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Biomedical subjects

A C Schaefers-Okkens

Publications and source records attributed to A C Schaefers-Okkens.

17 recordsLinked to original sources
PubMed2006

Ovariectomy during the luteal phase influences secretion of prolactin, growth hormone, and insulin-like growth factor-I in the bitch.

A decline in circulating progesterone concentration plays an important role in the ethiopathogenesis of pseudopregnancy in the bitch. Because growth hormone (GH) and prolactin (PRL) are essential for normal mammogenesis and the secretion of these hormones is influenced by changes in the circulating progesterone concentration, the purpose of this study was to investigate the effects of mid-luteal phase ovariectomy on the 6-h pulsatile plasma profiles of GH and PRL and the basal plasma concentrations of GH, PRL, and insulin-like growth factor-I (IGF-I) in six beagle bitches. Ovariectomy was followed by only mild or covert signs of pseudopregnancy. The sharp decrease of the plasma progesterone concentration was accompanied by decreased basal plasma concentrations of GH and IGF-I and a rise in basal plasma PRL concentration. GH and PRL were secreted in a pulsatile fashion both prior to and after ovariectomy. The mean basal plasma GH concentration was significantly higher before ovariectomy than on days 1 and 7 after ovariectomy. The mean area under the curve above the zero level (AUC(0)) for GH was significantly higher before than at 7 days after ovariectomy. The mean area under the curve above basal level (AUC(b)) and the frequency of GH pulses at 7 days after ovariectomy were significantly higher than before and 1 day after ovariectomy. Both the mean basal plasma PRL concentration and the mean AUC(0) for PRL increased after ovariectomy. In conclusion, ovariectomy of bitches in the mid-luteal phase stops progesterone-induced GH release from the mammary gland, as evidenced by the lowering of basal plasma GH levels, the recurrence of GH pulsatility, and the lowering of circulating IGF-I levels. The sudden lowering of plasma progesterone concentration is probably a primary cause of a prolonged increase in PRL secretion. These observations underscore the importance of similar, albeit less abrupt, hormonal changes in the cyclical physiological alterations in the mammary gland and in the development of pseudopregnancy.

Animals↗
PubMed2001

[The use of veterinary drugs during pregnancy of the dog].

To point out which antibiotics and NSAIDs are safe to use during pregnancy of the dog and which are not, a simple system for classification has been developed for veterinarians. To find out more information about what drugs and during what stage of pregnancy veterinarians prescribe, a random survey was carried out among veterinarians who work primarily with companion animals. To develop this system for classification, literature concerning the teratogenicity of veterinary drugs was evaluated. The results of the survey indicate that the possibility of a pregnancy is rarely taken into account when prescribing medications and that many drugs that have not been proven safe, are prescribed. From the evaluation of literature follows that benzylpenicillin, amoxicillin with or without clavulanic acid, cefadroxil, cefalexin and lincomycin are the safest and therefore the agents of choice during pregnancy. It would be better if NSAIDs were not to be used during the last stage of pregnancy, because they might cause delay of the delivery. Drugs that might be teratogenic should be avoided unless there is no alternative and the possible benefits for the bitch outweigh the risks for the foetus.

Abnormalities, Drug-Induced↗
PubMed2001

[The optimal mating time in the bitch based on the progesterone concentration in peripheral blood. A comparison of reliability between three ELISA test kits and a 125-iodine radioimmunoassay].

During oestrus the plasma progesterone concentration can be used to determine the optimal time for mating in the dog. In this study, the optimal time for mating for 26 bitches was determined by measuring progesterone concentrations with three ELISA test kits and a 125I-radioimmunoassay (125I-RIA). Two observers evaluated the ELISA results simultaneously. They graded the results independently and did not know which dog was being tested. For both observers, the optimal time for mating, based on progesterone concentrations measured with the Progesterone Small Rapid ELISA test and the Status-Pro test, differed significantly from that based on progesterone concentrations measured by 125I-RIA. Although the optimal time for mating based on the Ovucheck Premate test did not differ significantly from that based on the 125I-RIA, three out of 14 dogs (21%) for observer one and four out of 14 dogs (29%) for observer two would have been mated on a different day than that determined on the basis of results obtained with the 125I-RIA. The results did not change when the advised period for mating based on the RIA results was extended by two days. It is concluded that the progesterone concentrations measured with the ELISA test kits are too inaccurate for clinical use to determine the optimal time for mating. The only reliable results for determining the optimal mating period are obtained when plasma progesterone concentrations are measured with a RIA.

Animals↗
PubMed2001

[The reliability of vaginal cytology in determining the optimal mating time in the bitch].

The reliability of vaginal cytology for determining the optimal mating period is controversial. The importance of the site for obtaining the smear (the vestibule or the vagina) and the best staining method are also unclear. Therefore, we investigated the reliability of vaginal cytology as compared to plasma progesterone concentrations for determining the optimal mating period. Additionally, the influence of different locations for obtaining the smears and of the staining methods, i.e. May-Grünwald-Giemsa or Papanicolaou, a method that stains keratin in superficial cells, was examined. In total, the vaginal cytology of 35 bitches during the follicular phase was examined three times a week, until the optimal time for mating was established, based on plasma progesterone concentrations measured with a 125Iodine radio-immunoassay. The results indicate that vaginal cytology is not useful for determining the optimal mating period in bitches, since mating according to cytological findings would have resulted in only 28% of the bitches being mated at the proper time. The site for obtaining the smear and the staining method did not affect accuracy. It is therefore concluded that cytology is not useful in breeding management to determine the optimal mating period. It can be used, however, to determine the stage of the cycle in general, e.g. the early part of the follicular phase or the metoestrus and the detection of disorders in the follicular phase. For this purpose, a smear from the vestibule, stained with a morphological staining method, provides sufficient information.

Animals↗