Role of lymph-borne cells in the early stages of scrapie agent dissemination from the skin

Scrapie is a natural transmissible spongiform encephalopathy (TSE) of sheep, infecting the animal via the gastrointestinal tract or the skin. This project tested the hypotheses that lymph-borne cells (especially dendritic cells) are crucial for the systemic dissemination of the infectious agent from the site of infection in the skin, that PrP genotype affects PrPSC association with dendritic cells and that PrPSC carriage by cells affects their expression of cytokines. Skin, of scrapie-susceptible VRQ/ARR and scrapie-resistant ARR/ARR PrP genotypes, was scarified with FITC-labelled PrPSC. Pseudoafferent lymphatic cannulation was then used to monitor the presence of FITC-PrPSC over time in different lymph cell populations and plasma in the draining afferent lymphatics. The major observation was that PrPSC did not associate significantly with any lymphocyte or dendritic cell population in the 5 days following PrPSC scarification. The only cells seen to associate with PrPSC were neutrophils. Furthermore, despite the quantity of PrPSC used for scarification being equivalent to a standard infectious dose (the VRQ/ARR sheep dying at approximately 260 days) the only PrP found in afferent lymph during the 0-5-day period was proteinase K sensitive (i.e. soluble PrPC). No differences were observed between the PrP genotypes. Analysis of the effects of PrPSC scarification of cellular cytokine mRNA expression (by a nuclease protection assay) showed raised levels of IL-1beta and IL-8 in the susceptible VRQ/ARR group and raised levels of IFNgamma in the resistant ARR/ARR animals.     

Tuberculosis in cattle: strategic planning for the future

In the later stages of eradication of tuberculosis in cattle there is a need to take account of the fact that Mycobacterium bovis infection in cattle presents, not as cases of clinical disease but most commonly as apparently healthy animals showing an immunological response to tuberculin. This is an entirely different scenario to that seen when national eradication programmes were first devised, at a time when the protection of public health rather than animal health was the prime motivation. In countries with active programmes to eradicate bovine tuberculosis, it is critical for the programme's success that account is taken of this redefinition of tuberculosis, side by side with changes in modern animal production systems and their impact on the transmission of M. bovis. This paper highlights factors critical to the success of a national eradication programme, including a clear identification of the goals, of the policies that guide actions, and of the sequences of actions that are required within the programme to accomplish these goals. Experience has illustrated the adverse effects of compromise on outcome when the application of fundamental principles of disease control such as sound animal management, removal of known sources of infection, early diagnosis, quarantine, movement control and environmental hygiene are less than enthusiastically promoted and applied. The reality is that where these principles are applied in a sustained manner, the outcome is more likely to be successful. Therein lies the challenge for the risk manager.     

Radiographic evaluation of the Zurich cementless total hip acetabular component

OBJECTIVE: To radiographically evaluate the Zurich cementless total hip (ZCTH) cup and correlate lucency with clinical signs of implant instability, time since surgery, and implant generation, using zonal analysis. STUDY DESIGN: Retrospective study. ANIMALS: Client-owned dogs (n = 53). METHODS: Radiographs of dogs that had ZCTH arthroplasty (>1 year) were evaluated using zonal analysis, for lucency surrounding the cup-bone interface (number of zones, length, area). Dogs were examined for clinical signs of implant instability (lameness, hip pain). Lucency was correlated with lameness, time after surgery, and implant generation. RESULTS: Radiographs of 68 implants (18 generation I, 50 generation II) were evaluated. Eight dogs were lame (11.8%). Dogs with lameness were more likely to have lucency in > or =2 zones of analysis (per view), have >2 times the average curvilinear length of lucency, and have >4 times the average area of lucency surrounding the implant compared with non-lame dogs. A weak relationship was observed between time after surgery and implant generation; however, there was no relationship between time after surgery and lucency. CONCLUSIONS: Dogs with lameness after ZCTH arthroplasty were more likely to have lucency at the cup-bone interface. Lucency was better evaluated by radiographic projection than zonal analysis. Temporal progression of lucency was weakly correlated with implant generation. CLINICAL RELEVANCE: Dogs with lucency in > or =2 zones of analysis should be evaluated more frequently for clinical signs of implant loosening. Further investigation of serial radiographs after ZCTH arthroplasty is warranted.     

Monitoring presence and annual variation of trichomoniasis in mourning doves

Information about the annual variation of trichomoniasis in mourning doves (Zenaida macroura) may be important in understanding mechanisms affecting mourning dove populations. The objectives of this study were to monitor the presence and annual variation of Trichomonas gallinae for 6 yr in a local mourning dove population using hunter-killed doves. During 1998-2003, 4052 hunter-killed doves were sampled for the presence of T. gallinae; 226 (5.6%) tested positive (4.4%-10.6% range). Results of the monitoring effort were relatively consistent during the 6-yr period, with the presence of T. gallinae being within the range of previously reported estimates for mourning doves. Asymptomatic carriers in one segment of the dove population may provide a mechanism for spreading the disease to other segments of the mourning dove population.     

Possible adverse reaction to droncit in a miniature poodle

Abstract

Extract

Madam:— The N.Z.V.A. Nominee on the National Hydatids Council, Mr Peter Malone, in his annual report states that he knows of “no professional concerns that would allow certificates to be issued to exempt dogs from dosing with droncit, and on receipt of copies of such certificates will continue to forward them to the Veterinary Council to examine for disciplinary action”. (1 1985. Report of the N.Z.V.A. Nominee on the National Hydatids Council: N.Z.V.A. Annual Report 43–43.  [Google Scholar] In September 1985 I examined a nine year old miniature poodle dog that had been dosed with droncit by a hydatids control officer two hours previously. The dog had collapsed into lateral recumbancy, was pale and cyanotic with a rectal temperature of 37.3°C. Cardiac and thoracic auscultation was normal, and no other abnormal clinical signs were detected. There was no previous history of similar episodes and the dog has been dosed with droncit several times beforehand without problems. The dog was treated with betamethasone and millophylline and made a full recovery within 48 hours.     

Safety of elevated dosages of a 0.24% diflubenzuron pellet administered orally to horses

The safety of a feed-thru pellet formulation containing the insect growth regulator diflubenzuron (0.24%) for control of manure-breeding flies (Musca domestica L. and Stomoxys calcitrans L.) in horses was evaluated. Pellets were administered orally at 0, 1, 3, and 5 times the clinical dosage (0.12 to 0.20 mg/kg) on a daily basis for 31 consecutive days. Variables examined included daily clinical observations, hematology, coagulation, serum chemistry, acetylcholinesterase inhibition, body weights, and physical examinations. Horses remained healthy throughout the study, and no adverse reactions or events related to the pellets were observed. Statistically significant differences (P < or = 0.10) between dose groups (0x, 1x, 3x, and 5x) were observed for only four of the 44 serum chemistry and hematologic variables measured, none of which was dose related. Diflubenzuron can be safely administered orally to horses at 0.12 to 0.20 mg/kg for control of manure-breeding flies.