Effect of creep feeding on the incidence, duration and severity of post-weaning diarrhoea in pigs

The effect of creep feeding on the response of pigs weaned at two or three weeks old to infection with an enteropathogenic strain of Escherichia coli (O149; K91[B], K88 a, c [L]) was studied in two separate experiments. Gastric intubation was adopted to regulate the intake of creep feed during the sucking period. Animals were given the enteropathogenic strain either before weaning or at weaning and the course and outcome of the infection followed bacteriologically and clinically. The response of the animals to the infection varied considerably in accord with recent reports of multiple phenotypes (to K88 +ve organisms) among pigs but consumption of creep feed before weaning did not significantly affect the prevalence, duration or severity of the diarrhoea induced experimentally by the organism. Hence reputed immunological responses mounted against dietary antigens did not predispose to or protect against this infection.     

Fine structure and invasive behaviour of the early developmental stages of Theileria annulata in vitro

The interaction, in vitro, between bovine peripheral blood lymphocytes and sporozoites of Theileria annulata (Ankara) was studied by light and electron microscopy. Beginning five minutes following incubation, samples were taken for Giemsa-stained smears and glutaraldehyde-fixed pellets, for light and electron microscopy, respectively. Sporozoites of T. annulata measure an average of 0.9 microns long, 0.8 microns broad and possess a limiting unit membrane, the pellicle; a round-to-ovoid, eccentrically situated, non-chromocentric nucleus; double-membraned, tubular, acristate mitochondria; varying numbers of anisocytic, densely osmiophilic and pleomorphic organelles, the rhoptries which together with the polar ring form the apical complex; and numerous, loosely scattered, electron-dense ribosomal particles. As early as 5 min of incubation, sporozoites had made contact with, and penetrated, lymphocytes. Sporozoites consistently attached to the lymphocyte plasmalemma by their basal end, possibly at specific receptor sites. Apparently only a proportion of lymphocytes (up to 40% and more commonly 10-20%) were susceptible. Two subpopulations of the susceptible lymphocytes were observed; one which appeared to have receptor sites localized on one pole of the plasmalemma and the other subpopulation in which the receptor sites were distributed evenly around the plasmalemmal surface. Within individual susceptible lymphocytes, the number of interiorized sporozoites increased from 1 to 3 at 5-10 min to as many as 15 or more parasites at around 60 min of incubation. Theileria annulata sporozoites were interiorized by the invagination of the host cell plasmalemma which remained intact throughout the process but later fragmented. Within 30 min of interiorization, each sporozoite underwent dedifferentiation by the loss of its rhoptries and transformed into a trophozoite. Around 24 h, the trophozoite, a uninucleate, motile and feeding stage of the parasite, developed into a schizont by an acentric, closed mitosis.     

Effects of oral powder electrolyte administration on packed cell volume,plasma chemistry parameters,and incidence of colic in horses participating in a 6-day 162-km trail ride

This study evaluated the effects of administering oral powder electrolytes on packed cell volume (PCV), plasma chemistry parameters, and incidence of colic in horses participating on a 6-day 162-km trail ride in which water was not offered ad libitum. Twenty-three horses received grain with powder electrolytes daily while 19 control horses received grain only. Horses were ridden approximately 32 km a day at a walk or trot. Packed cell volume and plasma chemistry parameters were analyzed daily. Episodes of colic were diagnosed and treated by a veterinarian unaware of treatment group allocation. Blood parameters and incidence of colic were compared between treatment groups. Electrolyte administration did not alter PCV or plasma chemistry parameters compared to controls. The incidence of colic was significantly higher in treated horses (P = 0.05). Oral powder electrolytes did not enhance hydration status or electrolyte homeostasis and may be associated with colic in horses participating on long distance trail rides similar to this model.     

Experimental airborne transmission of porcine reproductive and respiratory syndrome virus and Bordetella bronchiseptica

Experiments were designed to determine if porcine reproductive and respiratory syndrome virus (PRRSV) or Bordetella bronchiseptica could be transmitted through indirect airborne contact. Three principal pigs were infected with PRRSV, B. bronchiseptica or both. Five days after the principal pigs were challenged, the three principal pigs and one direct-contact pig were placed into one isolation tent together, and three indirect-contact pigs were placed into another isolation tent which received its air supply from the first isolation tent. Airborne transmission of B. bronchiseptica occurred in 5/5 trials where B. bronchiseptica was the only agent used, and in 3/5 trials where the principal pigs were coinfected with both agents. Airborne transmission of PRRSV occurred in 4/5 trials where PRRSV was the only agent used, and in 2/5 trials where the principal pigs were coinfected with both agents. Thus, airborne transmission of both agents over short distances, such as within a barn, is probable.     

Neutrophil function in septic dogs

BACKGROUND: Leukocytes appear to enter a hypo-inflammatory state in human patients with a severe bacterial infection, whereas, in swine, intra-abdominal sepsis produces an initial increase and subsequent decrease in neutrophil Fc receptor mediated phagocytosis. HYPOTHESIS: Impaired neutrophil function (hypo-inflammatory state) develops in dogs with sepsis. ANIMALS: Thirteen adult client-owned dogs that developed clinical signs consistent with sepsis were assessed for evidence of neutrophil dysfunction. These results were compared with those of 12 healthy dogs. METHODS: Flow cytometry combined with the appropriate fluorescent markers allowed for quantification of the phagolysosomal oxidative burst after Fc receptor-mediated phagocytosis of immune complexes, neutrophil phagocytosis of opsonized Escherichia coli, and the intracellular concentration of reduced glutathione as a measure of oxidative stress. RESULTS: The phagolysosomal oxidative burst after Fc receptor-mediated phagocytosis was significantly lower in neutrophils from septic dogs (mean fluorescence intensity +/- standard deviation; 118 +/- 13 and 165 +/- 27 for septic and control dogs, respectively, p = 0.001), although the phagocytosis of opsonized E. coli was significantly increased (155 +/- 74 and 77 +/- 44 for septic and control dogs, respectively, p = 0.004). Intracellular reduced glutathione was not significantly different in neutrophils from septic and healthy control dogs. CONCLUSIONS: An important component of neutrophil function is decreased in septic dogs. The diminished oxidative burst after Fc receptor-mediated phagocytosis in neutrophils from septic dogs could hinder the ability of the innate immune system to clear bacterial infections or it might help protect these patients from the systemic consequences of infection.     

Kinetics of substrate oxidation and hydrogen peroxide production by Mycoplasma mycoides subsp. mycoides Large Colony (LC) type and Mycoplasma mycoides subsp. capri

Mycoplasma mycoides subsp. mycoides Large Colony (LC) type is a pathogen of goats causing contagious agalactia and respiratory disease, found on all continents where small ruminants are kept. It shares close genetic characteristics with M. mycoides subsp. capri. Substrate oxidation by 22 strains of M. mycoides subsp. mycoides LC from nine countries was compared with that of eight strains of M. mycoides subsp. capri from five countries. There was considerable similarity in the substrates used, but substrate saturation coefficients (K_s) varied for different substrates. Substrate utilization patterns and K_s values did not (1) significantly differentiate the LC strains from each other, (2) show any correlation with geographical origin, or (3) distinguish the LC strains from the capri strains. These results support previous studies justifying the reclassification of these subspecies as a single species.