Aspergillosis and other causes of mortality in the stitchbird in New Zealand.

Necropsy findings from natural deaths in free living and captive stitchbirds (Notiomystis cincta) were examined over a 3 yr period (November 1991-94) to establish whether disease was an important factor in translocation failures and captive breeding programs undertaken by the New Zealand Department of Conservation. Fresh and fixed material from seven free-living birds and 11 captive birds were examined and were compared with those of a retrospective study of archival material from captive and wild birds collected over a 13 yr period (1979-91). The causes of death in both the present and retrospective study showed a similar pattern with aspergillosis and aspiration pneumonia being the most significant cause of mortality in captive birds. Aspergillosis was diagnosed as the cause of death in 11 of 31 stitchbirds from Mt Bruce; eight of these deaths occurred in the winter months (June-August). The other causes of death in captive birds included trauma, coccidiosis, and sporadic bacterial infections. Hemosiderosis and airsacculitis were common histological findings in most of the wild and captive stitchbirds examined.

A quantitative assessment of haemosiderosis in wild and captive birds using image analysis.

An experimental model of haemosiderosis, using the chicken, was developed to examine the distribution of iron in the liver following an injection of iron dextran and to allow calibration of image analysis readings. Image analysis was used as a tool to quantify the stainable iron present in hepatic tissue obtained from wild and captive birds presented for necropsy. A retrospective study of 180 necropsy cases, representing 40 different species of bird, is described. Statistical evaluation of the amount and distribution of stainable iron in the liver tissue of birds from different taxonomic orders indicated that the concentration of iron measured in liver tissue was significantly different in different species of bird. The results of the study showed that hepatic haemosiderosis is a common histological finding in most avian species examined. Although not necessarily associated with overt liver disease, it is often associated with concurrent malignant and infectious diseases. The presence of excess stainable iron in the liver is probably a reflection of an altered iron metabolism associated with increased turnover of tissue iron. This alteration may occur following starvation or trauma.

Carcinoma with concurrent haemosiderosis in an Australian bittern (Botaurus poidloptilus).

A 15-year-old female bittern was presented for necropsy with a history of weight loss and ascites. There was a large neoplastic mass in the abdominal cavity closely attached to the gizzard with several smaller masses attached to the intestine and involving the liver. Much of the normal liver tissue had been obliterated. Histologically, there were many mitotic figures and in some sections the tumour had an acinar pattern. The overall morphology of the tumour was consistent with a carcinoma. The ovary was normal. There was concurrent hepatic haemosiderosis which was severe. As an incidental finding there were several small and two large cysts in the left and right kidneys.

Mycotic disease in the common New Zealand gecko (Hoplodactylus maculatus).

Two adult female geckoes (Hoplodactylus maculatus) from the National Wildlife Centre, Mt Bruce, Masterton, died within the period of a month and were presented to the Department of Veterinary Pathology and Public Health at Massey University for necropsy. The first gecko had numerous 1-2 mm diameter punctate ulcers of the skin over the ventral and dorsal regions of the body. The second animal had slight discolouration of some of the scales. Skin swabs were taken from each case for culture. There were no other gross lesions apparent at necropsy. Histologically, the only lesions in the first gecko were areas of epidermal and dermal ulceration involving fungi and bacteria. In the second gecko, there was limited inflammation in the skin, but in the lungs there was necrosis of the pulmonary septae and constituent muscle bundles caused by fungi whose septate mycelia extended into adjacent large blood vessels and caused mycotic thrombi; hyphae were also found in the spleen and liver. Paecilomyces sp. septate fungus was recovered from both geckoes and Pseudomonas spp. and a mixed Gram-negative flora were recovered from the cutaneous lesions on culture. The death of the first gecko was considered to be due to widespread ulcerative dermatitis, while that of the second gecko was thought to be due to mycotic pneumonitis and mycotic septicaemia. It is believed that environmental factors, such as cold temperature and high humidity, contributed to a reduction in the immune response in the affected geckoes, with the consequent development of overwhelming fungal infections.

Ultrastructural studies of the zygote and oocyst wall formation of Eimeria truncata of the lesser snow goose.

Zygote development and oocyst wall formation of Eimeria truncata occurred in epithelial cells in renal tubules and ducts of experimentally infected lesser snow geese (Anser c. caerulescens). Post-fertilization stages were present throughout the kidneys beginning nine days post-inoculation. Initially, a single plasmalemma enclosed the zygote, and type 1 wall-forming bodies (WF1) became labyrinthine and moved toward the surface. There, WF1 degranulated and formed the outer layer of the oocyst wall between the plasmalemma and a newly formed second subpellicular membrane. Several WF2 fused and formed the inner layer of the oocyst wall between the third and fourth subpellicular membranes. Six subpellicular membranes were observed during wall formation. Other features of oocyst development were similar to those of other eimerian species.

Ultrastructural studies of microgametogenesis and macrogametogenesis of Eimeria truncata of the lesser snow goose.

Microgamonts and macrogamonts of Eimeria truncata were observed in renal epithelial cells of collecting tubules and ducts and occasionally in macrophages of experimentally infected lesser snow geese (Anser c. caerulescens) beginning 8.5 days post inoculation. Intraparasitophorous vesicles in parasitophorous vacuoles of both types of gamonts appeared to originate in host cell cytoplasm and enter gamonts through micropores by budding of plasmalemma or by pinocytosis. Within the parasite's cytoplasm, the vesicles were broken down in Golgi-associated vacuoles. The surfaces of microgamonts were highly invaginated to facilitate extrusion of numerous microgametes. Formation and maturation of microgametes were similar to those of other eimerian species. Each microgamete had two flagella, a mitochondrion, and a peculiarly shaped electron-dense nucleus that was oval anteriorly in cross section and somewhat dumbbell-shaped posteriorly. A longitudinally arranged inner membrane complex lay between a portion of the mitochondrion and the plasmalemma. About five subpellicular microtubules extended the length of the microgamete body. Macrogametogony differed little from that described in other eimerian species. Type 1 wall-forming bodies (WFB) formed in Golgi complexes early in macrogametogony, and type 2 WFB formed in cisternae of endoplasmic reticulum in intermediate stages of macrogamont development.

Therapeutic and prophylactic effects of some antibiotics on experimental pneumonic pasteurellosis.

Pneumonic pasteurellosis was produced in cattle seronegative for bovine herpes virus-1 and Pasteurella haemolytica using their respective aerosols four days apart. When treated with four daily intravenous oxytetracycline injections one day prior, same day as and 24 hours after P. haemolytica aerosols cattle experienced a reduced mortality. Prophylactic sustained action antibiotics given 24 hours prior to the P. haemolytica aerosol also reduced mortality, however there appeared to be a variation associated with the products used.

Solid-phase enzyme immunoassay of bovine antibody responses following immunization against and natural infection with Pasteurella haemolytica.

A solid-phase enzyme immunoassay (EIA) was developed in order to monitor bovine antibody responses following immunization against and natural infection with Pasteurella haemolytica serotype A:1. Non-ionic surfactants, used in many antibody EIAs to reduce non-specific immunoglobulin binding, had to be avoided because they inhibited specific binding of bovine antibodies to P. haemolytica antigens. Calves were immunized with a KSCN extract of P. haemolytica. Subcutaneously immunized animals developed a significantly higher humoral antibody response than did intranasally vaccinated animals. Intranasally immunized calves developed a slightly, but not significantly higher nasal antibody response than did calves vaccinated subcutaneously. Field study results based on bacterial isolation and EIA detection of antibodies to P. haemolytica indicate that cattle can generate carrier states where bacteria are present in the upper respiratory tract, yet no humoral antibody response is induced. The converse was also found where cattle were free from P. haemolytica in the upper respiratory tract, yet possessed a good humoral antibody response to P. haemolytica.

Prevention of experimental bovine pneumonic pasteurellosis with an extract of Pasteurella haemolytica.

A total of 36 calves were used in three experiments to test the efficacy of a potassium thiocyanate extract of Pasteurella haemolytica in protecting against experimental pneumonia. In each of experiments A and B, 12 calves were divided into three equal groups. The first group was vaccinated with an aerosol of a potassium thiocyanate extract twice, two weeks apart; the second group was vaccinated subcutaneously once only with the same extract. The third group of calves in both experiments remained as unvaccinated controls. In experiment C, six calves were vaccinated intramuscularly and six were left as controls. Approximately one month after vaccination all calves were challenged with an aerosol of bovine herpesvirus 1 (isolate 108) followed in 4 d by an aerosol of P. haemolytica type A1 (the same strain from which the potassium thiocyanate extract had been made). Varying degrees of protection against subsequent development of experimental pneumonic pasteurellosis in cattle were seen in vaccinated calves as compared to control calves in these experiments. The results indicate that protection of cattle against pneumonic pasteurellosis may prove possible with a sub-cellular extract of P. haemolytica.

Susceptibility of bovid herpesvirus 1 to antiviral drugs: in vitro versus in vivo efficacy of (E)-5-(2-Bromovinyl)-2'-deoxyuridine.

The relative efficacies of a variety of antiviral drugs against bovid herpesvirus 1 was investigated. (E)-5-(2-Bromovinyl)-2'-deoxyuridine and trifluorothymidine were found to be inhibitory at doses of 0.01 micrograms/ml in in vitro yield reduction and plaque reduction assays. In contrast, acylovir was inactive even at concentrations as high as 1,000 micrograms/ml. Other drugs, including phosphonoformic acid, 9-beta-D-arabinofuranosyladenine, 5-iodo-2-deoxyuridine, and 1-beta-D-arabinofuranosylcytosine were active at concentrations previously shown to inhibit herpes simplex virus. Oral administration of (E)-5-(2-bromovinyl)-2'-deoxyuridine to calves infected with bovid herpesvirus 1 had no effect on the level of virus shedding, clinical signs, or susceptibility to secondary bacterial infection with Pasteurella haemolytica. The reason for this lack of in vivo activity was that sufficient levels of the drug in blood were not achieved by oral administration.

Resistance to Eimeria bovis produced after chemotherapy of experimental infections in calves.

Eighteen Holstein-Friesian four week old calves were inoculated with 5 X 10(5) sporocysts of Eimeria bovis by stomach tube. The calves were divided into three equal groups. The first group was treated with monensin, 1 mg kg-1 body weight daily, from the 10th-20th day inclusive after infection; the second group was treated with amprolium, 10 mg kg-1 body weight daily, for the same period of time and the third group acted as infected controls. Both drugs were for the most part effective in preventing clinical signs, in suppressing reduced rates of weight and in reducing oocyst production. The calves of all three groups were resistant to the second infection given 35 days after the first infection with E. bovis as measured by rates of weight gain, fecal oocyst output and lack of clinical signs.

Sensitivity and specificity of the indirect fluorescent antibody test in the study of four murine coccidia.

The sensitivity and specificity of the indirect fluorescent antibody (IFA) test for the detection of serum antibodies were examined in mice that were infected with Eimeria falciformis, E. ferrisi, E. papillata, or E. vermiformis. For the study of each species, five groups of mice were given graded inoculation doses of 10, 10(2), 10(3), 10(4), or 10(5) sporulated oocysts in a primary infection. The sixth group was infected with three sequential doses of 1.5 x 10(3), 1.5 x 10(4), and 1.5 x 10(5) sporulated oocysts per mouse at two- to three-week intervals. All groups of infected mice developed serum antibodies. Sera were titrated by the IFA test with purified sporozoites. Strong fluorescence and high IFA titers were observed with homologous reactions mainly with the sera from mice infected with the higher inoculation dose levels in primary infections and from those given three sequential inoculation doses. Immunological cross reaction among the four species of Eimeria occurred at dilutions of 1:10 to 1:160. Very weak or no fluorescence of free sporozoites was observed with sera from noninfected mice, and there was no fluorescence of sporozoites contained in intact sporocysts.

Oocyst discharge, rumen metabolism and performance of early weaned lambs with naturally occurring coccidiosis fed monensin.

Ninety-six 9.5 kg early-weaned lambs with naturally occurring coccidiosis were fed monensin either at 0, 11, 22, or 33 mg/kg of feed for 105 days. Fecal oocyst discharge during the first three days was highest with monensin 22 mg, lowest with monensin 33 mg and averaged 149.6 x 10(3) oocysts per gram feces for all lambs. Monensin at 22 mg/kg of feed reduced Eimeria ninakohlyakimovae and E. ahsata oocyst discharge. Organic matter and crude protein digestibilities were highest (P

Lasalocid and monensin in finishing diets for early weaned lambs with naturally occurring coccidiosis.

Early weaned male crossbred lambs (n = 90) with an average weight of 14 kg were used in 6 groups to evaluate the efficacy of monensin (22 mg/g of feed) and lasalocid (12.5, 25, 50, and 100 mg/kg of feed) on naturally occurring coccidiosis. Average 24-hour oocyst output at the start of the experiment ranged from 5.7 x 10(6) to 156.7 x 10(6) for monensin-treated and 100-mg lasalocid-treated groups, respectively. Monensin and lasalocid were effective against Eimeria ninakohlyakimovae of E ahsata. To day 103, body weight gains were similar for the 4 groups fed lasalocid (336 g/day) and averaged 6% higher (P greater than 0.05) than did gains in control and monensin-treated lambs. Feed efficacy averaged 9% higher (P less than 0.05) for lambs fed 25, 50, and 100 mg of lasalocid/kg of feed and 7% higher (P greater than 0.05) for lambs fed monensin and 12.5 mg of lasalocid/kg of feed. There were no treatment effects on digestibility, although lasalocid tended to increase (P greater than 0.05) crude protein digestibility (values were higher on day 76 than on day 28). Lasalocid and monensin were potent manipulators of rumen fermentation. Increasing the amount of lasalocid in the feed was associated with successive increases (P less than 0.05) in molar proportions of propionic acid and decreases (P less than 0.05) in acetic acid. Lasalocid and monensin controlled naturally occurring coccidiosis and improved performance in early weaned lambs (45 days old) under feedlot conditions.

Intranasal immunization of mice against Pasteurella multocida.

A potassium thiocyanate (KSCN) extract of Pasteurella multocida serotype III:A was shown to protect mice from an intranasal challenge with up to 300 50% lethal doses of P. multocida. In addition to preventing death, bacteria were rapidly cleared from the lungs of immunized mice so that by 72 to 96 h postchallenge no bacteria were present in the lungs of immunized mice, whereas up to 10(9) bacteria were present in lungs of nonimmunized mice. Immunization by the intranasal route was slightly better than that by the intramuscular route. Protection was considered specific, since immunization with P. multocida protected only against P. multocida and not against Salmonella agona. Furthermore, a similar KSCN extract from P. haemolytica did not protect against P. multocida challenge. A comparison of the KSCN extract with a Formalin-killed bacterin suggested that the KSCN extract may be superior to the bacterin.

Some pathophysiological changes associated with infection of Eimeria zuernii in calves.

Twelve Holstein-Friesian calves were divided into two groups, one of which was infected with Eimeria zuernii. Fecal oocyst output, weight changes and various blood, cellular, protein and biochemical constituents were examined for both groups. Maximal fecal oocyst output occurred 21 days after infection. Both groups of calves gained weight in a linear fashion until day 21 postinfection when the infected group lost weight rapidly. The packed cell volume of the infected calves appeared markedly reduced. Although there was a reduction in plasma proteins it did not appear significant. There was a significant reduction in plasma Na+ and Cl- ions of the infected calves. There were no significant changes in the other blood constituents examined.

A brief review of bovine coccidiosis in Western Canada.

Coccidiosis of beef cattle, in both its enteric and nervous forms, seen in feedlots in Western Canada is discussed. Cases of coccidiosis accompanied by nervous signs, occasionally up to 30% of those affected enterically, are most common during the coldest winter months. The pathogenesis of the nervous form of the disease is unknown. Clinical management of disease outbreaks using various chemotherapeutics is described. The importance of using anticoccidial drugs before the onset of clinical signs in cattle in contact with sick animals is discussed.

Experimental Eimeria bovis infection in calves: a histopathological study.

Eight male holstein calves, four to six weeks of age, were infected with 100,000 sporulated oocysts of a culture containing Eimeria bovis. The calves were injected with steroids on days 13, 14 and 15 and killed on days 16, 18, 19, 20, 21, 22, 24 and 26 postinfection. The lesions caused by experimental E. bovis infection in the small and large intestines are characterized by a diphtheritic typhilitis and colitis. Severe lesions were also seen in the last metre of the ileum in a calf killed 19 days after infection. Most of the damage of the intestinal mucosa is caused by the sexual stages. There is destruction and loss of epithelial cells with subsequent exposure of lamina propria and formation of diphtheritic membranes.