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At least 235 records · Page 13Linked to original sources

Acute gastric dilatation and volvulus in a free-living polar bear

A large, adult male polar bear ( Ursus maritimus ) was found dead on a barrier island north of Prudhoe Bay, Alaska (USA), in June 1987. There were no external signs of trauma. A twisted distended stomach, distinctive parenchymal and fascial congestion, and significant difficulty in repositioning the anterior abdominal organs, indicated that gastric dilatation-volvulus (GDV) was the proximate cause of death. Polar bears frequently consume large quantities of food at one time and have large stomachs that are well adapted to periodic gorging. The scarcity of food in winter and early spring, combined with voluntary fasting and protracted vigorous activity during the breeding season in late spring may have predisposed this bear to GDV. The relationship between GDV and postprandial exercise emphasizes the need for a better understanding of how the present human invasion of arctic habitats may influence polar bear activities.

Alaska

Brain cholinesterase inhibition in songbirds from pecan groves sprayed with phosaline and disulfoton

Brain cholinesterase (ChE) activities of songbirds collected in pecan groves 6 to 7 hr after separate applications of the organophosphorus pesticides, phosalone and disulfoton, were compared to mean ChE activities of controls (normals) as a measure of insecticide exposure. In general, reduction of brain ChE activity ≥2 standard deviations below the control mean indicates exposure to an anticholinesterase compound. Phosalone had little effect on brain ChE activity of birds from treated groves; only slight to moderate (21 to 38%) ChE inhibition was detected in blue jays ( Cyanocitta cristata ) and red-bellied woodpeckers ( Melanerpes carolinus ). However, 11 of 15 blue jays from disulfoton-treated groves had moderate to severe ChE depression, ranging from 32 to 72%. Inhibition ≥50% of normal may be diagnostic for cause of death. Direct mortality was not observed, but studies have shown that bird carcasses disappear rapidly from agricultural areas, many within 24 hr. We recommend additional field studies of the effects of disulfoton to wildlife, since large wheat-growing areas in the western United States are being considered for disulfoton treatment to control the Russian wheat aphid ( Diuraphis noxia ).

Journal of Wildlife Diseases

Serological investigation of the fish pathogen Edwardsiella ictaluri, cause of enteric septicemia of catfish

The serological relationships among 32 isolates of Edwardsiella ictaluri obtained from fish were studied. The strains were extremely homogeneous in protein and lipopolysaccharide preparations as observed by sodium-dodecyl-sulfate polyacrylamide gel electrophoresis. Only minor variations were observed in the structural O-side chain subunits in three isolates; however, such variation did not preclude antigenic recognition by two E. ictaluri antisera in either microagglutination or Western blot immunoassays. The antigenic homogeneity of E. ictaluri was further demonstrated by microagglutination assays with both formalin-killed and heat inactivated cellular antigens. The minimal degree of antigenic variability observed suggested that most isolates of E. ictaluri compose a single antigenic serotype.

Journal of Wildlife Diseases

Immune response of mallard ducks treated with immunosuppressive agents: Antibody response to erythrocytes and in vivo response to phytohemagglutinin-P

The ability of two in vivo tests to assay immune competence of mallard ducks ( Anas platyrhynchos ) treated with various immunomodulatory agents was examined. Skin responses to phytohemagglutinin-P (PHA-P) injected intradermally and serum antibody levels produced in response to sheep red blood cells (SRBC) were measured. As measured by the skin response to PHA-P, ducks injected intramuscularly with cyclophosphamide or cyclosporine did not respond differently from control-injected ducks. Dexamethasone injected intramuscularly significantly suppressed the skin response to PHA-P. As measured by antibody levels in response to SRBC, ducks injected intramuscularly with cyclophosphamide responded with antibody titers similar to controls. Cyclosporine injected intramuscularly reduced the level of immunoglobulin (Ig) G significantly in one of two experiments. Dexamethasone injected intramuscularly reduced peak total and IgG titers. These experiments provide information on the viability of these two in vivo tests to reflect immune competence of mallard ducks.

Journal of Wildlife Diseases

Isolation and phenotypic characterization of an oxidase-negative Aeromonas salmonicida causing furunculosis in coho salmon (Oncorhynchus kisutch)

An oxidase-negative Aeromonas salmonicida was isolated from coho salmon ( Oncorhynchus kisutch ) suffering from an epizootic of furunculosis at the state hatchery near Belfair, Washington. Typical, oxidase-positive A. salmonicida was isolated concurrently from the same population of fish. Mortality was controlled with medicated feed treatments. Evidence supporting the identification of the two types of A. salmonicida is presented. Methods for the proper identification of oxidase-negative A. salmonicida isolates are evaluated.

Journal of Wildlife Diseases

Seroepidemiology of leptospirosis in Minnesota wolves

Serum samples (n = 457) from wolves (Canis lupus) in northern Minnesota were collected from 1972 through 1986 and were tested for antibodies against Leptospira interrogans using a microtiter agglutination test. Twelve serovars included in the study were: australis, autumnalis, ballum, bataviae, bratislava, canicola, copenhageni, grippotyphosa, hardjo, pomona, pyrogenes, and tarassovi. Fifty-two (11%) sera had antibody titers of greater than or equal to 1:50 against one or more serovars of L. interrogans. The seroprevalence of different serovars in decreasing order was: grippotyphosa, bratislava, autumnalis, canicola, pomona, ballum, pyrogenes, hardjo, and copenhageni. No antibodies were found against australis, bataviae, and tarassovi. These results indicate that L. interrogans infection may occur in wolves of Minnesota.

Journal of Wildlife Diseases

Gray wolf density and its association with weights and hematology of pups from 1970 to 1988

We examined weights and hematologic profiles of gray wolf ( Canis lupus ) pups and the associated wolf density in the east-central Superior National Forest of northeastern Minnesota (USA) during 1970 to 1988. We collected weight and hematologic data from 117 pups (57 females, 60 males) during 1 September to 22 November each year. The wolf density (wolves/800 km 2 ) trend was divided into three phases: high (72 ± 7), 1970 to 1975; medium (44 ± 2), 1976 to 1983; and low (27 ± 2), 1984 to 1988. Wolf numbers declined ( P = 0.0001) 39 and 63% from 1970 to 1975 to 1976 to 1983 and from 1970 to 1975 to 1984 to 1988, respectively. Weight was similar between male and female pups and did not vary as wolf density changed. Mean hemoglobin ( P = 0.04), red ( P = 0.0001) and white blood cells ( P = 0.002), mean corpuscular volume, mean corpuscular hemoglobin concentration and mean corpuscular hemoglobin ( P = 0.0001) did differ among the multi-annual phases of changing wolf density. Weight and hematologic data also were compared to values from captive wolf pups. The high, but declining wolf density was associated with macrocytic, normochromic anemia in wolf pups, whereas the lowest density coincided with a hypochromic anemia. Although hematologic values show promise for assessing wolf pup condition and wolf population status, they must be used cautiously until data are available from other populations.

Minnesota

Weights and hematology of wild black bears during hibernation

We compared weights and hematological profiles of adult (>3-yr-old) female black bears ( Ursus americanus ) during hibernation (after 8 January). We handled 28 bears one to four times (total of 47) over 4 yr of varying mast and berry production. Mean weight of lactating bears was greater ( P < 0.0001) than that of non-lactating females. White blood cells ( P < 0.05) and mean corpuscular volume ( P = 0.005) also differed between lactating and non-lactating bears. Hemoglobin ( P = 0.006) and mean corpuscular hemoglobin concentration ( P = 0.02) varied among years; values were lowest during 1975, following decreased precipitation and the occurrence of a second year of mast and berry crop shortages in a three-year period. Significant ( P < 0.05) interaction between reproductive status (lactating versus non-lactating) and study year for hemoglobin, red blood cells, and packed cell volume, and increased mean corpuscular volume, suggested a greater nutritional challenge for lactating females compared to non-lactating females during the 1975 denning season. Our data suggest that hematological characteristics of denning bears may be more sensitive than weights as indicators of annual changes in nutritional status; however, other influential factors, in addition to mast and berry crop production, remain to be examined.

Journal of Wildlife Diseases

Nasitrema sp.-associated encephalitis in a striped dolphin ( Stenella coeruleoalba ) stranded in the Gulf of Mexico

An immature female striped dolphin ( Stenella coeruleoalba ) found dead on a northwestern Florida beach in 1988 exhibited severe inflammation bilaterally in the dorsal and mid-thalamus in association with adult trematodes ( Nasitrema sp.) and trematode eggs. Numerous specimens of Nasitrema sp. also were present in the pterygoid sinuses. Pneumonia in association with a heavy growth of Vibrio damsela was observed also. This report confirms the occurrence of Nasitrema sp.-associated encephalitis in striped dolphins and in small cetaceans from the Gulf of Mexico.

Journal of Wildlife Diseases

Energy metabolism and hematology of white-tailed deer fawns

Resting metabolic rates, weight gains and hematologic profiles of six newborn, captive white-tailed deer ( Odocoileus virginianus ) fawns (four females, two males) were determined during the first 3 mo of life. Estimated mean daily weight gain of fawns was 0.2 kg. The regression equation for metabolic rate was: Metabolic rate (kcal/kg 0.75 /day) = 56.1 + 1.3 (age in days), r = 0.65, P < 0.001). Regression equations were also used to relate age to red blood cell count (RBC), hemoglobin concentration (Hb), packed cell volume, white blood cell count, mean corpuscular volume, mean corpuscular hemoglobin concentration (MCHC), and mean corpuscular hemoglobin. The age relationships of Hb, MCHC, and smaller RBC's were indicative of an increasing and more efficient oxygen-carrying and exchange capacity to fulfill the increasing metabolic demands for oxygen associated with increasing body size.

Journal of Wildlife Diseases

Prevalence of antibody titers to leptospira spp. in Minnesota white-tailed deer

Serum samples (n = 204) from 124 white-tailed deer (Odocoileus virginianus) in northeastern Minnesota (USA) were collected from 1984 through 1989 and tested for antibodies to six serovars of Leptospira interrogans (bratislava, canicola, grippotyphosa, hardjo, icterohemorrhagiae, and pomona) using a microtiter agglutination test. Eighty-eight (43%) sera were positive at greater than or equal to 1:100 for antibodies against serovars pomona and/or bratislava; none was positive for any of the other four serovars. None of the 31 sera collected in 1984-85 was positive, whereas all 54 sera collected from 1986 through 1988 had titers of greater than or equal to 1:100. During 1989, only 34 (29%) of 119 sera had titers of greater than or equal to 1:100. Based on these results, we believe there to be wide variability in exposure of Minnesota deer to Leptospira interrogans.

Journal of Wildlife Diseases

Lead exposure and recovery rates of black ducks banded in Tennessee

American black ducks ( Anas rubripes ) wintering in Tennessee during 1986 to 1988 were tested for exposure to lead. Twelve percent of the birds had blood lead concentrations exceeding 0.2 ppm. Significant differences in the prevalence of lead exposure were found for adults (14.4%) and juveniles (8.2%). Exposed birds had higher blood lead concentrations at one study site, corresponding with a lower survival index.

Tennessee

Perinatal mortality in caribou from the Porcupine herd, Alaska

During the 1989 caribou ( Rangifer tarandus ) calving season on the Arctic National Wildlife Refuge, Alaska (USA), 61 calf carcasses were examined for cause of death and associated pathology. Dead calves were located by low-level aerial searches with two fixed-wing aircraft and a helicopter over high density calving areas between the Hulahula and Aichilik rivers. Primary diagnoses included emaciation (39%), malnutrition (8%), stillbirth (21%), trauma (16%), other primary causes (7%), and undetermined causes (8%). Twenty calves had contributory renal tubular degeneration. The findings indicate that factors contributing to nutritional deprivation in calves were the major cause of neonatal mortality; however, factors affecting stillbirth, abortion, or the urogenital system may have major effects on neonatal caribou and warrant further investigation.

Alaska

Nutritional restriction and acid-base balance in white-tailed deer

We examined the effect of progressive nutritional restriction on acid-base balance in seven captive, adult white-tailed deer ( Odocoileus virginianus ) from 4 February to 5 May 1988 in north central Minnesota (USA). Metabolic acidosis was indicated by low mean blood pH (7.25 to 7.33) in deer throughout the study. Mean urinary pH values declined ( P = 0.020) from a mean (±SE) baseline of 8.3 ± 0.1 to 6.7 ± 0.3 as restriction progressed. Acidemia and aciduria were associated with significant variations in mean blood CO 2 ( P = 0.006) and pO 2 ( P = 0.032), serum potassium ( P = 0.004) concentrations, and with a significant ( P = 0.104) handling date × group interaction in urinary potassium : creatinine values. Mean bicarbonate : carbonic acid ratios were consistently below 20:1 during nutritional restriction. Mean packed cell volume increased ( P = 0.019) and serum total protein decreased ( P = 0.001); thus there was evidence for progressive dehydration and net protein catabolism, respectively. Blood pCO 2 , serum sodium, and urinary sodium : creatinine were stable throughout the study. We propose that acidosis and aciduria are metabolic complications associated with nutritional restriction of white-tailed deer.

Journal of Wildlife Diseases

Isolation of Aeromonas salmonicida from paddlefish, Polyodon spathula

Aeromonas salmonicida was isolated from paddlefish ( Polyodon spathula ) mortalities collected during an epizootic of furunculosis at the Spring River State Hatchery, Arkansas (USA), in 1992. Isolates of the bacterium were obtained from culture of gill and kidney tissue. This is the first epizootic of bacterial etiology to be reported in paddlefish.

Arkansas

Use of sentinel mallards for epizootiologic studies of avian botulism

Captive-reared mallards (Anas platyrhynchos) were used as sentinels to study the epizootiology of avian botulism at the Sacramento National Wildlife Refuge, Willows, California (USA) from 1986 to 1989. Sentinel mallards were wing-clipped, and 40 to 50 birds were confined in 1.6-ha enclosures in 11 selected wetlands (pools). Enclosures were searched intensively three to four times weekly from July through October. Sick and dead wild and sentinel birds were collected, necropsied, and tested for type C botulism toxin. Botulism epizootics occurred in sentinel mallards in 1986, 1987, and 1989, but only a few isolated cases of botulism were detected in 1988. In most epizootics, botulism also was detected simultaneously in wild birds using the same pool outside the enclosure. Epizootics in sentinels were initiated and perpetuated in the absence of vertebrate carcasses. A sex-specific trend in the probability of intoxication was detected, with males contracting botulism at a higher rate than females. Daily mortality rates of sentinels during botulism epizootics ranged from 0.0006 to 0.0600, with a mean of 0.0190. These rates would result in the daily loss of 0.6 to 60 birds per thousand at risk. The use of sentinel birds provided an effective means of gathering site-specific epizootiologic data.

California

Relationship between resistance of salmonids to furunculosis and recovery of Aeromonas salmonicida from external mucus

Fish were sampled at the Ed Weed State Fish Hatchery (South Hero, Vermont, USA) in September 1992. Aeromonas salmonicida was common, with concentrations as high as 10 5 to 10 7 colony-forming units per gram of mucus, and readily recovered from most mucus samples obtained from furunculosis-sensitive populations of brook trout ( Salvelinus fontinalis ), lake trout ( Salvelinus namaycush ), and Atlantic salmon (Salmo salar) . The pathogen was the predominant microorganism and accounted for greater than 85% of the total number of bacteria isolated from the mucus of these fish. By comparison, A. salmonicida was recovered only from two rainbow trout ( Oncorhynchus mykiss ), and bacterial frequencies did not exceed 10 3 colony-forming units per gram of mucus. The pathogen was not recovered from the mucus of steelhead ( O. mykiss ) or Rome brown trout ( Salmo trutta ) selectively bred for resistance to furunculosis, even though there was widespread contagion throughout the hatchery and fish were cultured on a common, unprotected water supply.

Journal of Wildlife Diseases