Field experiments with viral arthritis/tenosynovitis vaccination of breeder chickens

Vaccination of three commercial broiler-breeder flocks at 15 weeks old with viral arthritis/tenosynovitis via the drinking water resulted in serologic conversion of two flocks to agar-gel-precipitin (AGP)-positive, while the third flock was still AGP-negative at 24 weeks, but was AGP-positive at 30 weeks old, presumably as a result of natural exposure. Progeny from the two successfully vaccinated breeder flocks remained free of clinical viral arthritis/tenosynovitis and had average condemnation rates of 0.99%. In contrast, six hatches of progeny from the third breeder flock experienced clinical viral arthritis/tenosynovitis and average condemnation rates of 3.64%.     

Repurposing Ionophores as novel antimicrobial agents for the treatment of bovine mastitis caused by Gram‐positive pathogens

Increasing reports of multidrug‐resistant bacterial infections in animals has created a need for novel antimicrobial agents that do not promote cross‐resistance to critically important antimicrobial classes used in human medicine. In response to the recent emergence of antimicrobial resistance in several bovine mastitis pathogens, in vitro antimicrobial susceptibility was determined for four polyether ionophores (lasalocid, monensin, narasin and salinomycin) against Staphylococcus spp. and Streptococcus spp. isolated from clinical cases. In addition, erythrocyte haemolysis and WST ‐1 cell proliferation assays were used to assess in vitro mammalian cell cytotoxicity and biofilm susceptibility testing was performed using the minimum biofilm eradication concentration (MBEC ?) biofilm assay. Lasalocid, monensin, narasin and salinomycin exhibited bacteriostatic antimicrobial activity against all pathogens tested, including methicillin‐resistant staphylococci, with MIC ₉₀ values <16 μg/ml. Narasin and monensin displayed the least toxicity against mammalian cell lines and all compounds significantly reduced viable cell numbers in a Staphylococcus aureus biofilm. Based on in vitro characterization, all four ionophores offer potentially novel treatments against bovine mastitis but in vivo studies will be essential to determine whether acceptable safety and efficacy is present following intramammary administration.     

Effects of intravenous administration of peripheral blood‐derived mesenchymal stromal cells after infusion of lipopolysaccharide in horses

BackgroundA systemic and dysregulated immune response to infection contributes to morbidity and mortality associated with sepsis. Peripheral blood‐derived mesenchymal stromal cells (PB‐MSC) mitigate inflammation in animal models of sepsis. Allogeneic PB‐MSC administered IV to horses is well‐tolerated but therapeutic benefits are unknown.HypothesisAfter IV lipopolysaccharide (LPS) infusion, horses treated with PB‐MSC would have less severe clinical signs, clinicopathological abnormalities, inflammatory cytokine gene expression, and oxidative stress compared to controls administered a placebo.AnimalsSixteen horses were included in this study.MethodsA randomized placebo‐controlled experimental trial was performed. Sixteen healthy horses were assigned to 1 of 2 treatment groups (1 × 10⁹ PB‐MSC or saline placebo). Treatments were administered 30 minutes after completion of LPS infusion of approximately 30 ng/kg. Clinical signs, clinicopathological variables, inflammatory cytokine gene expression, and oxidative stress markers were assessed at various time points over a 24‐hour period.ResultsA predictable response to IV LPS infusion was observed in all horses. At the dose administered, there was no significant effect of PB‐MSC on clinical signs, clinicopathological variables, or inflammatory cytokine gene expression at any time point. Antioxidant potential was not different between treatment groups, but intracellular ROS increased over time in the placebo group. Other variables that changed over time were likely due to effects of IV LPS infusion.Conclusions and Clinical ImportanceAdministration of allogeneic PB‐MSC did not cause clinically detectable adverse effects in healthy horses. The dose of PB‐MSC used here is unlikely to exert a beneficial effect in endotoxemic horses.     

Antibiotic resistance among enterotoxigenic Escherichia coli from piglets and calves with diarrhea

In vitro resistance to 8 antimicrobials among enterotoxigenic Escherichia coli from piglets and calves over a 13-year period was evaluated. Least resistance occurred against ceftiofur for all, followed by apramycin and gentamicin for porcine and florfenicol for bovine isolates. No significant differences were found between the first 8 and last 5 years.     

Phase I and pharmacokinetic evaluation of the combination of orally administered docetaxel and cyclosporin A in tumor-bearing cats

Intravenously administered docetaxel (DT) is problematic in cats because of the requirement for premedication to ameliorate acute vehicle-induced hypersensitivity reactions. Previously we have revealed that therapeutic plasma concentrations of DT can be achieved in normal and tumor-bearing dogs when DT is administered PO in combination with oral cyclosporin A (CSA). The purpose of this study was to identify the maximally tolerated dosage and characterize the pharmacokinetic disposition of oral DT combined with CSA in cats with tumors. Eighteen tumor-bearing cats were enrolled in this phase I dose escalation and pharmacokinetic study. DT was administered by gavage with CSA (5 mg/kg) twice over a 3-week period. The starting dose of DT was 1.0 mg/kg. Based on the clinical toxicity profile, with gastrointestinal adverse effects and hematologic toxicity the maximal tolerated dose of oral DT was 1.75 mg/kg in combination with 5 mg/kg CSA. Additional studies are necessary to determine the efficacy of DT/CSA in cats with epithelial tumors.     

Oyster Crassostrea virginica Spat Settlement as it Relates to the Restoration of Fish River Reef in Mobile Bay, Alabama

Abstract.— Oyster spat settlement at four oyster reefs in Mobile Bay, Alabama, USA, was studied from August through October 1998 and May through mid November 1999. Spat collectors at the reefs were replaced every 2 wk and spat-set estimated as number of oysters per meter square per day. Water quality data at Fish River Reef was monitored using remote sensors. Spat-set data revealed significant variation between the four sites and between the 2 yr. Spat settlement was 5 to 10 times greater at the other three reefs than at Fish River Reef. Dates and intensity of oyster settlement at Fish River Reef were different from dates and intensity of oyster settlement at Shell Bank Reef, both on the eastern side of the bay. However, settlement was similar between Cedar Point Reef and White House Reef, both on the western side of the bay. Spat set appears to occur 3 wk after a rapid decline in water temperature, provided adequate oxygen concentrations are present at the time of settlement. Data collected suggest that intensity of settlement at Fish River Reef is considerably less than at other reefs in this study but could be adequate to reestablish the reef, if cultch and environmental conditions are suitable. The data also suggest that the source of larval oysters at Fish River Reef is different from the source of larval oysters at the other sites tested in the present study.     

The bionomics of the African armyworm Spodoptera exempta in relation to its status as a migrant pest

A multidisciplinary study was undertaken on the bionomics of the African armyworm in eastern Africa as a basis for the development of control strategies for this important pest of cereal crops and pastures. Relevant findings from studies on seasonal distribution, migration, field infestations and population cycles are reviewed in relation to understanding the causes for the onset and spread of armyworm outbreaks. It is concluded that the onset of the first outbreaks of an armyworm epidemic is caused by oviposition at high density by moths concentrated by wind convergence at storm outflows. The sources of these moths seem to be low-density populations which survive from one season to the next at sites receiving unseasonable rainfall. Some areas in Tanzania and Kenya are particularly prone to early outbreaks which are potentially critical for the initiation of a subsequent spread of outbreaks downwind throughout eastern Africa. These areas have low and erratic rainfall, and are near the first rising land inland from the coast. Below average rainfall prior to the development of outbreaks increases the probability of their occurrence. Their subsequent spread is enhanced by storms downwind which concentrate moths in flight and by sunshine during caterpillar development. Persistent wet weather reduces the spread of outbreaks. This study demonstrates the importance and value of developing and implementing a long-term monitoring system over a large region, in this case in Africa, not only for the generation of data used by the forecasters for the prediction and location of possible outbreaks, but also for obtaining a clearer understanding of the epidemiology of a highly mobile pest.     

Vertebral plasma cell tumors in 8 dogs

The case histories of 8 dogs with spinal pain and neurologic deficits associated with vertebral plasma cell tumor are reviewed. Four dogs had solitary plasmacytoma, 3 had multiple myeloma, and 1 dog had 2 vertebral lesions with no evidence of disseminated disease. Four dogs were treated: 2 with multiple myeloma received chemotherapy only and survived 17 and 26 months, respectively. Two dogs with solitary plasmacytomas of the spine had chemotherapy and radiotherapy: the 1st survived 4 months and was euthanized after developing radiation myelopathy; the 2nd survived 65 months before developing multiple myeloma. The diagnosis of solitary plasmacytoma of the spine versus multiple myeloma is discussed.