The efficacy of selamectin in the treatment of naturally acquired infestations of sarcoptes scabiei on dogs

Selamectin, a novel avermectin, was evaluated for its effect on naturally occurring infestations of Sarcoptes scabiei in 42 dogs. In two controlled and masked laboratory studies conducted in the USA and Italy, infested dogs received treatment with either selamectin (6mgkg(-1); range: 6-12mgkg(-1)) or the vehicle only (negative control). Treatments were administered topically to the skin on each animal's back at the base of the neck in front of the scapulae. Study day 0 was defined as the first day of treatment administration. Dogs were treated on days 0 and 30, and efficacy was assessed by counting viable mites recovered from skin scrapings performed on each dog on days 14, 29 or 30, 44, and 60, and by categorising the clinical signs of canine scabies on the same days. Percentage reductions in geometric mean mite counts for selamectin, compared with vehicle, on days 14, 29 or 30, 44, and 60 were > or =98.1, > or =93.5, 100, and 100%, respectively. Analysis of variance, confirmed by Savage Scores, showed that ln(mite counts+1) values for selamectin-treated dogs were significantly lower (P< or =0.0391) than those for vehicle-treated dogs on all post-treatment assessment days. Clinical signs of scabies were markedly reduced in selamectin-treated dogs, compared with vehicle-treated dogs. Topical administration to the skin in a single spot of a single unit dose of selamectin, or of two unit doses given 1 month apart, each providing at least the recommended minimum dosage of 6mgkg(-1), was highly effective against naturally acquired infestations of S. scabiei in dogs, reducing mite counts by >93% (single dose) and 100% (two doses).     

Efficacy of selamectin against experimentally induced and naturally acquired infections of Toxocara cati and Ancylostoma tubaeforme in cats

The efficacy of selamectin against experimentally induced and naturally acquired infections of adult ascarids (Toxocara cati) and adult hookworms (Ancylostoma tubaeforme) was evaluated in five controlled studies in cats. Two studies evaluated the efficacy of selamectin against both ascarid (natural or induced) and hookworm (induced) infections; two studies evaluated the efficacy of selamectin against single natural infections of T. cati or A. tubaeforme; and the fifth study evaluated the efficacy of selamectin against induced infections of A. tubaeforme. Cats received selamectin topically in unit doses designed to deliver a minimum of 6mgkg(-1). Treatments were applied to the skin on each animal's back at the base of the neck in front of the scapulae. For experimentally induced infections, cats were inoculated orally with approximately 500 embryonated eggs of T. cati 56 days prior to treatment and/or approximately 150-250 larvae (L(3)) of A. tubaeforme 30 or 42 days prior to treatment. For both induced and naturally acquired infections, cats were allocated randomly to treatments (6-12 cats per treatment) on the basis of fecal egg counts to receive either selamectin or a vehicle containing the inert formulation ingredients. In all studies, adult worm counts were performed at necropsy 14 days after the last treatment administration. Against T. cati, a single application of selamectin provided a 100% reduction in the geometric mean number of adult worms for both experimentally induced and naturally acquired infections. Against A. tubaeforme, a single administration of selamectin provided a 99.4% reduction in the geometric mean number of adult worms in cats with natural infections, and an 84.7-99.7% reduction in adult worms in cats with induced infections.Two doses of selamectin administered at monthly intervals provided a 91.9% reduction in the geometric mean number of adult A. tubaeforme worms in cats with experimentally induced infections. The geometric mean numbers of adult worms (T. cati and A. tubaeforme) from selamectin-treated cats were significantly (P< or =0.0018) lower than for vehicle-treated cats in all studies. Thus, a single topical unit dosage providing a minimum dosage of 6mgkg(-1) selamectin was highly effective in the treatment of naturally acquired and experimentally induced infections of T. cati and A. tubaeforme in cats.     

Evaluation of the effects of selamectin against adult and immature stages of fleas (Ctenocephalides felis felis) on dogs and cats

The adulticidal, ovicidal, and larvicidal effects of selamectin against flea (Ctenocephalides felis felis) infestations on dogs and cats were evaluated in a series of seven controlled and masked studies (three in cats, four in dogs). Animals were randomly allocated to treatment with either selamectin at a minimum dosage of 6mgkg(-1) in the commercial formulation or one of two negative-controls (0.9% NaCl solution or the vehicle from the commercial formulation). Treatments were administered topically in a single spot on the skin at the base of the neck in front of the scapulae. Speed of kill, measured by flea comb counts at 12h intervals during the 48h immediately following a single treatment on day 0, was evaluated in two studies. One study was in dogs and the other in cats, and each animal was infested with approximately 100 unfed viable adult fleas prior to treatment. Reductions in geometric mean flea counts for selamectin compared with saline were >98% between 24 and 36h after treatment in dogs, and between 12 and 24h after treatment in cats (P< or =0.0006). Efficacy in reducing flea egg hatch and larval development was evaluated in four studies, in which dogs and cats were treated once on day 0 and then repeatedly infested with approximately 600 fleas. Flea eggs were collected approximately for 72h after each infestation, on days 3, 7, 14, 21, and 30, counted, and cultured to determine their hatchability and subsequent larval development. Compared with the vehicle, selamectin was highly effective in reducing flea egg hatch (>92% in cats) and larval development (> or =95% for dogs and cats), and emergence of adults (97.8-100% for dogs, 85.6-100% for cats) for 30 days. Effects of exposure to hair coat debris were investigated in a study with dogs treated once on day 0 and repeatedly infested with 100 adult fleas. Debris (dander, flea faeces, hair, scales) was collected on days 1, 7, 14, 21, and 30 and added to normal flea eggs or larvae for incubation. Compared with debris from vehicle-treated dogs, debris from selamectin-treated dogs was highly effective in preventing egg hatch (>96%), in killing larvae (>98%) and in preventing larval development to adults (>99%) (P相似文献   

Evaluation of efficacy of selamectin and fipronil against Ctenocephalides felis in cats

OBJECTIVE: To evaluate efficacy of monthly administration of selamectin and fipronil against Ctenocephalides felis in cats. DESIGN: Randomized controlled trial. ANIMALS: 36 healthy cats. PROCEDURE: Cats known to be free of fleas were infested with 100 unfed adult fleas on days -28 and -21. On days 0, 30, 60, 90, and 120, sixteen cats (8 pairs/treatment group) were treated by topical administration of selamectin (6 mg/kg [2.7 mg/lb] of body weight) or fipronil (7.5 mg/kg [3.4 mg/lb]). Four control cats (2 pairs) were not treated. On day -6 and every 2 weeks after initial treatment, comb counts were performed to detect fleas. Flea counts were recorded, and fleas (< or =50) that had been removed were replaced onto the cat. On day 89, fleas were not replaced. On day 91 and every 7 days until the end of the study (day 150), cats were challenged with 20 adult fleas. Flea counts were compared between and within treatments. RESULTS: 14 days after treatment, geometric mean flea counts were reduced by 71.2% by fipronil treatment and 35.3% by selamectin treatment. Both treatments resulted in 97 to 98% reduction in flea counts on day 29 and 99.8 to 100% reduction from day 44 to the end of the study. CONCLUSIONS AND CLINICAL Relevance: Selamectin is as effective as fipronil in treating infestation in cats housed for 3 months in a flea-infested environment under conditions known to support the flea life cycle and in protecting against subsequent weekly challenges with C felis for an additional 2 months.     

Effect of settled sludge on dissolved ammonia concentration in tanks used to grow abalone (Haliotis midae L.) fed a formulated diet

The relative contribution that solid waste or 'sludge', which accumulates at the bottom of abalone ( Haliotis midae L.) tanks, makes to dissolved ammonia has not been established. Sludge was allowed to accumulate in 10 fully stocked abalone tanks, fed a formulated feed (Abfeed^®; Marifeed, South Africa), for 24 days. Sludge was subsequently siphoned from five of these tanks. Total ammonia nitrogen (TAN) production and toxic, free ammonia nitrogen (FAN) were recorded in the tanks from which sludge was removed and compared with those from which sludge was not removed over the subsequent 50 h. Tanks with neither abalone nor sludge present were used as a control. The mean production of TAN (±standard deviation) was an average of 44% higher in tanks from which sludge was not removed compared with those from which it was, indicating that the sludge was a significant contributor to dissolved ammonia in the tanks. The toxic FAN concentrations were correspondingly higher in tanks with sludge present (2.3±0.3 μL⁻¹) compared with cleaned tanks (1.9±0.1 μL⁻¹). Our results indicate that regular removal of sludge from abalone tanks should significantly reduce the dissolved ammonia levels, thereby improving water quality in the culture environment.     

Earthquakes on dipping faults: the effects of broken symmetry

Dynamic simulations of earthquakes on dipping faults show asymmetric near-source ground motion caused by the asymmetric geometry of such faults. The ground motion from a thrust or reverse fault is larger than that of a normal fault by a factor of 2 or more, given identical initial stress magnitudes. The motion of the hanging wall is larger than that of the footwall in both thrust (reverse) and normal earthquakes. The asymmetry between normal and thrust (reverse) faults results from time-dependent normal stress caused by the interaction of the earthquake-generated stress field with Earth's free surface. The asymmetry between hanging wall and footwall results from the asymmetric mass and geometry on the two sides of the fault.     

Assessing inbreeding in perennial ryegrass (Lolium perenne) as a step towards F1 hybrid breeding

Perennial ryegrass is an important turf and forage grass in temperate regions worldwide. Limited genetic gains have been made with current breeding strategies compared with other grass crops, such as rice and maize, which benefit from Filial 1 (F1) hybrid breeding. One of the largest constraints on hybrid breeding in ryegrass is self-incompatibility preventing inbreeding, as homozygous parental lines are required to develop hybrids with maximal hybrid vigour. Obligate outcrossing in ryegrass has resulted in cultivars with high levels of heterozygosity, lacking trait uniformity across the population. A naturally occurring self-fertile (SF) locus that overcomes the self-incompatibility system has been identified in a European perennial ryegrass population. This study crossed the SF locus into an elite cultivar, producing a self-compatible population that was inbred for several generations. Genotyping-by-sequencing (GBS) was used to assess the population structure and degree of inbreeding in the self-compatible population. Phenotypic analysis indicated that increased homozygosity did not necessarily affect growth and performance. This study concludes that self-compatible ryegrass is a promising tool for hybrid breeding and agronomic improvement of perennial ryegrass.     

Dissimilar effects of human and elephant disturbance on woodland structure and functional bird diversity in the mopane woodlands of Zambia

Landscape Ecology - Humans and elephants are major disturbance agents in the African savanna woodlands. While both species remove trees, humans selectively harvest larger stems, which are less...