Characterisation of haemolytic RTX toxins produced by Australian isolates of Actinobacillus pleuropneumoniae

The haemolytic RTX toxins of 27 isolates of Actinobacillus pleuropneumoniae, representing all serovars that have been isolated in Australia, were characterised. The quantity of protein secreted by these isolates into the media was not significantly different between serovars, but haemolytic activity was detected only in the unconcentrated supernatants from cultures of serovar 1 and 5 isolates. Haemolytic activity in supernatants of serovar 2, 3 and 7 isolates was detected only after the supernatants were concentrated. On Southern hybridisation blots, genomic DNA of serovar 1 and 5 isolates contained regions that were similar to the cloned structural genes for Apxl (apxIA) and for ApxII (apxIIA). In contrast, genomic DNA of serovar 2,3 and 7 isolates only contained regions similar to, if not identical with, the cloned apxIIA gene. The haemolytic activity of the culture supernatant depends on the type or composition of media and adaptability of the bacteria to in-vitro cultivation. Low passage cultures of A pleuropneumoniae, which were characterised by waxy colonies, produced significantly weaker haemolytic activity than A pleuropneumoniae after several passages in vitro.     

Serum concentrations of ionized calcium, vitamin D3, and parathyroid hormone in captive thick-billed parrots (Rhynchopsitta pachyrhyncha).

Serum collected from 68 thick-billed parrots (Rhynchopsitta pachyrhyncha) from 15 institutions was analyzed for ionized Ca (iCa), total Ca (tCa), P, total protein (TP), albumin (Alb), parathyroid hormone (PTH), and vitamin D3. Values were not distributed normally; 95% frequency intervals were as follows: iCa (0.82-1.3 mmol/L), tCa (1.37-2.09 mmol/L,), P (0.35-1.75 mmol/L), TP (21-39 g/L), Alb (9-13 g/L), PTH (0-65.68 pmol/L), and vitamin D3 (5.2-51 nmol/L). Sixty percent (+/-7.5%) of tCa was ionized. Female thick-billed parrots had significantly higher mean iCa (1.11 mmol/L, n = 22) than male thick-billed parrots (1.05 mmol/L, n = 32). tCa and iCa values in thick-billed parrots were lower than the reported values for other psittacine species. A significant positive linear relationship existed between Alb-TP and iCa-tCa ratios. A significant inverse linear relationship was also identified between the tCa-P ratio and PTH. These findings are consistent with known domestic avian Ca physiology.     

Serum biochemistry of captive and free-ranging gray wolves (Canis lupus).

Normal serum biochemistry values are frequently obtained from studies of captive sedentary (zoo) or free-ranging (wild) animals. It is frequently assumed that values obtained from these two populations are directly referable to each other. We tested this assumption using 20 captive gray wolves (Canis lupus) in Minnesota, USA, and 11 free-ranging gray wolves in Alaska, USA. Free-ranging wolves had significantly (P < 0.05) lower sodium, chloride, and creatinine concentrations and significantly higher potassium and blood urea nitrogen (BUN) concentrations; BUN to creatinine ratios; and alanine aminotransferase, aspartate aminotransferase, and creatine kinase activities relative to captive wolves. Corticosteroid-induced alkaline phosphatase activity (a marker of stress in domestic dogs) was detected in 3 of 11 free-ranging wolves and in 0 of 20 captive wolves (P = 0.037). This study provides clear evidence that serum biochemical differences can exist between captive and free-ranging populations of one species. Accordingly, evaluation of the health status of an animal should incorporate an understanding of the potential confounding effect that nutrition, activity level, and environmental stress could have on the factor(s) being measured.     

Integration Between Different Hypothalamic Nuclei Involved in Stress and GnRH Secretion in the Ewe

This study investigated possible integrated links in the neuroanatomical pathways through which the activity of neurones in the paraventricular nucleus and arcuate nucleus may modulate suppression of gonadotrophin‐releasing hormone (GnRH) secretion during stressful situations. Double‐label immunofluorescence and laser scanning confocal microscopy were used to examine the hypothalamic sections from the follicular phase ewes. Noradrenergic terminals were in close contact with 65.7 ± 6.1% corticotrophin‐releasing hormone (CRH) and 84.6 ± 3.2% arginine vasopressin (AVP) cell bodies in the paraventricular nucleus but not with β‐endorphin cell bodies in the arcuate nucleus. Furthermore, γ‐amino butyric acid (GABA) terminals were close to 80.9 ± 3.5% CRH but no AVP cell bodies in the paraventricular nucleus, as well as 60.8 ± 4.1%β‐endorphin cell bodies in the arcuate nucleus. Although CRH, AVP and β‐endorphin cell terminals were identified in the medial pre‐optic area, no direct contacts with GnRH cell bodies were observed. Within the median eminence, abundant CRH but not AVP terminals were close to GnRH cell terminals in the external zone; whereas, β‐endorphin cells and terminals were in the internal zone. In conclusion, neuroanatomical evidence is provided for the ewe supporting the hypothesis that brainstem noradrenergic and hypothalamic GABA neurones are important in modulating the activity of CRH and AVP neurones in the paraventricular nucleus, as well as β‐endorphin neurones in the arcuate nucleus. These paraventricular and arcuate neurones may also involve interneurones to influence GnRH cell bodies in medial pre‐optic area, whereas the median eminence may provide a major site for direct modulation of GnRH release by CRH terminals.     

Serum antibody response to Mycoplasma hyopneumoniae measured by enzyme-linked immunosorbent assay after experimental and natural infection of pigs

Studies were conducted under experimental and field conditions to determine the effect of infection with M. hyopneumoniae on the immune response in serum as measured by ELISA. Following intratracheal challenge or contact exposure, serologically negative pigs derived from mycoplasma-free piggeries developed an immune response within 10 days. This response continued to rise for a further 50 days. In a field study in a commercial piggery, no animals (0/44) were observed to have M. hyopneumoniae antibodies at day 86 of life. However between day 86 and day 144, 97.7% (42/43) animals sero-converted. These results are discussed in terms of infection spread, particularly in the grower/finisher shed.     

Survey of parasites and bacterial pathogens from free-living waterfowl in zoological settings

To determine if free-living waterfowl residing in a zoological setting pose health risks for its animal collections, visitors, and employees, 450 fecal samples were collected and cultured for the presence of Campylobacter jejuni, Escherichia coli, Salmonella spp., and Pasteurella multocida. A survey of endoparasites infecting the waterfowl was also conducted. Sixty-seven percent, 42%, and 1.7% of the samples tested positive for E. coli, C. jejuni, and Salmonella spp., respectively. No P. multocida was isolated from the sampled population. Antimicrobial susceptibility testing for the bacterial isolates demonstrated that a majority of the isolates were susceptible to the antibiotics tested. A survey for parasites revealed 16% of the samples had coccidia oocytes; 8% of the sample had spirurid ova; and 17% of the sample had strongylate-type nematode ova. Ascaris spp. ova, Capillaria spp. ova, oxyurid ova, and mites were also noted in some fecal samples.     

Minimum anesthetic concentration of isoflurane in captive thick-billed parrots (Rhynchopsitta pachyrhyncha)

OBJECTIVE: To determine the minimum anesthetic concentration (MAC) of isoflurane in thick-billed parrots (Rhynchopsitta pachyrhyncha). ANIMALS: 15 healthy thick-billed parrots. PROCEDURES: Anesthesia was induced and maintained with isoflurane in oxygen. In the first bird that was anesthetized, end-tidal isoflurane concentration was maintained at 1.0% for 15 minutes. After this period of anesthetic equilibration, an end-tidal gas sample was obtained for verification of isoflurane concentration. A toe was pinched to determine the bird's response to pain, and the bird was then allowed to recover from aesthesia. To determine MAC, a so-called up-and-down approach was subsequently used in all 15 birds. Compared with the isoflurane concentration used for MAC determination in the first bird, maintenance isoflurane concentration for the second bird was increased by approximately 10% if the first bird reacted and decreased by approximately 10% if the first bird did not react to a toe pinch. These steps were then followed until all 15 birds had been anesthetized. Crossover events occurred when birds in sequence had discordant results (ie, 1 reactor and 1 nonreactor). The MAC was defined as the mean of the isoflurane concentrations measured during these crossover events. RESULTS: Mean MAC of isoflurane in thick-billed parrots was estimated to be 1.07% (95% confidence interval, 0.97% to 1.16%). CONCLUSIONS AND CLINICAL RELEVANCE: Isoflurane MAC appears to be lower in thick-billed parrots than the MAC determined for other bird species. Determination of the species-specific requirements of thick-billed parrots should allow isoflurane anesthesia to be performed more safely in this endangered species.