To determine the utility of blood symmetric dimethylarginine (SDMA) concentration measurement as a diagnostic tool for chronic kidney disease (CKD) in tigers (Panthera tigris) by comparing results for SDMA with those for traditional renal biomarkers and investigating correlations between these biomarkers and histopathologic kidney changes in tigers with CKD.
Blood, urine, and kidney samples from 35 tigers with CKD from 2 sanctuaries.
Blood (serum or plasma) and urine samples were collected antemortem. Necropsy, including gross and histologic assessment, was performed for tigers that died or were euthanized for quality-of-life reasons. Results for CKD biomarkers in blood (BUN, creatinine, phosphorus, and SDMA concentrations) and urine (protein concentration, urine protein-to-creatinine ratio, and urine specific gravity) were evaluated for correlation with histologic kidney damage scored with an objective grading scale defined by percentage of inflammation, fibrosis, and tubular atrophy.
Symmetric dimethylarginine had the strongest significant correlation (ρ = 0.667) with histologic kidney damage score, followed by urine specific gravity (ρ = –0.639), blood creatinine concentration (ρ = 0.624), and BUN (ρ = 0.588). No significant correlation with kidney score was identified for blood phosphorus concentration, urine protein concentration, or the urine protein-to-creatinine ratio.
We recommend SDMA be prioritized as a renal biomarker in tigers, with SDMA results considered in addition to those of other traditional renal biomarkers when assessing kidney function in tigers. Additionally, the grading scale we developed could be replicated across patients and pathologists for more consistent postmortem assessment of CKD in tigers.
To compare pregnancy-associated glycoprotein 1 (PAG1) concentrations in maternal (jugular vein) and fetal (uterine vein) circulations and amniotic fluid samples between pregnant ewes that were and were not experimentally infected with bovine viral diarrhea virus (BVDV).
11 healthy pregnant yearling ewes.
Before study initiation, all ewes were naïve to BVDV and confirmed pregnant by transabdominal ultrasonography at approximately 60 days of gestation. At 65 days of gestation, ewes were intranasally inoculated with a noncytopathic BVDV type 1b strain (concentration, 107 TCID50/mL; 2 mL/nostril; n = 6) or an equal volume of BVDV-free viral culture medium (control; 5). A blood sample was collected for measurement of PAG1 concentration before inoculation. At 80 days of gestation, each ewe was anesthetized and underwent an ovariohysterectomy. While sheep were anesthetized, blood samples from the jugular and uterine veins and an amniotic fluid sample were collected for measurement of PAG1 concentration. Fetal tissues underwent real-time PCR analysis for BVDV RNA, and placental specimens underwent histologic evaluation and immunohistochemical staining for BVDV antigen.
At 80 days of gestation, BVDV RNA in fetal tissues and mild placentitis were detected in 5 of 6 BVDV-inoculated ewes. Mean PAG1 concentrations in the maternal and fetal circulations of BVDV-inoculated ewes were significantly less than those in control ewes. Mean amniotic fluid PAG1 concentration did not differ significantly between the 2 groups.
CONCLUSIONS AND CLINICAL RELEVANCE
Concentration of PAG1 in the maternal circulation may be a useful biomarker for determining placental health in sheep after viral infection of the reproductive tract.