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June 2010 RVL Monthly Report

Cattle

Pneumonia was diagnosed in a number of "sudden death" cases in calves submitted to Sligo. Mannheima haemolytica was cultured from the lungs of several of these cases, and all had cranioventral consolidation of the lungs consistent with bronchopneumonia.  Dublin diagnosed pneumonia in calves submitted from several herds. Pathogens detected included Pasteurella multocida, Arcanobacter pyogenes and Mycoplasma bovis, while lesions consistent with Bovine Respiratory Syncytial Virus (BRSV) were detected in a number of bovine pneumonia  cases submitted to Dublin. Athlone diagnosed a case of pneumonic and septicaemic mannheimosis in a two-month-old calf which displayed diffuse fibrinous serositis; Mannheima haemolytica was isolated from affected tissue. Cork diagnosed calf diphtheria in two separate herds, one of which led to pneumonia.

Lead poisoning, particularly in calves, was a frequent finding in June.  Kilkenny reported several such cases. One example was a three-and-a-half month old calf, which had a history of nervous fitting and pyrexia ante-mortem.  Analysis of kidney revealed the presence of toxic levels of lead. This was the second case of lead poisoning in the same herd within a month. Careful disposal of waste material and especially potent sources of lead, such as lead batteries, was advised. Sligo also reported several cases of lead poisoning during the month - in one outbreak 13 calves died, while six calves died in another. Both ouitbreaks involved lead accumulator batteries and battery plate remnants were detected in reticular honeycombs on post mortem. Athlone found toxic levels of lead in two bullocks from a single herd, both of which were found dead, and in a separate investigation, a seven-week-old calf which was described as "walking in circles" ante-mortem was found to have toxic levels of lead samples of fresh kidney.

Sligo cultured Salmonella dublin from two one-month-old dairy calves, which presented with diffuse catarrhal enteritis, lymphadenopathy and dehydration on post mortem. Athlone made a presumptive diagnosis of salmonellosis in the case of a three-month-old calf with lesions of terminal dry gangrene on all four limbs. Salmonella dublin had been isolated from a similar case from the same herd a short time before. Athlone isolated Salmonella dublin from tissues from a two-week-old calf which had died suddenly after feeding, while Kilkenny isolated Salmonella dublin from an emaciated five-week-old calf which had a history of forelimb paresis. This calf had osteomylitis of the cervical spine, the body of vertebrae C6 was necrotic and compressed from anterior to posterior. A follow up investigation uncovered a very high mortality rate in calves in the herd of origin with a loss of twenty-five calves out of the eighty-five born in spring. All twenty- five had developed diarrhoea, twelve of these also developed paresis.

Kilkenny isolated Salmonella spp. from adult cows also. These cows frequently had diarrhoea, which in some cases was haemorrhagic. Liver fluke eggs were sometimes detected in the faeces of these diarrhoeic cows and in the case of one cow, which had suffered from acute watery diarrhoea, both liver fluke and rumen fluks eggs were detected; no other pathogen was found. Cork also detected liver fluke eggs in bovine faecal samples on several occasions.

Athlone diagnosed a case of mucosal disease in a 15-month-old heifer, which had a history of pining and diarrhoea. Post mortem examination of this animal revealed multiple small ulcers in the gastrointestinal tract while Bovine Viral Diarrhoea Virus (BVDV) antigen detection in tissues was confirmatory for mucosal disease. BVD antigen was detected in tissues of a 14-month-old heifer with severe acute diarrhoea ante mortem, while Kilkenny also investigated a case of ill-thrift and diarrhoea in a group of six young calves approximately three months of age and found that one was infected with BVDV.

Athlone diagnosed parasitic pneumonia (hoose) in a bullock; on post mortem examination there was a diffuse pneumonia and a heavy burden of lungworms was found in the bronchi and lower airways.  Kilkenny diagnosed hoose pneumonia on two separate farms. 

Athlone reported atresia of the terminal jejunum in a three-day-old Charolais calf, which had been found dead, while Sligo reported several cases of intestinal volvulus and torsion in young suckler calves. Kilkenny also found several cases of intestinal incarcerations and in one particular instance a cow and a calf were submitted to Kilkenny on the same day from the same premises, and a diagnosis of mesenteric torsion was made in the case of both.

Other interesting cases included systemic mycosis in a three-month-old calf, which had been treated for pneumonia and diarrhoea. On post mortem examination of this calf by Kilkenny, multifocal necrotic lesions were found in the liver (Figure 1), lung, spleen and reticulum, while histopathology confirmed the diagnosis. Athlone saw a case of congestive heart failure in a six-year-old cow, which was secondary to traumatic reticuloperitonitis.  Post mortem findings in this case included fibrinopurulent pericarditis, ascites, hepatic enlargement and fibrosis and the presence of a 10cm-long wire in the pericardial sac. Athlone also saw a case of septic polyarthritis in a week-old calf. Joint spaces were filled with turbid fluid and fibrin, and there was also marked pulmonary oedema and congestion with pleural haemorrhage. Escherichia coli was isolated from tissues and a diagnosis of neonatal colisepticaemia was indicated.

Multifocal liver necrosis

Figure 1: Multifocal necrosis in the liver of a three month old calf with systemic mycosis. Photo: Donal Toolan.

Abortion/Stillbirth in Cattle

Kilkenny diagnosed neosporosis in two bovine foetuses which were abortewd at five months gestation from the same herd. This diagnosis was based on maternal and foetal serology in one case, and maternal serology and foetal histological changes in the second case.  Dublin also diagnosed neosporosis in a seven-month-old aborted bovine foetus, on the basis of positive maternal and foetal serology, and foetal histological changes which included multifocal non-suppurative encephalitis and non-suppurative myocarditis.  Salmonellosis was diagnosed by Kilkenny in a case of bovine abortion, which occurred a few days after a cow on the same premises died of septicaemic salmonellosis. Kilkenny also diagnosed congenital joint laxity and dwarfism in a stillborn calf.  This diagnosis was also made in the case of a four-day-old calf from a different herd. In both cases the long bones of the limbs were shortened.

Sheep

Parasitism of  grazing sheep and lambs was a regular finding. Sligo diagnosed fasciolosis in a five-year-old ewe, which had liver fibrosis, while in a separate herd, Sligo found a heavy strongyle burden of 15000 eggs per gram of faeces in an adult ewe with chronic ill-thrift. Athlone diagnosed severe acute prepatent parasitic enteritis, consistent with nematodirosis, in a lamb which was found dead. Though eggs were not found in the faeces or watery intestinal contents, a large numbers of immature roundworms were found in the intestinal contents. Dublin diagnosed nematodirosis in a lamb that  died from a watery scour. Several other lambs had also died from the same clinical symptoms.

Other findings included ruminal acidosis in a three-month-old lamb submitted to Athlone, which had consumed a large quantity of cereal grain antemortem. Athlone also diagnosed a case of copper poisoning in a lamb, which was icteric, had dark-coloured kidneys and urine, and had toxic levels of copper in fresh samples of liver and kidney.  Kilkenny found abscessation of the body of the first lumbar vertebra in a three-month-old lamb with posterior paresis (Figure 2).  The abscess  on the spinal canal, compressing the spinal cord and Staphylococcus aureus was isolated from the site. Kilkenny diagnosed salmonellosis in a three-month-old lamb that died suddenly, with Salmonella dublin isolated from a range of tissues. Cork dealt with a suspect Foot-and-Mouth Disease case in a lamb with ulcerations in oesophagus and on the tongue, but investigation established that the lesions the result of dosing gun injuries. Histological examination of fixed lung from a ewe with pneumonia which was sent to Kilkenny revealed histopathological changes consistent with Jaagsiekte/Sheep Pulmonary Adenomatosis (SPA).

Abscessation of vertebra

Figure 2: Abscessation of the body of the first lumbar vertebra in a three month old lamb with posterior paresis. Photo: Donal Toolan.

Dublin investigated multiple deaths in a group of three-month-old lambs on grass. Findings were similar in the two lambs submitted for post mortem examination. Though the carcasses were fresh, the kidneys were autolysed, there was pulmonary oedema, excess pericardial fluid and marked intestinal congestion in evidence while each rumen contained large quantities of lush grass. Histopathology revealed numerous short, fat, gram-positive rods adherent to the mucosa of the small intestine (Figure 3). A presumptive diagnosis of Clostridium perfringens type D enterotoxaemia was made based on the post mortem findings, and the clinical history of a short illness and rapid death.  The flock had not been vaccinated against clostridial disease.

Gram positive rods in intestine

Figure 3: A multitude of gram positive rods adherent to the lining of small intestinal villi in a three month old lamb (gram stain; magnification x 40). Photo: Colm Brady.

Birds

Sligo diagnosed a synovial cyst compressing the distal spinal chord at the level of the synsacrum in a six-week-old pullet with hindlimb paralysis. Salpingitis was diagnosed by Sligo in a two-year-old laying hen. The uterus was impacted by with caseous necrotic material which contained shell fragments.  Sligo also identified visceral coccidiosis in a penhen based on histopathology; enteritis was also evident in this case.  Kilkenny diagnosed candidiasis in a six-week-old gosling with a history of choking. The gosling was found to have pneumonia and airsacculitis. Candida spp. was isolated.

Llama

Tuberculosis caused by Mycobacterium bovis was diagnosed by Dublin in a seven-year-old male llama, one of two pet llamas on the premises. The pre-scapular, mediastinal and mesenteric lymph nodes were enlarged and contained firm cream coalescing nodules of up to five centimetres in diameter. Similar nodules were seen in the lungs (Figure 4), liver, diaphragm, tracheal mucosa and omentum.

Nodules in lymph nodes and lung

Figure 4: Firm cream nodules in the mediastinal lymph nodes and lung of a seven month old llama. Photo: Ann Sharpe.