Delivery of sevoflurane to dogs using a Stephens anaesthetic machine.

OBJECTIVE: To investigate the sevoflurane concentrations produced within the Stephens anaesthetic machine circuit (vaporizer in-circle system) at different fresh gas flow rates (FGFRs), temperatures, vaporizer settings and vaporizer sleeve positions when used to anaesthetize dogs of different body sizes. STUDY DESIGN: Experimental non-blinded studies. ANIMALS: Eighteen mixed breed dogs, weights 4-39 kg. METHODS: Anaesthetic induction with propofol was followed by maintenance with sevoflurane in oxygen via the Stephens anaesthetic machine. In study 1, the vaporizer setting, temperature and circuit FGFRs were altered with the vaporizer sleeve down (n = 3), or in separate experiments, up (n = 3). Delivered (Fi'SEVO) and expired sevoflurane concentrations were recorded. Study 2 determined the vaporizer settings (sleeve up) required to achieve predetermined multiples of minimal alveolar concentration (MAC) of Fi'SEVO when sevoflurane was delivered to dogs (n = 12) of different bodyweights and at different FGFRs. RESULTS: Delivered concentrations of sevoflurane were sufficient to maintain anaesthesia in all dogs, regardless of bodyweight, FGFR, vaporizer temperature and sleeve position. Fi'SEVO increased with increasing temperature, when the vaporizer sleeve was down, when vaporizer setting was increased and when FGFR was decreased. As the FGFR increased or the dog's bodyweight decreased, higher vaporizer settings were required to produce the same Fi'SEVO. The median Stephens vaporizer settings to achieve an Fi'SEVO of 1.3 MAC ranged from 4.3 to 5.0 for a small dog (1-10 kg), 2.5 to 5.6 for a medium dog (15-25 kg) and 2.5 to 3.5 for a large dog (30-40 kg), depending on the FGFR. CONCLUSION AND CLINICAL RELEVANCE: The Stephens anaesthetic machine can deliver to dogs, weighing 4 kg and above, concentrations of sevoflurane sufficient or in excess of that required to maintain anaesthesia, at temperatures from 10 to 35 °C, FGFRs of 1 to 5 times the patient's estimated metabolic oxygen requirement and at any vaporizer sleeve position.

Spermiogenesis in the Australian cockatiel Nymphicus hollandicus.

Information on the ultrastructure of parrot spermatids and spermatozoa is limited to only four species with no comprehensive study of spermiogenesis conducted within the order Psittaciformes. The present study was undertaken to describe the development of the cockatiel spermatid using electron microscopy. Four phases of spermatid maturation were documented on the basis of nuclear morphology, development of the acrosome, perforatorium, and axial filament. These phases included 1) round nuclei, 2) irregular nuclei, 3) elongated nuclei with granular chromatin, and 4) elongated nuclei with homogenous chromatin. While development of the cockatiel spermatid was comparable to that of other domestic avian species, we have noted the hollow nature of some chromatin granules, an abnormal formation of the axoneme, the absence of the fibrous sheath around the axoneme of the principal piece, and the absence of an annulus.

Identification of plasmid-mediated extended-spectrum and AmpC beta-lactamases in Enterobacter spp. isolated from dogs.

The genetic determinants involved in reduced susceptibility to third-generation cephalosporins and aztreonam were identified in ten canine Enterobacter isolates associated with opportunistic infections in three veterinary hospitals in Brisbane, Australia. All isolates were evaluated by a combination of phenotypic (broth microdilution and disc susceptibility, modified disc diffusion and IEF) and genotypic (PFGE, plasmid analysis, Southern blot hybridization, bacterial conjugation, PCR and sequencing) methods to investigate genetic relatedness and to identify plasmid-mediated resistance genes, in particular beta-lactamase genes responsible for extended-spectrum cephalosporin resistance. The ten canine isolates were genotypically diverse based on PFGE and belonged to either Enterobacter cloacae or Enterobacter hormaechei on the basis of 16S rRNA gene sequence analysis. Plasmid profiles were also diverse. Nine isolates contained a transmissible blaSHV-12-carrying plasmid (approximately 140 kb) that also conferred resistance to chloramphenicol, gentamicin, spectinomycin, tetracycline, trimethoprim and sulfonamides. In all plasmid-mediated extended-spectrum beta-lactamase (ESBL)-producing isolates including transconjugants, blaSHV-12 was shown to reside in a approximately 6.5 kb plasmid fragment. The remaining isolate that was not an ESBL producer possessed an AmpC beta-lactamase gene (blaCMY-2) on a approximately 93 kb transmissible plasmid. This plasmid did not contain any other antimicrobial resistance genes. Additional plasmid-mediated beta-lactamases identified in some isolates included bla(TEM) and blaOXA-10. This is the first report of canine Enterobacter isolates containing transmissible plasmid-mediated blaSHV-12 and blaCMY-2 resistance genes. Therefore, Enterobacter isolated from opportunistic infections in dogs may be an important reservoir of plasmid-mediated resistance genes, which could potentially be spread to other members of the Enterobacteriaceae.

Molecular genetics of sudden cardiac death in small animals - a review.

Sudden cardiac death in small animals is uncommon but often occurs due to cardiac conduction defects or myocardial diseases. Primary cardiac conduction defects are mainly caused by mutations in genes involved in impulse conduction processes (e.g., gap-junction genes and transcription factors) or repolarisation processes (e.g., ion-channel genes), whereas primary cardiomyopathies are mainly caused by defective force generation or force transmission due to gene mutations in either sarcomeric or cytoskeleton proteins. Although over 50 genes have been identified in humans directly or indirectly related to sudden cardiac death, no genetic aetiologies have been identified in small animals. Sudden cardiac deaths have been also reported in German Shepherds and Boxers. A better understanding of molecular genetic aetiologies for sudden cardiac death will be required for future study toward unveiling aetiology in sudden cardiac death in small animals.

Simultaneous liquid chromatographic determination of doxorubicin and its major metabolite doxorubicinol in parrot plasma.

A new microscale method is reported for the determination of doxorubicin and its active metabolite, doxorubicinol, in parrot plasma. Sample workup involved acetonitrile protein precipitation, ethyl acetate extraction, followed by back extraction into HCl. Separations were achieved on a phenyl-hexyl column at 30 degrees C using acetonitrile (17%, v/v) in 0.01 M orthophosphoric acid (83%, v/v) delivered via a linear flow program. Fluorometric detection wavelengths were 235 nm (excitation) and 550 nm (emission). Calibration plots were linear (r2>0.999), and recoveries were 71-87% from 20 to 400 ng/mL. Assay imprecision was

Evaluation of haplotypes associated with copper toxicosis in Bedlington Terriers in Australia.

OBJECTIVE: To evaluate the haplotype distribution associated with the copper toxicosis gene and the segregation of the mutated allele in a Bedlington Terrier population in Australia. ANIMALS: 131 Bedlington Terriers. PROCEDURE: Samples of DNA and RNA were obtained from each dog. Genetic status of each dog was evaluated by use of the DNA markers C04107; single nucleotide polymorphism (SNP), which was adjacent to exon 2 of Murr1; and a deletion marker for exon 2. A subgroup of the study population was evaluated by use of biochemical and histologic techniques to elucidate the correlation between genotype and phenotype. RESULTS: We identified a recombination between the C04107 marker and Murr1 and a variation in a nucleotide in the splice site of exon 2 in our Bedlington Terrier cohort. Furthermore, we identified a novel haplotype associated with copper toxicosis in this cohort. CONCLUSIONS AND CLINICAL RELEVANCE: Our findings indicate that the deletion of exon 2 was not the sole cause of copper toxicosis, although only exon 2 deletion of Murr1 has been responsible for copper toxicosis in Bedlington Terriers. Although we failed to find a novel mutation in our cohort, we identified an affected dog family with an intact exon 2. Furthermore, we found that an SNP in the 5' splicing site of exon 2 may or may not be associated with a novel mutation of the Murr1 gene or other genes. Loss of linkage between the C04107 marker and the Murr1 gene was also identified in a certain family of dogs.

Current research in avian chemotherapy.

Chemotherapy as a treatment modality is increasingly being used in avian oncology. Currently, most chemotherapeutic agents can only be used empirically, as pharmacokinetic data in birds are lacking.Recently, the pharmacokinetic profile of the platinum analogs,cisplatin, and carboplatin has been reported in Sulfur-crested cockatoos,paving the way for clinical and toxicity trials.

Canine model for investigating the impact of oral enrofloxacin on commensal coliforms and colonization with multidrug-resistant Escherichia coli.

A model was developed in dogs to determine the impact of oral enrofloxacin administration on the indigenous coliform population in the gastrointestinal tract and subsequent disposition to colonization by a strain of multidrug-resistant Escherichia coli (MDREC). Dogs given a daily oral dose of 5 mg enrofloxacin kg(-1) for 21 consecutive days showed a significant decline in faecal coliforms to levels below detectable limits by 72 h of administration. Subsequently, faecal coliforms remained suppressed throughout the period of enrofloxacin dosing. Upon termination of antibiotic administration, the number of excreted faecal coliforms slowly returned over an 8-day period, to levels comparable to those seen prior to antibiotic treatment. Enrofloxacin-treated dogs were more effectively colonized by MDREC, evidenced by a significantly increased count of MDREC in the faeces (7.1 +/- 1.5 log(10) g(-1)) compared with non-antibiotic-treated dogs (5.2 +/- 1.2; P = 0.003). Furthermore, antibiotic treatment also sustained a significantly longer period of MDREC excretion in the faeces (26.8 +/- 10.5 days) compared with animals not treated with enrofloxacin (8.5 +/- 5.4 days; P = 0.0215). These results confirm the importance of sustained delivery of an antimicrobial agent to maintain and expand the colonization potential of drug-resistant bacteria in vivo, achieved in part by reducing the competing commensal coliforms in the gastrointestinal tract to below detectable levels in the faeces. Without in vivo antimicrobial selection pressure, commensal coliforms dominated the gastrointestinal tract at the expense of the MDREC population. Conceivably, the model developed could be used to test the efficacy of novel non-antibiotic strategies aimed at monitoring and controlling gastrointestinal colonization by multidrug-resistant members of the Enterobacteriaceae that cause nosocomial infections.

Prospects for whole genome linkage disequilibrium mapping in domestic dog breeds.

Linkage disequilibrium (LD) mapping is commonly used as a fine mapping tool in human genome mapping and has been used with some success for initial disease gene isolation in certain isolated in-bred human populations. An understanding of the population history of domestic dog breeds suggests that LD mapping could be routinely utilized in this species for initial genome-wide scans. Such an approach offers significant advantages over traditional linkage analysis. Here, we demonstrate, using canine copper toxicosis in the Bedlington terrier as the model, that LD mapping could be reasonably expected to be a useful strategy in low-resolution, genome-wide scans in pure-bred dogs. Significant LD was demonstrated over distances up to 33.3 cM. It is very unlikely, for a number of reasons discussed, that this result could be extrapolated to the rest of the genome. It is, however, consistent with the expectation given the population structure of canine breeds and, in this breed at least, with the hypothesis that it may be possible to utilize LD in a genome-wide scan. In this study, LD mapping confirmed the location of the copper toxicosis in Bedlington terrier gene (CT-BT) and was able to do so in a population that was refractory to traditional linkage analysis.