Biomedical subjects
Publications and source records attributed to R L Morter.
Systemic infection of mature beef cows with Salmonella typhimurium resulted in death of cows, abortions, and premature births. Salmonella typhimurium was isolated from the kidney, liver, and spleen of cows but not from an aborted fetus. Diarrhea was not a prominent clinical feature of the epizootic. The source of the salmonella was not determined.
Pasteurella haemolytica isolates, obtained from cattle with respiratory tract disease, were characterized as to serotype, antimicrobial susceptibility, and plasmid content. Strains isolated from 2 groups of cattle were compared. Remarkable similarity was seen in the plasmid profiles of isolates of the same serotype. In contrast, isolates of 2 different serotypes had totally different plasmid profiles.
Porcine necrotic ear syndrome is a disease of swine characterized by large erosive lesions at the margin of the pinna(e). The gross and microscopic characteristics of the lesions were studied in 38 pigs selected from eight affected swine herds. The progression of the lesions was examined in a herd of 174 weaned pigs in a total confinement nursery. The lesions began as a superficial vesicular dermatitis associated with superficial auricular trauma and progressed to become exudative and encrusted. Localized lesions slowly healed or sporadically progressed to deep necrotic ulcers. The early lesions resembled the epidermal changes produced by Staphylococcus hyicus. Deep ulceration and necrosis was attributed to the invasion of streptococci into the dermis resulting in cellulitis, vasculitis, thrombosis, ischemia, and necrosis.
A genetically engineered monoclonal antibody, given PO to calves within 12 hours of birth, reduced the severity of diarrhea caused by enterotoxigenic K99 E coli. In challenge studies, dehydration and deaths were markedly reduced in treated calves vs untreated controls (29% vs 82%, 28% vs 82%). Use of the antibody in double-blind field trials on dairy calves in 9 herds in 5 states markedly reduced the severity of E coli diarrhea.
Serological evidence with or without clinical signs of neonatal isoerythrolysis was experimentally produced in 6 of 8 foals born to mares allo-immunized with washed erythrocytes from the stallion. Blood group antigens were determined in all mares, stallions and foals, and the incompatible antigenic factor(s) responsible for the disease were defined. In 5 of 8 foals born to alloimmunized mares, a single antigenic factor difference accounted for the erythrocyte incompatibility between mare and foal. The erythrocyte antigen suspected as the most responsible for isoerythrolysis observed was A1. Agglutinin and hemolysin titers were measured in mare serum and colostrum. Of the presuckle anti-foal erythrocyte titers, colostral and hemolysins titers were greater than serum and agglutinin titers respectively. Foals were allowed to nurse and treatment of affected foals was not attempted which allowed full expression of disease and outcome.
A series of modified (field) tests were compared to a crossmatch between mare and foal for their reliability in predicting neonatal isoerythrolysis (NI) in eight foals born to experimentally alloimmunized mares. In the field tests, mare's serum, plasma and colostrum were combined with foal erythrocytes washed by a modified procedure to determine which combination was the best predictor of impending NI. A consistent grading system for agglutination and hemolysis was employed. The field tests using mare's plasma demonstrated less agglutination and hemolysis than tests where serum was employed. Immediate assessment of agglutination failed to demonstrate agglutinin activity when compared to tests where incubation was included. Rouleaux formation posed a problem in interpretation of minor agglutination, however the grading of hemolysis was simpler, quicker, and more accurate. The field test that was most reliable when compared to the crossmatch and presuckle anti-foal erythrocyte titers in demonstrating agglutinins was the combination of mare's serum and foal's erythrocytes. The tests for hemolysin detection in serum and colostrum which incorporated rabbit sera as a complement source were also reliable.
Three hundred and six heifers were randomly assigned to treatment groups in a three by six factorial design. Treatments were ovariectomy, melengestrol acetate (MGA), manual abortion, intramuscular estradiol cypionate (ECP) or Prostaglandin F2alpha and untreated controls. The Average Daily Gain (ADG) of the Ovariectomized Group was less (p < .01) during the first 24 days and not different (p > .05) for the total feeding period. Feed intake of the Ovariectomized Group was less (p < .05) than Manual Abortion, Prostaglandin or Control Groups during the first 24 days but essentially the same (p > .05) for the total period. The Prostaglandin Group required fewer days to reach slaughter condition than the Ovariectomy or MGA Groups (p < .05). The only difference in the cost/benefit analysis was in the direct cost of the treatments. Factors other than the various treatments interrupted many pregnancies. The effects of treatments varied with 100% of pregnancies terminated only in the Prostaglandin F2alpha Group.
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The cold hemagglutinin which appears after leptospiral infection of sheep was isolated consistently from the plasma by absorption to autologous erythrocyte stroma at 4 C and subsequent elution at 25 C. Immunoelectrophoretic tests disclosed that the purified preparations consisted primarily of a single detectable component with the electrophoretic, positional, and antigenic characteristics of ovine immunoglobulin M. The properties of the cold hemagglutinin included a rapid sedimentation rate, elution in the leading peak from G-200 Sephadex, high anionic-binding capacity, and rapid electrophoretic mobility. Thus, these methods also supported the identification of the cold hemagglutinin as a homogeneous protein with properties like immunoglobulin M. The occurrence of the cold hemagglutinin after the phase of leptospiremia and concurrent to the onset of hemolytic anemia suggests that this antibody may play a significant role in the genesis of leptospiral acquired hemolytic anemia.
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Antihistamine (Allermin) was used sucessfully in the treatment of naturally occurring edema disease of swine under the field and laboratory conditions. A high recovery rate (88.8%) was obtained in the group of pigs with mild clinical signs. The intravenous route of Allermin administration had definite beneficial value. The release of histamine induced by circulating immune-complexes may be responsible for the clinical signs characteristic of edema disease. Three pigs that recovered clinically following the Allermin treatment were examined histologically. Fibrinoid persisted in the vascular walls at least 30 days after the initiation of the treatment. The fibrinoid vasculitis, generalized eosinophilia at the tissue level, and favorable response of pigs to antihistamine treatment suggest that edema disease may be caused by allergy.
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