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VLA Oct Update - Respiratory Diseases Persistant

16 February 2011

UK - Parasitic bronchitis (husk) causes a number of respiratory diseases in cattle, according to the Veterinary Laboratory Agency's October report.

Reproductive diseases

Abortion

Preston also diagnosed Q fever as the cause of a single abortion in a110 cow herd. Appropriate advice was given regarding the disease in animals and humans and measures to avoid human infection.

Preston identified Salmonella Dublin as the cause of seven abortions in a group of 70 milking cows and Starcross diagnosed five cases, four in dairy herds and one in a beef suckler herd. In all cases the abortion occurred in mid to late gestation and in one case a severe systemic illness was described in the affected cow.

Alimentary tract diseases

Abomasal Volvulus

A recently purchased milking heifer was diagnosed with right displacement and volvulus of the abomasum at VLA Carmarthen. At post mortem, the abomasum was dilated and friable, and displaced dorsally to the right with torsion at the omasal abomasal junction.

PGE and Coccidiosis

Luddington investigated the cause of ill thrift affecting five, four-month-old Friesian calves being kept in an orchard. Post mortem examination of one fatality revealed a severe abomasitis, watery intestinal contents and mega colon; the rectum having a diameter of 18 cm. A heavy burden of Ostertagia spp was demonstrated with concurrent severe coccidiosis (6750 coccidial oocysts per gram). Prompt treatment of the remaining calves was advised.

Parasitic Gastroenteritis (PGE)

Shrewsbury diagnosed seven incidents of parasitic gastroenteritis in weaned calves of up to 15 months. The worm egg counts detected were as high as 3900 eggs per gram. In an eighth case, post mortem examination was undertaken on a 5 to 6 month old Holstein-Friesian heifer, the sixth death of a group of 22 calves which had been housed a month previously and had been wormed using a broad spectrum endectocide approximately four weeks before housing. Nematode parasites were visible grossly within the abomasum, and the small intestine showed reddish brown contents with foci of mucosal necrosis and raised plaques. A count of 1,250 eggs per gram was evident and assessment of the total worm burden revealed 600 Trichostrongylus axei in the abomasum and 63,400 Trichostrongyle species within the small intestine. In view of the worming history, the Veterinary Medicines Directorate had been informed via a SARSS (Suspected Adverse Reaction Surveillance Scheme) report.

Thirsk identified the typical ‘Moroccan leather’ appearance associated with ostertagiasis at necropsy of a yearling. The calf was part of a group affected by diarrhoea and ill-thrift. A total worm count carried out on an abomasal digest revealed a total of 17,000 Ostertagia species.

Starcross also diagnosed ostertagiasis as the cause of diarrhoea and death of a seven-month-old Friesian heifer.

Fasciolosis

Sutton Bonnington investigated the development of sub-mandibular oedema with concomitant milk drop, followed by profuse scour affecting a number of cows in a 200-cow dairy unit. Typical fluke eggs were identified in a faecal sample indicating fasciolosis to be the root cause of the problem

Preston reported Fasciolosis to be the second most common cause of diarrhoea in adult cattle after Johne’s disease. In one case faeces and blood samples were submitted to investigate diarrhoea and milk drop affecting 8 out of 120 dairy cows which had been housed 1 month earlier. No evidence of salmonella or coronavirus was detected but 3 out of the 4 faeces samples were positive for fluke eggs

Starcross diagnosed fluke infections on eight farms, including Fasciola hepatica on seven and Paramphistomum on four. On two farms co-infection with both species was also accompanied by Salmonella Dublin infection.

Salmonellosis

Shrewsbury isolated Salmonella Mbandaka from the faeces of an adult Holstein-Friesian which had developed haemorrhagic enteritis and died. Post mortem examination by the practitioner confirmed haemorrhagic inflammation extending from the duodenum to the ileum. It was the only animal affected in a milking herd of 260 cows. In another case Salmonella Montevideo infection was identified in an adult Holstein-Friesian, the third animal which developed diarrhoea in a herd of 330 cows.

Salmonella Dublin continued to be the most frequently isolated serovar and Preston reported its isolation as well as Salmonella Agama, Salmonella Montevideo and Salmonella Mbandaka which were all recovered from the faeces of scouring adult dairy cows.

Respiratory Diseases

Parasitic Bronchitis (Husk)

There were several reports of parasitic bronchitis (Husk) this month. Luddington investigated a case involving respiratory signs in a group of 20 suckler cows, calves and a bull managed in a permanent pasture since early summer. Despite treatments including wormers, anti-inflammatory drugs and antibiotics, one seven-year-old cow died four days after the onset of signs and was submitted for post mortem examination. Numerous adult lungworms were found throughout the respiratory tract confirming parasitic bronchitis as the cause of the clinical signs reported. Additionally, a perforated abomasal ulcer with resulting peritonitis was found on necropsy and was likely to have been the final cause of death.

Shrewsbury diagnosed eight incidents of Husk by detection of larvae in faeces in 5 cases, serology in 2 and by gross identification of parasites in the eighth. Four of the diagnoses were in adult cattle, three were in animals aged 2 years and in one case affected animals were around 14 months. Starcross also diagnosed the condition as the cause of coughing and poor condition in a group of 40 six-month-old Devon calves at pasture. Typical lungworm larvae were identified in the faeces by Baermann examination

Other diseases

Cerebellar Dysgenesis caused by BVDV

A case of partial hydranencephaly and cerebellar dysgenesis, due to in utero BVDV infection, was diagnosed at Carmarthen. Seven calves, born to heifers over a few weeks, were unable to stand, or were ataxic at birth. The heifers were on a farm where approximately 100 young stock were reared from a 200 cow dairy herd. The heifers were not vaccinated for BVD. A live calf that was less than 24 hour old was examined, and found unable to rise but able to sit unaided in dorsal recumbency. The calf was euthanased and at post mortem, the cerebellum was almost completely absent in the region of the lateral hemispheres (see figure 1).

Bovine Neonatal Pancytopaenia (BNP)

Winchester diagnosed a single case in a two-week-old calf from a group of organic suckler calves. The remainder of the group were reported to be clinically normal. Clinically the mucous membranes were pale with haemorrhages present on the nictitating membrane. Histopathological examination confirmed trilineage hypoplasia of the bone marrow.
,br> A large blood clot in the small intestinal lumen was the main finding noted during post-mortem examination of a 3-month-old Holstein heifer calf that had been submitted to Newcastle with a history of dyspnoea of three days duration prior to death. A diagnosis of Bovine Neonatal Pancytopaenia (BNP) was made on the basis of histological examination of bone marrow. It was reported that another case of BNP had been diagnosed in this herd last year.

Mycoplasma Wenyonii

Shrewsbury diagnosed Mycoplasma wenyonii infection by DGGE and PCR techniques in a dairy herd where around 20 animals had exhibited varying degrees of milk drop at varying stages of lactation, together with pyrexia and swelling of the legs over a period of several weeks. An increased number of abortions had also been reported.

Langford also diagnosed the infection in one of two cows presented with oedematous hind limbs, milk drop and pyrexia. Both were screened for Mycoplasma sp. with one animal found positive for Mycoplasma wenyonii by DGGE examination.

Botulism

Shrewsbury investigated three outbreaks of suspected botulism. Each case was associated with broiler litter on an adjacent premises. In one case, four broiler sheds had been mucked out and the litter, together with litter from a previous batch of birds which had been stored, was spread on a stubble field adjacent to a property where 150 heifers were at grass. Within five days, one heifer was found recumbent and weak and died within 24 hours. The next day two were found with hind leg weakness rapidly progressing to recumbency. Within one week, six heifers had died and botulism vaccine had been given to the entire group. Poultry litter on the stubble field was ploughed into the ground as soon as botulism was suspected.

Lead Poisoning

Sutton Bonnington diagnosed lead poisoning following necropsy of a suckler cow which died after being found in extremis with convulsions. It was one of a group of 32 cows with calves at grass in which two other cows had been found dead with no premonitory clinical signs the previous day. A bonfire had been initiated in the field unbeknown to the owner which contained various pieces of building material from a nearby renovation project including lead flashing. Lead poisoning was confirmed with a blood lead of 2.41µmol/l. A sample of the bonfire ash was also tested and a lead concentration of 50946mg/kg DM was recorded. Bonfire ash is know to be vary palatable to livestock and advice was provided to the owner with regards to the management of the grazing land contaminated by this material and the actions needed to protect the food chain.

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