Findings in the Regional Veterinary Laboratories

August 2004

Some Findings:-

Neospora caninum abortion, Blackleg, Respiratory Syncytial Virus (RSV), lungworm infestation, cerebrocortical necrosis, low serum copper values and focal abscess in optic chiasma in cattle;

Listeria innocua , parasitic gastroenteritis, Coccidiosis, Sarcosporidiosis and Copper toxicosis in sheep;

Ragwort Poisoning in horses; Bumble foot, in a broiler breeder flock and yolk sac infection with concurrent Salmonella Indiana in Turkey chicks


Dublin diagnosed Salmonella dublin abortion in four herds. Neospora caninum was identified as a cause of abortion in one herd. Antibodies to Neospora caninum were detected in five of six sera submitted to Dublin from cows in a herd with a history of Neospora caninum abortion. The original abortion outbreak in this herd was associated with feeding grass mowed from a field used to exercise greyhounds directly to cows.

Cerebellar hypoplasia was evident on microscopic examination of two foetuses submitted from different herds that had undergone in utero growth retardation. Athlone reported the birth of weak calves, a high incidence of neonatal diarrhoea and infertility in the breeding stock associated with very low serum copper values in the cows.

A two-day-old calf was presented to Kilkenny with a history of neonatal diarrhoea. Severe enteritis was noted on gross examination. The Zinc Sulphate Turbidity Test (ZSTT) for immunoglobulins gave a result of twelve units, which is well below the recommended minimum of thirty units. Salmonella dublin was isolated on culture from the intestine.

Salmonella dublin was also isolated by Sligo from lung tissue of a two day old calf that showed evidence of a bronchopneumonia. Athlone isolated Salmonella typhimurium from a young calf showing chronic enteritis

Kilkenny diagnosed several cases of Blackleg (Clostridium chauvoei) during the month. Some cases had the typical emphysematous haemorrhagic myositis of the skeletal muscle but in some cases the lesions were restricted to the cardiac muscle and/or the pericardium (see figure 1).

Kilkenny diagnosed parasitic gastroenteritis on a number of occasions during the month. The highest strongyle egg count recorded was 14,100 eggs per gram (epg) of faeces. High strongyle egg count puts animals under severe stress and other opportunistic pathogens e.g. Pasteurella spp . or Salmonella spp . can proliferate and cause clinical and fatal disease.

Kilkenny identified Respiratory Syncytial Virus (RSV) on Fluorescent Antibody Test (FAT) in a number of pneumonia cases presented during the month. The classic lesions for RSV pneumonia are pneumonia with emphysema and large bullae formation. However, concurrent lungworm infestation (see figure 2) and secondary bacterial pneumonia are often common findings. One particular case that was RSV positive also had lungworm present and a strongyle egg count of 14,100 epg. RSV is a very fragile virus and it is essential that very fresh cases be submitted for PME if the presence of RSV is to be confirmed. Post mortem examination at Sligo on a nine-month-old bovine heifer that died showing signs of respiratory distress revealed a severe pneumonia with multifocal areas of emphysema and generalized oedema. There was a severe haemorrhagic bronchitis and numerous adult lungworms were present in the trache a.

The carcass of a six-month-old heifer was presented with the ‘splits’ at the Sligo RVL for post mortem examination. There was extensive damage to the musculature and tendons on the median aspect of both hindlimbs, in particular, to the pectineus, vastus medialis, obturator and tendons in the region of the acetabulum. The fossa of the acetabulum was filled with blood stained fluid and fibrin. The possibility of a primary lesion in the CNS was investigated and histological examination of brain tissue confirmed

cerebrocortical necrosis . Sligo diagnosed polioencephalitis of unknown origin in a weanling bullock with 'CNS Recumbancy'. The animal was euthanised after showing no response to conventional therapy.

Streptococcus bovis type II was isolated from the CSF and the intestinal contents were sterile as a result of therapy.

A four-month old suckler calf with a history of sudden death was submitted to Limerick RVL. Post-mortem examination showed severe congestion of the viscera, widespread petechiation, and skeletal muscle pallor.

No other lesions were seen and routine bacteriology yielded no significant pathogens. Biochemical analysis of a section of the fifth rib gave a reading of 39.10% Calcium and 0.26% Magnesium. The

Calcium:Magnesium ration of 150:1 was suggestive of a severe Magnesium deficiency. The normal ratio should be in the region of 60:1. Deficiency is indicated when the ratio rises above 90:1. Athlone reported very low serum copper values in four out of seven samples submitted from weanlings showing ill-thrift and poor coats.

A severe fibrinopurulent meningitis due to Arcanobacter (Corynebacterium) pyogenes was the cause of death in a 15 month old Bull that died suddenly and was submitted to Sligo for PME. A change in behaviour was noticed six weeks earlier when it began to separate from the group. The first clinical sign was a unilateral conjunctivitis, and petechial haemorrhages were evident on the sclera and conjunctiva. A temperature of 103º F was recorded. Antibiotic and anti-inflammatory treatment commenced and the eye

‘returned to normal’. Two weeks later the clinical picture rapidly deteriorated. The bull was found in lateral recumbency and had a temperature of 98º F. Gross examination of brain tissue revealed a significant focal abscess located in the area of the optic chiasma.

Arcanobacter (Corynebacterium) pyogenes was isolated from brain tissue. Athlone reported Salmonellosis in a dairy herd. A number of animals were affected and three young cows became chronically ill and subsequently died. Salmonella dublin was isolated from faecal samples.


Sligo reported that Listeria innocua was isolated in a heavy pure growth from the liver and spleen of a twelve-week-old lamb, which had been found dead by the owner. Post mortem examination of the lamb had shown classical gross lesions of tick pyemia/septicaemia. At necropsy there was a grossly enlarged liver containing multiple pale foci, a grossly enlarged spleen with numerous subcapsular ecchymotic haemorrhages and sub-serosal petechial haemorrhages in the pleural and peritoneal cavities. As L. innocua is an unusual isolate and recognised only as an opportunist pathogen. This was the only death in the flock at the time of submission and there have been no further losses since

Kilkenny diagnosed parasitic gastroenteritis on several occasions. High strongyle egg count puts animals under severe stress and allows other opportunistic pathogens to multiply. One four-month-old lamb with severe enteritis had a strongyle egg count of 3,700 eggs per gram (epg) of faeces, 1,900 Strongyloides epg, and 200 Nematodirus epg. It also had lesions typical of Orf and Haemophilus pneumonia. 27% of all ovine faecal samples submitted to Kilkenny had strongyle egg counts of >1,000 epg and 9% had a count in excess of 10,000 epg. Lambs suffering from emaciation and diarrhoea that were repeatedly dosed with anthelminthics and coccidiostats were diagnosed with Coccidiosis by Dublin. Villous atrophy was a prominent feature in these lambs one lamb also had lesions consistent with sarcosporidiosis.

A sheep submitted to Cork with generalised jaundice, showed on post-mortem examination an icteric and firm liver with an accentuated lobular pattern and kidneys with bronze appearance. Copper toxicosis was suspected and liver copper levels turned out to be 100 times the normal range.


Athlone reported Ragwort Poisoning in two horses. One was a ten-year-old pony showing clinical evidence of the intoxication. Blood tests showed raised liver enzymes and low serum albumin values. The second case was a stallion that presented clinically with subcutaneous oedema of the abdomen and that failed to respond to treatment. Post mortem examination showed ascites and an enlarged heart. Liver histopathology showed cirrhosis and megalocytosis to establish a diagnosis..


Gumboro was diagnosed by Dublin in broilers from two flocks where poor thrive was a feature. Sligo diagnosed rupture of the gastrocnemius tendons in seven-week-old broiler chickens. Only one unit of birds was affected and the condition has not reappeared. Bumble foot, swelling of the foot with Staphylococcus aureus involvement, was confirmed by Cork in a broiler breeder flock. S. aureus had also been isolated some weeks earlier from birds in the flock with synovitis of the gastrocnemius tendons. A number of chickens from different broiler units were submitted to Limerick RVL during the month. The chickens were submitted from the slaughter unit when it was noticed that there were a high number of jaundiced birds.

Histopathological examination of some of the jaundiced livers showed changes consistent with aflatoxicosis.

It is likely that all of the units were being supplied feed from the one source. We believe that one of the ingredients contained in the feed may have contained a quantity of the mycotoxin.

Yolk sac infection with concurrent Salmonella indiana infection was the cause of high mortality in turkey chicks investigated by Cork. Deaths in juvenile pheasants, just recently received by a shooting club, were found by Cork to be due to aspergillosis. The source was ascribed to mouldy hay to which the birds had been exposed at the rearing premises. Large numbers of Syngamus trachea nematodes were found blocking the airway of a pair of pheasant submitted to Cork from a flock with symptoms of dyspnoea.


Figure 1 - Clostridial Pericarditis / Myocarditis – photo Pat Kelleher

Figure 2 –Parasitic bronchopneumonia – photo Pat Kelleher