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Biomedical subjects

R O Drummond

Publications and source records attributed to R O Drummond.

At least 19 recordsLinked to original sources
PubMed1998

Efficacy of amitraz (Taktic 12.5% EC) as a dip for the control of Boophilus microplus (Canestrini) (Acari: Ixodidae) on cattle.

Four groups of cattle infested with Boophilus microplus (Canestrini) were each dipped in a different concentration of amitraz diluted from a 12.5% EC formulation to determine the efficacy and performance of the product in an 11,400 l dipping vat. Except for the period when heifers were dipped, animals were restrained in stanchions placed individually inside 3.3 x 3.3 m2 stalls within an open-sided barn. The amitraz in the vat was stabilized with hydrated lime to maintain a pH of ca. 12. Analyses of vat samples showed that concentrations of amitraz in the vat were 7.6 to 13% lower than the targeted concentrations of 0.010, 0.015, 0.020, and 0.025% active ingredient (AI) for dilutions prepared according to instructions on the manufacturer's label. The large quantity of hydrated lime added to the vat (10 kg/1000 l) interfered with the HPLC analysis of vat samples. Therapeutic efficacy of each of the four observed concentrations (0.0088, 0.0131, 0.0174, and 0.0231% AI) of amitraz was excellent (> 99% control). However, the rapid detachment of all ticks from an animal within a few hours after treatment with amitraz, that has been frequently observed, was not pronounced in the present study. Only 47% of the B. microplus detached in the first 4 h post-treatment, and 84% detached within the first 24 h. All of the treatments, except the lowest concentration, provided protection of cattle against re-infestation by B. microplus larvae for 14 days post-treatment. Possibly as a result of the formation of a compact layer of lime and amitraz on the bottom after the vat was undisturbed for six weeks, intense agitation was required to re-suspend the active ingredient.

Animals↗
PubMed1985

Systemic activity of closantel for control of lone star ticks, Amblyomma americanum (L.), on cattle.

Cattle were treated once at 5 mg/kg orally or subcutaneously or daily at 0.1-5 mg/kg orally or 0.1-1 mg/kg subcutaneously with closantel, N-[5-chloro-4-[(4-chlorophenyl)cyanomethyl]-2-methylphenyl]-2-hydroxy-3, 5-diiodobenzamide, and numbers and weights of engorged females, weights of egg masses and hatch of eggs of lone star ticks, Amblyomma americanum, were recorded. Effectiveness of treatments on reproduction was determined by comparing total estimated larvae (EL) (EL = wt. egg mass X est. % hatch X 20000) of ticks from treated cattle with that of ticks from untreated cattle. With certain treatments, we also determined the effect of manure of treated cattle on survival of larvae of the horn fly, Haematobia irritans, or effect on survival and of fecundity of adult horn flies or stable flies, Stomoxys calcitrans, fed on blood from treated animals. The single oral treatment afforded essentially complete control of total EL only of ticks placed on the animal on the day of treatment, while the single subcutaneous treatment afforded greater than 92% control of total EL of ticks placed on animal on treatment day and for 6 weeks posttreatment. Daily treatments of 0.5 mg/kg or greater orally and 0.1 mg/kg or greater subcutaneously afforded essentially complete control of total EL of ticks throughout the treatment period (3-12 weeks) and for 1-7 weeks after treatment was discontinued. An estimated concentration of greater than 9 micrograms/ml of blood was calculated by probit analysis to be necessary to provide greater than 90% control of total EL of lone star ticks; that same concentration also provided greater than 90% control of hatch of eggs laid by treated females. A higher concentration (40 micrograms/ml) was necessary to prevent engorging of the females. No treatments tested were effective against larvae of the horn fly or adult horn flies or stable flies.

Animals↗
PubMed1985

New methods of applying drugs for the control of ectoparasites.

A brief history of the development of methods used to apply drugs (commonly called insecticides or acaricides) to domesticated animals for the control of ectoparasites is presented. The focus is on methods used in the United States for treating cattle, sheep and goats, and swine. Details of the evolution of treatment methods are presented for lice, flies, cattle grubs, keds, ticks, and other arthropods. In general, treatment methods have undergone some change over the years; while, in contrast, treatment materials have changed considerably. Three trends in treatment methods become obvious - (1) Gradual reduction in the amount of treatment material applied dermally from spray or dip to pouron, to spoton, and to insecticide-impregnated ear tags, (2) Increasingly wider use of animal systemic insecticides administered orally or percutaneously to control a variety of ectoparasites, and (3) The development of new methods (sustained release devices) to lengthen the residual effectiveness of treatments. Unfortunately, lengthened residual effectiveness may lead to resistance of important ectoparasites to the treatment materials.

Animals↗