Geology topics
Publications and source records attributed to Thomas J. Roffe.
Chronic Wasting Disease (CWD) has appeared widely in the media lately, but has actually been around for a while. It was first recognized in Colorado in 1967, in a captive research herd of mule deer. Its rapid expansion, to include eight states and two provinces by the year 2002, has created a crisis.
Tolazoline is a mixed alpha-1 and -2 adrenergic antagonist used to reverse the sedative, analgesic and muscle-relaxing effects of xylazine, a potent alpha adrenergic agonist. Tolazoline has been used in cattle and is superior to yohimbine, another alpha adrenergic antagonist, in this species. In white-tailed deer, tolazoline shortened recovery times and reversed xylazine-induced bradycardia, respiratory depression, and bloat following xylazine-ketamine anesthesia (Kreeger et al. 1986). We have used it for a number of years in moose without any detected adverse reactions. Caulkett et al. (2000) used tolazoline in wood bison to reverse the xylazine-induced effects of xylazine-tiletamine/zolazepam anesthesia and did not report any ill effects. However, the reported side effects of tolazoline in horses (species for which the drug was developed and is labeled) include abdominal discomfort, gastrointestinal hypermotility, diarrhea, tachycardia, ventricular dysrhythmia, hypertension and apprehensiveness.
Brucellosis in Greater Yellowstone Area (GYA) bison and elk has been a source of controversy and focus of the Greater Yellowstone Interagency Brucellosis Committee (GYIBC) for years. Brucellosis has been eradicated from cattle in the 3 states of Wyoming, Montana, and Idaho and all three states currently are classified as “brucellosis free” with regard to livestock. Yet free-ranging elk that attend feedgrounds in the GYA, and bison in Yellowstone and Grand Teton National Parks, still have high seroprevalence to the disease and are viewed as a threat to the state-federal cooperative national brucellosis eradication program. Recently, cattle in eastern Idaho were found infected with brucellosis and transmission was apparently from fed elk. The GYIBC, formed of state and federal agencies involved in wildlife and livestock management in the 3 states, has committed to eventual elimination of the disease from wildlife. Management tools to control or eliminate the disease are limited; however, wildlife vaccination is one of the methods currently employed. Effective wildlife vaccination depends on dose efficacy, deliverability, and safety to non-targeted species. We commenced a single-dose efficacy study of vaccine Brucella abortus strain 19 (S19) in elk in 1999.
The use of carfentanil with other drugs to immobilize moose (Alces alces) has yielded mixed results. Previous work on chemically immobilizing moose with these drugs reported mortality of 6–19%. Even the most recent study of free-ranging moose using the same drug combination as we used in this report (carfentanil and xylazine) had 6% mortality within several days of immobilization. Another recent study suggested that carfentanilxylazine produced unsatisfactory results in moose through exacerbated mortality risks induced by xylazine. As part of an ongoing study of carnivore effects on moose populations, we chemically immobilized 48 moose (41 adult females, one immature male, 6 calves) by charge-powered dart. Low-stress techniques were used, including quiet ground stalks by one individual and use of blindfolds and low noise during processing. On our few aerial captures we immediately withdrew the helicopter once the dart was placed and landed during induction. We found that capture-related mortality can be minimized by using effective immobilization dosages that maintain sternal recumbency, by providing naltrexone by intramuscular and subcutaneous routes, by effectively antagonizing xylazine, and by using low-stress techniques. Female moose survival was diminished when body condition was below a threshold, and some mortality occurred, likely due to poor condition per se and not as a direct result of immobilization. We provide a field protocol and drug doses that wildlife managers can use to safely immobilize moose.
We review nesting sea duck population declines in Alaska during recent decades and explore the possibility that contaminants may be implicated. Aerial surveys of the surf scoter (Melanitta perspicillata), white-winged scoter (M. fusca), black scoter (M. nigra), oldsqaw (Clangula hyemalis), spectacled eider (Somateria fischeri), and Steller's eider (Polysticta stellei) show long-term breeding population declines, especially the latter three species. The spectacled eider was recently classified threatened under the Endangered Species Act. In addition, three other diving ducks, which commonly winter in coastal areas, have declined from unknown causes. Large die-offs of all three species of scoters during molt, a period of high energy demand, were documented in August 1990, 1991, and 1992 at coastal reefs in southeastern Alaska. There was no evidence of infectious diseases in those scoters. The die-offs may or may not be associated with the long-term declines. Many scoters had elevated renal concentrations of cadmium (high of 375 micrograms/g dry weight [dw]). Effects of cadmium in sea ducks are not well understood. Selenium concentrations in livers of nesting white-winged scoters were high; however, the eggs they laid contained less selenium than expected based on relationships for freshwater bird species. Histological evaluation found a high prevalence of hepatocellular vacuolation (49%), a degenerative change frequently associated with sublethal toxic insult. Cadmium and selenium mean liver concentrations were generally higher in those birds with more severe vacuolation; however, relationships were not statistically significant. We do not know if sea duck population declines are related to metals or other contaminants.
Approximately 200 Canada geese ( Branta canadensis ) died at a playa lake in the Texas Panhandle shortly after a winter wheat field in the basin adjacent to the lake was treated with parathion to control newly invading Russian wheat aphids ( Diuraphis noxia ). No evidence of infectious disease was diagnosed during necropsies of geese. Brain ChE activities were depressed up to 77% below normal. Parathion residues in GI tract contents of geese ranged from 4 to 34 ppm. Based on this evidence, parathion was responsible for the goose mortalities. Parathion applications to winter wheat will undoubtedly increase if parathion is applied for control of both Russian wheat aphids and greenbugs ( Schizaphis graminum ). Geese may potentially be exposed to widespread applications of parathion from fall to spring, essentially their entire wintering period.
An unusual gross appearance of avian tuberculosis, where fluid-filled thin-walled cysts are produced and grossly apparent in preference to granulomas, is presented. Histopathology confirmed the granulomatous nature of the lesions and the presence of intracellular acid-fast organisms. Mycobacterium avium complex was cultured from affected organs. The unusual gross presentation in these cases indicates the need to consider tuberculosis in the differential of cystic diseases of avian livers.
In 1985 and 1986, large-scale natural die-offs of sandhill cranes in Texas were attributed to fusariomycotoxicosis. These birds demonstrated a progressive loss of motor control to the neck, wings, and legs. Based on necropsy and/or histopathology of 31 cranes, the most common lesions involved skeletal muscle and included hemorrhages, granulomatous myositis, thrombosis, and vascular degeneration. Serum chemistry results revealed that levels of creatinine kinase, aspartate aminotransferase, and alanine aminotransferase were above published normals. However, only alanine aminotransferase was higher in clinically affected cranes than in normal cranes collected from the same area.
An estimated 9,500 sandhill cranes (Grus canadensis) died in Gaines County, Texas and Roosevelt County, New Mexico between 1982 and 1987. The predominant clinical sign observed in sick cranes was their inability to hold their heads erect, both while standing and flying. Multiple muscle hemorrhages and submandibular edema were the most common lesions seen at necropsy. Mycotoxins produced by Fusarium sp. growing during cold, wet weather on peanuts left in the field after harvest, the predominant foods of the dead cranes at the time of these mortality events, were identified as the most likely cause of this mortality. Rendering moldy peanuts inaccessible to the cranes by conventional tillage resulted in reduced crane mortality in these areas.
In May 1985, epizootic mortality was reported in common egrets ( Casmerodius albus ) on Avery Island, Louisiana. Subsequent investigation revealed that more than 400 birds died. Severe peritoneal nematodiasis ( Eustrongylides sp.) was found on postmortem examination. A nearby breeding rookery on the same island was apparently unaffected. Reasons for this selective mortality are presented. Three other reports of epizootic mortality due to Eustrongylides sp. have been reported. This is the first report of this type of epizootic in gulf-coast birds.