Evaluation of Aqueous Humor as a Surrogate for Serum Biochemistry in California Sea Lions (<I>Zalophus californianus</I>)

Abstract

The aim of this study was to evaluate the use of post mortem aqueous humor analysis in estimating serum chemistry in California sea lions (Zalophus californianus). Serum and aqueous humor from the left eye were collected from 35 sea lions that were euthanized due to poor prognosis. Each animal was examined post mortem, and each head was preserved at ambient temperature. Aqueous humor was collected from the right eye either 24 or 48 h after death. All samples were analyzed with an automated chemistry analyzer by bichromatic photometry and potentiometry. Blood urea nitrogen, creatinine, sodium, chloride, and magnesium showed significant positive linear relationships between serum and aqueous humor values both at the time of death and 24 h later. For aqueous humor sampled after 48 h, the relationships were only significant for blood urea nitrogen and creatinine. For the remaining chemistry parameters, the relationship between levels of those from serum and in aqueous humor were not significant. Serum and aqueous humor collected from 15 animals diagnosed with renal failure were evaluated for antibodies to Leptospira using the microscopic agglutination test. All tested sera were positive for L. interrogans serovar pomona, with titers greater than 1:25,600. Of titers tested in the aqueous humor, 56% were positive, having values of 1:200 to 1:12,800. These results indicate that an accurate estimate of serum blood urea nitrogen and creatinine can be made from the analysis of aqueous humor at necropsy of California sea lions within 48 h of death, facilitating the diagnosis of renal failure in beached carcasses (one of the most common causes of death in wild sea lions).

Reference Intervals of Mineral Elements in Plasma of Anesthetized Free-Ranging Adult Females of South American Sea Lion, Otaria flavescens

“…In the same way, Ca, Mg, and K levels in SSL were similar to those reported in serum of Zalophus californianus [6] and in seals like Hydrurga leptonyx and L. weddelli [10] and Phoca vitulina [11,12]. This information, coupled with the low CV of each element suggest that the values presented as reference intervals correspond to normal physiological values from SSL anesthetized.…”

“…Therefore, reference intervals are a critical diagnostic tool used in the care of stranded animals and for population health investigations. In marine mammals from natural colonies, the information about essential elements in blood fractions is limited, and most reports refer to whole blood [1,[3][4][5][6].…”

Clinical signs and histopathology associated with domoic acid poisoning in northern fur seals (Callorhinus ursinus) and comparison of toxin detection methods

“…7) revealed a potentially valuable diagnostic tool for examining post mortem marine mammals. Aqueous humor is a thin, watery fluid filling the anterior chamber of the eye that is well-protected anatomically and therefore undergoes minimal post mortem change (Sarran et al, 2008). This fluid intermixes with the bloodstream (Johnson and Kamm, 1983) via ultrafiltration making it a very ''clean'' matrix that is easy to analyze and readily available in dead stranded animals.…”

“…This fluid intermixes with the bloodstream (Johnson and Kamm, 1983) via ultrafiltration making it a very ''clean'' matrix that is easy to analyze and readily available in dead stranded animals. Aqueous humor has been used as a surrogate for blood serum in humans, domestic animals and California sea lions for the detection of toxins and antibody titers (Sarran et al, 2008). The identification of aqueous humor as a potential diagnostic bodily fluid for algal toxin detection in marine mammals will be useful to wildlife veterinarians and animal health researchers for investigating the role of DA in mortality events.…”

Concentrations of Selected Essential and Non-essential Elements in Blood of Harbor Seal (Phoca vitulina) Pups of the German North Sea

“…Since elements like Fe, Zn, or Ca have important functions in the body, i.e., Fe as component of cytochromes and oxygen-binding molecules, Zn as components of more than 70 metalloenzymes, or Ca as important element for building of bones and teeth, for blood clotting, muscle contraction, or maintenance of cell membranes, these essential elements were determined in blood serum during medical investigations, such as on marine mammals [11][12][13][14][15][16][17]. Some studies focused on Se due to the strong relationship to mercury and the importance of the element in the detoxification process.…”