[Function of the hypophyseal-adrenal cortex system and administration of glucocorticoids to pigeons (Colomba livia domestica)].
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Animals↗
Biomedical subjects
I Westerhof
Publications and source records attributed to I Westerhof.
[A field study of the efficacy of ivermectin in propylene glycol in the treatment of mange in guinea pigs].
The clinical manifestation of mange in a guinea-pig population in Utrecht is discussed. The etiology and the treatment with two subcutaneous injections of ivermectin 0.2 mg/kg with a ten-day interval, is described. A total of 37 guinea-pigs with symptoms and 36 guinea-pig without signs of mange were treated. On the 21st day all previously infested guinea-pigs were free of symptoms. During this study side-effects occurred in 11 of the 73 animals. The most prominent side-effects were a (sub-)dermal necrosis in the younger animals and an inflammation of the cutis in the older animals. The side-effects were probably caused by propylene glycol which was used as a diluent.
Animals↗
[Vitamin A deficiency in the turtle].
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Animals↗
In vivo studies on the effects of ovine corticotrophin-releasing hormone, arginine vasotocin, arginine vasopressin, and haloperidol on adrenocortical function in the racing pigeon (Columba livia domestica).
This study investigates the effects of in vivo administration of pituitary stimulants in racing pigeons (Columba livia domestica). Plasma corticosterone concentrations were measured following intravenous administration of ovine corticotrophin-releasing hormone (oCRH) (0.1, 1, 10, and 100 micrograms/kg), arginine vasopressin (AVP) (0.01, 0.1, 1, and 10 micrograms/kg), arginine vasotocin (AVT) (0.01, 0.1, 1, and 5 micrograms/kg), and haloperidol (0.05, 0.5, and 5 micrograms/kg). Compared with mammals the pituitary-adrenocortical system of the pigeon appeared to be less sensitive to stimulation with oCRH, although high doses were well tolerated and gave a clear response. Both AVP and AVT stimulated corticosterone secretion, AVT in a more pronounced dose-dependent manner than AVP. The natural neurohypophysial peptide in birds, AVT, was less well tolerated in high doses than AVP. The clear response to haloperidol indicates that the hypothalamo-pituitary-adrenocortical system is under dopaminergic inhibition. Of the pituitary stimulants tested AVP (10 micrograms/kg) and oCRH (100 micrograms/kg) are the most appropriate for testing the integrity of the pituitary-adrenocortical system in the pigeon.
Adrenal Cortex↗
Ocular filariasis in a parakeet, a tropical surprise.
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Animals↗
Diseases in parrots.
This article can be regarded as a primer to psittacine medicine. An introduction to pet psittacine species and Dutch legislation with regard to keeping parrots as pets, is followed by diagnostic techniques. Some emergency therapeutic measures are highlighted. A review is presented of some characteristic or important parrot diseases.
Animals↗
[Lethal effects of various antimicrobial agents and clinically usable alternatives in rabbits and rodents].
The lethal effects of antibiotics which may be observed in rabbits and some rodent species are reviewed. A selection of antibiotics and chemotherapeutic agents and their respective dosages are referred to, which may be used therapeutically in these animals. Suggestions are made for the treatment of enterocolitis induced by antibiotics in rabbits.
Animals↗
Blood chemistry for the diagnosis of hepatobiliary disease in birds. A review.
A review is presented of current knowledge with regard to blood chemistry for the diagnosis of hepatobiliary disease in birds. Straightforward conclusions are difficult, because research on this subject has been limited. Jaundice caused by hyperbilirubinaemia occurs infrequently in birds, because the main bile pigment is biliverdin and not bilirubin. A yellow discolouration of avian plasma is often caused by the presence of carotenoids. The diagnostic value of plasma ALAT concentrations is controversial. Although ASAT and LD are not specific for the liver they appear to be sensitive enzymes to detect liver cell damage. GLDH is liver specific in a number of animal species (including birds) and might prove to be a useful enzyme for diagnostic purposes. AP and GGT seem less useful. Little information is available on the diagnostic value of plasma bile acids and plasma dye clearance tests.
Alanine Transaminase↗
Diurnal rhythms of plasma corticosterone concentrations in racing pigeons (Columba livia domestica) exposed to different light regimens, and the influence of frequent blood sampling.
The effects of two different light regimens and the frequency of blood sampling on the diurnal plasma corticosterone concentrations in racing pigeons (Columba livia domestica) were investigated. The daily light regimens tested were a period of light during the day (DL; lights on 0515-2215) and shifting of the light period by 12 hours (SL; lights on 1715-1015). In the first experiment, the influence of the frequency of blood sampling was investigated by comparing plasma corticosterone concentrations at 28-hr intervals for several days and at 4-hr intervals during one day. Sampling at 4-hr intervals resulted in significantly higher corticosterone concentrations in plasma than sampling at 28-hr intervals. Within both groups, the plasma corticosterone concentrations at the first and last sampling times did not differ significantly. Concentrations of plasma corticosterone were always highest during the dark period, and the corticosterone rhythm in the SL experiment was strictly in phase with the altered light/dark schedule.
Animals↗
Sensitivity of the hypothalamic-pituitary-adrenal system of pigeons (Columba livia domestica) to suppression by dexamethasone, cortisol, and prednisolone.
The sensitivity of the hypothalamic-pituitary-adrenal system in pigeons (Columba livia domestica) to glucocorticoid feedback was studied after single intravenous administration of dexamethasone (500, 100, 50, 10, 5, 1, 0.5, and 0.1 micrograms/kg), cortisol (15,000, 3000, 1500, 300, 150, 30, 15, and 3 micrograms/kg), and prednisolone (3500, 700, 350, 70, 35, 7, 3.5, 0.7, and 0.35 micrograms/kg). Dose responses, the threshold doses, and the onset of maximum suppression were determined by measuring plasma corticosterone concentrations around the expected peak of plasma corticosterone in pigeons kept on a shifted-light regimen. At 52 hr following the highest dose of dexamethasone, and at 48 hr following the highest doses of cortisol and prednisolone, plasma corticosterone concentrations were similar to the initial values and to the control values. Following the minimum doses that resulted in suppression of the normal diurnal variation in plasma corticosterone concentration (0.5 microgram dexamethasone/kg, 15 micrograms cortisol/kg, and 0.7 microgram prednisolone/kg), plasma corticosterone concentrations were similar to values of the control group and to initial values within 24 hr. The onset of suppression of plasma corticosterone concentrations was between 30 and 60 min following 1 microgram dexamethasone/kg, 7 micrograms prednisolone/kg, or 30 micrograms cortisol/kg. Suppression was greatest at 60 min following prednisolone and cortisol administration, and at 90 min following dexamethasone administration. It is concluded that the hypothalamic-pituitary-adrenal system of pigeons reacts to exogenous glucocorticoids by early delayed feedback, is more sensitive to suppression by glucocorticoids than that of mammals, and is suppressed for the longest time by dexamethasone. These observations indicate that some of the side effects of glucocorticoid therapy are likely to be at least as frequent and as severe in birds as in mammals.
Animals↗
Responsiveness of the glucocorticoid-suppressed pituitary-adrenocortical system of pigeons (Columba livia domestica) to stimulation with arginine vasopressin.
This paper reports on the duration of the suppressive effects of single high and low doses of dexamethasone, cortisol, and prednisolone on the pituitary-adrenocortical (PA) system in pigeons. In addition, the effects of long-term daily administration of a high dose of dexamethasone are reported. In Expt. 1, low and high doses of dexamethasone (0.5 microgram/kg and 0.5 mg/kg), cortisol (15 micrograms/kg and 1.5 mg/kg), and prednisolone (3.5 micrograms/kg and 3.5 mg/kg) were administered around the expected nadir (4 hr before the peak) of the diurnal plasma corticosterone concentration. The recovery of the PA system was investigated by measuring plasma corticosterone concentrations before and 30 min after arginine vasopressin (AVP) stimulation (10 micrograms/kg) around the expected peak of plasma corticosterone concentrations. In Expt. 2, one high dose of each of the three glucocorticoids was administered 4 hr before the peak, followed by AVP stimulation around the expected peak of plasma corticosterone concentrations each day for 3 days. In Expt. 3, the recovery of the PA system following long-term daily administration of 1 mg/kg dexamethasone was investigated by repeated stimulations with AVP after cessation of the treatment. The results of these experiments (I) confirm that the PA system of pigeons is very sensitive to the suppressive effects of dexamethasone, cortisol, and prednisolone in a dose-dependent manner, (II) demonstrate that after cessation of glucocorticoid treatment the response to AVP stimulation is restored earlier than basal corticosterone concentrations, (III) demonstrate that after long-term glucocorticoid treatment the responsiveness of the PA system recovers relatively fast, and (IV) demonstrate that long-term treatment with a high dose of dexamethasone not only results in complete suppression of the PA system but is also a serious risk for infection and death.
Adrenal Cortex↗
No evidence for diurnal variation in the responsiveness of the pituitary-adrenocortical axis of the pigeon (Columba livia domestica) to stimulation with adrenocorticotrophin and vasopressin.
The responsiveness of the pituitary-adrenocortical axis of the pigeon (Columba livia domestica) to intravenous administration of high and low doses of adrenocorticotrophic hormone (ACTH) and following arginine vasopressin (AVP) was investigated at two different moments of the diurnal rhythm. Administrations of ACTH and AVP were performed at the moment of low plasma corticosterone concentration and during high plasma corticosterone concentration. Plasma corticosterone concentrations following administration of AVP and ACTH did not change with the time of the day. It is concluded that for the assessment of pituitary adrenocortical function in pigeons the pituitary adrenocortical stimulation tests with AVP and ACTH can be used at any time of day.
Adrenal Cortex↗