A total of forty‐eight dogs were utilized to titrate and evaluate the activity of a new miticide, amitraz. The treatment was applied dermally and evaluated for efficacy against experimentally induced Demodex canis and Sarcoptes scabiei infestations. Five different concentrations (2000, 1000, 500, 250, 125 p.p.m.) of the active drug, N'—(2, 4‐dimethylphenyl)N—{[(2, 4‐dimethylphenyl) imino] methyl} ‐N‐methyl‐methanimidamide, were tested. The activity of amitraz was compared to a standard treatment, placebo treatment, and no treatment. A single dermal treatment with amitraz (all concentrations) indicated activity against both D. canis and S. scabiei. The lowest concentration of active drug (125 p.p.m.) was significantly less efficacious than the four higher concentrations (250, 500, 1000, 2000 p.p.m.). At the 250 p.p.m. (or higher) level the effectiveness of this new miticide was comparable to the standard treatment. The data indicate the 250 p.p.m. concentration is the optimal level and the recommended dilution for treatment of mange mites. Drug reactions related to amitraz were not observed.

Mares of mixed breeding (379 to 594 kg) were injected intramuscularly once with Prostin F2 alpha | (PGF20t) in doses ranging between 0 and 10 mg between days 6 and 9 after ovulation. Prostaglandin F2a caused luteolysis as measured by reduction in intervals between injection and either return to estrus or ovulation and by reduction in interovulatory intervals for four of eight, seven of nine, eight of nine, four of eight, seven of nine and eight of eight mares treated with .25, 1, 2.5, 3, 5 or 10 mg PGF2a, respectively. Duration for both estrus and the estrous cycle subsequent to administration of Prostin F2 alpha was within the range accepted as normal indicating no carryover effects of treatment. Sweating was not observed for mares treated with .25 mg PGF2a but was observed for mares treated with 1, 2.5, 3, 5 or 10 mg between 1/4 and 2 hr after injection. Most mares had ceased sweating within 1 hr after injection, but drying was not completed for up to 3 to 5 hr after injection. Rectal temperature was decreased significantly during the intervals 1/2 through 1, 1/2 through 4, 1/2 through 3", 1/2 through 5, or 1/4 through 5 hr after treatment of mares with 1, 2.5, 3, 5 or 10 mg PGF2a, respectively. Compared to appropriate controls, maximum temperature decrease of mares was on the order of .5 to .6 C for those treated with .25 or 1 mg, .9 to 1.2 C for those treated with 2.5, 3, or 5 mg, and 1.7 C for those treated with 10 mg PGF2a. Decreases in rectal temperature were associated with sweating and drying. Neither heart nor respiration rates were 1 Agricultural Research and Development. A portion of these data were presented at the 1975 A.S.A.S. meeting, Colorado State University. 2The authors express appreciation to E.

The impact of entrepreneurship on economic growth has been a hot topic of discussion among scholars in recent years. Based on the data of SMEs in the New Over the Counter Market, this paper establishes a fixed effects model to study the relationship between entrepreneurship and economic growth. Empirical research shows that entrepreneurship can promote economic growth; compared with the northeast and west, entrepreneurship has a greater role in driving economic growth in the central and eastern regions. It is necessary to focus on cultivating entrepreneurship in the central and eastern regions, give full play to the role of entrepreneurship in promoting economic growth, and ultimately promote the coordinated development of regional economies.