an 11-day period. By necessity, the diagnosis was based on clinicopathologic findings, as the toxin could not, by standard laboratory tests, be demonstrated in affected cattle. The predominant clinical findings were hindlimb weakness/ataxia rapidly progressing to persistent recumbency. Affected cattle were alert until just before death, which occurred without notable agonal movements or respirations after 6 to 72 hours' recumbency. Abnormal laboratory findings included neutrophilic leukocytosis (all affected cattle), proteinuria (most affected cattle), slight elevations of serum aspartate transaminase and low serum inorganic phosphorus (some affected cattle), and patchy areas of hyperemia/congestion of the mucosa in the small intestine (postmortem examination of 3 affected cattle). This report confirms the findings of others with regard to the difficulty of demonstrating the causative toxin in C botulinum type D-intoxicated cattle and presents available information on the clinicopathologic features of this intoxication that may aid in the differentiation of this condition from other causes of down cows.

Experimental subacute foal pneumonia induced by aerosol administration of Corynebacterium equi.

Subacute pyogranulomatous pneumonia was experimentally induced in 3 neonatal foals following multiple challenge with aerosols containing Corynebacterium equi. On each of 7 consecutive days the foals were exposed to approximately 3.5 X 10(7) viable C equi in droplets small enough to reach the terminal airways. Clinical, pathological and bacteriological features of the induced syndrome were indistinguishable from those exhibited by cases with spontaneous subacute C equi foal pneumonia. Radiographic evidence of advanced pulmonary damage preceded the appearance of clinical signs and ante mortem cultures were not consistent in determining the presence of C equi infection. As observed in spontaneous cases of C equi foal pneumonia, there was lymphocytic hyperplasia in the T-dependent paracortical areas of bronchial lymph nodes and spleen, and granulomatous pulmonary lesions. These histological changes suggested predominant stimulation of cell-mediated immune processes in C equi infected foals. Lesions were restricted to the lungs and pulmonary lymph nodes and C equi was recovered from each foal's lung tissue at necropsy; the organism was also cultured from the trachea, mediastinal lymph nodes, mesenteric lymph nodes and caecal contents of one foal and from the liver of another foal. Three control foals exposed to saline did not develop evidence of pneumonia.

Disseminated necrotizing panniculitis and pancreatic nodular hyperplasia in a dog.

An 8-year-old female Poodle had severe necrotizing skin disease characterized by numerous large red-purple, nonpruritic lesions. The larger lesions had soft, intensely discolored centers that contained sterile viscous blood-tinged material. Biopsies of the lesions revealed necrotizing panniculitis (subcutaneous fat necrosis). The dog did not respond to intensive therapy and euthanasia was performed. Necropsy findings included diffuse fat necrosis and pancreatic nodular hyperplasia. A pathoetiologic relation between pancreatic disease and diffuse fat necrosis in this dog was suggested.

Effect of immunosuppression on the genetic resistance of A2G mice to neurovirulent influenza virus.

A2G mice are genetically resistant to lethal infection with neurotropic and pneumotropic influenza viruses. A possible immunological explanation for this resistance was sought by assessing the effect of cyclophosphamide and X irradiation immunosuppression on the infection of A2G mice with lethal doses of neurovirulent virus. Immunosuppressed A2G mice survived lethal infection enen though rendered unable to produce specific antiviral antibody or to generate cell-mediated delayed-type hypersensitivity responses. Measurement of infectious virus replication and detailed observation of the infection by immunofluorescence microscopy show that immunosuppression does not potentiate or allow spread of the virus in A2G brains. Interferon levels were essentially the same in normal and immunosuppressed A2G brains but were 3 to 5 times lower than in the brains of susceptible mice dying of the infection. The results strongly suggest that the genetic resistance of A2G mice to the acute lethal effects of neurovirulent influenza virus infection does not depend on the induction of primary immune mechanisms as we currently understand them. Other possible explanations for this resistance are considered.