A rapid radioimmunoassay for determining plasma concentrations of LH in dogs

Abstract

Sepharose bead suspension containing anti-gamma-globulin, followed by incubation at room temperature for 30 min. The minimum detectable concentration in this assay, calculated from the precision profile, was 1\m=.\5 \ g=m\ g/ l . The amount of dog LH needed to cause 50% reduction of the initial binding was 1\m=.\57\ m=+-\0\m=.\13 ng/tube (15\m=.\7 \g=m\g/l for 100-\g=m\l samples). Daily blood samples were collected in heparinized tubes from the cephalic vein of 5 pointer and 7 beagle bitches from the onset of pro-oestrus until 3\p=n-\4 days after either the last mating or artificial insemination with frozen semen or until metoestrus. Samples were assayed for LH content by the short and normal incubations as well as for progesterone and oestradiol-17\g=b\ content. In all bitches plasma concentrations of progesterone increased rapidly within 1 week after the LH peak which indicates that they had ovulated. Comparison of the short (1\m=.\5h) with the normal (24 h) incubation system resulted in a regression equation: y = 1\m=.\0+ 0\m=.\7x (r = 0\m=.\95, n = 153 samples). The preovulatory LH peak averaged 10\m=.\4\m=+-\1\m=.\1and 11\m=.\9 \ m=+-\ 1 \ m=. \ 7 \g=m\g/l in the short and normal incubation assay, respectively. We suggest that this rapid LH assay can be used in practice to define the optimum time for mating and artificial insemination of the bitch or to study physiological aspects of the ovulatory period.

Termination of mid‐term pregnancy in the dog with oral RU 486

“…The plasma was removed and stored at -2OOC until assayed. Plasma luteinising hormone (LH) levels were measured using a heterologous dog LH radioimmunoassay (Smith and McDonald 1974, DePalatis and others 1978) modified by Madej and Linde-Forsberg (1991). The assay utilised radioiodinated ovine LH (LER-1056-C2), antiserum against ovine LH (GDN-15) at final dilution 1:150,000 and dog LH (LER-1685-1) as standard.…”