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May 2010 RVL Monthly Report

Cattle

The first cases of Bovine Neonatal Pancytopaenia were diagnosed in the RVLs during April and May.  Cork were the first to diagnose the condition with three cases,  Kilkenny had one case while Sligo had two cases.  Typically, the clinical signs in young calves can include excessive bleeding from small abrasions of the skin or even from injection sites and the passing of large clots of blood in the dung. Affected calves normally have a high temperature and become rapidly depressed. In the majority of cases, death follows within 24-48 hours (mortality of about 90% is commonly reported). Aggressive veterinary treatment, including blood transfusions normally providing only a temporary respite for the animal. On post-mortem examination of affected calves, significant damage to the bone marrow has been consistently reported. The bone marrow is responsible for producing the blood cells ¿ red blood cells responsible for transporting oxygen, white blood cells which play a role in protection against infection and platelets which are responsible for blood clotting. Of these three, the platelets are most severely affected giving rise to the typical clinical signs of poor clotting and widespread bleeding in the calf.

Submissions of calves exhibiting disproportionate dwarfism or those with angular limb deformities continued in May in Athlone, Sligo and Kilkenny. Most were born to Continental bulls, although Kilkenny saw 6 dwarf calves from one 250-cow Friesian dairy herd (Figure 1). Kilkenny also saw cases born to Brown SwissX heifers crossed with a Friesian bull in another herd. As the occurrence of these cases is believed to be associated with the exclusive feeding of pit silage indoors coinciding with the first trimester of pregnancy, many of these cases are only apparent late in the calving period. The introduction of 25% of the DM in the diet from non-silage sources during the housing period has been found to be effective in the controlling the occurrence of new cases in problem herds.

Dwarfism in a Friesian calf

Figure 1 Dwarfism in a Friesian calf (photo Donal Toolan)

Dublin examined two Charolais calves, one stillborn and one which died shortly after birth.  The herd reported 20% losses in calves this year due to deformities including short legs, weakness, susceptibility to infection and stillbirths. The stillborn calf had arthrogryposis, while the second calf had a cleft palate, a 1cm diameter ventricular septal defect, a short corkscrew tail and small ears. The findings and herd history suggest a diagnosis of a syndrome of arthrogryposis and palatoschisis (SAP) of Charolais cattle, an autosomal recessive hereditary disease causing a range of deformities. Pedigree analysis is required to determine whether the lineage of cases in this farm are consistent with SAP or a similar condition.

Enteritis continued to be regularly diagnosed in calves in the various RVLs.  Like in previous months hypogammaglobuinaemia continued to be a very significant predisposing factor.  Moderate to severe burdens of cryptosporidium were found in several calves less than one week of age presented to Athlone with acute enteritis. The prolonged housing period would have contributed to the build up of significant burdens in calf pens, particularly where calves of different ages were housed together.

Most of the RVLs encountered several cases of lead poisoning during May.  Athlone identified high lead levels in the kidneys of a one month old calf with a history of roaring and incoordination.  In another case, three 14 month old heifers died from lead poisoning after they had access to a field where a farmer had dug up some rubble which contained a lead battery.  Lead poisoning was diagnosed by Kilkenny in a yearling heifer with a history of blindness.  Sudden death is also a common presentation.  Sligo recovered a piece of bale wrap (60cm by 20cm) from the rumen of a calf with lead poisoning.  Lead continues to be one of the most common poisons encountered among cattle.  Anecdotally it seems to be most common during May. Lead poisoning can be avoided by the proper disposal of batteries.  Should a battery enter silage machinery or diet feeders, there can be devastating consequences

All the RVLs encountered an increase in the numbers of clostidial cases seen in May.  An extensive dry and gassy haemorrhagic lesion within the quadriceps muscle group of the right hind limb was discovered in a six week old calf with a history diarrhoea and "fitting" presented to Athlone. 

Dublin diagnosed botulism in two suckler cows, which died one week after poultry litter was spread adjacent to where they were grazing.  Both animals showed ataxia, weakness, drooling, low temperatures (37 ºC) and died within 36 hours of becoming sick. 

Severe pneumonia with consolidation and small abscess formation/bronchiectasis in all of the lung tissue of a ten week old calf presented to Athlone. Pasteurella multocida was isolated from affected tissue. Pasteurella multocida is usually a secondary infection following a primary viral or other insult to the respiratory tract but can also be a primary pathogen. Kilkenny diagnosed several cases of pneumonia caused by Pasteurella multocida during the month.  Necrotising pleurisy and fibrinous pericarditis due to Pasteurella multocida were diagnosed by Dublin in a one-month-old suckler calf. 

Terminal ischaemic necrosis was diagnosed by Athlone in a ten week old calf with bilateral necrosis of the distal parts of the hind limbs. There was a sharp demarcation between vital tissue and necrotic tissue proximal to the metacarpophalangeal joints.  This is a known sequel of Salmonella dublin septicaemia and ergot poisoning. A significant Salmonella titre was recorded on serology from this calf.

Cork diagnosed ragwort poisoning in four weanling from a batch of 22 animals.  All had marked abomasal oedema. Starvation and emaciation was diagnosed by Dublin in a two-week-old Friesian calf which had been given oral electrolytes exclusively for five days for the treatment of scour.  Large numbers of coccidial oocysts were detected in two emaciated and severeley dehydrated ten-week-old friesian/holstein calf carcases submitted to Athlone. Chronic fascioliasis was diagnosed by Dublin in recumbent adult dairy cows, soon after calving which were not responding to calcium and magnesium treatment. Kilkenny found severe oedema of the abomasal folds in two very thin yearlings with a history of weight loss.  Faecal samples contained 1300 and 6000 strongyle eggs per gram, leading to a diagnosis of Type II ostertagiasis.

Sligo found a profound selenium deficiency in dry suckler cows in a herd where there 20% morbidity and mortality.  Calves failed to respond to intensive fluid and antimicrobial therapy.  Mineral supplementation in the herd consisted of a single drench in December.  This case clearly showed the requirement for more prolonged dry cow supplementation. 

Sheep

Streptococcus bovis was cultured by Dublin from the foetal membranes, liver and abomasal contents of an ovine foetus from a flock with a 10% abortion rate in a group of 105 unvaccinated hoggets.  Brown circular lesions were seen in the intercotyledonary areas which corresponded to suppurative inflammation and vasculitis associated with bacterial colonies.  Streptococcus bovis is reported to cause sporadic abortions in cattle with no reports in the literature of it causing abortion in sheep.

Sligo saw several cases in lambs and calves in May where there was terminal pneumonia due to Mannheimia haemolytica (Pasteurella multocida in 2 calves) and an underlying segmental haemorrhagic enterocolitis due to coccidiosis(Figure 2). The histories were similar. The animals would present with dysentery but not appear too sick then would become rapidly depressed and die on the following or subsequent days.

Terminal pneumonia in a lamb

Figure 2 (3326) Terminal pneumonia due to Mannhaemia haemolytica in a lamb (photo Colm O' Muireagain)

Coccidiosis was diagnosed in two five week old lambs submitted to Athlone from a flock which had experienced almost 25 deaths over a few days. Lambs were scouring and exhibited tenesmus. Serum urea and creatinine were extremely high. On histology, kidneys showed nephrosis. Nephrosis is regularly associated with coccidiosis and appears to result from the significant dehydration associated with enteritis. Advice was given to treat the remainder of the flock for coccidiosis.

Clostridium novyi was isolated by Athlone from a 6 week old lamb, found dead. A serum clot was evident in the pericardium which can be indicative of Clostridial infection.

Sligo cultured Staphylococcus aureus from mastitis in two ewes.  Quarters in both ewes were grossly inflamed.  Sligo diagnosed nephropathy in a five year old ram that had wasted.  Sligo diagnosed severe fluke infestation in two ewes from a flock which suffered multiple losses, where management was in transition as a result of a family bereavement.

Avian

Dublin detected gapeworms (Syngamus trachea) in a ten-week-old pheasant and a partridge (Figure 3) that had died from the same rearing location.

Syngamus trachea

Figure 3 Syngamus trachea recovered from a 10 week old pheasant (photo William Byrne)

Porcine

Porcine Dematitis and Nephropathy Syndrome (PDNS) was diagnosed in a fattener pig submitted to Dublin which had multifocal red patch discolouration of the skin and pale enlarged kidneys. Histopathology revealed a glomerulonephritis in kidney tissue and an arteritis in the skin tissue.  This combination of lesions is considered characteristic of PDNS.