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Evaluation of virginiamycin in feed for treatment and retreatment of swine dysentery.

Virginiamycin, fed at a concentration of 110 mg/kg of feed for 2 weeks followed by concentrations of either 27.5 or 55 mg/kg for 3 weeks, was effective in treatment and control of experimentally induced swine dysentery. However, diarrhea recurred 4 days after withdrawal of medicated feed. Subsequently, the frequency of diarrhea decreased in 3 of 4 groups retreated with virginiamycin (110 mg/kg of feed) for 5 days. Feeding of virginiamycin (110 mg/kg) for 1 week after onset of diarrhea was of little value because of the development of a more severe (augmented) form of the disease after withdrawal of medicated feed. Feeding of virginiamycin (55 mg/kg) at the time of exposure and continuing for 3 weeks (followed by intermittent retreatments of 55 mg/kg) aided in treatment and control of swine dysentery. With this regimen, a few swine developed diarrhea during initial medication, but all developed diarrhea after withdrawal fo medicated feed. Frequency of diarrhea was less after each retreatment. This was attributed to the development of immunity from the recurring diarrhea.

Administration, Oral↗

Pathogenicity of vibrio coli for swine. I. Experimental infection of gnotobiotic pigs with vibrio coli.

Fifteen gnotobiotic pigs varying in age from three to eight weeks were exposed to 23 strains of V. coli isolated from swine with clinical and/or pathological signs of swine dysentery and also from clinically healthy pigs. Clinical or pathological signs of swine dysentery were not produced, although the organism was readly established in the sedimentary tract. Culture of feces, alimentary tract and environment revealed V. coli in large numbers, but no bacterial growth was obtained from other organs. The histopathology and serology are discussed.

Animals↗

Humoral antibody responses of swine infected experimentally with group E streptococcus. I. Whole cell agglutinin response.

Reference streptococcal antisera and sera collected from swine infected experimentally (by intranasal inoculation or contact exposure) with group E Streptococcus (GES) were studied in a tube agglutination system using whole GES cells. Specificity studies revealed common group specific antigen among GES serotypes I and III, GES strains devoid of type specific antigen (untypable by ring precipitin testing) and group P and group U Streptococcus. The group specific antigens were not agglutinated by GES type specific antisera or by group specific antisera against Streptococcus groups A, B, C, D, F, G, H, K, L, M, N, or O. Results of the study suggested that GES serotypes I and III are invalid; i.e., they are devoid of type specific antigen. Groug E Streptococcus type specific antigens II, IV, and V were agglutinated significantly only by their homologous antisera. Experimentally infected swine developed significant titers against both the group and type specific antigen of GES. Antibodies appeared from three to eight weeks postexposure and persisted for the duration of the experiment (six months). The potential utilization of the whole cell agglutination (WCA) test for detection of GES carrier swine is discussed.

Agglutination Tests↗

Humoral antibody responses of swine infected experimentally with group E streptococcus. II. Antistreptokinase and antistreptodornase responses.

Swine infected experimentally with group E Streptococcus (GES) produced significant antibody titers against streptokinase (streptococcal fibrinolysin, SK) and streptodornase (streptococcal deoxyribonuclease, SD). The antibodies directed against SK (antistreptokinase, ASK) appeared two to nine weeks postexposure and persisted for the duration of the experiment (nearly six months). The ASK inhibited SK produced by GES antigenic types III, IV, and V, by GES devoid of type specific antigen, and by a group P Streptococcus. Selected strains of GES serotypes I and II and group U Streptococcus did not produce detectable SK. The antibodies directed against SD (antistreptodornase, ASD) appeared two to three weeks postexposure, reached a peak about six weeks postexposure, and persisted at high levels for nearly six months (the duration of the experiment). The ASD inhibited SD produced by all known antigenic types of GES, by GES devoid of type specific antigen, and by strains of groups P and U Streptococcus. The antibodies failed to inhibit SD produced by group C Streptococcus. The potential utilization of ASK and ASD titers as serological means of identifying swine infected with GES (carrier swine) is discussed.

Animals↗

Efficacy of Bordetella bronchiseptica bacterin in controlling enzootic atrophic rhinitis in swine.

The efficacy of a Bordetella bronchiseptica bacterin was evaluated in 2 commercial swine herds affected with mild and severe enzootic atrophic rhinitis (AR). In the 1st herd study, (mild AR), the degree of clinical AR, nasal turbinate evaluation, blood serum titer to B bronchiseptica antigen, and adjusted days from birth to 100 kg were determined for individual pigs. Bacterin inoculation reduced the incidence and severity of gross turbinate atrophy 57% and reduced clinical AR over 93%. Inoculated swine had an average blood serum-agglutinating titer greater than 1:2,793 and noninoculated (control) swine had an average titer of 1:112. Increased serum titer significantly (P less than 0.05) correlated with decreased degree of nasal turbinate atrophy. Inoculated and control pigs reached 100 kg in an average of 171 and 178 days after birth, respectively. In the 2nd study (severe enzootic AR), inoculated and control pigs were individually evaluated for clinical AR and total average daily weight gain. Inoculation reduced clinical AR over 90%. The total average daily gain for the inoculated and control pits was 435.84 g and 340.50 g, respectively. Inoculated pigs and control pigs reached 100-kg market weight in 184 and 238 days, respectively.

Animals↗

Evaluation of different antigens in the complement-fixation test for diagnosis of Haemophilus pleuropneumoniae (parahaemolyticus) infections in swine.

The identification of new serotypes of Haemophilus pleuropneumoniae (parahaemolyticus) and the frequency of pleural adhesions due to contagious pleuropneumonia in many fattening swine herds have prompted the study of the complement-fixation (CF) test as a diagnostic tool for use in swine. Whole cell antigens, mixed antigens, autoclaved antigens, and phenol-water-extracted antigens derived from different serotypes were prepared and tested with immunized-swine sera by the CF test. Mixed antigen consisting of whole cells from all known serotypes was the best screening antigen for routine use. This antigen gave positive titers with all sera in which a positive reaction against the separate serotype antigen was registered. The most highly serotype-specific reactions were obtained with antigens prepared by phenol-water extractions of whole cells. When whole-cell antigens were used in the CF test, antibodies to superficial serotype-specific and common species-specific antigens could be detected.

Animals↗

Experimental infection of weanling pigs with A-swine influenza virus. 3. Immunity in piglets farrowed by antibody-bearing dams experimentally infected a year earlier.

Pigs experimentally infected as weanlings with swine influenza virus, as described in previous papers, were bred from when mature. Attempts to isolate virus at parturition from the placenta and from different organs of some of the piglets immediately after birth gave negative results. Antibody levels were determined in the sows and remaining piglets at different times after birth, and the clinical course, immunity and antibody formation were studied in some of the piglets challenged with swine influenza virus 10 days after birth. The levels were found to be generally higher in the sows than those in their offspring. Specific antibodies were detected in piglets that had presumably not ingested colostrum, but the possibility of unobserved ingestion of colostrum could not be excluded. Colostrum-fed piglets had specific antibody in their sera; an increase in antibody titre occurred by the 10th day after birth, remained until the 20th day and decreased steadily to the 30th day. Colostrum-fed piglets receiving antibodies from immune dams were resistant to a challenge of virulent swine influenza virus, and did not respond with an antibody rise during a 30-day observation period after challenge.

Animals↗

Therapeutic effects of various concentrations of lincomycin in drinking water on experimentally transmitted swine dysentery.

Three experimental studies were conducted in 232 growing pigs (8 to 12 weeks old) to evaluate the therapeutic effects of various concentrations of lincomycin in drinking water, against swine dysentery experimentally transmitted, by oral inoculation or by contact-commingling exposure. Four or 5 concentrations of lincomycin were used in each experiment (132, 66, 33, 16.5 or 0.0 mg/L of drinking water). Medication was initiated 7 to days after exposure and was continued for 6 to 10 days. Both methods of exposure were capable of transmitting the disease successfully. A more marked dose response was noticed in pigs inoculated orally than in pigs that were exposed by contact. All concentrations of lincomycin were effective for the treatment of swine dysentery by oral or by contact exposure. At the smaller concentration of 16.5 mg/L of drinking water, lincomycin was less effective for treating the disease than it was at greater concentrations. The suggested optimal concentration was 33 mg of lincomycin/L of drinking water for the treatment of swine dysentery.

Administration, Oral↗

Possible factors influencing the immunoglobulin G concentration in swine colostrum.

The immunoglobulin (Ig) G concentration in swine colostrum was determined by the single radial immunodiffusion method, using 157 samples collected from farm-raised sows in the Yamaguchi Prefecture of Japan during 1976 and 1977. The mean IgG value was 53.03 mg/ml, and the maximum and minimum values were 101.39 mg/ml and 11.74 mg/ml, respectively. The amount of IgG varied greatly among sows. To clarify the possible factors influencing the amount of IgG in colostrum, the following items were surveyed: season, district, breed, age of sows, number of parturitions, udder section from which samples were collected, kind of feed, vaccinations of swine erysipelas live-organism vaccine, hog cholera live-virus vaccine, Japanese encephalitis live-virus vaccine, tramsmissible gastroenteritis liver-virus vaccine, type of farming, and number of sows raised on a farm. Relationships between the amount of IgG in colostrum and each of these 13 items were analyzed. Seemingly, strong correlations with the amounts if IgG in colostrum were found with five items (district, number of parturitions, kind of feed, type of farming, and number of sows). To the contrary, five items (age, udder section, and vaccinations of swine erysipelas live-organism vaccine, hog cholera live-virus vaccine, and Japanese encephalitis live-virus vaccine) had poor correlations. Other items had moderate correlations. The multiple correlation coefficient obtained was 0.5499.

Age Factors↗

Pseudorabies virus antibodies in swine slaughtered in Iowa.

Sera from butcher swine (1,246 total) were evaluated qualitatively by the microimmunodiffusion test and quantitatively by the virus neutralization test for antibody to pseudorabies virus. Ten percent of the sera had antibody to pseudorabies virus. Follow-up contact with veterinarians whose clients included the farms from which the positive swine originated revealed that few feeder swine are vaccinated against pseudorabies and that most infections with pseudorabies virus are subclinical.

Abattoirs↗

Pathophysiologic features of swine dysentery: cyclic nucleotide-independent production of diarrhea.

Net electrolyte and water transport and unidirectional Na+ fluxes were examined in ligated colonic loops of clinically normal pigs and in pigs with swine dysentery (etiologic agent Treponema hyodysenteriae) in the presence or absence of theophylline. In normal pigs, theophylline abolished net Na+ absorption via a reduction in the lumen-to-blood flux, decreased Cl- absorption, and increased HCO3- accumulation in the lumen. In infected pigs, all net ion transport was abolished, with the addition of theophylline producing little effect. The absence of net Na+ absorption in infected pigs was also the result of a decreased lumen-to-blood flux. Seemingly, colonic malabsorption may be the primary transport alteration in swine dysentery. Concentrations of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) were measured in samples of colonic mucosa from normal and infected pigs after in vitro exposure to a Ringer's solution containing 0 or 20 mM theophylline. Basal values of cAMP or cGMP did not increase in infected colonic mucosa. There was a diminished capacity of the infected mucosa to respond to theophylline. Alterations in ion transport in conjunction with measurements of cAMP and cGMP indicated that the pathogenic mechanism(s) in swine dysentery were not similar to those of Salmonella, Shigella, Vibrio cholerae, or Escherichia coli diarrhea.

Animals↗

Detecting anti-Treponema hyodysenteriae antibodies in swine serum using immunofluorometry.

An indirect fluorescent antibody test was adapted for measuring serum anti-Treponema hyodysenteriae antibodies with a fluorometer. The immunofluorescence was recorded as fluorescent signal units. Cultures of T. hyodysenteriae and Treponema innocens were used as antigen. There was a significant (P less than 0.01) correlation between the immunofluorescence recorded with the fluorometer and that evaluated visually with a microscope. The swine exposed orally to swine dysentery infective inoculum and subsequently hyperimmunized by the intravenous inoculation of live cultures of T. hyodysenteriae had the highest average fluorescent signal unit, which was 104.5. There was a significant (P less than 0.01) correlation between the level of anti-T. hyodysenteriae antibody and the interval length between the last day of diarrhea and the day of bleeding. However, in measuring fluorescent signal units in serum from swine infected with nonpathogenic large spirochetes, (T. innocens), there was also a significant (P less than 0.01) correlation between T. hyodysenteriae and T. innocens as antigen. The coefficient of variation of the average fluorescent signal unit for a highly positive serum and a highly negative serum between 16 runs of assays were 5.7% and 19% respectively; the coefficient of variation of the average fluorescent signal unit for duplicate samples on 358 serum samples tested was 5.8%.

Animals↗

Influence of vitamin E and ICRF-187 on chronic doxorubicin cardiotoxicity in miniature swine.

Studies were made of the potential of vitamin E and ICRF-187 to protect against the cardiotoxicity resulting from chronic administration of doxorubicin. Miniature swine (19 to 40 kg) received six injections of doxorubicin (1.6 mg/kg) at 3-week intervals (total dose, 9.6 mg/kg), either alone or concurrently with vitamin E (5000 IU/day for 4 days and 1000 units/day for the next 17 days). In a second study, miniature swine received six injections of doxorubicin (2.4 mg/kg) at 3-week intervals (total dose 14.4 mg/kg), either alone or 30 minutes after 12.5 mg of ICRF-187/kg (intraperitoneally). All animals were sacrificed 3 weeks after the last injection. The frequency and extent of myocardial lesions (vacuolization and myofibrillar loss) were scored on a scale of 0 to 4+. Such lesions were noted in eight of nine pigs given 9.6 mg/kg of doxorubicin alone and in all pigs receiving doxorubicin and vitamin E; however, the severity of the lesions was decreased in the latter animals (average score 1.0, compared with 1.8 in those receiving doxorubicin alone). All swine receiving 14.4 mg/kg of doxorubicin alone developed myocardial lesions (average score, 2.7); these lesions were severe (3+) in four of the animals. In contrast, cardiac lesions were absent in two and minimal (average score, 0.7) in five of the seven animals given 14.4 mg/kg of doxorubicin in combination with ICRF-187.

Animals↗

Hemostatic function in swine as influenced by warfarin and an oral antibacterial combination.

Pertinent literature on naturally occurring hemorrhagic diseases in poultry and livestock were reviewed and compared with reports on recent outbreaks of a hemorrhagic syndrome in swine. Epizootiologic, clinical, and hematologic data from porcine hemorrhagic disease suggest vitamin K-responsive hypoprothrombinemia. In weanling pigs, the toxicity of warfarin was compared with that in swine given tylosin and sulfamethazine antibacterial combination versus those given warfarin only. Toxicosis was induced in weanling swine fed warfarin daily at dose level of 0.055 mg/kg of body weight. Approximately 5 days after feeding was started, signs of poisoning appeared: lameness, anorexia, subcutaneous hematomata, melena, and periarticular enlargement. Administration of warfarin at dose level of 0.017 mg/kg did not cause clinical toxicosis, and 0.028 mg/kg produced significant increases in one-stage prothrombin time (OSPT) and activated partial thromboplastin time (APTT), but no evidence of clinical bleeding. When tylosin-sulfamethazine antibacterial combination was fed at normal and high dose levels concurrently with warfarin at dose level of 0.017 mg/kg of body weight, increase of clotting time, OPST, or APTT did not occur due to antibacterial influence. The antibacterial combination fed alone did not produce changes in clotting time, OSPT, APTT, fibrinogen, total protein, differential leukocyte count, or packed cell volume.

Animals↗

Investigation of porcine natural-killer cell activity with reference to African swine-fever virus infection.

The natural killing of the human myeloid leukaemia cell line by pig mononuclear cells was investigated in an 18 hr assay; the most active natural-killer (NK) effectors were those cells not adhering to nylon-wool columns or rosetting with sheep red blood cells. Mononuclear cells cultured in the presence of African swine-fever virus maintained NK activity. Pigs infected with African swine-fever virus exhibited a suppressed NK activity, possibly due to the sensitivity of NK cells to increased temperatures. The possible role of NK cells in recovery from African swine fever is discussed.

African Swine Fever↗

[Detection of C-strain virus in pigs following vaccination against swine fever (author's transl)].

During and shortly after a mass vaccination campaign against swine fever with C-strain virus, samples were received from five vaccinated herds, which were found positive on examination with the cryostat immunofluorescent technique (IFT). In four cases fluorescence was due to C-virus antigen as determined by rabbit inoculation. The samples concerned were derived from 4 to 13 week old pigs which had been vaccinated 6 to 7 days prior to death. The fluorescence was notably bright and was confined to the epithelial lining of the tonsillar crypts. The persistence of C-virus following vaccination was studied in twelve-week-old pigs susceptible to swine fever. The animals were immunosuppressed by a concurrent treatment with corticosteroids. Virus antigen was detected by immuno-fluorescence in the tonsils and kidneys till 15 days following vaccination. The replication of virus in these organs is believed to be responsible for the spreading of C-virus observed in the field. Isolation of vaccine virus in rabbits was also possible till 15 days after vaccination. It is concluded that vaccination with C-virus may interfere with the laboratory diagnosis of swine fever by the fluorescent antibody technique applied to tissue sections for at least two weeks.

Animals↗

An agglutination test for the detection of Bordetella bronchiseptica infection in swine.

An agglutination test with the use of formalin-killed antigen of the cell carrying the capsule was developed and used for the detection of antibody in swine naturally infected with Bordetella bronchiseptica. Under optimum antigen concentration and reaction temperature 210 or 60% of 342 serum samples tested from 42 conventional swine herds were positive for Bordetella infection. In contrast, only 34 or 10% of 342 nasal swabs from the same animals were positive for Bordetella by culture technique. The test was relatively free of cross-reactivity to related organism. However, 2.7 and 13.0% of sera from growing pigs and mature hogs, respectively, reacted with antigen of Pasteurella multocida. Because of this, only agglutinin reactions in 1:20 dilutions or higher to Bordetella were considered positive. The bulk of the antibody activity of selected sera tested from various age ranges of swine was mercaptoethanol sensitive, suggesting that serum antibody in Bordetella infection may be associated with immunoglobulin IgM. Because of the high agglutinability and stability of formalin-killed antigen the test may be useful as an auxiliary aid for the diagnosis of Bordetella infection where the organism cannot be identified by culture means.

Agglutination Tests↗

Enteropathogenicity testing of Treponema hyodysenteriae in ligated colonic loops of swine.

Multiple, ligated loops of swine colon were used as an in vivo model in which to test enteropathogenicity of isolates of Treponema hyodysenteriae. Gross and microscopic lesions observed in 21 of 22 colonic loops in pigs killed 48 to 72 hours after inoculation with isolates known to be enteropathogenic were characteristic of swine dysentery. These lesions were not observed in 12 loops exposed to uninoculated media or in 12 loops inoculated with nonpathogenic isolates of T hyodysenteriae. The swine-loop technique provides a relatively rapid, economical, reliable model in which to test enteropathogenicity of T hyodysenteriae isolates.

Animals↗