Complement activation and fibrinolysis during infection with Theileria parva (East Coast fever) in cattle

The role played by complement and fibrinolysis in the pathogenesis of pulmonary oedema and the disseminated, subendothelial, petechial haemorrhages in cattle infected with $\text{Theileria parva}$ was investigated. There was a marked reduction in total haemolytic complement in animals that died of this disease whereas the survivors showed only transient changes. The reduction in C3 levels in animals with severe disease, however, was equivalent to that in the survivors. Neither circulating soluble immune complexes nor free antibody against macroschizonts were detected in sera from cattle with severe infection. In addition to the complement changes, high levels of fibrinogen degradation products (FDPs) were detected in sera from the infected animals. The rate of production of FDPs and reduction in total haemolytic complement paralleled the clinical course of the disease. It is, therefore, suggested that the pulmonary oedema and disseminated petechial haemorrhages seen in East Coast fever may be the direct result of the combined effects of complement activation and consumption of fibrinogen and fibrin.     

Hemorrhagic septicemia in fallow deer (Dama dama) caused by Pasteurella multocida multocida.

Four outbreaks of hemorrhagic septicemia caused by Pasteurella multocida multocida occurred in a population of 1,800 fallow deer (Dama dama) during 1992-1996. A total of 340 fallow deer were submitted for postmortem examination. Pasteurellosis was diagnosed in 273 of 312 deer suspected of having septicemia. Pasteurella multocida was isolated from 257 animals, and the diagnosis was based on typical pathologic changes alone in the other 16 animals. Pasteurella multocida was isolated in pure culture from 219 of 248 samples of cerebrospinal fluid. Eighteen animals were observed moribund with severe depression, foamy nasal discharge, and respiratory distress, and 257 were found dead. Major clinical signs and pathologic changes included extensive swelling of the head and the neck and peracute or acute septic pneumonia, petechial and ecchymotic hemorrhages on serous membranes, and severely hemorrhagic adrenal glands and abomasum. Rhinitis and necrotic pharyngeal mucosae were common. Histologically, the most advanced lesions were in the nasal mucosa and pharynx. The swelling of the head and the neck arose from a diffuse cellulitis in the subcutaneous and intermuscular tissues. The earliest lesions in the lungs included large numbers of bacteria in the pulmonary capillaries, but various degrees of fibrinous exudation to the alveoli and infiltration with heterophils usually were observed.     

Clostridium fallax infection in poultry

Summary A disease causing high mortality in young chickens following listlessness, inappetence and diarrhoea is described from Malawi. Haemorrhagic enteritis, splenic enlargement and congestion with petechial haemorrhages, and subcutaneous oedema were seen at post mortem.Clostridium fallax was isolated from affected birds. Coccidiosis was a possible predisposing factor.     

Disseminated acute concomitant aspergillosis and mucormycosis in a pony

A 6-year-old female pony died after 2 days of prostration. Clinical signs included hyperthermia and abnormal pulmonary auscultation sounds. Necropsy revealed diffuse severe necrohaemorrhagic colitis and splenitis, multiple visceral ecchymoses, petechial haemorrhages in the brain and lungs. Microscopical examination showed acute necrohaemorrhagic colitis, encephalitis, pneumonia and splenitis associated with fibrinoid vasculitis, thrombosis and fungal hyphae within and around vessels. Immunohistologically, concomitant aspergillosis (caused by Aspergillus fumigatus) and mucormycosis (causde by Absidia corymbifera) were identified in the colonic and pulmonary lesions, whereas pure mucormycosis was observed in cerebral and splenic lesions. Dual mycotic infections are very rarely described, and the present case emphasizes the need of immunohistochemistry in order to obtain a clear-cut diagnosis of mixed fungal infections.     

Pulmonary pathology of harbour porpoises (Phocoena phocoena) stranded in England and Wales between 1990 and 1996

The pathological changes observed in the lungs of 197 freshly dead to moderately decomposed harbour porpoises (Phocoenaphocoena) stranded in England and Wales between October 1990 and December 1996 were reviewed. In 135 (69 per cent of the cases) macroscopic nematode infections of the bronchial tract with Pseudalius inflexus and Torynurus convolutus, either singly or in combination, were recorded, and 106 (54 per cent) also had P inflexus within the pulmonary blood vessels. All the macroscopically parasitised porpoises were adults or juveniles although two neonates had histological evidence of nematode infection. There were 62 cases of mild to severe, subacute to chronic bronchitis and bronchiolitis, 113 cases of mild to severe chronic granulomatous interstitial pneumonia, and 34 cases of mild to severe vasculitis or thrombovasculitis of pulmonary blood vessels attributable to these nematode infections. In 35 cases necropurulent or purulent (broncho)pneumonias were attributed either to secondary bacterial infections of the lungs or to septicaemias associated in seven cases with Streptococcus canis, in two cases with group B Salmonella species, in one case with Escherichia coli and in one case with Streptococcus lactis. The pulmonary lesions in 67 animals known or diagnosed to have been entrapped in fishing gear were non-specific and included persistent foam in the airways in 45 cases, diffuse congestion in 53, oedema in 50, and multifocal intra-alveolar haemorrhage in 33 cases. Seven cases of acute fibrinous or chronic fibrous pleuritis, seven cases of chronic necropurulent pneumonia associated with mycotic infections, four porpoises with traumatic lesions of the thorax and other parts of the body consistent with fatal attack from bottlenose dolphins (Tursiops truncatus), and one case of diffuse bronchointerstitial pneumonia associated with generalised morbillivirus infection were also recorded.     

Lesions in the central nervous system associated with perinatal lamb mortality

OBJECTIVE: To identify and describe the occurrence of neurological lesions that could have an effect on lamb mortality. PROCEDURE: The central nervous system was investigated macroscopically (n = 92) and microscopically (n = 72) in lambs dying in the perinatal period during 3 years in flocks of adult Corriedale ewes. The central nervous system was removed intact and samples of cerebral cortex, basal ganglia, thalamus, hippocampus, mesencephalon, cerebellar cortex, medulla oblongata, and cervical spinal cord were scored microscopically for the severity of neuronal dead, cytotoxic and perivascular oedema, and haemorrhage. RESULTS: Neurologic findings between birth and 6 days included haemorrhages in meninges, brain congestion and oedema, neuronal ischemic necrosis, intraparenchymal haemorrhages in medulla oblongata and cervical spinal cord, parasagittal cerebral necrosis, and periventricular leukomalacia. No significant lesions were found in anteparturient deaths or in those aged between 7 and 16 days. Oedema was more severe in the brain than in other regions of the central nervous system. Ischaemic neurons first appeared 24 hours post partum, increased linearly in number between 48 hours and 5 days post partum, and had a laminar distribution in the cerebral cortex, indicating a hypoxic-ischemic encephalopathy. Haemorrhages were most severe in the gray matter of medulla oblongata and cervical spinal cord, suggesting trauma due to instability of atlantoaxialis joint. CONCLUSION: Lesions in the central nervous system can explain most deaths at birth and within 6 days of birth. The lesions were hypoxic-ischemic and appeared to be related to birth injury.     

副猪嗜血杆菌人工感染猪的病理学观察

用副猪嗜血杆菌分离株感染断奶仔猪,发病仔猪临床表现为体温中度升高、精神不振、被毛粗乱、站立不稳、厌食、呼吸困难。尸体剖检,可见胸腹腔纤维素渗出严重,有大量的渗出液、肺出血及脑充血等;病理组织学表现为,肺脏、心脏、脾脏等脏器含有大量的中性粒细胞的纤维蛋白性多发性浆膜炎、脑膜炎及支气管肺炎。结果表明,此分离株为一高致病潜力的菌株。     

MENINGEAL HAEMORRHAGE AND CONGESTION ASSOCIATED WITH THE PERINATAL MORTALITY OF BEEF CALVES

Thirty Angus, Hereford and Shorthorn term calves dying before, during or within 7 days of birth in a large beef herd were autopsied. Selected specimens were examined histologically. Two carcasses were classified in the category of ante-parturient death, 24 as parturient, and 4 were classified in the post-parturient death category. Three of the latter showed evidence of starvation. Eight of the calves in the parturient death category were assisted during delivery, and 16 were not assisted. The incidence of nulliparous dams among assisted parturient deaths was significantly higher than among the unassisted group. A high incidence of meningeal haemorrhages and congestion were observed at single or multiple sites, within and around the cranial and spinal meninges. The lesions comprised subdural and epidural haemorrhages, bloodstained cerebrospinal fluid and leptomeningeal haemorrhage and congestion. They were seen in calves in both parturient and post-parturient death categories but not in the ante-parturient group. All calves classified in the parturient death category which were assisted during delivery showed haemorrhages involving the cranial and/or spinal meninges. Additional birth injuries, including separation of the costo-chondral junctions, fractured ribs, haemorrhage into the hip joints, inter-vertebral fibrocartilages and axillae, and rupture of the liver, were frequently present. Ten of the calves in the parturient death category which were unassisted during delivery showed meningeal haemorrhage and congestion. Two of the 4 calves in the post-parturient death category showed similar lesions and both showed evidence of starvation. The meningeal haemorrhages and congestion were similar to those observed in perinatal lamb mortality. They are considered manifestations of injury to the CNS arising from trauma and/or hypoxia during birth. Gross or microscopic evidence of infection was present in 2 calves in the post-parturient death category. Calves which had starved showed subcutaneous oedema of the distal limbs, congestion and focal haemorrhage of the adrenal cortex and red-brown fat depots. It is suggested that these changes are evidence of cold injury, and that fat in newborn calves responds to cold and starvation in a manner similar to the brown fat of newborn lambs.     

Treatment and control by vaccination of erysipelas in farmed emus (Dromaius novo-hollandiae)

Objective To study erysipelas in farmed emus and the treatment and control of the disease by vaccination.
Design A retrospective study of field outbreaks in emus and challenge experiments in mice using field and vaccine strains of the organism.
Procedure Outbreaks of the disease were described. Field strains of the organism were identified and tested by challenge experiments in mice against commercial vaccine strains.
Results Erysipelas was characterised by sudden death in yearling emus. Deaths mainly occurred during the cold wet months. Mortalities of 6 to 10% were seen within the first 7 to 10 days of an outbreak. Clinical signs were uncommon but some birds exhibited lethargy and greenish diarrhoea. Necropsy findings included marked petechial haemorrhages on the serosal surface of the large intestine in particular, pericardial effusion and congestion and mottling of the liver. Treatment consisted of individual or mass medication with procaine penicillin, reduction of stress factors such as overcrowding, and spelling and rotation of paddocks. Isolates from two field outbreaks were identified as strain 21. Complete protection was provided by a commercial strain 2b vaccine against challenge by strain 21 field isolates in mice. Annual vaccination of birds at 4 weeks and again at 8 weeks of age appeared to control further outbreaks on farms where the disease had previously occurred and vaccination appeared to protect for at least 12 months.
Conclusion Treatment of birds with antibiotics may be feasible in the face of an outbreak. However, annual vaccination of birds with an appropriate vaccine is recommended.     

Characteristics of H7N2 (nonpathogenic) avian influenza virus infections in commercial layers, in Pennsylvania, 1997-98

Between January 1997 and March 1998, 11 cases of H7N2 avian influenza (nonpathogenic) were diagnosed at the Laboratory of Avian Medicine and Pathology, Kenneth Square, PA. These cases involved either commercial leghorn laying hens or leghorn pullets raised in Pennsylvania. Grossly and histologically, the most striking lesion associated with disease was salpingitis, usually with edema and occasionally with oviduct necrosis. Fluid, fibrinous, and egg yolk material in the peritoneum (egg yolk peritonitis) as well as pulmonary congestion and pulmonary edema were also frequently seen. Oviduct lesions have rarely been described in association with avian influenza infections in previous outbreaks. Mortality in affected houses was mild to moderate (less than 4% total mortality during the outbreak), with concurrent mild to moderate egg production declines (2%-4% at the time of disease onset).     

Haemorrhagic lesions resulting from Trypanosoma vivax infection in Ayrshire cattle

Infection of Ayrshire cattle with a stock of Trypanosoma vivax from the Galana Ranch, Kenya, resulted in an acute disease characterised by profound anaemia and haemorrhage, which reached maximum severity between 3 and 5 weeks after infection. Bleeding from the ears, nose and rectum occurred. At necropsy, petechial and ecchymotic haemorrhages were widespread, but were particularly severe in the gastrointestinal tract. In confirmation of the gross findings, congestion, haemorrhage and degenerative changes in most tissues and organs were found histologically. Thrombi were seen in the lymphatic vessels and clots of fibrin were present in the ventricles of the brain. The anaemia was a consequence of frank blood loss through haemorrhaging, exacerbated by erythrophagocytosis of deformed red blood cells, whose occurrence was indicative of microangiopathic changes. Animals were euthanised between 23 and 36 days after infection when they became recumbent with PCV values as low as 9%. There is no doubt that animals affected by this syndrome in the field would die within a few weeks of infection, if left untreated.     

Atmospheric flash injuries in roe deer (Capreolus capreolus)

The pathological and histopathological examination of two female roe deer found dead after a severe thunderstorm is described. One of the two roe deer was killed by a direct hit of atmospheric flash, while the other animal, lying 1.5 m from the first one, died as a consequence of ground current strike. The major part of the coat and skin of the animal that was killed by a direct hit was covered with scorched streaks. The trachea and bronchi of both animals contained a considerable amount of aspirated light-red foam. Necropsy revealed diffuse haemorrhages over the epicardium of the right atrium with a diameter of 1 millimetre. The liver and the kidney exhibited severe congestion.     

Microscopic lesions associated with the isolation of Haemophilus somnus from pneumonic bovine lungs

Sixty-one of 68 sets of bovine lungs from which only Haemophilus somnus was isolated had microscopic lesions of purulent bronchiolitis and bronchopneumonia. In 37 of 61 lungs, the bronchiolar exudates were markedly necrotic with accompanying necrosis of the adjacent bronchiolar epithelium. Bronchiolitis obliterans was prominent in 23 of 28 lungs affected with chronic lesions with abscesses present in seven. Alveolar filling with inflammatory cells (neutrophils with fewer macrophages) was limited to peribronchiolar alveoli in 25 of 61 lungs and was multifocal to diffuse in the other 36. Lesions in the remaining lungs (7 of 68) were classified as fibrinous pneumonia with bronchiolitis (2), fibrinous pleuritis (2), suppurative interstitial pneumonia with vasculitis (2), and diffuse congestion (1).     

Yersiniosis in Farmed Deer

Samples from 77 chital (Axis axis), 42 fallow (Dama dama), 26 red (Cervus elaphus), 7 rusa (Cervus timorensis) and 1 sambar deer (Cervus unicolor) were examined. Yersinia pseudotuberculosis infection was diagnosed as the cause of death in 6 (23%) of the red and 23 (30%) of the chital deer. Yersiniosis was the most common infectious cause of death diagnosed. Affected deer were usually found moribund or dead, often with faecal staining of the perineum. Gross pathology in chital included a fibrinous enterocolitis, enlarged congested mesenteric lymph nodes and multiple pale foci through the liver. Gross changes in red deer were limited to intense congestion of the intestinal mucosa and enlargement and congestion of mesenteric lymph nodes. Microscopic intestinal changes in both species consisted of microabscessation or diffuse suppurative inflammation of the intestinal mucosa with numerous bacterial colonies in the lamina propria. Multifocal suppurative mesenteric lymphadenitis was a common finding. Multifocal suppurative or non-suppurative hepatitis was frequently present in the liver of chital but was uncommon in the red deer. Yersiniosis occurred during the cooler months from June to November, with younger age classes most commonly affected. Y. pseudotuberculosis serotypes I, II and III were isolated in the ratio 17:3:0 in the chital deer and 1:1:2 in red deer. The clinical, epidemiological and bacteriological features are similar to those documented previously by New Zealand workers. The increased susceptibility to disease of red deer and chital compared to fallow deer and perhaps other species has not previously been documented.     

CAMBENDAZOLE TOXICITY IN CALVES

The death of 3 of 8 dairy calves was associated with the administration of 98.5 mg/kg cambendazole. Significant lesions consisted of marked pleural effusion, severe pulmonary oedema and necrotic lymphadenopathy.     

Observations on outbreaks of respiratory disease in calves associated with parainfluenza type 3 virus and respiratory syncytial virus infection.

In four outbreaks of indoor calf pneumonia, dyspnoea was a prominent clinical finding. At necropsy it was associated with pneumonia involving the cranial lobes of the lung and severe pulmonary emphysema. Histological examination of lung tissue revealed bronchiolitis and alveolitis with alveolar epithelial cell hyperplasia and multinucleate syncytium formation. Intraalveolar haemorrhage, intra-alveolar oedema and hyaline membrane formation were also noted. In all cases parainfluenza type 3 (PI3) virus was isolated from the lungs. In each of the four outbreaks there was evidence of PI3 virus and respiratory syncitial virus (RSV) infection.     

CLINICO-PATHOLOGICAL EFFECT OF BLUETONGUE VIRUS SEROTYPE 20 IN SHEEP

Fifty-four Merino crossbred sheep were inoculated with bluetongue virus serotype 20 (BTV-20) by the intravenous, subcutaneous and intradermal routes. BTV-20 was successfully transmitted by Culicoides (Avaritia) spp. No. 5 to two additional sheep. Clinical and pathological effects were studied. In the artificially infected sheep, clinical signs were observed after an incubation period of 6 to 10 days and consisted of pyrexia, oral and subcutaneous hyperaemia mild oedema of the ears, face and lips, and coronitis. The major internal pathological changes were petechial and ecchymotic haemorrhages in the tunica media of the pulmonary artery near its junction with the heart and mild haemorrhage and mild oedema in the intestines, coronet, lips, cheeks and ears. Viraemia was detected between day 2 and day 14 post inoculation. The two sheep infected by insect transmission were mildly affected and became viraemic between 16 and 19 days after transmission. No deaths occurred and under experimental conditions BTV-20 caused only mild disease in housed sheep. To date there has been no reported outbreak of natural bluetongue infection in Australia. Compared to other serotypes BTV-20 appears to be of low pathogenicity in sheep.     

Tyzzer's disease in a Eurasian otter (Lutra lutra) in Scotland

A Eurasian otter (Lutra lutra) cub found in weak condition on the Isle of Harris, Scotland, developed bilateral corneal oedema 16 days after being admitted to a rehabilitation centre. It died unexpectedly on day 26. On postmortem examination, there was excess clear fluid in the body cavities and the liver was swollen with numerous pale focal lesions and petechial haemorrhages throughout. Histopathological examination revealed bundles of bacilli morphologically typical of Clostridium piliforme within hepatocytes. Comparative analysis of the nucleotide base sequence of a 16S rdna fragment amplified from the infected liver tissue revealed that it was identical to a C piliforme 16S rdna sequence. The possibility of concurrent infection with canine adenovirus type 1 was considered but none of the characteristic histopathological lesions was observed and examination of the liver by transmission electron microscopy was negative for virus particles. This appears to be the first record of Tyzzer's disease in an otter and the first in a wild animal in Britain.     

Sudden death in turkeys with perirenal hemorrhage: pathological observations and possible pathogenesis of the disease.

A pathological study was conducted on 32 turkeys that died of sudden death with perirenal hemorrhage syndrome. Turkeys were selected from routine necropsy cases in a diagnostic laboratory. A higher incidence was observed in heavy tom turkeys. In addition to the characteristic gross lesions of perirenal hemorrhage, splenomegaly, and pulmonary congestion, turkeys in most cases had a hypertrophic cardiopathy. Microscopic lesions included moderate-to-marked acute passive congestion of all tissues examined (32/32), severe perirenal hemorrhage (32/32), and splenic lymphoid depletion (25/32). Changes in the thyroid follicular epithelium of most birds suggested an increased glandular activity. No lesions suggestive of arterial hypertension were observed. Adenoviral infection was detected in only four of 32 birds. Bacteriological cultures revealed no significant pathogen. Results suggest that sudden death in turkeys with perirenal hemorrhage is caused by an acute congestive heart failure consecutive to a hypertrophic cardiopathy. The perirenal hemorrhage would be a consequence of a severe passive congestion in kidneys.     

Pathology of experimentally-induced, acute toxoplasmosis in macropods

SUMMARY Thirteen Tammar wallabies (Macropus eugenii) were dosed orally with 500, 1000 or 10 000 oocysts of Toxoplasma gondii, as part of a vaccination trial. Eleven animals died of acute toxoplasmosis 9 to 15 days after challenge. The lesions were similar in all animals, consisting of foci of necrosis and inflammation in the intestines, lymphoid tissue, adrenal cortex, heart, skeletal muscle and brain, and severe generalised pulmonary congestion and oedema. Free and intracellular tachyzoites of Toxoplasma were associated with the lesions. The remaining 2 animals had shown no signs of disease when euthanased four months after challenge. Small, focal, non-suppurative inflammatory lesions were seen in brain, heart and skeletal muscle of these animals and chronic Toxoplasma infection was confirmed by mouse inoculation.