Peanut agglutinin (PNA) and surface immunoglobulin (SIg) were investigated as markers for T and B lymphocytes in blood and lymphoid tissues of dogs of various ages. In the blood study, 4 age groups (n = 8 dogs/group) were used. The mean (+/- SD) percentages of PNA-positive (PNA +) cells were 68.4 +/- 8.6% (group 1, < 1 year old), 70.3 +/- 9.2% (group 2, 1 to 2 years old), 72.0 +/- 3.7% (group 3, 5 to 6 years old), and 63.8 +/- 10.1% (group 4, 10 to 11 years old). The mean percentages of SIg-positive (SIg+) cells in blood were 32.1 +/- 10.6% (group 1), 43.2 +/- 7.0% (group 2), 34.3 +/- 4.8% (group 3), and 35.0 +/- 6.8% (group 4). The mean total percentages of PNA+ and SIg+ cells were 100 +/-6% (group 1), 113.5 +/- 4.9% (group 2), 106.3 +/- 5.3% (group 3), and 98.9 +/- 9.2% (group 4). The proportions of PNA+ and SIg+ cells in dogs of group 2 were significantly (P < 0.05) different from those in dogs of the other groups. Serial changes in PNA+ and SIg+ cells were investigated in blood of 6- to 29-week-old pups (n = 8). A significant (P < 0.05) transient decrease in PNA+ cells and a corresponding increase in SIg+ cells was observed in pups between 14 and 17 weeks old. Lymphoid tissue specimens and blood samples were obtained from 2- to 6-month-old dogs (n = 11) and from 6- to 12-month-old dogs (n = 10). Percentages reflected the combined data from both groups because there were no significant differences between the 2 age groups. The mean percentages of PNA+ cells were: blood, 68.4 +/- 8.6%; thymus, 86.6 +/- 16.3%; spleen, 29.5 +/- 16.0%; lymph node, 48.5 +/- 16.0%; and bone marrow, 30.8 +/- 26.4%. The mean percentage of SIg+ cells were: blood, 32.1 +/- 10.6%; thymus, 3.1 +/- 5.5%; spleen, 69.3 +/- 10.3%; lymph node, 55.4 +/- 15.2%; and bone marrow, 65.4 +/- 22.4%. The procedureto identify T lymphocytes in blood and lymphoid tissue was easy to perform, was reproducible, and could be performed on as few as 10(6) cells. Percentages of T lymphocytes identified compared favorably with those of other studies.

In vitro testing of bacterial susceptibility to a combination of ticarcillin and clavulanic acid was done, using 406 aerobic gram-positive and gram-negative isolates (considered to be pathogens) cultured from equine and small animal specimens. A microdilution broth technique of susceptibility testing was performed, using trays with wells containing a range of doubling concentrations of dehydrated ticarcillin (range, 0.50 to 128 microgram/ml) with fixed concentration of clavulanic acid (4 microgram/ml). The following isolates of equine origin were (90%) susceptible to concentrations of ticarcillin and clavulanic acid combinations of less than or equal to 16 and 4 microgram/ml, respectively: Staphylococcus aureus, S intermedius, Klebsiella pneumoniae, Enterobacter aerogenes, Ent agglomerans, Ent cloacae, Escherichia coli, Actinobacillus sp, Corynebacterium pseudotuberculosis, Rhodococcus equi, Proteus vulgaris, and Bordetella bronchiseptica. Isolates of small animal origin (90%) susceptible to less than or equal to 16 and 4 microgram of ticarcillin-clavulanic/ml included S aureus, S intermedius, Ent aerogenes, Ent agglomerans, Pasteurella multocida, B bronchiseptica, Pr mirabilis, and Serratia sp.

The effect of T-2 toxin, a radiomimetic immunosuppressive agent, on resistance to the facultative intracellular bacterial pathogens Listeria monocytogenes (strain EGD), Mycobacterium bovis (BCG Copenhagen 1331), and Salmonella typhimurium was determined. Female Swiss ICR mice were given a single dose of T-2 toxin (4 mg/kg of body weight) by gastric gavage. On the seventh day after toxin administration, the mice were infected by intraperitoneal inoculation with L monocytogenes, S typhimurium, or M bovis. Mice given the toxin also were exposed to respirable droplet nuclei containing L monocytogenes or M bovis. The effect of the toxin on the course of infection was monitored by observing mortality or by enumeration of bacteria in te spleen or lungs of infected mice. The toxin increased resistance to infection with L monocytogenes initiated by intraperitoneal inoculation, but reduced resistance to M bovis infection initiated by intraperitoneal inoculation. The toxin had no appreciable effect on the course of salmonellosis or on resistance to infection initiated by inhalation of L monocytogenes or M bovis aerosols. Therefore, it was concluded that T-2 toxin does not necessarily reduce resistance to infection in mice. The toxin's effect on the course of in vivo bacterial infections depends on the nature of the infective agent and the route of inoculation.

To determine resistance of small strongyles to albendazole, 3 female ponies (group 1) were grazed on a pasture from May to November 1985 and were treated with 7.5 mg of albendazole/kg of body weight, PO, 2 days before turnout in May and again in June and in July. Three other female ponies (group 2) grazed on a similar pasture from May to July, were treated with 7.5 mg of albendazole/kg, and were removed to another pasture until November. In December, ponies from both groups were treated with 7.5 mg of albendazole/kg, and 8 days later, they were euthanatized and necropsied for a critical test. Worm egg counts in the ponies' feces revealed that the May treatment of group 1 and the July teatment of group 2 were more effective than were later treatments. Numbers of small strongyles were higher in group 1 than in group 2. Efficacy of treatment against all developmental stages of small strongyles were higher in group 2 than in group 1. Efficacy was low in both groups against parasitic 3rd- and 4th-stage larvae. Fifteen species of small strongyles were identified at necrospy. Efficacy was limited against adult Cyathostomum coronatum, Cya labratum, Cylicostephanus calicatus, and Cyl poculatus in both groups; Cylicocyclus nassatus, Cyl minutus, and Cyl longibursatus in group 1; and Cya labiatum in group 2. Efficacy was 100% against Cya catinatum, Cyl goldi, and 5 other species that were found in low numbers.

Ten-day-old chicken embryos were inoculated with isolates of myeloblastosis-associated virus that induced osteopetrosis of slow or rapid onset. Bursa of Fabricius, thymus, spleen, bone marrow, kidney, liver, and lung were examined at 15, 17, and 19 days in ovo and at 7 and 25 days after hatching by histologic and immunoperoxidase techniques. Tissues from 19-day-old in ovo embryos also were examined by electron microscopy. The lymphoid organs of embryos inoculated with all isolates manifested changes suggesting inhibited development. Virus was most often associated with macrophages, heterophils, and non-lymphoid stromal cells in these organs. Viral particles and antigen were abundant in tissues from embryos inoculated with slow-onset isolates, but cell necrosis was infrequent. The kidney and bursa had especially abundant viral particles and antigen. Conversely, viral particles and antigen were minimal in tissues from embryos inoculated with the rapid-onset isolate, yet intravascular cellular thrombi, substantial cell necrosis, and increased heterophils and hemocytoblasts were found.

A strain of Pasteurella multocida of avian origin expressed high molecular weight outer membrane proteins when grown in turkey plasma or in brain-heart infusion broth containing the iron chelator dipyridyl. The proteins were not detected when this strain was grown in brain-heart infusion broth or in brain-heart broth containing dipyridyl and excess iron.

Effects of placing intracisternal bead devices (ICB) into teat cisterns of 6 dairy cows, from the end of lactation through parturition, were studied. Lacteal secretion samples were collected weekly from each mammary quarter during the nonlactating period to monitor composition changes in ICB-fitted and nonfitted quarters. In quarters remaining uninfected (n=15), there were significantly higher mean somatic cell counts (P less than 0.05), percentage of neutrophils (P less than 0.019), and cell viability (P less than 0.038), but significantly lower percentage of macrophages (P less than 0.013) in ICB-fitted quarters compared with those in nonfitted quarters. The ICB had no significant effect on mean weekly values for percentage of lymphocytes, pH, lactoferrin, citrate, citrate/lactoferrin molar ratio, serum albumin, alpha-lactalbumin, and N-acetyl-beta-D-glycosaminidase. In infected quarters (n=9), pH of mammary secretions was significantly (P less than 0.004) higher in ICB-fitted quarters, but concentrations of lactoferrin (P less than 0.004), alpha-lactalbumin (P less than 0.013), and N-acetyl-beta-D-glucosaminidase (P less than 0.028) were significantly lower, compared with those in nonfitted quarters. Coagulase-negative staphylococci comprised approximately 90% of all infections. Over the nonlactating period, 16.4 and 41.5% of samples from nonfitted and ICB-fitted quarters, respectively, contained coagulase-negative staphylococci. Microscopic examination of ICB from uninfected quarters revealed a thin coating of plaque with adhering neutrophils, macrophages, and multinucleated giant cells. Microscopic examination of plaque on devices from ICB-fitted quarters harboring coagulase-negative staphylococci revealed numerous adherent cocci and neutrophils.

A variety of in vitro cloning assays have been used for studying hematopoiesis in mice and human beings. However, these techniques have had limited use in dogs, a species used extensively as a model for hematopoietic research, particularly hematotoxicity. We have adopted cloning assays for in vitro growth of canine colony-forming unit-erythroid (CFU-E) and colony-forming unit-granulocyte/macrophage (CFU-GM) progenitor cells, using modified microplasma clot and soft agar culture systems respectively. Marrow mononuclear cells separated by density-gradient centrifugation were added to the aforementioned culture systems. Erythroid colonies were stimulated with sheep plasma erythropoietin and incubated at 37 C in 5% CO2 for 2 days. The CFU-E colonies were fixed with 5% glutaraldehyde, stained with benzidine, counted, and expressed as a mean of 8 replicates. The CFU-GM colonies were stimulated with pooled serum from endotoxin-treated dogs and incubated for 8 days at 37 C in 10% CO2. Using an inverted microscope, the CFU-GM colonies were counted and expressed as a mean of 6 replicates. The number of colonies was proportional to the plated cell concentrations. The addition of 10% autologous serum to CFU-GM cultures increased the number of colonies by 80 to 100%, but markedly reduced the size and number of CFU-E colonies. The marrow cloning capacity among dogs of comparable age was similar, and little variation was noticed when bone marrow cells from the same dogs were cultured repeatedly over a period of 3 to 4 months. We concluded that these cloning assays are fast, reliable, and reproducible and that they allow quantitative determination of canine hematopoietic progenitor cells. The assays may be useful in screening the hematotoxic potential of various therapeutic agents and are particularly suited for studying the pathogenetic mechanisms of drug-induced blood disorders and their reversibility.

Peritoneal lavage was performed on ponies to determine the effect on peritoneal surfaces. Lavage solution (20 L) was introduced into each pony's peritoneal cavity through catheters placed in the paralumbar fossa, and the solution was removed by drainage from the ventral portion of the abdomen. Six ponies each were lavaged with sterile saline (0.9% NaCl) solution, sterile saline solution containing 5 X 10(6) U of potassium penicillin and 3 g of neomycin or povidone-iodine diluted to 3% by volume with sterile saline solution, and 3 ponies were lavaged with povidone-iodine diluted to 10% with sterile saline solution. Peritoneal lavage catheters were inserted in 3 control ponies, but lavage fluids were not administered. Peritoneal fluid specimens were collected at 6, 24, 48, and 96 hours after lavage. Nucleated cell counts, RBC counts, total protein determinations, and cytologic analysis were performed. The ponies were euthanatized at 96 hours, and representative sections of the peritoneum were examined. Lavage with saline solution and saline solution with antibiotics induced a mild, transient inflammatory response in the peritoneal fluid, with minimal or no changes observed at necropsy. Solutions containing povidone-iodine induced chemical peritonitis, which was severe in ponies lavaged with 10% povidone-iodine solutions. Peritoneal lavage with povidone-iodine solutions as dilute as 3% cannot be accomplished without causing inflammation of peritoneal surfaces.

Healing of cancellous bone graft donor sites in the proximal tibial metaphysis of 12 healthy adult dogs was studied histologically. Cancellous bone was curetted from the metaphysis of the proximal end of the tibia, via a 1-cm diameter circular opening in the medical cortex. A hematoma and fibrovascular tissue filled the bone defect at 2 weeks. At 4 and 8 weeks, endosteal callus, composed initially of cartilage and woven bone and later of lamellar bone, filled the marrow cavity. At 12 weeks, the normal structural arrangement of lamellar bone and hematopoietic marrow was reestablished in the marrow cavity. The medial cortex defect was filled only with lamellar trabecular bone. It was concluded that, in adult dogs, a second cancellous bone graft could be collected from the proximal portion of the tibial metaphysis 12 weeks or more after an initial collection.