January 2010 RVL Monthly Report
Most of the common agents associated with abortion in Ireland including Salmonella Dublin, Arcanobacterium pyogenes, Neospora caninum, Listeria monocytogenes, Bacillus licheniformis, Campylobacter spp. and bovine viral diarrhoea virus (BVDV) were detected in aborted foetuses submitted to the RVLs during the month. Inappetance and lethargy were clinical signs among cows in one Salmonella dublin related outbreak investigated by Dublin. Sligo detected BVD virus in a foetus from a suckler herd where there had been vaccination programme for a number of years. The herdowner had complained of ongoing high levels of calf mortality (circa 20%) in recent years. BVD virus was identified in live animals in the herd.
Figure 1: Vertebral deformity in a single full term calf (Photo - Donal Toolan)
Athlone observed that fat deposits in many bucket reared diarrhoeic calves were greatly depleted at post mortem. This suggests that the calves were energy deficient due to inadequate feeding of milk. This can occur when milk is withdrawn from calves with diarrhoea. Calves with diarrhoea should continue to be fed milk to provide them with energy while receiving oral fluid therapy to treat dehydration. Starvation along with the increased energy demand placed on calves by cold weather can rapidly exhaust a calf's fat reserves resulting in higher death rates in outbreaks of diarrhoea.
The onset of the anticipated seasonal increase in neonatal calf enteritis as "spring-calving" dairy and suckler herds commenced from mid-January. Poor passive immune transfer as evidenced by low ZST readings was regularly noted by all the RVLs during the month. Some of these cases had evidence of advanced septicaemia with pleurisy, pneumonia, pulmonary oedema, splenomegaly, omphalophelblitis, peritonisis and joint ill. Acranobacter pyogenes, E. coli and Streptococcus dysgalactiae were isolated respectively from such cases submitted to Dublin (peritonitis), Kilkenny (navel abscess and from pneumonic lung ) and Sligo (joint ill). Athlone detected Rotavirus and Coronavirus in faeces from a three day old septicaemic calf, which had evidence of diffuse fibrinous peritonitis and pleural ecchymoses.
Kilkenny found a 360 degree intestinal torsion in a calf had been noticed kicking its abdomen the previous evening. This was the second calf to die of colic in a short time on the farm. Sligo detected BHV 1 virus in a two month old suckler calf, where there was severe pneumonia and pleurisy. Kilkenny diagnosed Salmonella septicaemia in a ten day old calf bleeding from its anus. There were multiple bleeding points on the mucosa of the abomasum and urinary bladder, with a 2 cm diameter x 20 cm long clot in the rectum. Dublin examined four, two to three-week-old home-bred dairy calves where twelve calves had died. Fibrinous or fibrinosuppurative pleuropneumonia, pericarditis, omphalophlebitis (navel infection), a perforating abomasal ulcer,multiple hepatic abscesses and a severe glossal ulcer were among the lesions.
Dublin detected Clostridium chauvoei in the muscles of the shoulder, neck and thigh of a Belgian Blue yearling. Sligo also diagnosed blackleg from the forequarter muscles of an 18 month old charolais bullock.
Kilkenny found extensive chronic pneumonia in many weanlings in poor condition from several farms. On one farm, 15 of 40 weanlings dead, while many others were thin. Many had been purchased as calves. Affected animals were often stunted and not thriving. Arcanobacter pyogenes was commonly isolated from these cases, and lung consolidation varied from 65% to 90%. The condition has to be long standing for this level of tissue to be affected. Concurrent liver and rumen fluke and stomach worm infestation is commonly diagnosed in these cases.
Botulism was strongly suspected in a 10 month old weanling submitted to Athlone, with a history of recumbency and frothing at the mouth and contact with poultry. Diagnosis of botulism is very difficult and relies on the history and ruling other diagnoses out. Botulism deaths are usually caused by respiratory failure. Therefore the pulmonary congestion and oedema found in this case would be consistent with botulism.
Sligo cultured Arcanobacter pyogenes from a myocardial abscess and vegetative endocarditis in a 9 year old cow with a history of abortion, pulmonary problems, body condition loss poor response to to therapy and sudden death. (Figure 2)
Figure 2: Myocardial abscess in a 9 year old cow (Photo - Colm 0'Muireagain)
Athlone suspected water deprivation due to frozen pipes led to the deaths of 18 of 25 beef bulls in a shed over a very short period during the very cold weather. In another bull beef production unit in the midlands Athlone diagnosed rumenal acidois (2 cases) and abomasal ulceration/perforation and peritonitis (1 case).
Kilkenny diagnosed Salmonella dublin infection in cows on several different farms. Salmonella dublin was cultured from a 6 year old cow, with a bloody vagina discharge, from a farm where sick cows and abortions were reported. Salmonella dublin was also diagnosed on another farm in two cows, dried off a week earlier, that were anorexic, afebrile, with severe weight loss over a few days and some blood in the rectum.
Rumen and liver fluke were identified in a number of faeces samples submitted to the various RVLs during the month. Cork found acute and chronic fasciolisis in association with Salmonella dublin infection in an adult dairy cow from a 60 cow herd where seven had died. Kilkenny found a severe fluke infestation in an emaciated 22 month old bullock in association with serous atrophy of the perirenal fat and oedema of the mediastinum (Figure 3).
Figure 3: Severe chronic liver fluke infestation in a bullock (Photo - Donal Toolan)
Sheep submitted to Athlone, Dublin, Sligo and Kilkenny from different holdings which were found dead were found to have significant liver fluke damage with marked perihepatitis and myriad migratory tracts. Some of the ewes were also found to have a significant rumen fluke burden. In some cases there was evidence of both chronic and acute fasciolosis where regular dosing had been undertaken. Rapid reinfection due to high numbers of miracidia on pasture, underdosing or possibly anthelmintic resistance were suspected as potential risk factors. Salmonella dublin was also isolated from a number of such affected ewes. Acute fascioliasis was diagnosed by Dublin in a pedigree Lleyn ewe on an organic farm. The ewe had been treated for coccidiosis based on previous parasitological investigations, when there was no evidence of fascioliasis. This case highlights the need to autopsy sheep from organic flocks to rule out prepatent parasitic conditions. Sligo diagnosed fascioliasis, parasitic gastroenteritis and cobalt deficiency in three eight month old lambs from a flock where 15 cohorts had died in the previous week. The lambs examined were extemely anaemic and in poor condition with fibrosed livers, ascites and hydrothorax.
Kilkenny isolated Campylobacter foetus from aborted foetuses from two farms, while toxoplasmosis was commonly diagnosed in aborted lambs in the various RVLs. Marked hyperplasia of the caudal lung lobe (14cm x 8cm x 8cm), displacing the heart and lungs cranially was observed in a stillborn lamb submitted to Dublin. The cause of the dramatic hyperplasia of what seems to be the caudal lung lobe is unknown, but blocking the trachea can cause hyperplasia of the lungs in foetal lambs.
Athlone investigated an outbreak of ewe mortality (6%) and abortion (10%) in a 450 ewe flock affecting both indoor and outdoor managed ewes. Approximately 25% of the ewes showed evidence of previous fluke infestation. Salmonella dublin was cultured from both the ewes and lambs. Antibiotic therapy and vaccination were among the control options discussed with the referring veterinary surgeon. Dublin diagnosed Salmonella dublin as the cause of an abortion storm affecting 20% of the housed part of a pedigree Texel flock. As other batches of pregnant ewes with later lambing dates were due to be housed, strict biosecurity measures were advised to avoid cross-infection. Kilkenny isolated Pasteurella multocida from a recently lambed ewe with metritis and peritonitis.
Athlone diagnosed acidosis in two ewes that died suddenly with grainy, sweet smelling "porridgy" ingesta with a low rumen pH were found in two acidotic ewes.
Sligo diagnosed "Pregnancy Toxaemia" in an overly conditioned goat from a herd that had already lost one pregnant nanny with similar symtoms. Toxoplasmosis was diagnosed by Kilkenny in two almost full term foetuses and a mummified foetus from a newly established goat herd.
Mannhaemia haemolytica was isolated from the sinus and lungs of a hen presented to Sligo. Dublin diagnosed E. coli-associated egg peritonitis in layers from three flocks, where a slight increase in mortality but where no decrease in production was reported.
Streptococcus suis septicaemia was diagnosed by Dublin in one weaner pig from a herd reporting increased losses in weaner pigs. Two cohort pigs had severe necrotic enteritis of the large intestine with consequent localised peritonitis from which Salmonella typhimurium was isolated
Equine and Assinine
An old (40 years) donkey with a history of acute lameness in a single forefoot was euthanased. Kilkenny found an abscess under the sole of the affected foot. Sligo diagnosed "Infectious Hepatic Necrosis" ('Black Disease') in a 7 year old pony mare found dead. Adult fluke were present in the liver and histopathologically the lesion resembled a fluke tract surrounded by intensely fibrinous coagulative necrosis and an inflamatory cell margin which contained many Bacilli.
Sligo found a piece of plastic in the stomach of a dog with a history of vomiting.