Description of outcomes of experimental infection with feline haemoplasmas: Copy numbers, haematology, Coombs’ testing and blood glucose concentrations

The aim of this study was to compare blood copy, haematological and glucose values between cats experimentally infected with either Mycoplasma haemofelis (Group HF: 10 cats), ‘Candidatus M. haemominutum’ (Group HM: 3 cats) or ‘Candidatus M. turicensis’ (Group TU: 3 cats). Blood samples were collected regularly up to 85 days post-infection (DPI) for haemoplasma real-time quantitative PCR, haematology, Coombs’ testing and blood glucose measurement. Statistical analysis was performed using a general linear model (ANOVA) appropriate for a repeated measures experiment with significance set as P < 0.05. Cats in Group TU had significantly lower blood copy numbers than cats in Group HF (P < 0.001) and HM (P < 0.001). All Group HF cats developed anaemia (often severe), macrocytosis and evidence of erythrocyte-bound antibodies whereas Groups HM and TU cats did not. Group HF had significantly lower PCVs, haemoglobin concentrations and red blood cell counts, and significantly higher mean cell volumes, than Groups HM and TU. In Group HF, erythrocyte-bound antibodies reactive at 4 °C (both IgM and IgG) appeared between 8 and 22 DPI and persisted for two to four weeks, whereas those reactive at 37 °C (primarily IgG) appeared between 22 and 29 DPI and persisted for one to five weeks. In most cats antibodies appeared after the fall in haemoglobin started. Although Group TU had significantly lower glucose concentrations than Groups HF (P = 0.006) and HM (P = 0.027), mean blood glucose concentrations remained within the reference range in all groups. This study demonstrates that M. haemofelis infection, in contrast to ‘Candidatus M. haemominutum’ and ‘Candidatus M. turicensis’ infection, can result in a severe macrocytic anaemia and the development of cold and warm reactive erythrocyte-bound antibodies.     

Pharmacodynamics and pharmacokinetics of flunixin in the cat

The non-steroidal anti-inflammatory agent (NSAID) flunixin was administered as single doses both orally and intravenously to six cats at a dose rate of 1.0 mg/kg in a two-part cross-over study. After oral dosing rapid absorption to a mean peak concentration of 2.586 micrograms/ml occurred at a mean time of 1.33 h. Similar mean plasma concentration-time AUC values for oral and intravenous dosing indicated that absorption by the former route was virtually complete. The decline in plasma concentration occurred fairly rapidly with both routes, and elimination half-life was approximately 1.0-1.5 h. The time course of inhibition of serum TXB2 concentration was similar for the two routes of administration, suggesting that similar dosing schedules are likely to be appropriate for evaluation of flunixin in clinical trials.     

Comparison of bronchoalveolar lavage cytospins and smears in dogs and cats

Differences in the cytological interpretation of bronchoalveolar lavage fluid (BALF) after cytospin preparation (CP) or manual smearing of pelleted cells preparation (MSP) were investigated in client-owned dogs and cats with inflammatory or infectious lower respiratory disease. Bronchoalveolar lavage fluid from healthy cats was also examined. With MSP, cell lysis was more frequently observed, and cellular distribution was more heterogeneous throughout the slide. When samples from healthy and diseased animals were considered together, a significantly greater percentage of neutrophils was seen on CP than on MSP slides (P<0.002). Cytospin preparations were considered of better quality in all individual comparisons. Cytospin preparation is advised in the evaluation of BALF with low total cell count. When only MSPs are evaluated, clinicians should be aware that differential neutrophil counts may underestimate the counts found on CP slides.     

Veterinary aspects of ecological monitoring: the natural history of emerging infectious diseases of humans,domestic animals and wildlife

Proliferation of disease pathogens capable of affecting humans, domestic livestock and wildlife increasingly threatens environmental security and biodiversity. Livestock and wild animals in proximity to human beings are often in the chain of transmission and infection. Globalization of industrial livestock production (especially poultry upon which so much of the burgeoning human population depends) often permits transcontinental disease spread. Rapidly expanding (and often illegal) international trade in wild and domestic animals and their products are increasingly involved in the emergence of new diseases that may have the ability to transmit among humans, livestock and wildlife. Rapidly increasing urbanization has led in many places to overcrowded townships that rely on “bushmeat” for sustenance and has contributed to the emergence of virulent zoonotic pathogens. The emergence and proliferation of pathogens are exacerbated by anthropogenic transformation of natural landscapes in order to increase agricultural and livestock production. This paper posits that data gathered by veterinary ecologists should be interpreted and used by other disciplines. The importance of a thorough knowledge of the “natural history” (ecology) of the disease agent and its human, domestic and wild hosts is stressed.     

Porcine adenovirus as a delivery system for swine vaccines and immunotherapeutics

Porcine adenovirus (PAdV) has many qualities which make it an ideal choice for use as a delivery vector in swine. It is a low grade pathogen, present almost world-wide in a number of serotypes varying in their virulence and tissue tropism, which may allow for serotype specific vaccine targeting. PAdV is species specific having only been isolated from swine, reducing the possibility of its spread to other animals or man following administration. When engineered to contain a foreign gene, recombinant PAdV (rPAdV) can be grown to high titres in tissue culture cells making it cheap to produce. Knowledge of the complete nucleotide sequence of the PAdV genome has enabled rationally directed insertions of foreign genes which remain stably inserted in the genome and can be expressed at high levels following delivery to the target host. Importantly, recombinant PAdV can be administered by injection or by the oral route in feed or drinking water. We have delivered a range of antigens and immunomodulatory molecules to commercially available pigs using rPAdV and found it to be a very effective delivery system. Significantly, recombinant PAdV serotype 3 is highly effective as a delivery vehicle even when administered in the face of high levels of artificially induced serotype specific neutralising antibody to the vector.     

Retrospective study of bacterial infective arthritis in 31 dogs

OBJECTIVES: To characterise the presenting signs and pathological changes of canine bacterial infective arthritis in 31 dogs, and to document the response to different treatment regimens. Risk factors that may predispose joints to bacterial infective arthritis and influence the success of treatment were also investigated. METHODS: A retrospective review of cases of bacterial infective arthritis that were presented to three university veterinary referral hospitals over a five-year period (January 1997 to January 2002) was performed. RESULTS: The elbow joint (38 per cent) and stifle joint (44 per cent) were most commonly affected. Radiographic changes consistent with pre-existing osteoarthritis were identified in 14 joints, which had no history of previous surgery (articular or periarticular) or penetrating wound. No significant difference (P = 0.78) was identified between the outcome of combined surgical and medical management, and medical management alone. There were trends for poorer outcomes with increased bodyweight of the dog, longer duration of lameness and a higher nucleated cell count of the affected joint fluid at presentation. The overall infection rate for articular surgical procedures at one institution was 1-3 per cent. CLINICAL SIGNIFICANCE: Medical and/or surgical management were usually successful in resolving infection (94 per cent). However, they were frequently unsuccessful in restoring full joint function; this may in part have been due to the nature of the underlying joint