25-OH-vitamin D, parathyroid hormone, and calcium serum levels in captive common marmosets (Callithrix jacchus): Reference values and effect of age, sex, season, and closure of long bone epiphyses

Quality of hematology and clinical chemistry results in laboratory and zoo nonhuman primates: Effects of the preanalytical phase. A review

Most errors in clinical pathology originate in the preanalytical phase, which includes all steps from the preparation of animals and equipment to the collection of the specimen and its management until analyzed. Blood is the most common specimen collected in nonhuman primates. Other specimens collected include urine, saliva, feces, and hair. The primary concern is the variability of blood hematology and biochemistry results due to sampling conditions with the effects of capture, restraint, and/or anesthesia. Housing and diet have fewer effects, with the exception of food restriction to reduce obesity. There has been less investigation regarding the impact of sampling conditions of nonblood specimens.

Radiographic study of the axial and appendicular skeleton of Callithrix jacchus and Callithrix penicillata

BACKGROUND

Marmosets are small arboreal primates. Knowledge of normal radiographic parameters and frequent disorders is limited. The objectives of this study were to evaluate possible variations between quantitative analyses and injuries to the appendicular and axial skeleton of Callithrix jacchus and Callithrix penicillata and their relationship with the environment.

METHODS

Radiographic images of 29 marmosets were used. Skeletal lesions were described, long bones were measured, and pelvimetry, vertebrae, and sternebras were counted.

RESULTS

Measurements of long bones and pelvimetry were similar between species. Evaluation of vertebrae and sternebras exhibited variations relative to the literature. Lesions on the skull, spine, thoracic and pelvic limbs were present in 48%, 54%, 44%, and 52% of marmosets, respectively.

CONCLUSION

Skeletal disorders, especially of traumatic and metabolic origin, have a high prevalence in marmosets.

Vitamin D Metabolism and Profiling in Veterinary Species

The demand for vitamin D analysis in veterinary species is increasing with the growing knowledge of the extra-skeletal role vitamin D plays in health and disease. The circulating 25-hydroxyvitamin-D (25(OH)D) metabolite is used to assess vitamin D status, and the benefits of analysing other metabolites in the complex vitamin D pathway are being discovered in humans. Profiling of the vitamin D pathway by liquid chromatography tandem mass spectrometry (LC-MS/MS) facilitates simultaneous analysis of multiple metabolites in a single sample and over wide dynamic ranges, and this method is now considered the gold-standard for quantifying vitamin D metabolites. However, very few studies report using LC-MS/MS for the analysis of vitamin D metabolites in veterinary species. Given the complexity of the vitamin D pathway and the similarities in the roles of vitamin D in health and disease between humans and companion animals, there is a clear need to establish a comprehensive, reliable method for veterinary analysis that is comparable to that used in human clinical practice. In this review, we highlight the differences in vitamin D metabolism between veterinary species and the benefits of measuring vitamin D metabolites beyond 25(OH)D. Finally, we discuss the analytical challenges in profiling vitamin D in veterinary species with a focus on LC-MS/MS methods.

Evaluation of vitamin D3 metabolites in Callithrix jacchus (common marmoset)

Vitamin D₃ (cholecalciferol) is endogenously produced in the skin of primates when exposed to the appropriate wavelengths of ultraviolet light (UV-B). Common marmosets (Callithrix jacchus) maintained indoors require dietary provision of vitamin D₃ due to lack of sunlight exposure. The minimum dietary vitamin D₃ requirement and the maximum amount of vitamin D₃ that can be metabolized by marmosets is unknown. Observations of metabolic bone disease and gastrointestinal malabsorption have led to wide variation in dietary vitamin D₃ provision amongst research institutions, with resulting variation in circulating 25-hydroxyvitamin D₃ (25(OH)D₃ ), the accepted marker for vitamin D sufficiency/deficiency. Multiple studies have reported serum 25(OH)D₃ in captive marmosets, but 25(OH)D₃ is not the final product of vitamin D₃ metabolism. In addition to serum 25(OH)D_3, we measured the most physiologically active metabolite, 1,25-dihydroxyvitamin D₃ (1,25(OH)₂ D₃ ), and the less well understood metabolite, 24,25-dihydroxyvitamin D₃ (24,25(OH)₂ D₃ ) to characterize the marmoset's ability to metabolize dietary vitamin D₃ . We present vitamin D₃ metabolite and related serum chemistry value colony reference ranges in marmosets provided diets with 26,367 (Colony A, N = 113) or 8,888 (Colony B, N = 52) international units (IU) of dietary vitamin D₃ per kilogram of dry matter. Colony A marmosets had higher serum 25(OH)D₃ (426 ng/ml [SD 200] vs. 215 ng/ml [SD 113]) and 24,25(OH)₂ D₃ (53 ng/ml [SD 35] vs. 7 ng/ml [SD 5]). There was no difference in serum 1,25(OH)₂ D₃ between the colonies. Serum 1,25(OH)₂ D₃ increased and 25(OH)D₃ decreased with age, but the effect was weak. Marmosets tightly regulate metabolism of dietary vitamin D₃ into the active metabolite 1,25(OH)₂ D₃ ; excess 25(OH)D₃ is metabolized into 24,25(OH)₂ D₃ . This ability explains the tolerance of high levels of dietary vitamin D₃ by marmosets, however, our data suggest that these high dietary levels are not required.