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November Monthly Report 2011

Cattle

Salmonella

A 16-month-old heifer was submitted to Athlone with a history of diarrhoea, post mortem examination revealed mesenteric lymph node enlargement and haemorrhagic enteritis. Salmonellosis was confirmed when Salmonella Typhimurium was isolated from tissues, the submitting client was advised of the zoonotic potential and hazards of Salmonella Typhimurium. Dublin also isolated Salmonella Typhimurium from the faeces of a cow with a history of haemorrhagic diarrhoea while Sligo confirmed Salmonella Dublin infection in an 18-month-old heifer with a clinical history of enteritis. Salmonellosis was also seen in calves, Kilkenny diagnosed salmonellosis in a one-month-old calf which suffered an acute episode of depression ante mortem. The calf belonged to a group which had been imported from Northern Ireland three weeks previously and which had suffered a number of mortalities over this period. Post mortem examination revealed an enteritis and typhlitis while the diagnosis was confirmed when Salmonella Dublin was isolated from tissues. From a separate herd, Kilkenny investigated the death of a one- month-old calf which was recumbent and depressed for approximately 24 hours ante mortem. Post mortem examination of the calf revealed dehydration, enteritis and mesenteric lymph node enlargement, Salmonella Dublin was isolated from tissues.

Cardiovascular disease

Athlone found an interventricular septal defect on post mortem examination of a two-week-old calf which had a history of recumbancy and tachycardia. Athlone also necropsied a seven-month-old weanling with a history of weight loss and stiffness for two weeks ante mortem, and found suppurative pericarditis, myocarditis and endocarditis at the level of the semilunar valves; Bacillus licheniformis was isolated from the lesions. Sligo diagnosed endocarditis in a bullock and isolated Streptococcus bovis 2 from the lesion, while Athlone found a severe vegetative endocarditis, thickening of the aorta and nutmeg liver in a cow which had been euthanased. Kilkenny examined a two- year-old bullock with a history of sudden death and found a large ruptured abscess at the apex of the heart; the pericardial sac was filled with blood. The cardiac abscess had ruptured into the pericardial sac releasing pus and blood resulting in cardiac tamponade. Sligo found multifocal abscessation of the lungs on post mortem examination of a dairy heifer with a history of epistaxis ante mortem, findings were consistent with pulmonary thrombo-embolism. Athlone diagnosed caudal vena caval thrombosis in five-year-old bull with a history of sudden death. Post mortem examination revealed a liver abscess which had ruptured into the caudal vena cava. It is considered that ruminal acidosis predisposes to the development of liver abscesses.

Pneumonia

A one-day-old calf which did not suck or stand after birth was submitted to Athlone for post mortem examination. Milk was found in the larynx while the lungs were oedematous and congested. Histology of the lungs revealed diffuse suppurative pneumonia with milk present in the bronchioles leading to a diagnosis of aspiration pneumonia. Limerick necropsied a nine-month-old Aberdeen Angus weanling which was submitted from a group showing signs of coughing. Diffuse pneumonia and emphysema were found and Bovine Respiratory Syncytial Virus (BRSV) infection was confirmed on PCR testing of tissues, laboratory testing also revealed this weanling to be infected with Bovine Viral Diarrhoea Virus (BVDV). Athlone necropsied a three-month-old suckler calf which was found dead, extensive bilateral cranioventral pulmonary consolidation was evident; Pasteurella multocida was isolated from affected lung. From a separate herd, a fifteen-month-old heifer was submitted to Athlone with a history of sudden death. Fibrinous pleuritis and bilateral cranioventral pulmonary consolidation was evident on post mortem examination while Mannheima haemolytica was isolated from the lungs. Limerick investigated an outbreak of suspect pneumonia in a group of 18-month-old housed cattle which were suffering from pyrexia, drooling from the mouth and excessive lacrimation. Lung samples were submitted from one animal which was found dead, while nasal swabs were submitted from other live animals in the group. Mannheima haemolytica and Pasteurella multocida were isolated from the lung tissues while testing of the swabs yielded a positive result for Bovine Herpes Virus 1 (BHV 1). Athlone encountered fibrinonecrotic tracheitis and bronchointerstitial pneumonia on post mortem examination of a 16-month-old bull with a history of respiratory problems. Lung tissue tested positive for BHV1 and BRSV by PCR while Arcanobacterium pyogenes was isolated from lung on bacterial culture. A nine-month-old bull was submitted to Kilkenny with a history of suspected pneumonia. Post mortem examination revealed tracheitis, pulmonary consolidation and septal oedema, hoose worms were also found in the bronchial tree. PCR testing of lung tissue revealed BHV1 and PI3 infection, Infectious Bovine Rhinotrachietis (IBR) and concurrent hoose pneumonia were diagnosed. Dublin received a six-month-old Aberdeen Angus heifer with a history of recumbancy for two days ante mortem. Post mortem examination revealed pulmonary atelactesis and groundglass emphysema on pleural surfaces, exploration of the bronchial tree confirmed heavy infestation of lungworm.

Gastrointestinal Disease

Athlone reported several cases of ruminal acidosis in November. In one case two 18-month-old bullocks were submitted from the one farm. There was a strong fermentative smell of the carcass and from rumen contents in particular, the rumen pH for both animals was very low at 5.0, a finding indicative of ruminal acidosis. In a separate case, Athlone diagnosed ruminal acidosis in an 18-month-old heifer which was found dead, again rumen pH was 5.0. In yet another case from a separate herd a five-month-old calf which was found bloated ante mortem was presented to Athlone for post mortem examination. Grain was present in ingesta and rumen pH was again 5.0.

Kilkenny diagnosed cryptosporidiosis in a one-week-old calf with a history of drowsiness and diarrhoea. Cork necropsied a two-and-a-half-year-old heifer which had been euthanased after a period of chronic ill thrift, mucosal thickening of the small intestine was found on gross post mortem while histology revealed diffuse granulomatous enteritis with invasion of lamina propria by Langhan’s giant cells (Figure 1), suggestive of Johne’s disease, confirmation of Johne’s disease based on cultural isolation of Mycobacterium avium subspecies paratuberculosis (MAP) is pending.

  Early Johnes disease 

Figure 1; Invasion of intestinal lamina propria by Langhan’s giant cells in a two and a half year old heifer with lesions consistent with Johne’s disease. Photo Cosme Sanchez

Omphalitis

Dublin necropsied a 10-day-old female calf with a history of navel infection, depression and pyrexia for two days ante mortem and found a swollen umbilicus which contained floccules of pus. Pus was also found along the round ligament arising from the navel and attaching to the liver. Widespread petechiation was found on peritoneal surfaces, multifocal necrotising hepatitis was found on histology and E. coli were isolated from several organs. Findings were consistent with colisepticaemia; the likely portal of entry of infection was the infected navel. Omphalitis was diagnosed in a one-month-old calf submitted to Sligo when a navel abscess was found on post mortem examination. Arcanobacterium pyogenes was isolated from the abscess while concurrent infection with BVDV was found on PCR testing of serum.

Clostridial disease

Kilkenny diagnosed Blackleg in a yearling submitted for post mortem examination after being found dead. Lesions consistent with blackleg were found in the muscles over the left shoulder and the gluteal muscles of the hindlimbs. Detection of Clostridium chauveoi in affected muscle using Fluorescent Antibody Testing (FAT) was supportive of the diagnosis. Dublin suspected Black disease in the case of a three-year-old suckler cow which was submitted after an acute episode of illness. Post mortem examination revealed marked pleural and peritoneal effusions, peri-tracheal and peri-oesophageal haemorrhage and a large focus of necrosis in the liver which on histology was found to be infiltrated at the periphery by gram positive rod shaped bacteria morphologically consistent with Clostridia spp. Black disease is most commonly initiated by migrating fluke larvae which create anaerobic foci facilitating the germination of Clostridium novyi spores and endotoxin release.

Disease of the nervous system.

A nine-month-old housed Belgian Blue bull which was found dead was submitted to Dublin. Post mortem examination revealed suppurative meningitis, owing to the poor state of preservation of this submission, a pathogen was not isolated. Kilkenny examined a cow which was submitted with a history of nervous signs including blindness and confirmed Cerebro Cortical Necrosis (CCN) on histology.

Other

Dublin examined a nine-day-old Friesian heifer calf which was found to have scleral haemorrhage ante mortem. Post mortem examination revealed anaemia; haemorrhage into the intestine and into skeletal muscle and widespread petechiation. PCR testing of tissues yielded a negative result for BVDV while histopathological examination of bone marrow revealed tri-lineage haematopoietic cell aplasia consistent with a diagnosis of Bovine Neonatal Pancytopaenia. Dublin diagnosed hypogammaglobulinaemia in a 10-day-old calf submitted for post mortem examination with a history of diarrhoea. The Zinc Sulphate Turbidity Test (ZSTT) was very low at five units, the calf’s fat reserves were depleted, the abomasom was empty while focal broncho and pleuropneumonia and fungal rumenitis were also found. The fungal rumenitis (Figure 2) was likely to have been secondary to prolonged antimicrobial therapy. Sligo found a low ZSTT reading in a week-old calf which had been given an artificial colostrom feed; Sligo reported several similar cases in the past, raising questions about the usefulness of such products. Dublin examined a Friesian yearling which was found dead. It was one of a group of sixty yearlings which were out on pasture, two others from the group had also recently been found dead. Post mortem examination revealed the carcass to be dehydrated, elongated ulcers approximately six cm in length (Figure 3) were found along the whole of the small intestine. Intestinal contents were watery and blood tinged. PCR testing of tissues confirmed BVDV infection in this case. Sligo diagnosed babesiosis in a Hereford bull which had been purchased one month ante mortem. Post mortem examination revealed jaundice, blood was watery while examination of urine revealed haemoglobinuria. Sligo also diagnosed severe gangrenous mastitis in a five-year-old cow which was recently calved. Streptococcus dysgalactiae was isolated from the affected gland.

 Fungal rumenitis 

Figure 2; Fungal rumenitis in a 10-day-old calf; Photo Ann Sharpe

 intestinal ulceration with BVDV infection 

Figure 3; Ulceration of small intestinal mucosa in a one-year-old heifer with BVDV infection. Photo Colm Brady.

Cork necropsied a two year old bullock which had died suddenly. Post mortem examination found focal area of hard consistency in the liver which on histology was revealed as necrotising hepatitis with gram negative coccobacilli present. Oedema of the gall bladder and petechiation on serosal surfaces was also seen. Based on histological findings a tentative diagnosis of Bibersteinia trehalosi was made.

Bovine Abortion

Athlone isolated Salmonella Dublin from a five-month-old bovine foetus submitted from a herd where multiple abortions were occurring. In addition PCR testing of pleural fluid yielded a positive result for BVDV. Only first-time calvers were affected in this abortion outbreak, suggesting that older animals had prior exposure and therefore may have had some immunity. While the role of BVDV in the abortion outbreak could not be fully ascertained, it may have played a part in facilitating the spread of Salmonella Dublin in the herd. Athlone also isolated Listeria monocytogenes from two foetuses, each from a separate herd in November. Kilkenny noted the usual seasonal increase in bovine foetal abortions in November, Salmonella Dublin was the most commonly isolated abortifacient, however Listeria monocytogenes, Arcanobacterium pyogenes and Bacillus lichiniformis were also isolated in other cases. Sligo investigated an outbreak of abortion in a dairy herd; Salmonella Dublin was isolated from aborted foetuses submitted from this outbreak.

Ovine

Parasitology

A five-year-old ewe with a history of sudden death was submitted to Athlone. Post mortem examination revealed a large volume of fluid in the thorax, and while the sheep had been treated for liver fluke one week earlier, the friable nature of the liver was consistent with liver fluke damage. A heavy strongyle burden was also detected on testing of faeces and a reassessment of parasite control in the flock was advised. Sligo also reported deaths in sheep in November due to both acute and chronic-active fascioliasis. Sligo also diagnosed a number of cases of parasitic gastroenteritis including a case of ostertagiasis in a pedigree Texel lamb.

Pneumonia

Dublin investigated the death of a number of aged mountain black face ewes which were part of a larger group of purchased mountain ewes. Post mortem examination of one of the ewes revealed diffuse fibrinous pneumonia and a focal chronic pulmonary abscess; the ewe had no teeth and was in poor body condition. Mannheima haemolytica and Arcanobacterium pyogenes were isolated from pulmonary tissues. One ram which was found dead after showing clinical respiratory symptoms was submitted to Cork and found to have abnormally firm and heavy lungs on post mortem examination. Histological examination of tissue revealed interstitial pneumonia with mononuclear infiltrate and smooth muscle hypertrophy consistent with Maedi visna.

Other

Sligo diagnosed Bibersteinia trehalosi septicaemia and pneumonia in two seven-month-old store lambs submitted from the same batch which had experienced several sudden deaths after housing. Pathological change encountered on post mortem examination of these lambs included fibrinous pleuropneumonia, pericardial effusion with fibrin clots, splenomegaly and multifocal visceral petechiations. A farm experiencing losses in bought-in aged adult ewes submitted two ewes to Dublin for post mortem examination. One ewe was found to have a retropharyngeal lymph node abscess with suppuration extending into the atlanto-occipital joint and the meninges. The second ewe was jaundiced and had severe pleural and abdominal effusions. The liver was small and firm due to extensive portal tract bridging fibrosis, most likely secondary to chronic liver fluke damage. Two hoggets with a history of nervous signs ante mortem were submitted to Kilkenny, they were part of a group of 200 housed hoggets on a concentrate diet, 20 of which had died. Post mortem examination in both cases revealed laminar apple green fluorescence of cut surface of cerebral cortex under UV light, CCN was confirmed on histology. Limerick diagnosed renal tubular urolithiasis in a six-month-old lamb based on histological examination of kidneys. The lamb had been suffering from ill thrift and pining over a two week period ante mortem and other lambs in the group had been similarly affected. An examination of the management and diet of the lambs was advised.

Pigs

Three 12-week-old fattner pigs which had been found dead were submitted to Dublin. Post mortem examination revealed acute fibrinosuppurative pleuropneumonia in all three, Pasteurella multocida and Actinobacillus pleuropneumonia were isolated from affected lung tissue. Kilkenny necropsied a weaner with a history of sudden death and found a severe pneumonia and pleurisy with evidence also of septicaemia, Streptococcus suis was isolated from several organs. A three-month-old saddle back pig was submitted to Kilkenny with a history of sudden death, post mortem examination revealed a large abscess in the cerebral cortex, Streptococcus bovis 1 was isolated from the abscess.

Deer

Hoose pneumonia was diagnosed in a 16-year-old doe submitted to Athlone. Post mortem examination revealed the bronchial tree to be infested with lungworm.

Poultry

Dublin investigated a number of separate cases of disease in turkeys in November.

In one such case, Dublin examined four 10-week-old turkeys from a fattening flock which had been found dead. Post mortem examination revealed the spleens to be enlarged and containing multiple white focal lesions while almost the entire intestine was distended with fibrinohaemorrhagic exudates. Histopathology revealed lymphoid depletion in the spleen, necrotising splenitis, and haemorrhagic enteritis with intranucleur inclusions. The pathological change and presence of intranucleur inclusions was charachteristic of haemorrhagic enteritis virus of turkeys which is a siadenovirus. This viral infection is very variable in terms of morbidity for different flock infections.

In another case, Dublin examined a 16-week-old turkey which was the second out of a backyard flock of 25 to die in two weeks. Post mortem examination revealed fibrinous peritonitis, multifocal white foci scattered throughout parenchyma of liver and spleen, while a number of white nodules were attached to intestinal serosa. Histology revealed these lesions to be granulomata with coagulative necrosis at their centre, Escherichia coli was isolated from tissues. Findings were consistent with coligranuloma, a condition caused by E. coli infection, environmental stress can predispose to the disease.

From another backyard flock, a 17-week-old turkey was submitted to Dublin with a history of lethargy for a few days ante mortem. Post mortem examination revealed the presence of slender white worms approximately 5cm long in the small intestine, while histology revealed necrotic tracts in the liver consistent with larval migration. The parasite was identified as Ascaridia dissimilis, a helminth parasite of turkeys which infects the small intestine and also migrates through the liver resulting in mortality.

Limerick examined canaries submitted from a group of 42 birds where 12 mortalities had occurred over a three-week period. A clinical history of respiratory distress and inappetence was reported. Histological examination of lung tissue from the submitted canaries revealed hyperplasia of the epithelium of the parabronchi, inclusions were seen in some of the cells while a heavy infiltration of lymphocytes, plasma cells, macrophages and heterophils in the surrounding interstitium was in evidence. The changes seen were suggestive of canary pox.

Wild Birds

Dublin was involved along with the State laboratory in the investigation of deaths of a number of red Kites that had been re-introduced to this country as part of a long-term project of the Golden Eagle Trust and the National Parks and Wildlife Service to re-introduce specific birds of prey into Ireland. Internal haemorrhage was found in the case of two red kites and Broadafacoum, an anticoagulant rodenticide, was detected in samples from these kites submitted to the state laboratory for toxicology analysis.