Historical Control Data of Spontaneous Pathological Findings in C57BL/6J Mice Used in 18-Month Dietary Carcinogenicity Assays.

A retrospective analysis in C57BL6/J mice used in dietary carcinogenicity studies was performed to determine the survival rate, causes of death and incidences of spontaneous non-tumoral and tumoral findings. Data were collected from 1600 mice from control dose groups of sixteen 18-month carcinogenicity assays performed between 2003 and 2021 at the same test facility with similar environmental conditions and experimental procedures. The survival rate was high in both sexes (81%-85%) and the causes of humane euthanasia or death were mainly non-tumoral (chronic ulcerative dermatitis, atrial thrombosis). Benign tumors were more frequent than malignant tumors and females were more affected than males. Pituitary gland adenoma in females, lymphoma, bronchioloalveolar adenoma, and harderian gland adenoma in both sexes were the most common tumors. Systemic amyloidosis, the most frequent non-tumoral lesion, was observed variably across studies without sex predilection. The analysis by cohort (3 time periods of 6 years) showed a tendency toward higher incidences of lymphoma and pituitary gland adenoma and lower incidences of amyloidosis over time. The results presented here provide for the first time a robust set of control historical data in untreated C57BL/6J mice kept for 18 months contributing to build in depth knowledge of this animal model.

Causes of Mortality and Pathological Findings in European Hedgehogs (Erinaceus europaeus) Admitted to a Wildlife Care Centre in Southwestern France from 2019 to 2020.

The European hedgehog (Erinaceus europaeus) is a nocturnal, solitary and non-territorial mammal endemic across Europe and central Asia. Due to population decline in recent decades in Europe, this species was declared as protected and registered as 'Least Concern' on the International Union for Conservation of Nature Red List of Threatened Species. Previous studies pointed to the possible contribution of human activities to hedgehog mortality but few reports provide a complete overview of the pathological processes associated with mortality of the European hedgehog. The aim of this study was to identify the causes of mortality and pathological findings in 35 wild adult European hedgehogs that died spontaneously or were euthanized at the Wildlife Care Centre of the Ecole Nationale Vétérinaire de Toulouse between 2019 and 2020. The main causes of mortality were trauma (41%) including collision (9%), predation (9%), trapping (6%) and trauma of unknown origin (17%). Infectious diseases associated with systemic and local bacterial infections accounted for 34% of the cases and included cutaneous wounds (23%), mandibular abscesses and botryomycosis (23%), exudative bronchopneumonia (9%), suppurative rhinitis (7%) and otitis (3%). One hedgehog (3%) had a large subcutaneous tumour consistent with a malignant peripheral nerve sheath tumour. Parasitism was associated with mortality in 11% of cases with severe debilitation, massive infestation and active larval migration. Incidental findings included splenic and hepatic extramedullary haematopoiesis (100% and 69%, respectively), pulmonary crenosomiasis (91%), gastrointestinal capillariasis (61%), renal lipofuscinosis (59%), chronic renal infarction and interstitial nephritis (50%). These data emphasize the need for further study of hedgehog mortality and of the genetic, behavioural and environmental factors that may contribute to population decline.

Additional Value of Second Harmonic Generation Microscopy in the Diagnosis of Feline Collagen Type III Glomerulopathy.

A 1.5-year-old neutered female Domestic Shorthair cat was euthanized after the diagnosis of end-stage protein-losing nephropathy associated with the onset of nephrotic syndrome. At necropsy, both kidneys were diffusely pale and swollen with a granular cortex. Histologically, glomeruli had diffuse global mesangial and capillary wall expansion by homogeneous pale eosinophilic material. This material was Congo red negative, blue with Masson's trichrome stain, weakly positive with periodic acid-Schiff stain, bright red with Picrosirius red and birefringent under polarized light. Transmission electron microscopy and second harmonic generation (SHG) microscopy revealed mesangial and subendothelial collagen fibril deposition. Type III collagen deposition was confirmed by immunohistochemistry. This study provides an original and complete description of feline collagen type III glomerulopathy and emphasizes the possibility of directly diagnosing glomerular collagen deposition on unstained slides through SHG microscopy.