17 February 2011

6 minute read

Europe

Bacterial Abortion

Bacterial pathogens were associated with several outbreaks of abortion. Penrith diagnosed Campylobacter fetus venerealis intermedius as a cause of abortion in a dairy herd. At necropsy there was evidence of an associated multifocal necrotising purulent placentitis. Preston identified Bacillus licheniformis as the likely cause of abortion in two separate cases, each involving a single abortion within the herd. Starcross identified Salmonella Dublin as the cause of three abortions in a 200 cow dairy herd.

Preston identified Aspergillus fumigatus as the cause of abortion in a herd where 3/200 cows had aborted at approximately 6-7 months of gestation branching septae fungal hyphae were seen on examination of the foetal stomach contents from which Aspergillus fumigatus was recovered.

Winchester investigated an abortion storm in a dairy herd in which 12 cows aborted in quick succession with four abortions in four days. Two foetuses were submitted, and Neospora infection was suggested by positive IFAT testing of foetal fluid and confirmed by immunohistochemistry of foetal myocardium. High titres to Neospora were also demonstrated on serology in two of the aborted cows, and a necrotising placentitis typical of neosporosis was seen in submitted fixed placental tissue. The evidence suggested a point source of Neospora infection.

Alimentary tract diseases

Thirsk diagnosed patent liver fluke infestation in an 18-month-old beef finisher bullock which had shown gradual wasting despite having been wormed. Clinical examination was unremarkable. Langford diagnosed the disease on five occasions. In four incidents, diarrhoea was the principle presenting sign. The fifth, a recently calved dairy cow, presented with submandibular oedema. Aberystwyth investigated six incidents involving cattle aged 20 months and older, presenting with 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 evidence of Paramphistomum infection.

Black disease was diagnosed as the cause of death in an 18 month old heifer submitted to VLA Carmarthen. The heifer was one of a group of 25 from which a previous animal had been found dead one month earlier. The day prior to death, the submitted animal was seen to be anorexic, and had a subnormal rectal temperature and the head was described as swollen. Necropsy revealed a classical black disease lesion in the liver (see figure 1) which tested positive by FAT for Clostridium novyii, confirming the diagnosis. Advice was given regarding vaccination with a multivalent clostridium vaccine. It was also advised that an appropriate fluke treatment be administered to animals in this management group.

Johne’s disease continued to be the most commonly diagnosed cause of diarrhoea in adult cattle although Preston reported equal number of cases of Johne’s disease (mostly diagnosed on serology) and fasciolosis in adult cows with clinical signs of diarrhoea, wasting and milk-drop. In one case a single Holstein/Friesian bulling heifer from a group of 45 was found to have both a patent fluke burden and Johne’s disease.

Salmonella Dublin continued to be the most prevalent serovar affecting cattle. Preston diagnosed several cases during the month both in adult dairy cows with diarrhoea and from aborted foetuses. In one case, the faeces from both a scouring dairy cow and its calf were submitted and both were found to be positive for Salmonella Dublin. Carmarthen found the death of a three day old calf was due to septicaemia with both Salmonella Dublin and Mannheimia haemolytica. Six calves in a 300 cow dairy herd had died, mainly at five days of age or older.

Respiratory Diseases

Penrith diagnosed lungworm as the cause of respiratory disease in a group of Limousin suckers of mixed ages. Larvae were demonstrated in a sample of pooled faeces. Starcross diagnosed patent lungworm infection in a two-year-old Holstein cow. Clinical signs described included anorexia, coughing and milk drop and Langford diagnosed the condition in ten out of 18 four-to-six-month old Friesian Holstein heifers at grass.

Histophilus somni, Pasteurella multocida and Mycoplasma dispar were identified from a six-week-old calf, from a group of 20 that was not thriving and with some recent mortality. The calves were reared indoors in group pens holding up to six each. Leahurst diagnosed pleuropneumonia in a 14-day-old calf associated with Mannheimia haemolytica infection. At necropsy the same organism was isolated from muco-fibrinous exudate found in the left middle ear and there was evidence of parapoxvirus infection. This was the fifth of 5 calves, all born on the same day to die from pneumonia in a 4 day period, despite treatment with enrofloxacin.

Sutton Bonnington examined samples from two adult dairy cows with clinical signs suggestive of IBR. The herd had been vaccinated with a marker vaccine in July of this year. FAT examination confirmed IBR virus to be present and an additional investigation has been initiated to establish the source of the virus.VMD were also informed and the results of additional investigations are awaited.

Preston detected BVH1 virus by fluorescent antibody testing of a nasal swab from a five year old Holstein/Friesian dairy cow with pyrexia and an increased respiratory rate. 2/200 animals were said to be affected and one animal had died. In a separate case, rising antibody titres to IBR was thought to be significant in a dairy herd in which 10/180 cows were showing respiratory signs and milk drop.

Carmarthen also investigated a case in which a large proportion of the herd developed pyrexia and nasal discharge. A number of the affected group also aborted. Examination of single blood samples from 10 affected animals using the gE IBR ELISA identified nine out of the ten animals to be seropositive consistent with exposure to field virus. In a second case paired blood samples from two affected animals were received. In this 400 cow dairy herd approximately 40 animals were coughing and had nasal discharge and two animals had died. Clinically significant seroconversion to IBR virus was detected.

Sutton Bonnington investigated a case in which a calf developed respiratory disease with dyspnoea ten days after vaccination with a multivalent vaccine against respiratory disease. Gross necropsy findings were suggestive of an acute bacterial bronchopneumonia. BVD virus type I was detected by PCR. Further investigation revealed BVD virus to be circulating within the affected group possibly compromising the immune response to the vaccine.

Metabolic Diseases

Thirsk investigated a case in which six from a group of ten, nine-month-old, beef fattener calves were affected with “dog sitting” and recumbency. Some of the animals were “bow legged” and some may have been blind. The animals were fed on a mixture of barley, wheat, concentrate pellets, chopped straw and a mineral supplement. Necropsy of one affected animal revealed markedly enlarged costochondral junctions, pathological fractures of the ribs and the left femur, and in combination with the soft pliable ribs suggested poor mineralisation of bone. Both vitamin A and E were below reference range on blood samples and the vitamin A level in the liver was 3.7 µmol/kg WM (ref. range >10.4 µmol/kg WM). The feed company producing the concentrate pellets, later accepted that due to an internal mistake the usual package of vitamin A, E and D had not been added.

Nervous Diseases

Starcross diagnosed louping ill in a six-month-old Belted Galloway heifer which had been found collapsed in lateral recumbency having demonstrated tonic-clonic seizures. The group were grazing on moorland and two other animals had been found dead over a period of two weeks. Several ticks were noted on clinical examination and encephalitis was suspected at necropsy. HAIT examination of a blood sample for antibody to Louping ill virus proved positive at a titre of 1/640. Much of the antibody was IgM suggesting recent infection.

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