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Biomedical subjects

E W Howerth

Publications and source records attributed to E W Howerth.

At least 55 records · Page 3Linked to original sources
PubMed1992

Chlamydiosis in a red-tailed hawk (Buteo jamaicensis).

A red-tailed hawk (Buteo jamaicensis) with signs of respiratory distress and diarrhea was captured in the Manchac Wildlife Management Area, Louisiana (USA) and died the following day. At necropsy, the carcass was emaciated and there were splenomegaly, and fibrinous pericarditis, airsacculitis, and perihepatitis. Microscopically, there were fibrinous pericarditis and airsacculitis, myocardial necrosis, necrotizing hepatitis, splenic necrosis with reticuloendothelial cell hyperplasia, interstitial pneumonia and focal pancreatic necrosis. Intracytoplasmic chlamydial inclusion bodies were noticed in macrophages in the fibrinous exudate covering air sac and pericardium, and in spleen, liver, heart, lung, and pancreas. Schizonts compatible with a Sarcocystis sp.-like protozoon were present in the walls of air capillaries in the lung. A Chlamydia sp.-like organism was isolated in embryonating chicken eggs and cell culture and identified as C. psittaci with immunofluorescent staining.

Animals↗
PubMed1990

Epidemiologic features of an intracranial abscessation/suppurative meningoencephalitis complex in white-tailed deer.

Case records of 683 white-tailed deer (Odocoileus virginianus) submitted to the Southeastern Cooperative Wildlife Disease Study (Georgia, USA) for diagnostic purposes from 1971 to 1989 were reviewed for the occurrence of pyogenic infections of the central nervous system, specifically intracranial abscessation or suppurative meningoencephalitis. These conditions, either alone or in combination, were diagnosed in 24 of 683 (4%) deer. Thirteen genera of bacteria were isolated; the most frequent species was Actinomyces pyogenes. The disease was strongly sex biased (P less than 0.01); 88% of the cases occurred in males. Cases were more prevalent (P less than 0.05) in older bucks; the median age of infected bucks was 3.2 yr, and 71% of these were greater than or equal to 2.5-yr-old. Intracranial abscessation/suppurative meningoencephalitis cases accounted for 20% of the diagnoses among 56 bucks greater than or equal to 3-yr-old. Cases were seasonal, occurring only from October to April. Characteristic necrosis, erosion, and pitting of skull bones were common, and this bone damage may be useful in determining cause of death when only skeletal remains are found. Males, especially older bucks, apparently are predisposed to intracranial abscessation/suppurative meningoencephalitis because of the cycle of antler development and behavioral traits associated with reproduction. The strong bias toward prime age bucks suggests that these infections could specifically hinder management strategies designed to produce populations with older buck age structures.

Actinomycosis↗
PubMed1989

Leukoencephalomalacia in a white-tailed deer from North Carolina.

Leukoencephalomalacia similar to equine leukoencephalomalacia occurred in a white-tailed deer (Odocoileus virginianus) from North Carolina. The deer was recumbent and stuporous when presented for examination. It was believed that the disease resulted from ingestion of moldy field corn, infected with Fusarium moniliforme.

Animals↗
PubMed1988

Experimentally induced bluetongue virus infection in white-tailed deer: coagulation, clinical pathologic, and gross pathologic changes.

Ten yearling white-tailed deer (Odocoileus virginianus) were inoculated with bluetongue virus serotype 17. Two yearling white-tailed deer were inoculated with sonicated heparinized noninfected blood and served as controls. Clinical signs of bluetongue virus infection included increased rectal temperature, erythema, facial edema, coronitis, and stomatitis. By postinoculation day (PID) 8, excessive bleeding and hematoma formation at venipuncture sites, dehydration, and diarrhea developed. At necropsy, the most consistent findings were oral lesions and widespread hemorrhage, which ranged from petechia to massive hematoma formation. Bluetongue virus caused progressive prolongation of activated partial thromboplastin time and prothrombin time, and progressive reduction of Factors VIII and XII plasma activities beginning on PID 6. A progressive decrease in platelet numbers also developed on PID 6. Changes in platelet size were not detected. Mean thrombin time was shortened, but prolongation developed in 1 deer. Mean fibrinogen concentration and Factor V plasma activity initially increased and then decreased, but remained above preinoculation values. Factor V activity was low in a few deer. Results of screening tests for inhibitors of the intrinsic coagulation system were positive in 2 deer. High concentrations of fibrin(ogen) degradation products were first detected between PID 3 and 6. Hematologic changes included leukopenia, lymphopenia, neutrophilia, and low total plasma protein concentration. Differences in PCV, hemoglobin concentration, or RBC counts were not detected between infected and control deer. Serum total bilirubin concentration increased by PID 6, primarily because of increased unconjugated bilirubin concentration. Mild to severe increases in serum aspartate transaminase activity were accompanied by more marked increases in creatine kinase activity. Indirect Coombs test results were negative in all deer.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Experimentally induced bluetongue virus infection in white-tailed deer: ultrastructural findings.

White-tailed deer (Odocoileus virginianus) were inoculated with bluetongue virus serotype 17 and sequentially euthanatized during infection. Ultrastructural changes in the microvasculature of tongue, buccal mucosa, heart, and pulmonary artery, platelets, and bone marrow were evaluated. Bluetongue virus was found in endothelial cells of the microvasculature by postinoculation day 4. Viral replication was associated with the development of viral matrices, viral-associated macrotubules, and aggregates of mature viral particles in the cytoplasm of infected cells. Viral infection of pericytes and vascular smooth muscle cells developed subsequent to endothelial cell infection. Viral infection was associated with striking changes in the endothelial lining of the microvasculature by postinoculation day 4. Endothelial cell degeneration and necrosis, which resulted in denudation of the endothelial lining, and endothelial cell hypertrophy frequently were observed. Thrombosis, hemorrhage, and vessel rupture developed subsequent to endothelial damage. Bluetongue virus neither infected nor directly damaged platelets or bone marrow cells. It was concluded that viral-induced endothelial damage is the primary triggering mechanism for disseminated intravascular coagulation in bluetongue virus infection. Vascular damage coupled with the development of disseminated intravascular coagulation is responsible for the hemorrhagic diathesis, which is characteristic of bluetongue virus infection in white-tailed deer.

Animals↗
PubMed1985

Diseases diagnosed in wild turkeys (Meleagris gallopavo) of the southeastern United States.

Diagnostic findings are presented on 139 sick or dead wild turkeys examined during the period 1972 through 1984. Turkeys originated from eight southeastern states (Alabama, Arkansas, Florida, Georgia, South Carolina, Tennessee, Virginia, West Virginia) and included 31 turkeys categorized as capture-related mortalities and 108 turkeys categorized as natural mortalities. Frequent diagnoses (greater than or equal to 10% of case accessions) in the natural mortality group were trauma, avian pox, and histomoniasis. Less frequent diagnoses (less than or equal to 4% of case accessions) included malnutrition/environmental stress syndrome, coligranuloma-like condition, crop impaction, bumblefoot, organophosphate toxicosis, infectious sinusitis, a lympho-proliferative disease, salmonellosis, aspergillosis, toxoplasmosis, crop trichomoniasis, and melorheostosis.

Animals↗
PubMed1984

Pathology of naturally occurring chlamydiosis in African clawed frogs (Xenopus laevis).

Chlamydiosis was diagnosed in six African clawed frogs (Xenopus laevis) from a tank of laboratory-bred frogs experiencing sudden deaths. Gross findings were hepatomegaly, distention of the gall bladder, and splenomegaly. Hepatic lesions were present in each frog and were characterized by mononuclear cell infiltrates, necrosis of hepatocytes, Kupffer's cell proliferation, and sinusoidal fibrin thrombi. Cholestasis, hemosiderin-laden Kupffer's cells, parenchymal infarction, and multinucleated hepatocytes were less common findings. Other lesions included degenerative and inflammatory changes in the kidneys, epicarditis and myocarditis, and reticuloendothelial cell proliferation, lymphoid depletion, and necrosis in the spleens. Intracytoplasmic inclusions typical of chlamydiae were seen by light microscopy in hepatocytes and reticuloendothelial cells of the spleen. Electron microscopy demonstrated that these inclusions were composed of three distinct types of particles consistent with the life stages described for chlamydiae.

Animals↗
PubMed1984

Measurements of mass, length and valve diameters from normal formalin-fixed ovine hearts.

Hearts from 60 Merino sheep of known age, sex and live mass and with no known history of disease were collected and fixed in buffered 10% formalin. Systematic light microscopical examination did not indicate any abnormality in hearts of any of the sheep. The mass of various parts of the hearts, the length of the hearts and the diameters of the heart valves were measured to establish a basis for quantitative assessment of possible pathological changes associated with the ingestion of cardiotoxic plants. The mass measurements and, to a lesser degree, the lengths of the hearts varied considerably, but the ratio of the mass of the left ventricle plus ventricular septum divided by the right ventricular free wall mass was remarkably stable, and is promising as an indicator of right ventricular hypertrophy.

Age Factors↗
PubMed1983

Fatal soft tissue calcification in suckling puppies.

Renal, pulmonary and vascular calcification was observed in 2 suckling puppies. The lesions were similar to those associated with hypervitaminosis D and possibly hypervitaminosis A. It was suspected that high contents of vitamin D and A in the diet of the lactating bitch had elevated the activity of these vitamins in the milk to levels toxic for the suckling puppies.

Animal Population Groups↗
PubMed1983

Fatal cardiomyopathy in feedlot sheep attributed to monensin toxicosis.

Three outbreaks of fatal cardiomyopathy in feedlot sheep are reported which were associated with the introduction of pelleted feed that contained greater than recommended concentrations of monensin. Gross and histopathological examination of some of these sheep revealed evidence of cardiomyopathy. Myocardial lesions which had a predominantly epicardial distribution are described. Lesions were also observed in skeletal muscle and in brain.

Animals↗