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VLA Dec Update - Outbreaks Of Bacterial Pneumonia

18 February 2011

UK - Outbreaks of bacterial pneumonia in cattle have been identified, according to the Veterinary Laboratory's monthy disease update for December.

Reproductive diseases

Shrewsbury identified Streptococcus uberis as the cause of two abortions in a group of 30 unvaccinated suckler cows, due to begin calving from 1st March. It was considered to be an opportunist infection, with no other underlying cause identified.

Truro diagnosed mycotic abortion in a 100 cow dairy herd where three cows had calved early over a period of approximately 2 months. Fungal hyphae were detected in the stomach content of a foetus submitted for laboratory examination; Aspergillus fumigatus was isolated on culture.

Starcross reported that Salmonella Dublin continued to be the most frequently diagnosed cause of abortion in their area in December. In one case, samples were submitted from a dairy heifer which had aborted at five months gestation.

Alimentary tract diseases

Cryptosporidiosis

Sutton Bonnington diagnosed cryptosporidium as the cause of a sudden increase in calf diarrhoea and mortality in a 400 cow dairy herd. The herd was undergoing a change in its breeding programme and had purchased a large number of pregnant Montbeliard females to replace its Holstein Friesian animals and the calving facilities of the unit had been stretched beyond capacity. The clinical presentation was severe diarrhoea at two weeks of age with 25 per cent of calves affected. Advice was provided on management of the calving area.

Monophasic Salmonella Typhimurium

Langford isolated Monophasic Salmonella Typhimurium (so described because the flagellae normally used to determine serotype cannot be determined) associated with disease on two occasions. In one of these, six of a group of 100 cows showed profuse, watery scour in freshly calved animals; in the other case, three of a group of 20 freshly calved cows developed pyrexia and diarrhoea.

Winter Dysentery

Langford diagnosed winter dysentery in six dairy herds with a transient scour reported to affect the majority of animals in the herd over a two to four week period. Blood samples subsequently submitted from typically affected animals in were all found positive for the bovine coronavirus antibody ELISA.

Atresia Coli

Atresia coli was diagnosed by RVC as the cause of sudden collapse of a large two-day-old neonatal calf weighing 48kg. The small intestines, caecum and proximal colon were markedly distended by a large volume of fluid and gas right up to the point in the second loop of the colon which ended in a blind sac.

Fasciolosis

Eggs of both Fasciola hepatica and Paramphistomum sp were detected by Carmarthen in the faeces of a recently purchased Hereford cross cow which had dark diarrhoea despite having been treated with a closantel and ivermectin pour-on eight days before sampling.

In another case Fasciola hepatica eggs were also demonstrated in the faeces of a 10 year old Friesian cow which had been losing weight and had pale mucous membranes. This was the only animal clinically affected in a herd of 100.

Fasciolosis was also diagnosed by Aberystwyth in six cases involving cattle aged 20 months and older, causing weight loss in some cases and diarrhoea in others. Three cases were in beef suckler animals and three were in dairy cattle. Two cases also had Paramphistomum eggs. Salmonella Dublin and fasciolosis were diagnosed concurrently in a five year old dairy cow with weight loss, profuse diarrhea and milk drop.

Johne’s Disease

Penrith made 32 diagnoses of Johne’s disease in December. One case involved an 8-year-old dairy cow that was a suspect clinical Johne’s disease case but which had proved negative on the ELISA test on three occasions. A subsequent faeces sample was positive by PCR, and the disease subsequently confirmed on post-mortem examination which revealed scant acid-fast bacilli seen in the smear of the ileum and fewer bacteria than usual on histological sections. The pattern of the lesions was similar to the paucibacillary-type Johne’s disease seen in sheep.

Respiratory Diseases

IBR

Langford diagnosed IBR on several occasions in December. In one case a single adult animal from a large dairy herd was seen in respiratory distress with pyrexia, increased upper respiratory sounds and ocular discharge. Paired serology revealed a rise in titre to IBR but the FAT on nasal swabs was negative. This may have been due to insufficient virus cells on the swab.

Mannheimia Haemolytica

Shrewsbury diagnosed Mannheimia haemolytica infection in two herds following bacterial culture and histopathological examination of lung samples submitted by practitioners. In one herd of 180 Holstein-Friesians 2 deaths had been reported in milking cows over a 6 day period. In the second case only a single 6 week old suckler bull calf was affected. The same organism was suspected to be the cause of pneumonia in 4 week old Jersey calves with all 6 in a group showing respiratory disease and 2 deaths reported: only fixed lung was available for examination and showed a severe acute fibrino- suppurative pneumonia.

Mannheimia Haemolytica and Mycoplasmosis

Thirsk also identified Mannheimia haemolytica and Mycoplasma canis as the cause of severe respiratory disease affecting three adult cows in a 150-cow Holstein Friesian dairy herd which became inappetent and dull with no other clinical signs. Two of the affected cows had died, over a ten-day period, within a few days of falling ill. Figure 1 shows the changes seen in the lungs at necropsy. Mannheimia haemolytica was isolated in profuse pure growth from the affected lung tissue. The presence of RSV was also detected on FAT on mucus from the airways and Mycoplasma canis was detected using DGGE. The other affected cow on the farm responded to prompt antibiotic treatment and was back to full production with no further cases seen. Preston also diagnosed a case involving multiple pathogens involving 100 per cent morbidity and 20 per cent mortality rate amongst a group of 30 five month old dairy heifer calves with respiratory signs. Following necropsy Mannheimia haemolytica and Histophilus somni were recovered from the lung on routine culture and Mycoplasma canis by DGGE.

Mycoplasmosis

Mycoplasma canis was the only pathogen identified by Shrewsbury in a broncho-alveolar lavage sample from calves aged 6 to 8 months on a finishing unit with an ongoing respiratory disease problem.

Histophilus somni

Thirsk isolated Histophilus somni from four bronchio-alveolar lavage (BAL) samples and Mycoplasma dispar was also identified using DGGE. The samples were submitted as part of an investigation into respiratory disease in 60, 12-month-old dairy calves which had been vaccinated with PI3 and RSV intranasally and with a live IBR marker vaccine. It was considered that both bacteria played a primary role in the disease.

Bibersteinia trehalosi

Starcross received a lung sample from a yearling Holstein heifer which had died shortly after the development of respiratory signs. A post-mortem carried out on farm had identified typical pneumonic changes in the lungs and Bibersteinia trehalosi was isolated.

Nervous Diseases

Salmonella Dublin

Salmonella Dublin was isolated from the brain of a four-week-old calf from a rearing unit submitted to Sutton Bonnington for post-mortem. The calf represented the fourth death from a group of 40. An array of clinical signs had been recorded in the affected calves, which were bought in at a week old and included pneumonia, diarrhoea, recumbency and nervous signs. Advice was provided with regards to the zoonotic implications of the condition and its control.

Thromboembolic meningoencephalitis

Starcross received a live eight-month-old Charolais cross heifer for necropsy following the development of sudden collapse and recumbency. Another five animals out of a group of 380 had been similarly affected within the space of a week. Post-mortem examination failed to identify any significant gross abnormalities. Histopathological examination of the brain however identified a severe, subacute, necrotising, suppurative encephalitis with neutrophilic vasculitis and intralesional Gram negative coccobacilli morphologically typical of Histophilus somni. These findings were consistent with thromboembolic meningoencephalitis, a rare condition in the UK and more widely recognised in North American feedlots.

Other Diseases

Babesiosis

Langford diagnosed babesiosis in a suckler cow at pasture which developed sudden onset diarrhoea and haemoglobinuria. The affected suckler herd was kept on the edge of the Mendips on a farm which had only recently experienced its first case.

Bovine Neonatal Pancytopaenia

Penrith diagnosed BNP in a 16-day-old calf submitted from a farm which had experienced previous cases of “bleeding calf syndrome”. There had been no signs of external bleeding, or diarrhoea, just general vague illness. Post-mortem examination revealed multiple haemorrhages internally and into the lumen of the small intestine. Histology confirmed bovine neonatal pancytopenia. In another case the condition was confirmed in a 14-day-old calf demonstrating haemorrhagic diarrhoea with epistaxis.

Skin Diseases

Psoroptic mange

Shrewsbury investigated an outbreak of Psoroptic mange affecting a herd of 50 suckler cows and calves with three breeding bulls. Four hundred fattening beef cattle were distributed through various pens in three sheds. Cattle were regularly purchased from market with up to 80 per cent coming from the Carmarthen area. The last batch of purchased cattle had arrived in August. Newly arrived cattle had been given one worming treatment based on macrocyclic lactones and those at grass were wormed as required. Up to 20 cattle, aged 12 months and older, were reported to have developed skin lesions in the previous two weeks. Advice on treatment and control was given.

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