April 2010 RVL Monthly Report
A large proportion of the workload of the RVLs in April was investigation of deaths in young calves. Calf enteritis and septicaemia most commonly diagnosed in the calves of less than two weeks of age, as in previous years and with pneumonia cases also accounting for some deaths including those of older calves. Rotavirus, cryptosporidium, Salmonella dublin and coccidial infections in either diarrhoeic calves submitted for post mortem examination or in submitted faecal samples from other diarrhoeic calves. Hypogammaglobulinaemia was a predisposing factor in many of these cases.
IBR virus was detected by PCR in the liver of a six month foetus submitted to Dublin. It had acute multifocal hepatitis and splenitis. Kilkenny cultured Arcanobacter pyogenes from the tongue and lungs in a case of diphtheria in an emaciated six week old calf (Figure 1).
Figure 1 Necrotic lesions in the tongue of a calf with diphtheria (Photo Donal Toolan)
Chondrodystrophic dwarf calves from a number of herds throughout the catchment area were presented to Sligo in April. Their dams were for the most part on a silage only diet, many since last October. Most were fed pit silage. For next year farmers were advised to add hay and or straw into the dry cow diet, so that the cows were not just fed grass silage.
Transposition of the aorta (arising from the right ventricle) was seen by Dublin in a suckler calf which lived for only 2 hours (Figure 2). Other heart defects included ventricular septal defect and patent ductus arteriosus. Kilkenny also found cardiac defects in an eight month old foetus, where there no interventricular septum and both the aorta and the pulmonary artery arose from the right atrium. The same calf also had a lumbar vertebral defect with ankylosis of hind limb joints. Clinical anophthalmus and an atrial septal defect was found in a one-day old calf presented to Limerick. Kilkenny found a congenital bowel deformity causing obstruction in a 3 day old calf with a swollen abdomen. There was a membrane blocking the lumen of the mid jejunum.
Figure 2 Transposition of the aorta, ventricular septal defect and patent ductus arteriosus in a newborn suckler calf (Photo Ann Sharpe)
Omphalophlebitis (navel infection) was a common diagnosis in young calves submitted to Sligo in April. On occasion concurrent joint ill was noted, but concurrent peritonitis was a more common finding. In some cases pleurisy and pericarditis were found. Many had a low ZST reading, which predisposed to them to the condition. Suppurative infection of the navel which ascended through a thickened fibrous umbilical vein into a suppurative focus within the liver was found in a three-week-old Holstein / Freisian calf submitted to Dublin. Kilkenny found navel ill, joint ill and multifocal liver abscessation in a three week calf with a history of fever.
Kilkenny isolated Haemophilus somnus from a one month old calf with fibrino-suppurative pneumonia affecting the whole of one lung. Severe interstitial pneumonia, with syncytial cells and hyaline membranes, due to BRSV was diagnosed by Dublin in a three-month-old calf. Secondary bronchopneumonia due to Pasteurella multocida was also present.
Nephritis was found in a calf presented to Sligo with a history of enteritis. Dehydration and prolonged treatment with non steroidal anti-inflamatories and antibiotics were suspected as predisposing factors.
Kilkenny suspected hypomagnesaemia in a five month old calf that had a seizure and died suddenly. Bone magnesium was low and eye magnesium was marginal. Hypomagnesaemia usually affects rapidly growing calves that are being fed on milk only.
Kilkenny diagnosed bloat in two two-year- old heifers that died suddenly. Eight heifers had been found dead a few days earlier. Rumens contained roughage and localised areas of cereal grains and beet. They were said to be fed on silage only but it transpired that they occasionally got access to concentrate not finished by cows.
Malignant Catarrhal Fever was diagnosed on a blood sample submitted to Limerick from a 14-month old Charolais bullock. The animal had a rectal temperature of 107oF, had corneal opacity and was drooling from the mouth.
Cork diagnosed fatty liver disease in a dairy herd. The clinical history was not that of fat cows. It is thought that some upset had occurred in the diet when the herd had to be housed a second time due to adverse weather conditions.
Four cases of lead poisoning involving three separate farms were diagnosed by Limerick during the month. In the case involving two animals, a broken up battery was discovered in a recently reseeded field.
Sligo investigated an outbreak of ill-thrift in an 80 cow dairy herd. Rumen fluke had been identified a few weeks earlier. However despite treatment the owner was still not satisfied with cow condition. At a farm visit it transpired that the cows were fed poor quality hay for six weeks after drying, during which time they lost a substantial amount of condition. The farmer was advised to keep dry cows on a maintenance diet in future, to regularly monitor body condition and correct if need be. He was also advised to adopt a more vigorous parasite control programme in wet years.
Dublin found intussusception of terminal ileum in a 17 day old charolais calf, which had been at grass with its dam. It had became bloated and depressed over a period of two days antemortem. (Figure 3).
Figure 3 ("Intussusception 2") Incarcerated black and necrotic ileum contrasts with adjacent loop of more normal intestine which is pale pink (photo Colm Brady).
Limerick investigated a problem on a dairy farm involving first and second calvers. Cows typically presented with high temperature, milk drop and depression. A clear nasal discharge was seen in a small number of affected cows. New cases occurred every few days. The animals responded well to antibiotic therapy but the milk yield took some time to recover. This problem had been occurring shortly after turnout on the farm for a number of years. Different combinations of respiratory virus vaccines had been tried but did not seem to have any effect on reducing the incidence of disease. Blood samples (in EDTA) were taken from a number of the recently affected cows. Intracellular parasitic inclusions were seen in many of the white blood cells (mostly neutrophils) in smears examined. These were considered most likely to be Anaplasma phagocytophila, a rickettsial organism carried by the tick Ixodes ricinus. Tick-borne fever tends to be seasonal in occurrence, linked with the feeding activity of the tick vector.
Ovine abortion due to Campylobacter fetus was diagnosed by Dublin. Kilkenny diagnosed toxoplasmosis on foetal serology (1/32) in an aborted lamb.
Sligo encountered several cases of clostridial endotoxaemia in lambs. The lambs tended to be strong and growing well. In one such lamb there was a pericardal effusion, hyperplasia of the mesenteric lymph nodes and rapid autolysis of the kidneys. Clostridium perfringes was detected by Cork in the abdominal fluid of a well conditioned lamb. Pulpy kidney was suspected.
Kilkenny suspected, but did not confirm, Border Disease in a deformed lamb with a tiny brain, an undershot mouth, anoptalmus and eye sockets very close together. The wool was long and coarse.
Severe fibrinous pneumonia and pericarditis due to Mannheimia haemolytica was diagnosed by Dublin in a one-month-old lamb. The lamb presented with a temperature of 40.3°C, nasal discharge, a hunched stance, abdominal breathing and was easily caught in the field. Fifteen other lambs died during the outbreak. The ewes had not been vaccinated against pneumonia during pregnancy.
Dublin detected puncture wounds that penetrated the skin and thorax, along with three fractured ribs, in a week old lamb that was found dead. No predator was reported and the carcase had not been scavenged.
Dublin found granulomas, containing numerous acid-fast bacilli, in multiple locations in an emaciated dead badger. It had been found dead on the farm which had a large outbreak of tuberculosis in cattle in the previous year.
A buzzard (Buteo buteo) and two magpies (Pica pica) from the same field in East Cork had alpha-chloralose detected in the gizzards.
Kilkenny suspected anticoagulant poisoning in a free range cockerel. There was haemorrhage in the wattles and bluish staining of the crop contents.
Dublin diagnosed fibrinous peritonitis and fibrous pleuritic adhesions in a sixteen-week-old gilt from a herd that had increased mortality many of which were found to have died suddenly. Streptococcus suis was isolated from the fibrinous peritoneal tags and from many other tissues indicating a diagnosis of S. suis septicaemia.
Dublin also detected septicaemia due to Salmonella typhimurium and Streptococcus suis type II which caused sudden deaths in six-week-old weaner pigs (Photo Ann sharpe).
Kilkenny diagnosed bowel oedema on gross findings in four eight week old pigs, that had died suddenly. Oedema of the stomach wall and the forehead were seen to varying extents in the pigs. Haemalytic E. coli and Streptococcus suis II were isolated.
Kilkenny isolated Salmonella dublin from faeces of a two year old horse that had lost weight, had poor appetite but no diarrhoea. The isolation was repeated two weeks later. In the third week, the horse had put on weight and was eating, without having received any treatment for the salmonellosis.
Sligo diagnosed leptosporosis by in a year and a half old dog.
Athlone identified on histopathology a large number of oxalate crystals in the renal tubules of a two year old dog with a history of "difficulty walking and fitting". Ethylene glycol (antifreeze) toxicity was considered the most likely cause for these findings.