Morphological evidence for the physiological nature of follicular atresia in veiled chameleons (Chamaeleo calyptratus).

Follicular atresia (FA) has been assumed to serve different functions in reptiles, e.g. helping to develop hierarchies, limiting clutch size, and regression of ovarian structures. Reproductive output is dependent on a balance between ovulations and FA. Excessive rates of FA may not only be detrimental for the survival of a population, but have also been associated with pathological conditions. In order to gain insights into the physiological and potentially pathological processes of FA, we performed a decriptive study on the morphological features of the ovaries in sexually mature female veiled chameleons (Chamaeleo calyptratus, VC). Of 60 clinically healthy female VC with continuous ovarian cycling and at least one confirmed cycle with FA over at least 1.5 years, 30 were selected for macroscopic evaluation of ovarian appearance and 7 were subjected to histology and immunohistology. While FA of previtellogenic follicles happened at a low rate, expected for a species with two germinal beds per ovary and polyautochronic reproductive pattern, atresia in the late vitellogenic stage affected entire generations of follicles, consequential to ovulatory failure. Histologically, no pathological processes were identified in any of the animals. Rather, three stages of FA (early, middle, late) were defined and vitellogenic follicles showed two distinct morphological types of FA: yolky and cystic. Yolky FA was found in 21/30 (70%) animals, while cystic FA co-occurred in 9/30 (30%) of the animals.

Fecal adrenal hormone patterns during ovulatory and non-ovulatory reproductive cycles in female veiled chameleons (Chamaeleo calyptratus).

The relationship between the reproductive (hypothalamic-pituitary-gonadal; HPG) and adrenal (hypothalamic-pituitary-adrenal; HPA) hormone axes is complex and can vary depending on the species and environmental factors affecting an individual. In an effort to understand this relationship in female veiled chameleons (Chamaeleo calyptratus), the patterns of fecal metabolites of corticosterone (C), estradiol (E), testosterone (T), and progesterone (P) were analyzed by enzyme immunoassay (EIA) during ovulatory (OC; eggs laid) and non-ovulatory cycles (NOC; no eggs laid). Glucocorticoid (GC) metabolites in the fecal extracts were characterized by HPLC and corticosterone EIA performance was assessed by parallelism, accuracy and precision tests. The results indicated that the assay chosen reliably measured the hormone metabolites present in the fecal extracts. Regular, cyclical hormone metabolite patterns consisting of an E peak followed by peaks of T, P and C in close succession were observed during both ovulatory and non-ovulatory cycles; relative levels of P and C, however, were higher during ovulatory cycles. Corticosterone metabolite levels, in particular, increased throughout vitellogenesis and peaked in late vitellogenesis (in non-ovulatory cycles) or around the time of ovulation, and remained elevated throughout the gravid period, falling just prior to oviposition. The results provide evidence of variation in glucocorticoid production throughout different stages of the reproductive cycle, including a role in the ovulatory process; the physiology, however, remains unclear.

REVIEW: PSYCHOPATHOLOGIES IN CAPTIVE NONHUMAN PRIMATES AND APPROACHES TO DIAGNOSIS AND TREATMENT.

Despite the growing knowledge and literature on primate medicine, assessment and treatment of behavioral abnormalities in nonhuman primates (NHPs) is an underdeveloped field. There is ample evidence for similarity between humans and great apes, including basic neurologic physiology and emotional processes, and no substantial argument exists against a concept of continuity for abnormal conditions in NHPs that emerge in response to adverse experiences, akin to human psychopathology. NHPs have served as models for human psychopathologies for many decades, but the acquired knowledge has only hesitantly been applied to primates themselves. This review aims to raise awareness among the veterinary community of the wealth of literature on NHP psychopathologies in human medicine and anthropology literature and calls for the necessity to include mental health assessments and professionally structured treatment approaches in NHP medicine. Growing understanding about causes and pathogenesis of abnormal behavior in NHP will not only help to prevent the development of undesirable behaviors but also allow for treatment and management of long-lived, already affected animal patients.

CONTINUOUS INTRAVENOUS INFUSION ANESTHESIA WITH MEDETOMIDINE, KETAMINE, AND MIDAZOLAM AFTER INDUCTION WITH A COMBINATION OF ETORPHINE, MEDETOMIDINE, AND MIDAZOLAM OR WITH MEDETOMIDINE, KETAMINE, AND BUTORPHANOL IN IMPALA (AEPYCEROS MELAMPUS).

In order to develop a long-term anesthesia for flighty antelope species in field situations, two different protocols for induction and maintenance with an intravenous infusion were evaluated in wild-caught impala ( Aepyceros melampus ). Ten adult female impala were induced with two induction protocols: one consisted of 0.2 mg/kg medetomidine, 4 mg/kg ketamine, and 0.15 mg/kg butorphanol (MKB) and one consisted of 0.375 mg/kg etorphine, 0.2 mg/kg medetomidine, and 0.2 mg/kg midazolam (EMM). In both treatments, anesthesia was maintained with a continuous intravenous infusion (CII) at an initial dose rate of 1.2 µg/kg per hr medetomidine, 2.4 mg/kg per hr ketaminen and 36 µg/kg per hr midazolam. Partial reversal was achieved with naltrexone (2 : 1 mg butorphanol; 20 : 1 mg etorphine) and atipamezole (5 : 1 mg medetomidine). Evaluation of anesthesia included respiratory rate, heart rate, rectal temperature, arterial blood pressure, oxygen saturation, end tidal carbon dioxide tension, and tidal volume at 5-min intervals, palpebral reflex and response to painful stimuli at 15-min intervals, and arterial blood gases at 30-min intervals. Plasma cortisol concentration was determined after induction and before reversal. Duration and quality of induction and recovery were evaluated. EMM caused a faster induction of 9.5 ± 2.9 min compared to 11.0 ± 6.4 min in MKB. Recovery was also quicker in EMM (EMM: 6.3 ± 5.4 min; MKB: 9.8 ± 6.0 min). However, EMM also produced more cardiopulmonary side effects, including hypoxemia and hypercapnia, and calculated oxygenation indices (PaCO2-PETCO2) were worse than in MKB. One animal died after induction with EMM. The CII provided surgical anesthesia in 7 of 10 animals in MKB and in 9 of 9 animals in EMM for 120 min. In conclusion, the MKB induction protocol had advantages for prolonged anesthesia in impala with significantly less cardiopulmonary depression compared to EMM. The comparably decreased anesthetic depth could easily be adjusted by an increase of the CII.

Noninvasive analysis of fecal reproductive hormone metabolites in female veiled chameleons (Chamaeleo calyptratus) by enzyme immunoassay.

The noninvasive technique of gonadal steroid metabolite measurement in feces for evaluation of reproductive activity has proven an effective and important tool for population management in various captive species, but has not yet been validated and used in reptile species. In this study, enzyme immunoassays (EIAs) were validated for the analysis of fecal samples from female veiled chameleons (Chamaeleo calyptratus) for estrogen (E2), testosterone (T), and progesterone (P) and their metabolites. High performance liquid chromatography and physiological methods (GnRH stimulation) were used for the validation of the assays. Biological events, such as skin color changes indicative of ovarian activity and oviposition, correlated with the cyclical pattern of E2, T and P metabolites in feces over a period of two reproductive cycles. This is the first study to report frequent longitudinal measurements of fecal hormone levels by EIA in a reptile species.

Cerebral xanthomatosis in three green water dragons (Physignathus cocincinus).

Cerebral xanthomatosis was diagnosed in three female green water dragons (Physignathus cocincinus), all of which presented with progressive neurologic signs. No antemortem evidence for xanthomatosis was identified, but on postmortem examination cholesterol granulomas, composed of cholesterol clefts surrounded by macrophages and multinucleated giant cells, were found in the forebrain of each animal and were associated with significant displacement and pressure on the adjacent brain. Although the cause of xanthomatosis in these animals is unknown, nutrition and trauma may be involved in the pathogenesis of this condition. Cerebrum, cholesterol, green water dragon, Physignathus cocincinus, xanthoma.

Fecal hormone patterns during non-ovulatory reproductive cycles in female veiled chameleons (Chamaeleo calyptratus).

Reproductive failure, in particular preovulatory stasis, is a common problem in captive female reptiles. For a better understanding of its pathogenesis, the patterns of fecal estradiol (E2), testosterone (T), progesterone (P) and their metabolites of 21 anovulatory female veiled chameleons, Chamaeleo calyptratus, were compared with those of 25 animals which ovulated during at least one cycle over the study period. Regular, cyclical hormone patterns, consisting of E2 peaks followed by simultaneous T and P peaks, were observed in all animals, regardless of whether oviposition occurred, indicating continuous ovarian activity. P concentrations were; however, significantly lower in animals undergoing anovulatory cycles. The average time period between the E2 and the T peak was 24.8 days, between the E2 and the P peak 26.5 days, and between the T and P peak 2.6 days. The mean length of reproductive cycles between two sequential ovulatory complexes (oviposition to oviposition) was 132.5 days (range 112-156 days). The results provide evidence that reproductive "failure" occurs more frequently than suspected with some females alternating between ovulatory and anovulatory cycles without any outward evidence of the variation in ovarian cycles. It is proposed that this may be related to physiological adaptation to adverse environmental conditions for breeding and that husbandry factors in captivity are primarily responsible for the progression from a physiological to pathological process.

Characterization of fecal hormone patterns associated with the reproductive cycle in female veiled chameleons (Chamaeleo calyptratus).

Reptiles have gained popularity in the North American and European pet trade. Large numbers of captive-born veiled chameleons, Chamaeleo calyptratus, are produced annually but knowledge of their reproductive cycle has been limited to anecdotal observations. This study describes the hormonal changes associated with reproductive cycling in female veiled chameleons using non-invasive fecal evaluation of metabolites of the three principal ovarian steroids, estradiol (E2), testosterone (T), progesterone (P), and their metabolites, by enzyme immunoassays. The hormone patterns were compared with follicular development and ovulation as determined by magnetic resonance imaging (MRI). Three main cycle stages were identified on MRI: the previtellogenic stage (PV) with the absence of visible follicular structures, vitellogenic stage (V) with the presence of round follicular structures >2mm diameter, and the gravid stage with the presence of oval egg structures. Although the absolute values of the baselines and peaks for each hormone varied among animals, approximately 24-fold increases over mean P baseline values and 7.5-fold increases over mean E2 and T baseline values were associated with biological events. E2 rose during vitellogenesis, peaked in late vitellogenesis and fell shortly thereafter. P rose during the late vitellogenic stage, peaked in mid-gravidity and fell to baseline values at oviposition. Ovulation occurred with the decreasing E2:P ratio. T levels varied during the pre- and vitellogenic stages then mirrored P with a distinct peak during the time of ovulation and gravidity. These data provides us with the necessary background for future studies on the reproductive biology of this species.

Pharmacokinetics of buprenorphine after single-dose subcutaneous administration in red-eared sliders (Trachemys scripta elegans).

Buprenorphine, a mu opioid receptor agonist, is expected to be a suitable analgesic drug for use in reptiles. However, to date, dosage recommendations have been based on anecdotal observations. The aim of this study was to provide baseline pharmacokinetic data in red-eared sliders (Trachemys scripta elegans) targeting a plasma level of 1 ng/ml reported effective for analgesia in humans. Serial blood samples were taken after subcutaneous injection of buprenorphine, and plasma buprenorphine levels were measured by radioimmunoassay. Pharmacokinetic parameters of a lower dose (0.02 mg/kg) injected into the forelimb were compared with a higher dose (0.05 mg/kg) given in the same forelimb as well as a lower dose (0.02 mg/kg) given in the hind limb of the same animals with 2 wk between studies. After administration of 0.05 mg/kg in the front limb, 85% of animals maintained the minimum effective plasma level for 24 hr, while only 43% of animals maintained this level after 0.02 mg/kg. After hind limb injection at 0.02 mg/kg, maximum plasma concentrations and areas under the buprenorphine concentration-time curve were less than 20% and 70%, respectively, of values after forelimb injection, consistent with substantial first pass extraction by the liver. Furthermore, a secondary rise in the buprenorphine level was found after having only a hind limb injection, probably from enterohepatic recirculation of glucuronidated drug. In conclusion, buprenorphine dosages of at least 0.075 mg/kg s.i.d. should be appropriate for evaluation of analgesia efficacy, and front limb administration may be preferable to hind limb administration for optimal drug exposure.