Current Findings in the Regional Veterinary Laboratories

April 2005

Cattle

Brucella abortus was isolated from bovine foetuses submitted to Limerick from one dairy herd in county Clare. These were the first isolates of the pathogen by the laboratory since September 2004. Athlone reported salmonella abortion in a recently repopulated dairy herd. This was the second abortion in two weeks. Salmonella dublin was isolated from foetal stomach contents.

Kilkenny diagnosed atresia coli in a two-day old calf. Limerick reported a number of congenital problems, including atresia of the anus and rectum, hydrocephalus, hydranencephaly, cerebellar hypoplasia and malformations of the vertebral and appendicular skeleton. Hyperplastic goitre was diagnosed in a herd with at least eight undersized full-term stillborn or early neo-natal deaths. Two stillborn calves submitted weighed 25kg and 23kg and had thyroid glands weighing 100g and 46g respectively. Hyperplasia was confirmed in both thyroids following histological examination.

April is typically the month when calf scour problems reach their peak. Approximately 802 calf faecal samples were analysed by the laboratory service during the month. The table confirms that rotavirus and cryptosporidia continue to be the most common pathogens identified in samples submitted to all RVLs (figure 1).

Dublin diagnosed serofibrinous peritonitis caused by an intussusception in a one-week old bucket-reared calf with a history of loss of appetite, weakness and rapid death. Hypopyon (pus in the anterior chamber of the eye) and enteritis were found in another one-week old calf from the same farm. Blood from three calves from this farm had low ZST readings, indicating hypogammaglobulineamia and inadequate absorbtion of colostrum antibodies within the first six to twelve hours of life.

A one-week old calf submitted to Cork with a history of respiratory symptoms and high temperature had infectious bovine rhinotracheitis (IBR) pneumonia confirmed on histopathology, with intranuclear inclusions present in respiratory epithelial cells. Kilkenny examined a four-month old calf with a history of panting and frothing from mouth. Extensive pneumonia was found with consolidation and fibrinous pleuritis. A fluorescent antibody test (FAT) was positive for respiratory syncithial virus (RSV) and Mannheimia haemolytica was isolated on culture. Cork investigated a pneumonia problem in a group of pre-weaning calves where over thirty deaths had occurred. Post-mortem examination showed severe necrotising pneumonia and pleuritis. Pasteurella multocida and Mannheimia haemolytica were isolated on culture and Mycoplasma bovis on antigen-capture ELISA. A six-week old calf with diffuse lung abscessation was FAT positive for IBR virus and ELISA positive for Mycoplasma bovis. Another calf, four-months old, with similar post-mortem findings was also positive for Mycoplasma bovis, and Arcanobacter pyogenes was isolated on culture.

Meningitis was diagnosed by Dublin in a three-week old, bought-in calf that displayed nervous signs before death. Salmonella Dublin was isolated from the brain, spleen and liver. Septicaemia associated with Salmonella dublin was reported by Athlone in a group of thirty two-week old calves. A total of nine calves showed clinical disease and three of these died despite treatment. Cork had eight incidences of Salmonella typhimurium confirmed for the first quarter of this year. This compared with two to three incidences in bovines in each quarter of the previous two years.

A two-month old calf submitted to Cork with a distended abdomen was found to have pyloric stenosis. The healing process associated with a large ulcer in the area was thought to have lead to the blockage (figure 2). Very little ingesta had been able to pass from the abomasum into the duodenum. Kilkenny and Athlone diagnosed mesenteric torsion in a number of calves varying in age from one week to twelve weeks of age. Limerick diagnosed abomasal torsion with rupture in a month-old calf.

A two-month calf was presented to Cork for post-mortem following meningitis-type clinical signs. It was the second calf to die with similar symptoms in this herd. A kidney lead concentration of 215 µmol/kg (normal value 0-24 µmol/kg) was consistent with lead poisoning. The source was identified as lead paint licked from an old door. Three yearlings also died from lead poisoning in another Cork herd. One of the animals submitted had a kidney lead value of 208 µmol/kg. The source in that case was a discarded car battery. Athlone also reported lead poisoning in a group of six-week old calves. Three had died before the lead source was identified and eliminated.

A total of eight animals from seven different farms were diagnosed by Cork as positive for bovine viral diarrhoea (BVD) antigen. They included one six-month-old calf, two one-year olds and three one-and-a-half year olds (two of them bulls). A three-year old with history of ill-thrift and periodical episodes of lameness was also positive, as was a six-year old cow, (the current calf of which died of suspect mucosal disease). The two previous calves out of this cow of had both died shortly after birth. Limerick identified BVD virus antigen in a three-month-old calf with lesions of haemorrhagic disease. BVD antigen was found in a three-day old calf presented to Kilkenny. Post-mortem examination showed that there were numerous shallow ulcerative lesions in the abomasal mucosa.

Low blood phosphorus values were demonstrated by Cork in a herd of dairy cows where one had shown signs of post-parturient haemoglobinuria. As with another dairy herd in March, excess intake of sugar beet pulp was considered to be the cause.

Sheep

Kilkenny diagnosed border disease in four lambs submitted from one flock. They were not typical hairy shakers. One had almost complete absence of cerebellum, two had dilated lateral ventricles and one had a malformed midbrain.

Athlone reported that two twelve-day old lambs were submitted with a history of weakness and refusal to suck. Gross post-mortem examination showed very severe anaemia in both lambs. Histopathological examination showed centrilobular necrosis of the livers. It was subsequently confirmed by the submitting veterinary surgeon that these lambs had been fed bovine colostrum. Bilateral pyelonephritis was diagnosed by Dublin in a one-month old female lamb that died suddenly. Staphylococcus aureus was isolated from the kidney lesions. An ascending infection from the umbilicus via the urachus was considered to be the most likely route of infection in an animal of this age. Athlone diagnosed nephrosis of unknown aetiology in a one-month old lamb. Listeria monocytogenes septicaemia was identified by Cork as the terminal cause in the death of two young lambs from one flock. Predisposing factors of mismothering in one and a congenital heart defect in the second were identified.

Two nine-week-old lambs from the same flock were submitted to Cork as sudden deaths. Abomasal lesions suggestive of Clostridium sordelli infection were seen in one of them but its presence was not confirmed. The second lamb had marked congestion of rumen, abomasum, small and large intestine and, while all these organs had contents of normal appearance, Clostridium perfringens was isolated from the small intestine of this lamb.

Poultry

Shell defects were identified in two laying flocks referred to Cork. In one flock, housed in cages and with two age groups of 57 weeks and 62 weeks, there were shell faults, a change in shell colour and a marginal production drop. The changes coincided with the consumption of the remains of one batch of feed and the arrival of a new batch. There was a dramatic return to normal following vitamin and methionine supplementation. The disruption was considered to be the result of a large amount of dust remnants from the end of the old feed batch. In the second flock, free-range and 32 weeks old, the shell faults were more severe and soft shells were also present. In addition, this flock had a ten per cent drop in production. Three weeks on from the start of the problem in this flock, production is still low at 84%, below the target figure of 94.5%, with 2% of eggs rejected because of defects. In neither flock was there serological evidence of infection with the viruses associated with egg drop syndrome or infectious bronchitis.

Other Species

Athlone identified Damalinia caprae (biting louse) in a skin scraping from a goat that had shown pruritis over a two-week period.

Limerick isolated Streptococcus equi equi from a swab taken from a mandibular abscess of an eight-year old pony.

Two fancy pigeons were submitted to Limerick from a pigeon loft in Clare. Both had a short history of inappetance and poor form. One showed hepatitis from which Streptococcus bovis type 1 was isolated. The other showed lesions of septicaemia from which Salmonella typhimurium was isolated. The owner was warned about the zoonotic risks associated with this pathogen.

CAPTIONS FOR PHOTOS

Figure 1 “Calf enteric pathogens identified by the RVLs during April”

Figure 2 “Pyloric ulcer in a calf – photo Pat Sheehan”