Efficacy of nemadectin, a new broad-spectrum endectocide, against natural infections of canine gastrointestinal helminths

Nemadectin, a new broad-spectrum endectocide, was highly efficacious against natural infections of all the major canine gastrointestinal helminths. At single oral dosages of 0.2-0.4 mg kg-1 body weight (BW), a liquid formulation administered in gelatin capsules was 100% effective in eliminating natural infections of Toxocara canis, Toxascaris leonina, Ancylostoma caninum and Uncinaria stenocephala. Tablets (267 mg) containing 4.6% nemadectin given at a rate of 1/3 tablet per 20 kg BW (0.2 mg nemadectin kg-1) were 100% active against T. canis, A. caninum and U. stenocephala. With both formulations, an increase in the dose rate to 0.6-0.8 mg kg-1 BW resulted in 99-100% elimination of Trichuris vulpis infections. No adverse reactions were observed in any of the treated dogs.     

A specific DNA probe which identifies Babesia bovis in whole blood.

A genomic library of Babesia bovis DNA from the Mexican strain M was constructed in plasmid pUN121 and cloned in Escherichia coli. Several recombinants which hybridized strongly to radioactively labeled B. bovis genomic DNA in an in situ screening were selected and further analyzed for those which specifically hybridized to B. bovis DNA. It was found that pMU-B1 had the highest sensitivity, detecting 25 pg of purified B. bovis DNA, and 300 parasites in 10 microliters of whole infected blood, or 0.00025% parasitemia. pMU-B1 contained a 6.0 kb B. bovis DNA insert which did not cross-hybridize to Babesia bigemina, Trypanosoma evansi, Plasmodium falciparum, Anaplasma marginale, Boophilus microplus and cow DNA. In the Southern blot analysis of genomic DNA, pMU-B1 could differentiate between two B. bovis geographic isolates, Mexican strain M and Thai isolate TS4. Thus, the pMU-B1 probe will be useful in the diagnosis of Babesia infection in cattle and ticks, and in the differentiation of B. bovis strains.     

Quantitative Aspects of Thyroid Scintigraphy With Pertechnetate (99mTcO4) in Cats

Thyroidal ^99mTcO₄(pertechnetate) uptake percentages were determined in unanesthetized euthyroid (n = 13) and hyperthyroid (n = 18) cats. Maximal uptakes were observed 60 minutes after IV injection of the radionuclide and ranged from 0.3 to 3.9% of the dose in euthyroid cats (median 2.23%) and from 5.2% to 23.9% of the dose in hyperthyroid cats (median 14.8%) ( P < .05). There were no overlaps in pertechnetate uptake percentages during any of the intervals evaluated. It is concluded that the optimal time for visualization of the thyroid by ^99mTcO₄-scanning is 60 minutes after IV injection of the radionuclide. Calculation of the percentage uptake is of additional diagnostic value.     

Principles of fracture fixation in growing animals.

Changes in bone structure and conformation can occur very rapidly in growing animals. Injury to the bones or articular surfaces warrant special consideration because of the potential devastating consequences of secondary growth deformities in the animal. Disturbance of normal growth plate activity, imperfect fixation of an articular fracture, and conformational defects in long bones may create lifelong problems for the animal.     

Use of Echinococcus granulosus worm antigens for immunodiagnosis of E. granulosus infection in dogs.

Echinococcus granulosus worm excretory/secretory antigens (WES) were used in ELISA for diagnosis of E. granulosus infection in dogs and compared with protoscolex somatic antigens (PSM). Sera from 224 dogs were tested. There was no correlation between ELISA absorbance values and E. granulosus worm burdens using either antigen. There was a significant linear relationship between absorbance values of sera tested in the ELISA using WES (W-ELISA) and the ELISA using PSM (P-ELISA). However, there was a small but significant difference between the absorbance values of the sera tested against the two antigens. Western blot analysis of WES using sera from E. granulosus-infected and uninfected dogs revealed antigenic components of relative molecular mass (Mr) larger than 94,000, Mr 94,000-68,000 and Mr 43,000-39,000 in worms, and these were specific for E. granulosus and not identified in PSM; these antigenic differences may be responsible for differences in reactivity in ELISA. The sensitivities of W-ELISA and P-ELISA were 80.8% and 75.6%, respectively. The specificities of W-ELISA and P-ELISA were 93.7% and 97.9%, respectively. The reduced specificity in W-ELISA was mainly attributable to increased background reactivity of sera from Taenia hydatigena-infected dogs. Despite the reduction in specificity, both ELISAs are valuable epidemiological tools to determine the prevalence of antibody to E. granulosus in dog populations and to monitor the success of hydatid control campaigns.     

Comparative virulence of NAD-dependent and NAD-independent Actinobacillus pleuropneumoniae strains.

The virulence of a NAD-independent Actinobacillus pleuropneumoniae serotype 2 strain and NAD-dependent serotype 2, 3 and 9 strains was compared under experimental conditions. Hysterectomy-derived piglets were inoculated endobronchially with 50-500 cfu of these strains. All 23 piglets inoculated with the NAD-dependent strains developed acute disease within 12 hours post inoculation. Twenty-two of these piglets died within 24 hours after the first clinical signs. Three of nine piglets inoculated with the NAD-independent strain did not develop clinical disease. In the other six piglets, disease signs were similar as in the piglets inoculated with the NAD-dependent strains. No differences in clinical disease were observed between colostrum deprived piglets and piglets that obtained colostrum from a SPF sow.