Lisa M. Pohlman

Stability of osmolality in previously frozen canine serum and urine samples

BACKGROUND The measurement of osmolality is of interest in several clinical conditions and has been investigated in multiple veterinary studies. However, the stability of osmolality over time in frozen canine serum and urine has not been established. OBJECTIVES The purpose of this study was to determine the stability of osmolality in canine serum and urine stored frozen at -20°C and -80°C up to 90 days, and to assess the effect of storage temperature on osmolality measurement. METHODS Serum and urine samples collected from 5 healthy Greyhound dogs were aliquoted and stored at -20°C and -80°C until measurement. Osmolality, assessed by freezing-point depression, was measured at 0, 7, 14, 30, and 90 days of storage. RESULTS For both serum and urine, osmolality at day 7 was not statistically different from day 0, but osmolality at days 14, 30, and 90 was significantly lower than at day 0. There was no significant effect of storage temperature on serum osmolality. However, the osmolality of urine samples stored at -20°C was slightly, but significantly lower than the osmolality of those stored at -80°C. CONCLUSIONS Osmolality measurement in the serum and urine of healthy dogs appears to be stable for at least 7 days in frozen samples. The small changes observed after day 7 are unlikely to be relevant for individual patients, but could have implications in research study protocols.

In vitro increase of mean corpuscular volume difference (dMCV) as a marker for serum hypertonicity in dogs

Spurious increase in erythrocyte mean corpuscular volume (MCV) on automated cell analyzers is a well-characterized lab error in hypertonic patients. A difference between automated and manual MCV (dMCV) greater than 2 fl has been shown to predict hypertonicity in humans. The purpose of this study was to investigate dMCV as a marker for serum hypertonicity in dogs and to examine the relationship between dMCV and three methods of estimating serum tonicity: measured (OsMM), calculated (OsMC), and calculated effective (OsMCE) osmolalities. OsMC, OsMCE, and dMCV were calculated from routine blood values and OsMM was directly measured in 121 dogs. The dMCV of hypertonic dogs was significantly larger than that of normotonic dogs for all three osmolality methods. dMCV predicted hypertonicity as estimated by OsMM better than it predicted hypertonicity as estimated by OsMC and OsMCE. A cutoff of 2.96 fl yielded the best sensitivity (76%) and specificity (71%) for hypertonicity estimated by OsMM.

Splenopancreatic ductal adenocarcinoma with multiorgan metastasis in a northern water snake (Nerodia sipedon)

Abstract: A 16-yr-old northern water snake (Nerodia sipedon) presented with a large, firm midcoelomic swelling. A complete blood count, survey radiographs, coelomic ultrasound, and fine needle aspirate of the mass were performed. Survey radiographs revealed a soft tissue opacity mass. Ultrasonographic examination confirmed the presence of the mass but could not aid in its visceral localization. After 2 weeks, the snake presented again because of continued anorexia and poor quality of life. Euthanasia was performed. Gross necropsy revealed a multilobulated mass attached to and effacing the splenopancreas. Histologically, the mass was composed of cuboidal to columnar neoplastic epithelial cells forming tubules surrounded by variable amounts of fibrovascular stroma. Histological examination and immunohistochemical staining of other tissues revealed local invasion in the subserosa and tunica muscularis of the stomach, metastasis within the liver, in the mesovarium, and an intravascular metastasis within the ventricle of the heart surrounded by a thrombus.

Effect of orally administered sodium bicarbonate on caecal pH

REASONS FOR PERFORMING STUDY Caecal acidosis is a central event in the metabolic cascade that occurs following grain overload. Buffering the caecal acidosis by enterally administered sodium bicarbonate (NaHCO3 ) may be beneficial to affected horses. OBJECTIVES To determine the effect and duration of enterally administered NaHCO3 on caecal pH in healthy horses. STUDY DESIGN Experimental study using horses with caecal cannulas. METHODS Nine horses had been previously fitted with a caecal cannula. Six horses received 1.0 g/kg bwt NaHCO3 and 3 control horses were given 3 l of water via nasogastric tube. Clinical parameters, water consumption, venous blood gases, caecal pH, faecal pH and faecal water content were measured at 6 h intervals over a 36 h study period. RESULTS Horses that received enterally administered NaHCO3 had significantly increased caecal pH that lasted the duration of the study. Treated horses increased their water intake, and developed metabolic alkalaemia, significantly increased plasma sodium concentrations and significantly decreased plasma potassium concentrations. CONCLUSIONS Enterally administered NaHCO3 may be beneficial in buffering caecal acidosis.

REFRACTOMETRIC URINE SPECIFIC GRAVITY OF FREE-LIVING EGYPTIAN FRUIT BATS (ROUSETTUS AEGYPTIACUS)

Abstract In both human and veterinary medicine, urine specific gravity (USG) is commonly measured by refractometry to indirectly reflect the osmolality of urine to thereby evaluate the kidneys ability to concentrate or dilute urine according to physiologic need and certain disease conditions. However, for accurate interpretation of the significance of any value, knowledge of the expected USG for the healthy species in question is required. It is generally believed that fruit bats, and Egyptian fruit bats (Rousettus aegyptiacus) in particular, are unable to highly concentrate their urine. In this study, the USG was determined using a handheld urine refractometer in 43 free-living Egyptian fruit bats of both sexes. The calculated nonparametric 90% confidence interval for Egyptian fruit bats in this study was 1.006–1.050, with no association with capture site, sex, weight, or packed cell volume and total solids. Results suggest that free-living Egyptian fruit bats are able to highly concentrate their urine.

SELECTED PLASMA BIOCHEMISTRY ANALYTES OF HEALTHY CAPTIVE SULCATA (AFRICAN SPURRED) TORTOISES (CENTROCHELYS SULCATA)

Abstract The sulcata or African spurred tortoise (Centrochelys sulcata) is a large tortoise species that is commonly kept in zoologic collections and as a pet. The objectives of this study were to establish reference intervals for selected biochemical analytes in clinically healthy captive sulcata tortoises and to evaluate the impact of blood sampling site and sex. Blood samples were collected from 60 tortoises from either the dorsal coccygeal (tail) vein or the subcarapacial venous plexus based on their body size. The packed cell volume and refractometric total solids (TS) were determined. The concentrations of selected plasma biochemical analytes were determined using the VetScan VS2 analyzer and included albumin, aspartate aminotransferase, bile acids, calcium, creatine kinase, globulins, glucose, potassium, sodium, phosphorous, total proteins (TP), and uric acid. The calcium-to-phosphorous ratio was calculated. Reference intervals were determined and evaluated for the potential effects of blood sampling site and sex. There were significant differences (P < 0.05) associated with the blood sampling site in TS, TP, phosphorus, and globulins, with higher values in samples from the tail versus the subcarapacial sampling site. No significant statistical differences were noted in the plasma biochemistry analytes between the sexes. Reading of the globulins by the analyzer failed in 36 of 60 of the samples and was largely associated with the subcarapacial plexus sampling site. The reference intervals defined by the VetScan analyzer in this study can be used for clinical medicine and conservation of this tortoise species. Sampling site was identified as a factor significantly affecting some blood analytes in this study; this factor should thus be taken into consideration when assessing sulcata tortoise health status and using this testing methodology.

Evaluation of mean corpuscular volume difference as a marker for serum hypertonicity during water deprivation in dogs

OBJECTIVE To evaluate mean corpuscular volume difference (dMCV) as a marker for hypertonicity induced by water deprivation in dogs. ANIMALS 5 healthy Greyhounds maintained in a research colony. PROCEDURES Water was withheld for 24 hours. Blood and urine samples were collected before (time 0) and every 6 hours during water deprivation. Serum and urine osmolality were measured on the basis of freezing point depression, and dMCV was calculated from routine hematologic variables. RESULTS Serum and urine osmolality significantly increased and body weight decreased over time in healthy Greyhounds during water deprivation, although most dogs developed only a slight increase in serum osmolality. The dMCV also increased over time, but the value at 24 hours did not differ significantly from the value at time 0. However, a significant correlation was found between serum osmolality and dMCV. A dMCV ≥ 5 fL yielded 100% specificity for predicting hypertonicity when hypertonicity was defined as serum osmolality ≥ 310 mOsM. CONCLUSIONS AND CLINICAL RELEVANCE dMCV may be a useful marker for detection of mild hypertonicity in dogs and may have clinical and research applications for use in screening canine populations for hypertonicity.

PLASMA THYROXINE (T4) CONCENTRATION IN ZOO-KEPT BLACK-TAILED PRAIRIE DOGS (CYNOMYS LUDOVICIANUS)

Abstract This study was conducted to determine plasma thyroxine (T4) concentrations in zoo-kept black-tailed prairie dogs (Cynomys ludovicianus). Thirty-one healthy prairie dogs of both sexes were studied as part of their annual clinical health evaluation, performed under general isoflurane anesthesia. Each animal underwent a complete physical examination, complete blood count, plasma biochemistry, and venous blood gas analysis. Heparinized venous blood samples were collected individually and processed for plasma T4 analysis using a veterinary biochemistry analyzer. The median plasma T4 concentration for the prairie dogs in this study was 4.1 μg/dl (minimum = 0.6 μg/dl; maximum = 8.0 μg/dl). The mean ± standard deviation plasma T4 concentration was 4.49 ± 2.39 μg/dl. No significant differences were found for varying ages, sexes, weights, or housing systems. The data presented in this report can promote better physiologic understanding and improve clinical management of this rodent species.

Regional Nodal Metastasis of Humeral Chondrosarcoma in a Dog.

A 6 yr old castrated male English springer spaniel was evaluated with a 1 mo history of progressive right forelimb lameness with recent swelling around the elbow joint. Physical examination findings included lameness of the right forelimb, muscle atrophy around the right shoulder, grade 2/6 heart murmur, and moderate dental disease. Results of a complete blood cell count and serum biochemical analysis were unremarkable with the exception of a mildly increased alkaline phosphatase (368 U/L; reference range, 128-328 U/L). Radiographs of the right elbow revealed a mixed lytic and proliferative osseous lesion most consistent with either neoplasia or infection. Thoracic radiographs and the echocardiogram were unremarkable. Fine-needle aspiration of the bone lesion was performed. The cytological diagnosis was chondrosarcoma. The right forelimb was amputated and the axillary lymph nodes were collected. Histopathological examination of the bone lesion and axillary lymph nodes revealed chondrosarcoma with metastasis to the lymph nodes. Lymph node metastasis of chondrosarcoma is rare and needs to be further evaluated as a prognostic indicator.