Evaluation of the safety of ivermectin-praziquantel administered orally to pregnant mares

OBJECTIVE: To evaluate the safety of an orally administered ivermectin and praziquantel paste with regard to variables associated with clinical findings, parturition, lactation, maternal care, and neonate viability in pregnant mares. ANIMALS: 40 pregnant mares. PROCEDURE: Mares were randomly allocated into treatment (n = 20) and control (20) groups and administered a placebo or 3 times the therapeutic dosage of ivermectin (0.6 mg/kg) and praziquantel (4.5 mg/kg) at 14-day intervals until parturition. Physical examinations were performed on mares and their foals after parturition (on postpartum days 30, 60, and 90) to identify any drug-related effects. As an aid in assessing general health, hematologic and serum biochemical analyses were performed monthly on the mares. RESULTS: In blood constituents, minor alterations that were not biologically important were observed. Reproductive performance was not affected by the unusual treatment duration or high dosage, although the drugs were administered during a crucial period of equine embryonic development (30 to 60 days). Neither adverse effects on mares nor abortions occurred. Follow-up evaluations of the foals for a 3-month period did not detect any abnormalities. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of the ivermectin-praziquantel paste appears to be safe in pregnant mares and their foals.     

Cecal colonization of chicks by bovine-derived strains of Campylobacter

Campylobacter jejuni and Campylobacter coli strains were isolated from feces of dairy cattle at farms with no known problem due to campylobacteria. Farms were located in the northeast, desert southwest, and Pacific west. Twenty isolates were identified by ribotyping with a RiboPrinter. The ability of these bovine isolates to colonize the ceca of chicks was determined by challenge inoculation and reisolation of the challenge strain from the ceca at 1 and 2 wk after challenge. Isolates recovered from chick ceca were examined by ribotyping to assure they matched the challenge strain. One hundred percent of the bovine-derived challenge strains were capable of colonizing chicks. These results indicate that dairy cattle may be asymptomatic Campylobacter carriers and potential sources of campylobacteria contamination of poultry facilities.     

Relationships of testicular iron and ferritin concentrations with testicular weight and sperm production in boars

The inverse relationship of testicular size and circulating follicle-stimulating hormone (FSH) concentrations has been documented, and accompanying this relationship is the change in color of the parenchymal tissue of the testes. Large testes (300 to 400 g) are pink to light red and small testes (100 g) are dark maroon with color gradations for weights in between. It was hypothesized that this color most likely represented an iron protein. Chromatographic analysis of testicular tissue indicated that the Fe was associated primarily with ferritin, and immunohistochemistry showed that Leydig cells were the primary location of ferritin storage within the testes. Concentrations of Fe and ferritin were higher in small testes and decreased as testes weight increased (P < 0.05). As testicular Fe concentrations increased, daily sperm production (DSP) and total DSP declined (P < 0.05). Genotyping six generations of Meishan x White composite boars (n = 288) for a quantitative trait locus that is indicative of elevated FSH and small testes in boars indicated that the Meishan genotype had elevated testicular iron concentrations and darker color in conjunction with reduced total DSP (P < 0.01). It is not thought the elevated iron concentrations affect testicular weights but are probably a result of elevated FSH and FSH inducement of Fe transport. The storage of Fe in Leydig cells may provide a reservoir of Fe for easy access by Sertoli and germ cells, but still provide a degree of protection to germ cells from ionic iron.     

Antibiotic resistance--an evolving problem

In 1998, an influential report on antimicrobial resistance from the House of Lords Select Committee on Science and Technology highlighted the threat posed to public health by resistance, and called for products to be used more prudently in both human and veterinary medicine. Here, Lord Soulsby, who chaired the Lords' committee on antimicrobials, and Richard Wise, who advised the committee and is now chairman of the Government's Specialist Advisory Committee on Antimicrobial Resistance, consider what has been achieved since then, along with the challenges that remain.     

Genetic characterization of 2 novel feline caliciviruses isolated from cats with idiopathic lower urinary tract disease

Feline caliciviruses (FCVs) are potential etiologic agents in feline idiopathic lower urinary tract disease (I-LUTD). By means of a modified virus isolation method, we examined urine obtained from 28 male and female cats with nonobstructive I-LUTD, 12 male cats with obstructive I-LUTD, and 18 clinically healthy male and female cats. All cats had been routinely vaccinated for FCV. Two FCVs were isolated; I (FCV-U1) from a female cat with nonobstructive I-LUTD, and another (FCV-U2) from a male cat with obstructive I-LUTD. To determine the genetic relationship of FCV-U1 and FCV-U2 to other FCVs. capsid protein gene RNA was reverse transcribed into cDNA, amplified, and sequenced. Multiple amino acid sequence alignments and phylogenetic trees were constructed for the entire capsid protein, hypervariable region E, and the more conserved (nonhypervariable) regions A, B, D, and F. When compared to 23 other FCV isolates with known biotypes, the overall amino acid sequence identity of the capsid protein of FCV-U1 and FCV-U2 ranged from 83 to 96%; identity of hypervariable regions C and E ranged from 58 to 85%. Phylogenetically, FCV-U1 clearly separated from other FCV strains in phenograms based on nonhypervariable regions. In contrast, FCV-U2 consistently segregated with the Urbana strain in all phenograms. Clustering of isolates by geographic origin was most apparent in phenograms based on nonhypervariable regions. No clustering of isolates by biotype was apparent in any phenograms. Our results indicate that FCV-UI and FCV-U2 are genetically distinct from other known vaccine and field strains of FCV.