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June 2011 RVL Monthly Report

Bovine

The laboratory service saw a diversity of submissions in terms of species and disease presentation, and the high number of calf submissions reported by the laboratories in recent months continued in June.

Kilkenny reported a number of cases of umbilical and hepatic abscessation in calves. In one such case a three-week-old calf with a history of respiratory distress ante mortem was found on post mortem to have an umbilical abscess greatly distended with pus while several abscesses were found within the liver. Escherichia coli was the only pathogen isolated from these lesions. From a separate herd Kilkenny found abscessation in the umbilicus and liver of a three-week-old calf with a history of ill thrift, and again E coli was isolated from the lesions. Cork found a very large umbilical abscess in a two-month-old calf which had been found dead. Arcanobacterium pyogenes was isolated from the abscess, while Pasteurella multocida was isolated from lung, which was partially consolidated. Post mortem examination of a ten-week-old calf submitted to Kilkenny revealed an umbilical abscess 15cm diameter, and large abscesses were also found in the liver. Sligo reported several cases of umbilical and hepatic abscessation in calves which were usually between six and ten weeks of age. Arcanobacterium pyogenes was the common bacterial isolate in such cases, these lesions were most likely to have been a consequence of umbilical infection arising from poor hygiene and management of the calves as neonates.  

Gastrointestinal disease seen by the laboratory service in June included a fatal E. coli K99 infection in a two-day-old calf submitted to Kilkenny which had been normal at birth but which rapidly succumbed to  enteritis. Kilkenny also examined 10-day-old twin calves with a history of acute scour and demonstrated rotavirus, coronavirus and Cryptosporidium infection on faecal testing. In a separate case, Kilkenny found concurrent rotavirus and Cryptosporidium infection in a nine-day-old calf with acute scour. Dublin examined a two-month-old calf which was found dead. Necropsy of the calf revealed dehydration and haemorrhagic enteritis, and faecal examination confimed a heavy coccidial oocyst burden in faeces. Coccidiosis was diagnosed based on the parasitology and pathology findings. Athlone necropsied a ten-month-old heifer with a history of diarrhoea and ill thrift which was unresponsive to treatment. Post mortem examination revealed fibrinonecrotic enteritis, BVD PCR testing yielded a negative result and idiopathic necrotising enteritis was diagnosed. Sligo diagnosed several cases of intestinal volvulus and torsion in calves submitted for post mortem, invariably the abdomen was found to be distended while histories often described abdominal pain. Some of the submissions had been found dead. Sligo also reported several cases of abomasal ulceration in calves, trichobezoars (Hairballs) were also commonly found in such cases. Kilkenny diagnosed perforated abomasal ulceration and peritonitis in a number of two-month-old calves, from different farms.

Limerick diagnosed parasitic pneumonia (hoose) as the cause of death in a four-month-old Friesian calf with a history of coughing, respiratory distress, inappetence and dehydration. Pulmonary consolidation and emphysema were evident on post mortem examination and large numbers of lungworm larvae were found in airways. Athlone necropsied a one-year-old heifer which had been found dead. Lung worms and coagulated blood were present in the airways and histology confirmed peracute parasitic pneumonia. Kilkenny also diagnosed lungworm infection in the case of a fifteen-month-old weanling with a history of pneumonia. Necropsy of the submitted carcass revealed the presence of lungworms in airways, and while Pasteurella multocida and Arcanobacterium pyogenes were also isolated from the lungs, these pathogens were likely to have been secondary invaders. Other pneumonia cases included an 18-month-old bullock submitted to Kilkenny with a history of pneumonia, which was confirmed at post mortem, while bovine herpesvirus 1 (BHV1/IBRV) infection of lung tissue was identified using PCR. In a separate case, Kilkenny also detected BHV1 in the lungs of a two-month-old calf with a history of pyrexia, hyperpnoea, conjunctivitis and nasal discharge. Athlone received a five-month-old heifer with a history of sudden death. Post mortem examination revealed severe diffuse pneumonia, bullous emphysema with a well demarcated area of consolidation in the apical lobes. Histological findings were consistent with bovine respiratory syncytial virus (BRSV) infection while bacteriology confirmed secondary infection with Pasteurella multocida. Dublin also diagnosed BRSV infection in a six-week-old calf with a history of depression for four days with acute respiratory distress terminally.  Post mortem examination revealed rubbery consolidation of lungs and the histological findings supported a diagnosis of viral pneumonia associated with BRSV.

Other viral infections seen in June included a persistent BVD infection in a three-year-old heifer submitted to Athlone with a history of diarrhoea, inappetence and pyrexia. Post mortem examination of the carcass revealed ulcerative colitis, swollen Peyer’s patches and bloody intestinal contents, and PCR testing of tissues confirmed the diagnosis.   

The laboratories reported a number of cases of salmonellosis in June. A three-week-old calf with a history of weakness and dehydration was submitted to Kilkenny, where bacteriology confirmed Salmonella Dublin-associated septicaemia. Kilkenny also isolated Salmonella Dublin from the faeces of a two-month-old calf with terminal gangrene of distal hind limbs, ears, and tail while Athlone detected significant Salmonella titre on blood samples from two calves, both two-months-old, that had a history of terminal gangrene affecting their feet.  

Clostridial disease was also seen in cattle in June. A 13-week-old Charolais suckler calf was submitted to Limerick with a history of an acute episode of depression and recumbency ante mortem; the animal had not been vaccinated against clostridial disease. Post mortem examination in this case revealed lesions suggestive of blackleg in the psoas muscles beneath the transverse processes of the lumbar vertebrae. A positive fluorescent antibody test (FAT) result for Clostridium chauvoei  in a sample of affected tissue confirmed the diagnosis. Dublin investigated the death of an eight-month-old Friesian heifer with a history of acute lameness ante mortem. Necropsy revealed fibrinohaemorrhagic pleuritis while the musculature over the left hip was dark, dry and emphysematous. Laboratory testing detected Clostridium chauvoei at the lesion site confirming a diagnosis of clostridial myositis (blackleg).

Athlone examined a 10-year-old cow with a history of a stiff gait and rapid weight loss over three days ante mortem. Gross post mortem examination revealed multifocal masses throughout both of the lungs consistent with pulmonary embolism, while vegetative lesions were found attached to the left atrioventricular valve of the heart, and multifocal abscessation of the kidneys was also noted. A diagnosis of valvular endocarditis with embolic pneumonia and nephritis was reported. This condition is a sequel to septicaemia, caused possibly by a primary lesion such as a hoof abscess or mastitis which might have subsequently resolved. Athlone also diagnosed a massive dilated cardiomyopathy in a three-month-old calf which was found dead, and Kilkenny identified myocardial abscessation in a four-month-old calf with a history of chronic ill thrift and lameness.

The laboratory service detected a number of cases of lead poisoning in June. Sligo diagnosed lead poisoning in an adult cow, and Kilkenny diagnosed lead poisoning in a 10-week-old calf with a history of bawling and staggering ante mortem. In a separate case, Kilkenny also diagnosed lead poisoning in an eight-week-old calf that was noticed to be of dull demeanour and was found dead one day later.  Athlone diagnosed lead poisoning in a three-month-old calf which was found dead in a field. While the source of the lead was suspected to be a  vehicle battery that had been in the field and had been removed prior to the arrival of the calf, the herdowner was advised that lead acetate may have leaked from the battery and contaminated the surrounding environment. Lead poisoning was also diagnosed by Limerick in the case of a 30-month-old heifer that had been found dead. This animal was the second animal in the group to have died in such circumstances within seven days. Further investigations revealed that the source of the poisoning was a car battery in a corner of the field. 

Limerick diagnosed cerebro-cortical necrosis (CCN) in a three-month-old male calf that had been at grass for six weeks, and which had a short history of recumbency, paddling of limbs and severe agitation. Examination of cut sections of brain under ultraviolet light revealed laminar apple-green autofluorescence, and histopathology confirmed the diagnosis. Dublin also diagnosed CCN in a four-month-old calf with a clinical history of muscle tremors, recumbency and rigid paralysis of forelimbs. This was the third calf from the same group to present in such a way; the other two responded to Vitamin B therapy. In the case submitted to Dublin, the diagnosis was confirmed by neurohistopathology.

Athlone diagnosed chronic renal failure in a fourteen-week-old calf with a history of stiffness and depression for several days ante mortem. Post mortem examination revealed a chronic bilateral suppurative nephritis caused by bacterial infection, possibly caused by an ascending infection from the urinary bladder. Cork investigated the death of a three-month-old calf with a history of respiratory distress ante mortem. Post mortem examination revealed a distended rumen and the atelectasis (collapse) of much of the lung parenchyma, probably as a result of abdominal compression of the thorax. Exploration of the rumen revealed numerous foreign bodies (Figure 1). The rumen also contained a lot of grain, and the rumen pH was 5.0 which were consistent with rumenal acidosis. Kilkenny investigated the death of a four-year-old cow that had presented with nervous clinical signs. Histology of the liver revealed fibrotic changes characteristic of ragwort poisoning, and hepatic encephalopathy was also noted. Babesiosis (Redwater) was diagnosed in a cow submitted to Sligo; the carcass was anaemic, icteric and dehydrated.

Foreign bodies  

Figure 1: Foreign bodies found in the rumen of a three-month-old calf. Photo: Mercedes Gomez-Parada

Bovine Abortion

Kilkenny isolated Arcanobacterium pyogenes from two unconnected cases of bovine abortion. Dublin diagnosed cleft palate in an aborted seven-month-old foetus (Figure 2). Tests for BVD and other infectious cause of abortion yielded negative results.

Cleft palate  

Figure 2: Cleft palate in a seven-month-old bovine foetus. Photo: William Byrne

Ovine

Kilkenny confirmed a diagnosis of CCN at the  necropsy of a two-month-old lamb which had shown nervous signs ante mortem. Parasitic gastroenteritis was also diagnosed, with a strongyle egg count in this case of 1400 eggs per gram of faeces. Sligo frequently diagnosed clostridial disease in lambs in June, and pneumonia and cobalt deficiency were also commonly encountered by Sligo. Sligo diagnosed dematophilosis in a seven-year-old goat, based on histology of the skin. The pathological changes were widespread in the skin and the condition had persisted for weeks ante mortem, cobalt deficiency and a heavy strongyle burden were also detected in this case.

Avian

Athlone necropsied a three-month-old chicken which had suffered from leg weakness ante mortem. This was the sixth hen out of a backyard flock of 18 birds to have shown such symptoms. The flock had been recently assembled following their purchase at local markets. The histopathological changes encountered consisted of neural lymphomatosis with lymphocytic infiltration of other organs, this change was consistent with Marek’s disease. Dublin necropsied two pullets submitted from a small poultry flock and found that both were in very poor body condition, had soiled vents and haemorrhagic intestinal contents. A heavy coccidial oocyst burden was found in the faeces and coccidiosis was diagnosed.  However histopathology of one of the two pullets also revealed well circumscribed lymphoid infiltrations in liver, lung, and spleen. These changes were consistent with lymphoid leukosis which is frequently associated with avian leukosis virus infection. Limerick diagnosed coccidiosis in a free range hen with haemorrhagic enteritis. This hen was submitted from a backyard flock following the death of a number of cohorts.  Dublin diagnosed aspergillosis in a mute swan in poor body condition; multifocal pneumonia and air-sacculitis were observed on histology while Aspergillus sp. was isolated on culture. Two pigeons from a flock of 100 with a history of a yellow discharge from the beak ante mortem were submitted to Cork. PCR testing of tissues yielded a positive result for Newcastle’s disease. Sligo necropsied a two-year-old free range Maran hen which had been submitted with a history of sudden death. Post mortem examination revealed fatty liver and hepatic rupture (Figure 3). The hens in the flock were described as being in very good condition and in peak lay. Fatty liver syndrome in hens is usually attributed to an energy protein imbalance with possible Vitamin E deficiency; it is most common in layers during the summer months. Vitamin supplementation and reduction in carbohydrate in diet was recommended in this case.

Fatty liver syndrome  

Figure 3: Fatty liver syndrome in a Maran hen. The hen died when the liver spontaneously ruptured - note the pale colour, rounded edges, and the large haematoma attached to the lower edge. Photo: Colm O Muireagain

Badger

Sligo confirmed miliary pulmonary tuberculosis in a yearling badger sow submitted for post mortem examination (Figure 4). Multifocal granulomatous lesions were scattered throughout lung tissue, Mycobacterium bovis was isolated on culture of lesions.

Pulmonary TB  

Figure 4: Pulmonary tuberculosis in a yearling badger sow. Photo: Colm Ó Muireagáin