Cutaneous plasmacytoma in three golden hamsters (Mesocrietus auratus)

Spontaneously occurring cutaneous tumours in three golden hamsters were characterized using histological, immunohistochemical and ultrastructural methods. Histologically, the tumours were composed of sheets of round to oval plasmacytoid cells with eccentrically placed nuclei. Tissue sections were weakly positive for anti-B lymphocyte antigen (BLA) staining. Ultrastructurally, large amounts of rough endoplasmic reticulum in the cytoplasm were observed. BLA positivity and characteristics of ultrastructure showed the plasma cell origin.     

Naturally acquired enteric adenovirus infection in Syrian hamsters (Mesocricetus auratus)

Intranuclear inclusions indicative of adenovirus infection were detected microscopically in formalin-fixed intestinal tissues from preweanling Syrian hamsters. The amphophilic intranuclear inclusion bodies were observed in ileal enterocytes from 16-to 24-day-old hamsters. Electron microscopy revealed large numbers of 72 +/- 3-nm viral particles typical of adenoviridae in enterocytic nuclei. Serum antibodies reacted with mouse adenovirus strains K87 and, to a lesser extent, FL, by indirect fluorescent antibody testing. Clinical disease was not associated with the adenoviral infections. Hamsters from 10 production colonies, including all major commercial Syrian hamster suppliers in the United States, were surveyed and all had serologic or histopathologic evidence of adenovirus infection.     

Effects of hypothyroidism on gonadal function after transition of short day photoperiod in male golden hamsters (Mesocricetus auratus)

Thyroid hormones permit the annual reproductive transition of seasonal breeders. Although, precise function of thyroid hormones in seasonal breeding is not well understood. In the present study, we examined effects of hypothyroidism on the hypothalamus-pituitary-gonadal axis in adult male golden hamsters after transition of the short-day photoperiod (SD; 8 h light: 16 h dark) condition. We confirmed that hypothyroid, which had been induced by administration of thiouracil in drinking water for 4 weeks, did not have direct effects on testes in male hamsters under the long-day photoperiod. Plasma concentrations of free T3 and T4 decreased 15 weeks after transition of SD condition. Plasma concentrations of testosterone in the hypothyroid group decreased earlier than in the control group after the transition from LD to SD. In animals treated with testosterone after castration, plasma concentrations of LH in the hypothyroid group decreased earlier than in the control group after the transition of SD. On the other hand, pituitary response to GnRH for LH release did not change in castrated hamsters as a result of hypothyroidism. These results suggest that thyroid hormones act the hypothalamus and might be required to maintain GnRH secretion in male golden hamsters.     

Behavioural and endocrinological changes in Syrian hamsters (Mesocricetus auratus) under domestication

This study aimed to quantify differences in response to stress between two strains of Syrian hamsters to evaluate the consequences of domestication in this species by measuring behavioural traits in the open-field, adrenal gland masses (ADR), and faecal and blood corticosterone concentrations (CC). We studied a laboratory (lab)- and a wild-derived population (wild). The lab hamsters were significant heavier than the wild hamsters. The lab males had the highest ADR, and it was independent of their high body mass (BM). The ADR of lab females and wild hamsters was linearly dependent of BM. The lab males had the highest faecal and blood CC, whereas the lab females had the lowest CC. In the open field, the lab hamsters began later to groom, groomed shorter, groomed less frequently, began later to rear, reared longer and reared less frequently. In the lab population, females reared more often and groomed longer than males. The sex differences in the behaviours of the lab population and the differences between the populations mirror the differences neither in the ADR nor in the CC. The founder effect and the breeding history of lab Syrian hamsters are discussed as causes of the differences between the studied populations.     

Turkey respiratory tract adenoviruses: oncogenic potential in neonatal hamsters (Mesocricetus auratus)

The tumorigenic properties of 3 turkey adenoviruses (CUA, NC-K, and MST) isolated from turkeys with respiratory tract disease and injected into neonatal hamsters (Mesocricetus auratus) have been determined. One of 30 adenovirus isolates (CUA) induced tumors at the site of inoculation (subcutaneously or intracranially) in neonatal hamsters. The tumors were identified as fibrosarcomas and undifferentiated sarcomas. The tumors were found to be free of infective virus, but hamsters which had tumors produced antibody to the virus-specific tumor antigen detectable by the complement-fixation test. The antibody titers for the tumor antigen were from 1:8 to 1:16. Abnormalities were not observed in the major organs collected from hamsters inoculated with the virus. Inoculations of hamster embryo cells and of adult and baby hamster kidney cells with the 3 turkey adenoviruses at a high multiplicity of infection did not produce transformed cells in monolayers. Hamster cells were permissive for CUA virus, since cytopathic effect was observed in 3 to 5 days after inoculation.     

Extramedullary plasmacytoma of the salivary gland in two Syrian hamsters (Mesocricetus auratus)

Two Syrian hamsters developed marked swelling of the ventral neck. Histologic examination of both masses revealed that the submaxillary salivary glands were effaced by large numbers of neoplastic plasma cells. In one hamster, neoplastic cells had infiltrated the adjacent lymph node. The neoplastic cells expressed CD79a antigen and were negative for CD3, lambda, and kappa light chains. Ultrastructural features of neoplastic cells in the salivary gland of one hamster included abundant cytoplasmic rough endoplasmic reticulum profiles, and peripherally displaced nuclei that contained marginated heterochromatin, consistent with plasma cells. Salivary gland plasmacytomas are extremely rare in humans and have not previously been reported in nonhuman species. The occurrence of such neoplasms in two hamsters suggests that this species may be predisposed to developing tumors of this type.     

Suspected case of hyperadrenocorticism in a golden hamster (Mesocricetus auratus).

Dermatologic disease is a common problem in pet rodents. This article describes the case of a pet golden hamster (Mesocricetus auratus) with dermatologic and other clinical signs (polyuria, polydypsia) similar to those found in other mammalian species with hyperadrenocorticism. Among other diagnostic tests, the urine cortisol/creatinine ratio was measured and was found to be increased, which appeared to support the diagnosis. Treatment with ketoconazole was initiated, without apparent success.     

Evaluation of terbinafine treatment in Leishmania chagasi-infected hamsters (Mesocricetus auratus).

The objective of the present study was to assess the effect of terbinafine treatment in hamsters infected with Leishmania chagasi. Four of five groups of hamsters were infected with 3 x 10(7) L. chagasi promastigotes by the intracardiac route and submitted to different treatments of 30 days duration starting on the 30th day after inoculation. Group 1 was treated with 100mg/kg terbinafine PO, group 2 was treated with 80 mg/kg Glucantime IM, and group 3 was treated with a combination of the same dose of each drug by the same routes. Group 4 (control) received vehicle (Tween 80 [0.1%]+CMC[0.5%]+H(2)O [0.5 ml], PO). Spleen parasite burden and spleen relative weight were determined 3 days after the end of the treatment. The results were analyzed by the Kruskal-Wallis test (P < 0.05). There was no difference between the infected untreated and terbinafine-treated groups in spleen parasite burden (15.81+/-15.81 vs. 13.00+/-12.94, respectively). Terbinafine plus Glucantime (6.11+/-5.90) and Glucantime alone (4.83+/-4.82) significantly reduced spleen parasite burden compared to the infected untreated group (15.81+/-15.81, P<0.01). There was a difference in the relative weight of the spleen between the na?ve and the infected untreated groups (2.5+/-0.2 vs. 9.8+/-1.0, respectively) as well as between the na?ve and terbinafine groups (2.5+/-0.2 vs. 10.0+/-1.4, respectively). Glucantime alone and Glucantime plus terbinafine (2.5+/-0.2 and 4.2+/-0.6) significantly reduced the weight of the spleen in comparison with the infected untreated group. Even so, the spleen parasite burden was directly related to spleen weight. Terbinafine alone at the dose and schedule used had no effect on spleen parasite burden or relative spleen weight of L. chagasi-infected hamsters.     

Effect of host age in the distribution of adult Trichinella zimbabwensis in the small intestines of golden hamsters (Mesocricetus auratus) and Balb C mice

Golden hamsters (Mesocricetus auratus) and Balb C mice were experimentally infected with Trichinella zimbabwensis to determine the effect of host age in the distribution of adult stages in the small intestines. The hamsters and mice were divided into two groups of young and old animals. Hamsters aged 90 days were designated as young and those aged 360 days were designated as old while mice of 30 days of age were designated as young and those aged 90 days as old. To recover the adult parasites of T. zimbabwensis, the small intestines of each animal were separated and divided into four equal parts and each part was slit open longitudinally. The contents were incubated in 0.85% saline for 4 h at 37 degrees C before the adult worms were recovered from the saline. They were fixed in 70% alcohol and counted under a dissecting microscope. In both young and old hamsters and mice, T. zimbabwensis adult worm counts were significantly higher (P < 0.05) in the second segment of the intestines thus invariably reflecting a significantly high count (P < 0.05) in the first (anterior) half of the small intestines. From this study it was demonstrated that host-age had no effect on the distribution of T. zimbabwensis adult worms in the different segments of the small intestines of golden hamsters and Balb C mice.     

Number of coronary ostia in Syrian hamsters (Mesocricetus auratus) with normal and anomalous coronary arteries

Little attention is being paid to the presence of accessory coronary artery ostia in man and non-human mammals due to their limited clinical relevance. However, information about their frequency and the cardiac territories irrigated by the vessels arising from them is of interest to obtain an accurate survey of the establishment of the coronary artery system in each species. The aim here was to compare the incidence and significance of the accessory coronary ostia in Syrian hamsters with normal coronary arteries and several coronary anomalies characterized by the absence of a left coronary artery originating from the left aortic sinus. The hearts from 2829 hamsters were examined using a corrosion-cast technique, micro-dissection, histochemical techniques, and scanning electron microscopy. Overall, 148 specimens displayed accessory ostia. A limited number of them belonged to the conal artery which supplies the wall of the right ventricular outflow tract. The other accessory ostia led to the septal artery, a vessel which irrigates the most part of the interventricular septum. The incidence of accessory ostia in normal and anomalous coronary artery patterns was quite similar. This suggests that the morphogenetic deviations producing the coronary artery anomalies reported in this study do not alter the connections of the septal and conal arteries to the aorta. The present observations lead to the notion that in the Syrian hamster, the septal artery should be regarded as a third coronary artery.     

Separate origin of the main components of the left coronary artery in Syrian hamsters (Mesocricetus auratus)

This study describes a rare congenital coronary artery anomaly in the Syrian hamster; namely, the separate origin of the obtuse marginal and left circumflex arteries which are the main components of the left coronary artery. The hearts of nine affected animals were examined by means of a corrosion-cast technique and histology. The hamsters belonged to a laboratory inbred family with a high incidence of coronary artery anomalies and bicuspid aortic valve. The aortic valve was tricuspid in three hamsters and bicuspid in the other six hamsters. In all cases, the right coronary artery was normal, whereas the left coronary artery main trunk was absent. The present anomalous coronary artery patterns could be classified into two main entities: (i) ectopic origin of the obtuse marginal artery from the right aortic sinus or from the right coronary artery, with the left circumflex artery arising from the left side of the aortic valve; and (ii) ectopic origin of both the obtuse marginal artery from the right aortic sinus or from the right coronary artery and left circumflex artery from the dorsal aortic sinus. In all cases, the obtuse marginal artery coursed to the right side of the heart through the ventral wall of the right ventricular outflow tract. When the left circumflex artery arose from the dorsal aortic sinus, it formed an acute angle with the aortic wall. This report seems to be the first to describe the separate origin of the main components of the left coronary artery in a non-human mammalian species. In man, the congenital coronary artery and aortic valve defects reported herein may entail the risk of clinical complications. However, none of the affected hamsters showed signs of disease.     

A novel phenomenon predicting the entry into a state of hibernation in Syrian hamsters (Mesocricetus auratus)

When Syrian hamsters (Mesocricetus auratus) are bred in a cold and short-day environment, most animals go into hibernation after a certain period of time. However, to date it has not been possible to predict which hamster will enter hibernation. In this study, we subcutaneously implanted thermo-loggers in hamsters bred in the cold environment, and recorded the subcutaneous temperature at short intervals until they went into hibernation. A time series analysis of temperature disclosed that a fall of 0.4 to 0.8 degrees C in subcutaneous temperature was seen 5 to 16 days before entering hibernation, and this phenomenon continued for three days or more. No hamster went into the hibernation without displaying this signal. Although the mechanism by which this phenomenon takes place is not clear, it is a sign from the body, which is useful for indicating if a hamster will enter hibernation shortly.     

Lymphoma associated with an epizootic of lymphocytic choriomeningitis in Syrian hamsters (Mesocricetus auratus).

A hamster-associated epizootic of lymphocytic choriomeningitis (LCM) virus infection in medical center personnel at the University of Rochester in 1973 necessitated prompt termination of the Syrain hamster colony. Necropsies were performed on 130 hamsters, blood speciments were obtained from 60 for serotest, and viral isolation procedures were done on 47. Active virus infection, as shown by virus isolation, was associated with the presence of lymphoreticular infiltrate in liver and kidney. Intraabdominal lymphoma was seen only in groups of hamsters from which LCM virus was isolated, but LCM virus was not isolated from many of the hamsters with lymphoma. Although frequency of intraabdominal lymphoma could be markedly increased in LCM-positive hamsters treated with 7,12-dimethylbenz(a)anthracene, lymphoma was not induced in LCM-negative hamsters with this carcinogen.     

Nerve fibres in the parathyroid gland of the golden hamster (Mesocricetus auratus): immunohistochemical and ultrastructural investigations

We investigated the morphology and the distribution of the nerve fibres in golden hamster (Mesocricetus auratus) parathyroid glands using antibodies to calcitonin gene-related peptide (CGRP) and substance P, and electron microscopy. CGRP-immunoreactive nerve fibres were densely distributed in the interstitial tissues and the capsules of the hamster parathyroid glands. Some nerve fibres were detected in close proximity of the parathyroid chief cells. The distribution pattern for substance P-immunoreactive nerve fibres was roughly the same as for CGRP-immunoreactive fibres. Ultrastructurally, we found numerous nerve fibres joining the blood vessels. Axon bundles were located adjacent to the smooth muscle cells of the arterioles. The axons formed structurally specialized neuromuscular junctions with the vascular smooth muscle cells. Some axons were in close vicinity to the parathyroid chief cells. These findings indicate that the hamster parathyroid gland contain CGRP and substance P, which may regulate the blood flow and the secretory activity of the gland.