Mercury and selenium concentrations in livers and eggs of common loons (Gavia immer) from Minnesota.

Mercury and selenium act as mutual antagonists in mature birds, but their toxicity is additive or synergistic in avian embryos and immature birds. Twenty eggs and livers from 18 mature and 9 immature common loon carcasses found in Minnesota were collected. Livers and eggs were analyzed for mercury and selenium by atomic emission and atomic absorption spectroscopy. Liver mercury concentrations were significantly higher in mature loons compared to those of immature loons and eggs. Liver selenium concentrations were significantly higher in mature loons than those of immature loons, and selenium concentrations in immature loon livers were significantly higher than levels in eggs. There was a significant positive correlation between mercury and selenium in loon livers. There was a negative correlation between mercury and selenium in eggs.

A case of anaemia in a neonatal warthog (Phacochoerus aethiopicus) and evaluation of serum-soluble iron in warthogs.

A 38-day-old male warthog (Phacochoerus aethiopicus) with marked anaemia (haematocrit = 14 %) presented to the Denver Zoological Gardens hospital with ataxia, tachypnoea, suspected stunted growth and cardiomegaly. The piglet demonstrated some features consistent with both iron deficiency anaemia and autoimmune haemolytic anaemia. Serum-soluble iron was below the level of detection (< 8.96 micromol/l). Iron deficiency anaemia is a well recognised entity in domestic swine reared on concrete and denied access to soil. Fifteen captive warthogs were subsequently evaluated for serum soluble iron content (mean = 21.62 +/- 4.36 micromol/l as well as 5 neonatal warthog piglets that required hand-rearing. Only 1 of 5 neonatal warthog piglets had measurable serum soluble iron (9.50 micromol/l). These data suggest that warthogs are similar to domestic swine and are born with low iron stores. Some form of iron supplementation should be considered for captive neonatal warthog piglets, especially if they are reared on concrete.

A retrospective study on the disappearance of blood lead in cattle with accidental lead toxicosis.

Lead poisoning in cattle and other food animals is of public health significance because of the potential for human exposure to lead through ingestion of contaminated meat and milk products derived from lead-poisoned animals. In Michigan, lead poisoning in livestock is a reportable disease, and positive cattle are quarantined until they test negative (<0.05 ppm blood lead). There is surprisingly little information on blood lead kinetics in cattle. The half-life has been variably reported as 9 weeks and 1-2 months. Because these data did not fit those obtained from cases received at the Michigan State University Animal Health Diagnostic Laboratory, a retrospective study was conducted to review all cases of accidental lead poisoning in cattle between 1990 and 1998. This information is needed to estimate when quarantined lead-poisoned cattle can be released. The results showed that the half-life of blood lead was quite variable and ranged from 48 to 2,507 days. The shortest half-lives (48, 56, and 57 days) were found in a lactating herd of 20-month-old heifers. The longest half-life, 2,507 days, was found in a 9-month-old castrated bull, which ingested a discarded automobile battery. Of the 24 animals monitored, only 8/24 (33%) had half-lives between 6 and 14 weeks. In conclusion, the half-life of blood lead is difficult to predict in accidental cases of cattle poisoning.

Relationship between plasma iohexol clearance and urinary exogenous creatinine clearance in dogs.

The objective of this study was to determine if plasma iohexol clearance, computed by a 1-compartment model defined by 3 plasma samples. was an accurate measure of glomerular filtration rate (GFR) in dogs. Twenty-two adult Beagle dogs of both genders were studied. Ten dogs had intact kidneys, and 12 dogs had surgically reduced renal mass. A bolus injection of iohexol was made, and blood was obtained for plasma iohexol assay after 120, 180, and 240 minutes. Plasma was analyzed for iohexol concentration by means of 3 assay methods: chemical, high-performance liquid chromatography (HPLC), and inductively coupled plasma emission spectroscopy (ICP). Urinary clearance of exogenous creatinine was used to measure GFR for three 30-minute periods occurring between 150 and 240 minutes after iohexol injection. Plasma clearance of iohexol and renal clearance of creatinine were compared by linear regression analysis and by limits of agreement techniques. Plasma iohexol clearance and urinary exogenous creatinine clearance were significantly correlated (chemical R2 = .90; HPLC R2 = .96; and ICP R2 = .96). The 1-compartment iohexol clearance:exogenous creatinine clearance ratios were 1.04 +/- 0.17, 1.05 +/- 0.14, and 1.10 +/- 0.15 for the chemical, HPLC, and ICP methods of assay, respectively, indicating that plasma iohexol clearance slightly overestimated GFR. Assuming a +/- 2 standard deviation interval for error, corrected plasma iohexol clearance measured GFR with +/-34% accuracy for the chemical, +/-26% accuracy for the HPLC, and +/-27% accuracy for the ICP method. These results indicate that plasma iohexol clearance should have utility for detection of renal dysfunction earlier in the course of progressive renal disease than is possible with measurement of plasma creatinine or urea concentrations.

Intracellular magnesium concentrations in dogs with gastric dilatation-volvulus.

OBJECTIVE: To quantify and compare intracellular magnesium concentrations (Mgi) in clinically normal dogs (control dogs) and dogs that have gastric dilatation-volvulus (GDV dogs) and to determine whether there is a difference in Mgi and serum magnesium concentrations (Mgs) between GDV dogs with and without cardiac arrhythmias. ANIMALS: 41 control dogs and 21 GDV dogs. PROCEDURE: Rectus abdominis muscle specimens were obtained from control and GDV dogs for determination of Mgi. Blood samples were obtained from GDV dogs for determination of Mgs, and dogs were monitored for 48 hours for cardiac arrhythmias. Muscle specimens were frozen at -40 C, oven dried at 95 C, and digested with concentrated nitric acid. Multielemental analyses were performed by simultaneous/sequential inductively coupled plasma-atomic emission spectroscopy with fixed-cross flow nebulization. The Mg, was standardized to sulfur content to correct for the amount of fat and fascia in the muscle specimen. Mean (+/- SEM) values were recorded in parts per million (ppm). Results-There were no significant differences in Mgi between control (627 +/- 11.1 ppm) and GDV (597 +/- 20.5 ppm) dogs, in Mgi between GDV dogs with (590 +/- 34 ppm) and without (584 +/- 29 ppm) cardiac arrhythmias, and in Mgs between GDV dogs with (1.77 +/- 0.26 ppm) and without (1.51 +/- 0.09 ppm) cardiac arrhythmias. There was no correlation between Mgs and Mgi (R2 = 0.0001). CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that Mg depletion is not pathophysiologically important in dogs with GDV and does not play a role in the cardiac arrhythmias detected in these patients.

Augmentation of mercury-induced nephrotoxicity by endotoxin in the mouse.

Endotoxin (lipopolysaccharide; LPS) and mercury are compounds of food safety concern. Endotoxin is a product of cell walls of gram negative bacteria. Humans are constantly exposed to LPS through infection plus translocation into circulation from the gastrointestinal tract. Food is the major source of mercury in humans. The toxic interaction between LPS and mercury has not been well investigated. In a previous study, we demonstrated that LPS potentiated mercury-induced nephrotoxicity in the rat. Whether this observation was species specific was not clear. In this study we tested the hypothesis that LPS enhances mercuric chloride (HgCl(2))-induced nephrotoxicity in mice. In a 2x2 factorial design, mice received either Escherichia coli 0128:B12 endotoxin (2.0 mg/kg body weight) or 200 microliter of 0.9% sodium chloride (saline), and this was followed 4 h later by either mercury (1.75 mg mercuric chloride per kg body weight) or 200 microliter of saline. Mice were monitored for 48 h. Monitored end-points included body and renal weights, urine volume, renal histology and ultrastructural pathology, serum urea nitrogen and creatinine, selected serum and urine cytokines, and renal mercury concentrations. Endotoxin by itself was not nephrotoxic at the dose used in this study. Overall, mice given LPS plus mercury were the most severely affected. Mice given LPS and mercury also had significantly greater renal mercury concentration than those given mercury alone (P

The use of blood analyses to evaluate mineral status in livestock.

Animal responses are useful means of evaluating and assessing nutritional status. Blood mineral concentrations can be useful nutritional responses, although there are important limitations. The nutritional value in monitoring blood mineral concentrations varies with the specific mineral, being generally most valuable for those minerals in which homeostasis is regulated primarily by renal excretion, as opposed to regulation by variable absorptive efficiency. Examples of minerals for which blood concentrations are good measures of nutritional intake are selenium and magnesium. Blood mineral concentrations are affected by multiple variability factors. The strategy for use in mineral status assessment is to minimize non-nutritional variation by grouping animals for testing based on physiologic factors that affect, or are likely to affect, the concentration of the mineral or minerals being tested. Care should be taken to use the proper sampling protocol, so as not to cause artifactual variation. Removal of the serum from the clot within 2 hours of sample collection is an important step, among others. Sampling adequate numbers of animals and evaluating the herd mean and SD can minimize the effect of random variation on interpretation.

The postmortem diagnosis of cholecalciferol toxicosis: a novel approach and differentiation from ethylene glycol toxicosis.

The objectives of this study were to develop a novel approach to postmortem diagnosis of cholecalciferol (CCF) toxicosis in dogs using kidney, bile, and urine samples, and to differentiate CCF from ethylene glycol (EG) toxicosis. To achieve these objectives, specimens collected from 2 previous laboratory studies in which dogs were given a single oral toxic dose of CCF (8.0 mg/kg) were used. For EG toxicosis, historical data from the previous 13 years (1985-1998) were reviewed and confirmed cases of EG toxicosis were selected. The historical data were used to compare trace mineral concentrations, specifically of calcium and phosphorus to differentiate between intoxications caused by CCF from that caused by EG in dogs. Kidneys, bile, and urine from dogs that died of CCF toxicosis were analyzed for 25 monohydroxy vitamin D3 (25(OH)D3) and 1,25 dihydroxy vitamin D3 (1,25(OH)2D3) and compared to known control unexposed dogs. Results of this study show that biliary and renal 25(OH)D3 concentrations and renal calcium to phosphorus ratio are of diagnostic value in dogs exposed to toxic concentrations of CCF. The renal calcium to phosphorus ratio was <0.1 in normal dogs, 0.4-0.9 in dogs that died of CCF toxicosis, and >2.5 in dogs that died of EG toxicosis.

Potentiation of mercury-induced nephrotoxicity by endotoxin in the Sprague-Dawley rat.

Endotoxin (lipopolysaccharide; LPS) and mercury are nephrotoxic compounds of food safety concern. Endotoxin is a product of cell walls of gram negative bacteria. Humans are constantly exposed to LPS through food, water and air. Food is the main source of mercury exposure for humans. Endotoxin potentiates the toxicity of a number of xenobiotics, but its interaction with nephrotoxic heavy metals has not been investigated. We tested the hypothesis that endotoxin enhances mercury-induced nephrotoxicity. Thirty-two, 41-43-day-old, male Sprague-Dawley rats were allocated randomly to four groups of eight rats each as follows: group I received 0.9% sodium chloride, group II received 2.0 mg of Escherichia coli 0128:B12 LPS kg(-1) once, group III received 0.5 mg mercuric chloride kg(-1) once, and group IV received 2.0 mg E. Coli 0128:B12 LPS kg(-1) once 4 h before receiving 0.5 mg mercury chloride kg(-1) once. Mercury, LPS and 0.9% sodium chloride were all injected IV through the tail vein. Rats were monitored for 48 h after mercury injection. Serum creatinine, urea nitrogen, and polyuria were significantly increased in rats given LPS plus mercury relative to those given either agent alone or saline (P

Effects of methimazole on renal function in cats with hyperthyroidism.

The purpose of this study was to investigate the effects of methimazole on renal function in cats with hyperthyroidism. Twelve cats with naturally occurring hyperthyroidism and 10 clinically normal (i.e., control) cats were included in this study. All cats initially were evaluated with a history, physical examination, complete blood count, serum biochemistry profile, basal serum total thyroxine concentration, complete urinalysis, and urine bacterial culture. Glomerular filtration rate (GFR) was estimated by a plasma iohexol clearance (PIC) test. After initial evaluation, hyperthyroid cats were treated with methimazole until euthyroidism was achieved. Both groups of cats were then reevaluated by repeating the initial tests four to six weeks later. The mean (+/-standard deviation) pretreatment estimated GFR for the hyperthyroid cats was significantly higher (3.83+/-1.82 ml/kg per min) than that of the control cats (1.83+/-0.56 ml/kg per min). Control of the hyperthyroidism resulted in a significantly decreased mean GFR of 2.02+/-0.81 ml/kg per minute when compared to pretreatment values. In the hyperthyroid group, the mean increases in serum urea nitrogen (SUN) and creatinine concentrations and the mean decrease in the urine specific gravity after treatment were not statistically significant when compared to pretreatment values. Two of the 12 hyperthyroid cats developed abnormally high serum creatinine concentrations following treatment. These results provide evidence that cats with hyperthyroidism have increased GFR compared to normal cats, and that treatment of feline hyperthyroidism with methimazole results in decreased GFR.

Gas chromatography/mass spectrometry identification and quantification of isazophos in a famphur pour-on and in bovine tissues after a toxic exposure.

A sample identified as "Warbex pour-on," expected to contain 13.2% famphur, and bovine tissue samples from 2 heifers that died after exhibiting signs of organophosphate intoxication were analyzed by gas chromatography/mass spectrometry (GC/MS). A product formulation problem was suspected because brain cholinesterase activities were depressed in both animals. Electron impact (EI) GC/MS of the pour-on revealed 9.7% famphur and an unidentified peak with approximately 76% of the peak area of the famphur. The unidentified peak showed a molecular ion at m/z 313, with a single Cl isotope cluster. Methane chemical ionization (MeCI) MS confirmed the molecular weight at 313 (1 Cl). A search on the molecular formula C9H17N3O3PSCl yielded a single match, isazophos. EI and MeCI GC/MS of reference isazophos confirmed the identity of the suspect peak. The concentration of isazophos in the pour-on was determined to be 6.0%. Famphur and isazophos were identified by their EI spectra and GC retention times in extracts of liver and brain from the 2 deceased animals. A GC/MS procedure utilizing selected ion monitoring (SIM) was developed for quantification of isazophos in liver, kidney, muscle, and fat of additional affected animals sacrificed at various times after exposure. Isazophos remained in animal tissues for as long as 94 days after topical exposure. Isazophos was present in fetal liver 70 days after exposure of the dam. High levels (6-3,500 ppm) of isazophos and famphur remained on the skin at 39 days postexposure.

Use of pamidronate disodium to reduce cholecalciferol-induced toxicosis in dogs.

OBJECTIVE: To determine whether pamidronate disodium can reduce cholecalciferol-induced toxicosis in a dose-related manner. ANIMALS: 20 clinically normal, 8- to 12-month-old male Beagles. PROCEDURE: All dogs were given 8 mg of cholecalciferol (CCF)/kg of body weight once orally, then were randomly assigned to 4 groups of 5 dogs each. Dogs were treated with IV administration of 0.9% NaCl solution (SC group), 0.65 mg of pamidronate/kg in 0.9% NaCl solution (LP group), 1.3 mg of pamidronate/kg in 0.9% NaCl solution (MP group), or 2.0 mg of pamidronate/kg in 0.9% NaCl solution (HP group) on days 1 and 4 after administration of CCF. Dogs were observed for 14 days, and serial blood samples were collected for serum biochemical, electrolyte, and 25-hydroxyvitamin D3 analyses. Urine samples were collected for determination of specific gravity. Glomerular filtration rate (GFR) was determined by plasma iohexol clearance. Histologic examination of renal tissue was performed. RESULTS: One dog in the SC group was euthanatized 3 days after administration of CCF because of severe clinical signs of toxicosis. Dogs in the HP group had significantly higher mean GFR (day 3), serum potassium concentrations (day 14), and urine specific gravity (days 7 and 14) and significantly lower mean serum creatinine concentrations and total calcium X phosphorus concentration product (days 4 and 7) than dogs in the SC group. Dogs in the HP group had no abnormal findings on histologic examination of renal tissue, dogs in the LP and MP groups had trace to mild mineralization of renal tissue, and dogs in the SC group had moderate mineralization and cellular necrosis of proximal renal tubules. CONCLUSIONS AND CLINICAL RELEVANCE: Pamidronate disodium is a potentially useful drug to reduce CCF-induced toxicosis and other causes of hypercalcemia associated with increased bone resorption in dogs.

Use of pamidronate to reverse vitamin D3-induced toxicosis in dogs.

OBJECTIVES: To determine whether pamidronate disodium can reduce vitamin D3-induced hypercalcemia in dogs and whether combination treatment with calcitonin is more effective than treatment with pamidronate alone. ANIMALS: 20 clinically normal male Beagles. PROCEDURE: All dogs were given 8 mg of cholecalciferol (CCF)/kg of body weight once orally, then were assigned randomly to 4 groups of 5 dogs each. Dogs were given 0.9% NaCl solution IV (group 1), calcitonin SC and 0.9% NaCl solution IV (group 2), pamidronate and 0.9% NaCl solution IV (group 3), or a combination of all 3 agents (group 4). Dogs were observed for 28 days, and serial blood and urine samples were collected for determination of serum biochemical, electrolyte, and 25(OH)D3 values, CBC, and urine mineral excretion. Samples of kidney, stomach, lung, aorta, liver, duodenum, and brain were evaluated by light microscopy and quantitative mineral analysis. RESULTS: Two dogs in group 1 were euthanatized 4 days after CCF administration because of severe clinical signs of disease. Dogs in group 3 lost less weight and had significantly lower serum phosphorus, total and ionized calcium, and urinary zinc concentrations, compared with dogs in group 1. On day 4, serum urea nitrogen concentration was significantly lower in dogs of groups 3 and 4, compared with dogs in group 1. Mild to moderate mineralization of kidneys and stomach were observed in the 2 group-1 dogs euthanatized on day 4. CONCLUSIONS: Pamidronate administration effectively prevents CCF-induced hypercalcemia and mineralization of soft tissues. CLINICAL RELEVANCE: Pamidronate is a potentially useful antidote against CCF toxicosis in dogs.

Health evaluation of free-ranging rockhopper penguins (Eudyptes chrysocomes) in Argentina.

As part of annual colony counts in Santa Cruz Province, Argentina, a health survey of rockhopper penguins (Eudyptes chrysocomes) was conducted in 1994. Forty-five birds were examined during handling procedures, and blood and fecal samples were collected for laboratory analysis. All birds appeared to be in good condition. No ecto- or endoparasites were found. Hematology, plasma chemistry, and plasma mineral levels were measured and correlated with the results of bacterial and viral serology. Antibodies against Chlamydia sp., avian adenovirus, avian encephalomyelitis virus, infectious bronchitis virus, avian reovirus, and paramyxovirus-1, -2, and -3 were found. Mean plasma chemistry and mineral values differed between individuals testing positive and negative on serologic tests. There was no serologic evidence of exposure to avian influenza virus, duck viral enteritis, infectious bursal disease, infectious laryngotracheitis, Aspergillus sp., or Salmonella pullorum. Trace amounts of endrin were found in the plasma of one bird, but all other chlorinated pesticide and polychlorinated biphenyl levels were below detectable limits.

Health evaluation of free-ranging guanaco (Lama guanicoe).

Twenty free-ranging guanaco (Lama guanicoe) in Chubut Province, Argentina, were immobilized for health evaluations. All but two animals appeared to be in good condition. Hematology, serum chemistry, and vitamin and mineral levels were measured, and feces were evaluated for parasites. Serology tests included bluetongue, brucellosis, bovine respiratory syncitial virus, bovine viral diarrhea/mucosal disease, equine herpesvirus 1, infectious bovine rhinotracheitis, Johne's disease (Mycobacterium paratuberculosis), foot and mouth disease, leptospirosis (17 serovars), parainfluenza-3, and vesicular stomatitis. Blood samples from 20 domestic sheep (Ovis aries) maintained in the same reserve with the guanaco were also collected at the same time for serology tests. No guanaco had positive serologic tests. Sheep were found to have antibody titers to bovine respiratory syncytial virus, Johne's disease, leptospirosis, and parainfluenza-3. There was no apparent difference in external appearance or condition, or statistical difference in blood test values, between the animals that were positive or negative for parasite ova.

Immobilization and health assessment of free-ranging black spider monkeys (Ateles paniscus chamek).

Eight free-ranging black spider monkeys (Ateles paniscus chamek) were immobilized with Telazol in Bolivia for the purpose of radio-collaring. During this procedure, the animals received complete medical examinations, and samples were collected for health analyses. Biochemical test results varied with the degree of condition of the animals, and a variety of physical abnormalities were found. Evidence of previous infections with Leptospira sp., encephalitis virus, and yellow fever virus was found. All findings contribute to establishing baseline health values for the species. The handling of primates for research projects provides a valuable opportunity to collect health-related data and samples that can contribute to wildlife management and conservation efforts. The capture and handling of free-ranging primates is always accompanied by risk of injury or mortality. It is ethically important to maximize the amount of information gathered during these procedures. Furthermore, sharing the undesirable impacts with the scientific community enables informed decisions to be made during future project development.

Biopsy mineral analysis by inductively coupled plasma-atomic emission spectroscopy with ultrasonic nebulization.

Liver copper concentration is generally considered the best measure of copper nutritional status in cattle. Ultrasonic nebulization in conjunction with inductively coupled plasma-atomic emission spectroscopy (ICP-AES) was investigated as a method to provide adequate sensitivity to allow accurate simultaneous measurement of copper and 14 additional elements from needle biopsy samples. The element concentration frequency distribution profile of 12 elements routinely present in liver was compared to profiles of the elements in fat, muscle, vena cava, kidney, and clotted blood. The profiles could be used to confirm the authenticity of the liver biopsy sample. Element concentrations in biopsy samples taken in triplicate from the five lobes of a bovine liver were compared to those from triplicate wedge sections taken adjacent to the biopsies and analyzed by conventional ICP-AES. Precision between biopsies was equal to or better than precision between wedge samples. Some element concentrations determined by the biopsy procedure differed statistically from those determined by the wedge procedure, but differences were not sufficient to influence clinical interpretation of data.

Measurement of serum iohexol by determination of iodine with inductively coupled plasma-atomic emission spectroscopy.

We used inductively coupled plasma-atomic emission spectroscopy to measure serum iodine to determine plasma clearance of iohexol, an iodinated radiographic contrast agent. We determined I at 178.276 nm on the phosphorus 178.287 nm channel of the polychromator by utilization of spectrum shifter offset software, while correcting for P with the sequential P 214.914 nm emission line. Determination of I on the polychromator provided excellent precision in the measurement of serum I, even though the interelement correction of P was done with a sequential P line. Total imprecision (CV) (n = 13) was 16% (at 13.7 mg/L I), 8.6% (28.7 mg/L), 3.6% (59.0 mg/L), 2.6% (120.5 mg/L), 1.7% (237.8 mg/L), 1.2% (478.7 mg/L), and 1.8% (597 mg/L). The linear range was 15 to 600 mg/L. Iohexol added to serum (mg/L I) and recoveries (%) were 15 (91.3%), 30 (95.7%), 60 (98.3%), 120 (100.4%), 240 (99.1%), 480 (99.7%), and 600 (99.5%). Studies on dogs and cats administered a single intravenous injection of iohexol indicated that a dose of 300 mg I/kg body weight was sufficient for measurement of glomerular filtration rate by using a single compartment model for plasma clearance with three samples drawn 3 to 7 h after treatment. With this protocol, correlation coefficients were > 0.99 on the beta phase of the plasma disappearance curve.