Post-Therapy Antibody Titers in Dogs With Ehrlichiosis: Follow-Up Study on 68 Patients Treated Primarily With Tetracycline and/or Doxycycline

The clinical and serological responses to therapy were evaluated for at least 1 year in 68 dogs with antibody titers positive for Ehrlichia cam's. Treatments were of variable periods with primarily tetracycline hydrochloride and/or doxycycline. Sixteen dogs had initial titers of 1:20 and, at the end of the year, were asymptomatic, no longer receiving medication, and had negative serology. The average length of treatment with tetracycline HCI and/or doxycycline was 85 days (range, 14 to 360 days). Of 39 dogs with initial titers of 1:2,560 or greater, 1 died, 25 were asymptomatic, and 13 were lost to follow-up at the end of the study. The average length of treatment was 210 days (range, 21 to 630 days). Twenty-seven dogs were seropositive at ≥ 1:2,560 when the sera was last tested. Thirteen dogs had initial titers of 1:80 to 1:1,280. Of these 13 dogs, 2 died, 2 were lost to follow-up, and 9 were asymptomatic and had titers ranging from negative to ≥ 1:2,560 at the end of the study. The persistence of antibodies, prolonged subclinical phase, and delayed relapses despite long-term medication, suggest inadequate chemotherapeutic agents or may be natural features of latency of ehrlichiosis in dogs. J Vet Intern Med 1996;10:271–274. Copyright © 1996 by the American College of Veterinary Internal Medicine .     

Antithrombotic actions of aspirin in the horse

The antithrombotic effects of aspirin at two dose rates (4 mg/kg and 11 mg/kg bodyweight [bwt] were evaluated in normal, healthy ponies by measuring template bleeding time. Inhibition of platelet aggregation in response to adenosine diphosphate (ADP) and collagen was evaluated and cyclo-oxygenase activity was monitored by radioimmunoassay of thromboxane B2 (TXB2), the stable metabolite of thromboxane A2 (TXA2). TXB2 was measured in serum and platelet rich plasma. Bleeding time was prolonged significantly until 48 h after treatment at 12 mg/kg bwt and until 4 h at the lower dose rate. Synthesis of TXB2 and collagen induced aggregation were diminished for much greater periods with similar results at each of the dose rates. The prolonged effects of aspirin on platelet function occurred in spite of a very short plasma half-life of aspirin, because of its irreversible action on platelet cyclo-oxygenase. The results show that low dose aspirin has a potential role in antithrombotic therapy in horses although the relationship between skin bleeding time in normal horses and improvement of clinical conditions requires further research and evaluation in clinical trials. TXB2 measurement appears to overestimate the duration of antithrombotic effects of aspirin in vivo.     

Synthesis, transport, and release of posterior pituitary hormones

Vasopressin and oxytocin are made and released by neurons of the hypothalamo-neurohypophysial system. Pulse labeling these neurons with radioactive amino acid indicates that the two hormones and their respective neurophysin carrier proteins are synthesized as parts of separate precursor proteins. The precursors seem to be processed into smaller, biologically active molecules while they are being transported along the axon.     

Cross-reacting antigens between Mycoplasma ovipneumoniae and other species of mycoplasma of animal origin, shown by ELISA and immunoblotting with reference antisera

Using enzyme-linked immunosorbent assays with Mycoplasma ovipneumoniae as antigen, the cross-reactivity of antigens between this species and 22 other mycoplasma species was examined using reference polyclonal antisera. Significant cross-reactivity with M. ovipneumoniae was demonstrated by five species, only, viz. M. bovoculi, M. dispar, M. flocculare, M. hyopneumoniae and M. hyorhinis. Using one-dimensional SDS-PAGE and immunoblotting techniques with homologous and heterologous antisera, cross-reacting antigens of M. dispar, M. flocculare, M. hyopneumoniae and M. ovipneumoniae were further investigated. Cross-reacting antigens with apparent molecular weights of 64, 44 and 32 kDa were common to all and a 184 kDa cross-reacting antigen occurred in all except M. ovipneumoniae. Further cross-reacting antigens (one-way and two-way) between two of the four species are reported. Four monoclonal antibodies against different antigens of M. ovipneumoniae did not recognise any antigen in the other three species examined.