Background Plasma citrulline (CIT) concentration is considered to be a reliable marker of functional enterocyte mass, primarily in humans. However, information about CIT levels along with related metabolites, arginine (ARG), nitric oxide (NO), and ammonia in neonatal calves are lacking. Objectives To compare plasma CIT, ARG, NO, and whole blood ammonia concentrations in neonatal calves with acute diarrhea with those in healthy calves and to assess their possible relationships with diarrhea‐related criteria. Animals Seventy neonatal calves (60 with acute diarrhea and 10 healthy). Methods Observational case‐control study. Diarrheic calves were classified into subgroups on the basis of etiology, severity of diarrhea, degree of dehydration, and systemic inflammatory response syndrome (SIRS) status. Plasma CIT and ARG concentrations were measured by liquid chromatography/tandem mass spectrometry. Results Plasma CIT (median [range]: 67.5 [61.9‐75.4] vs 30.1 [15.0‐56.1] μmol/L) and ARG (170.7 [148.5‐219.5] vs 106.1 [54.4‐190.7] μmol/L) were lower and plasma NO (4.42 [3.29‐5.58] vs 6.78 [5.29‐8.92] μM) and blood ammonia concentrations (28.7 [26.1‐36.9] vs 59.8 [34.6‐99.5] μmol/L) were higher in the neonatal calves with diarrhea (P < .001). Plasma CIT (β = −0.29, P = .02), ARG (β = −0.33, P = .01), NO (β = 0.55, P < .001), and blood ammonia (β = 0.63, P <.001) were affected by SIRS status. Except for ammonia (0.52), the effects sizes for severity of diarrhea and degree of dehydration were small (ηp2 ≤ 0.45) for CIT, ARG, and NO. Conclusions and Clinical Importance The changes in these variables might have diagnostic, prognostic, and therapeutic value in diarrheic neonatal calves.

Canine visceral leishmaniasis has been denoted as neglected despite being a very well-known disease. Trace element alteration has been recognized in humans with visceral and cutaneous leishmaniasis, together with canine visceral leishmaniasis. The trace elements occupy a vital position in the immunological system, and host immune responses mitigate defense against leishmaniasis. We aimed to select trace elements in a total of 45 dogs of several breeds; those at the age of 11 months to 6 and from both sexes (26 male and 19 female) were enrolled in the study. The dogs included in the study were divided into leishmaniasis-infected and noninfected groups. All cases in this study were included according to written owner consent. The trace element analysis of serum samples was carried out by using an inductively coupled plasma-optical emission spectrometry. The results of our study revealed that between the canine visceral leishmaniasis infected group and the uninfected group, Leishmania-positive dogs had significantly lower levels of Se (p < 0.001) and Zn (p < 0.001) compared to the negative ones. These results should be carefully elucidated in an attempt to analyze immune responses in dogs with canine visceral leishmaniasis.