Relationship between thyroid function and sex hormones in female German shepherd dogs.

BACKGROUND: Several variables influence the serum concentration of thyroid hormones in dogs, including breed, age, drugs, and concurrent diseases. However, data regarding the interaction between thyroid function and the estrous stage of female dogs are limited. HYPOTHESIS: Estrous stage may influence thyroid function in German Shepherd dogs. METHODS: Longitudinal, observational, non-randomized cohort study. The dogs were monitored during the complete estrous cycle, and different stages were determined by vaginal cytology. Two blood samples were collected at the beginning and end of each stage to analyze the following: total thyroxine (TT4), free thyroxine (fT4), total triiodothyronine (TT3), free triiodothyronine (fT3), canine thyrotropin (cTSH), progesterone, 17-ß-estradiol, triglycerides, and cholesterol concentrations. Hematological and biochemical evaluations were performed at the beginning and end of the study period. ANIMALS: Seventeen German Shepherds were included, of which 7 were bred during the study period. One dog was excluded for estrus interruption and another for suspected hypothyroidism. RESULTS: Serum concentrations of T4, fT4, and fT3 were negatively correlated with age. Total thyroxine demonstrated significant changes in serum concentrations between estrous stages, with higher concentrations in estrus and diestrus. Total thyroxine concentrations were positively correlated with progesterone concentrations and negatively correlated with 17-ß-estradiol concentrations. Free thyroxine did not show significant variations but was positively correlated with progesterone concentrations. Canine TSH concentrations were positively correlated with 17-ß-estradiol concentrations. No significant differences in thyroid hormones and cTSH concentrations were observed between diestrus during pregnancy and pseudopregnancy. CONCLUSIONS: Different stages of estrus can influence the measurement of TT4 in female dogs.

Bacteriological and pathological investigations on the preputial glands of one-year-old C57BL/6NCrl mice maintained in individually ventilated cages.

Spontaneous infections of the preputial glands represent overlooked health problems in mice that could raise welfare concerns and potentially confound scientific experiments. Agents involved in preputial gland infections have rarely been investigated, with opportunistic pathogens of laboratory animals usually detected in inflamed preputial glands. The aim of this study was to investigate the prevalence of bacterial infection in the preputial glands and the relationship between haematological and pathological changes and infection status. We analysed 40 preputial glands from 20 one-year-old C57BL/6NCrl male mice by using bacteriology, haematology and pathology. Bacteria were isolated from 16/20 (80%) mice, for a total of 32/40 (80%) examined preputial glands. Enterobacter cloacae, Pasteurella spp., Klebsiella spp. and Staphylococcus aureus were identified in 35%, 17.5%, 15% and 12.5% of the examined glands, respectively. Preputial gland inflammation was identified in 29/40 (72.5%) glands and was classified as chronic interstitial adenitis in 27 cases and suppurative adenitis in the remaining two glands. No haematological changes were found in mice with infected glands. Histologically, the presence of intralesional bacteria, intraluminal necrotic material, intraluminal keratin accumulation, interstitial inflammatory cell infiltrate and granulocytes (intraluminal and/or interstitial), along with total inflammatory score and total histopathological score, were significantly increased in infected glands and correlated with the bacterial load. Most severe inflammatory changes were identified after S. aureus infection, while ductal hyperkeratosis was significantly increased in glands infected with Klebsiella spp. In conclusion, preputial gland infection was a common event in one-year-old C57BL/6NCrl mice, and bacterial load correlated with pathological findings, while systemic effects were not highlighted by haematology.

Repeated oral administration of low doses of silver in mice: tissue distribution and effects on central nervous system.

BACKGROUND: Widespread use of silver in its different forms raises concerns about potential adverse effects after ingestion, the main exposure route for humans. The aim of this study was to investigate in CD-1 (ICR) male mice the tissue distribution and in vivo effects of 4-week oral exposure to 0.25 and 1 mg Ag/kg bw 10 nm citrate coated silver nanoparticles (AgNPs) and 1 mg Ag/kg bw silver acetate (AgAc) at the end of treatment (EoT) and after 4 weeks of recovery. RESULTS: There were no treatment-related clinical signs and mortality, and no significant effects on body and organ weights at the EoT and after recovery. Treatment-related changes in hematology and clinical chemistry were found after recovery, the most relevant being a dose-dependent lymphopenia and increased triglycerides in AgNP-treated mice, and increased levels of urea in all treated groups, associated with decreased albumin only in AgAc-treated mice. At the EoT the highest silver concentration determined by Triple Quadrupole ICP-MS analysis was found in the brain, followed by testis, liver, and spleen; much lower concentrations were present in the small intestine and kidney. Tissue silver concentrations were slightly higher after exposure to AgAc than AgNPs and dose dependent for AgNPs. After recovery silver was still present in the brain and testis, highlighting slow elimination. No histopathological changes and absence of silver staining by autometallography were observed in the organs of treated mice. At the EoT GFAP (astrocytes) immunoreactivity was significantly increased in the hippocampus of AgNP-treated mice in a dose-dependent manner and Iba1 (microglial cells) immunoreactivity was significantly increased in the cortex of 1 mg/kg bw AgNP-treated mice. After recovery, a significant reduction of Iba1 was observed in the cortex of all treated groups. TEM analysis of the hippocampus revealed splitting of basement membrane of the capillaries and swelling of astrocytic perivascular end-feet in 1 mg/kg bw AgNP- and AgAc-treated mice at the EoT. CONCLUSIONS: Our study revealed accumulation and slow clearance of silver in the brain after oral administration of 10 nm AgNPs and AgAc at low doses in mice, associated with effects on glial cells and ultrastructural alterations of the Blood-Brain Barrier.

Long-Term Study on the Effects of Housing C57BL/6NCrl Mice in Cages Equipped With Wireless Technology Generating Extremely Low-Intensity Electromagnetic Fields.

The recent development of mouse cages equipped with monitoring wireless technology raised questions on the potential effects on animals induced by electromagnetic fields (EMFs) generated by electronic boards positioned underneath the cages. The aims of this study were to characterize the EMF produced by digitally ventilated cages (DVC) and perform a clinicopathological study on mice maintained in DVC for up to 1 year. The EMFs were measured in empty individually ventilated cages (IVC) and DVC. Male (n = 160) and female (n = 160) C57BL/6NCrl mice were randomly housed in IVC and DVC in a single rack, 4 mice per cage. Body weight and food and water consumption were recorded at 14-day intervals. At sacrifice (days 60, 120, 180, and 365), body and testes weight was measured, and necropsy, hematology, bone marrow cytology, histology, and immunohistochemistry for cleaved-caspase 3 on the testes were performed. Digitally ventilated cages produced extremely low-intensity electric fields ranging from 5 Hz to 3 GHz. No exposure-related clinical signs and mortality occurred. Occasional statistical differences in body weight, food and water consumption, hematology, bone marrow, and histopathology were recorded, but considered without biological or clinical relevance. In conclusion, long-term maintenance in DVC had no definite effects on C57BL/6NCrl mice.