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May 2009 RVL Monthly Report

Cattle

A one-week old Simmental calf was presented to Dublin with a history of scour, bloating and depression. It had been treated initially with fluoroquinolone, fluids and halofuginone and had initially responded but then relapsed and died following a period of severe pain. It was the 4th calf to die in the herd within a week. On post mortem examination a 180-degree torsion of the abomasum was found (Figure 1). The organ was markedly dilated and had a very darkened and friable wall. The lumen contained a large volume of blood. Laboratory tests on faeces were positive for Cornonavirus and Cryptosporidia. Mannheimia haemolytica was isolated from the lung and a zinc sulphate turbidity (ZST) test result for maternally-derived antibodies in serum was three units, which was well below normal (>20units). A two-week old calf presented to Cork with a history of sudden death was also found to have a torsion of the abomasum, 360-degrees in this case.

 Abomasal torsion in calf

Figure 1: Abomasal torsion in one-week old Simmental calf (photo: Rosemarie Slowey).

A six-week old calf was examined in Athlone with a history of poor thrive and of hooves, tips of ears and tail falling off.  Gross post mortem examination showed that the pericardium was attached to the heart, but other than that no other internal lesions were noted.  Salmonella dublin was isolated from the gall bladder and faeces. Dublin observed mild jaundice and petechial haemorrhages in the myocardium and spleen of a two-month old Friesian heifer calf that had been coughing for a week and had failed to respond to treatment. Salmonella Dublin was isolated from several organs.

A ten-day old Friesian calf was presented to Dublin with a history of diarrhoea. It was the 5th calf in the herd to die. There was a small abscess present at the umbilicus. The liver was enlarged with rounded edges and there was some free fluid in the abdomen. The heart was enlarged and globular, with thickening of the cordae tendineae. A 2-3 centimetre ventricular septal defect was identified. Salmonella Dublin was isolated from the spleen and Arcanobacterium pyogenes from the umbilical abscess. Histopathology showed congestion of alveolar walls with areas of atelectasis as well as congestion and hepatocyte atrophy around the central veins of the liver, which was consistent with congestive heart failure. Athlone examined a thirteen year old heavily pregnant cow that went down one day before death. It was the second cow to die. The carcass was very thin, almost emaciated and dehydrated. The colon contents were scant but were fluid when present. The endometrium exhibited multifocal to coalescing nodules and plaques and the placental cotyledons were yellow/orange in colour and oozing. Salmonella dublin was isolated from the uterus.

Salmonella typhimurium was isolated from tissues and faeces taken from two calves submitted to Athlone which had reported clinical signs of navel ill, septicaemia and jaundice. Six calves out of 20 had died on this farm.  Gross pathological lesions included diffuse jaundice, oedematous lungs, septic navel and severe enteritis. The zoonotic risks of Salmonella typhimurium were highlighted in the report. Salmonella typhimurium was isolated by Dublin from a faeces sample from a bullock with a history of unresponsive diarrhoea of more than one week¿s duration.

Cork diagnosed cerebro-cortical necrosis (CCN) in one of a group of 100 weaned calves at grass. One of the calves died and a few others had shown nervous signs. Following treatment with thiamine no new cases of the disease were seen.

Kilkenny diagnosed Mannheimia haemolytica septicaemia and pneumonia in a ten-week old calf from a farm where ten per cent of the calves had died with clinical signs of pneumonia. The presented calf was emaciated and had apical lobe pneumonia and peritonitis. M. haemolytica was isolated from both lung and liver, while Pasteurella multocida was also isolated from the lung. A yearling heifer, one of a group of sixty that were bought in, was presented to Dublin with a history of severe depression and pyrexia for a number of days before death. Gross post mortem examination revealed lesions of severe fibrinous pleuropneumonia. There were also multiple ulcerations of the abomasal wall, with the abomasal lumen filled with blood and the intestinal tract containing dark digested blood. Mannheimia haemolytica was cultured and Bovine Herpes Virus 1 (BHV1) and Bovine Respiratory Syncytial Virus (BRSV) were also detected in lung tissue. A yearling heifer which had been sick for two weeks with inappetance, coughing and dyspnoea was submitted to Athlone after it died. There was a thick band of fibrin and scar tissue with pockets of suppuration around the pharynx. An accompanying retropharyngeal space contained rotting food material. The findings were consistent with a traumatic penetrating injury of the pharynx, suggestive of a dosing gun injury.

Yew tree poisoning was diagnosed by Athlone in two bullocks which were found dead with no history of sickness. No gross lesions were seen on post mortem examination, but twigs and leaves from the yew tree (Taxus baccata) were found in the rumen of both animals. Lead poisoning was diagnosed in two weanlings from one farm that died within twelve hours of each other and were presented to Athlone. Both were found in a stream. On post mortem examination the only lesion observed was oedema of the abomasal mucosa. Kidney lead levels were very high in both animals ( >130 micromols per kilogram wet matter- normal range 0-24 micromols per kg). Following notification of the result a search of the grazing area uncovered the source of the poisoning- an old battery that had deteriorated and cracked open. Liver fibrosis, as a sequel to ragwort poisoning was diagnosed by Sligo in two cows submitted from the same herd over a two week period.

Athlone examined an eight-year old cow which had calved three weeks and was sick since calving. It had presented with scour which was sometimes bloody. There had been no response to treatment and it died shortly after. It was one of a number in the herd with similar signs. Some of the cows presented with anaemia and low temperatures. The carcass was in good physical condition. There was diffuse subcutaneous oedema on the ventral aspect of the carcass. Lungs showed diffuse oedema with froth in the airways. There was a significant amount of fluid in the thorax. The liver was enlarged and yellow in appearance (Figure 2). The omentum and mesentery showed diffuse petechiation. Ketone levels were very high in the urine and there was also blood present. A diagnosis of fatty liver was made based on the gross findings and treatment of other affected cows was suggested.

Fatty liver in eight-year old cow

Figure 2: Fatty liver in an eight-year old calved Friesian cow (photo: Ger Murray).

Sheep

All centres reported on cases of gastro-intestinal parasitism in lambs. Cases of nematodirus-associated enteritis and coccidiosis were the most common. In older sheep, both acute and chronic fascioliasis was diagnosed.  

A six-week old lamb that died suddenly was presented to Dublin from a flock in which listeriosis was previously diagnosed. Post mortem examination revealed consolidation of the left and right cranial lung lobes. Listeria monocytogenes was isolated from a swab of the meninges. Histopathology showed acute fibrino-suppurative pneumonia. There were multifocal abscesses and perivascular cuffing  present in the CNS. Kilkenny also diagnosed listerial encephalitis in two six-week old lambs from different farms. In both of these cases the diagnosis was made based on histopathological examination of brain tissue.

The carcass of a lamb with crusting skin lesions with or without alopecia on the ears, neck, muzzle, crown, lips and medial aspects of fore and hind limbs was submitted to Athlone. Dermatophilus congolensis was isolated from the skin lesions. Histology showed a severe superficial exudative dermatitis and folliculitis with intralesional filamentous segmented ("train track-like") bacteria. This lamb had a severe case of dermatophilosis (rain scald). In the surviving animals mild cases can self cure, whereas in severe cases antimicrobial treatment with penicillin-streptomycin or oxytetracycline is required and is usually effective if combined with removal from rain and exposure to skin trauma (e.g. arthropods and thorny plants).

Pigs

Haemophilus parasuis was isolated from pigs presented to Cork with a history of increased mortality and polyserositis.

Poultry

Live birds from a 60-bird mixed breed backyard flock were submitted to Sligo following the deaths of a number of young birds with wheezing and respiratory signs. The problem started approximately one week after the introduction of a small number of Rhode Island Reds to the flock. These were the first birds to show signs of disease. Tests for avian influenza were negative but serological tests for Mycoplasma gallisepticum infection were positive.

Other Species

A three-day old foal was presented to Athlone with a history of depression and distended abdomen. Approximately 10-15 litres of clear, light yellow fluid was present in the abdomen and this was identified as urine. A six-centimetre linear partial thickness tear was found in the dorsal surface of the bladder, with a round perforation in the middle of the tear, through which the urine had escaped. A diagnosis of bladder rupture, uroperitoneum and post-renal azotaemia was made. Rupture of the bladder occurs in 0.2 to 2.5% of newborn foals, with males most often affected. Some ruptures are congenital but it is probable that the majority are caused by birth trauma.