Mannheimia haemolytica in a six-week-old calf
Accidental formalin poisoning in calves during a routine TB test
Epidermolysis bullosa in a three-day-old calf
Further cases of bovine neonatal pancytopenia
These are among matters discussed in the Northern Ireland animal disease surveillance quarterly report for January to March 2013
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Respiratory disease was identified in 98 cattle postmortem submissions between January and March 2013. The most common pathogens identified included Mannheimia haemolytica (21 cases), Pasteurella multocida (18 cases), Mycoplasma bovis (13 cases), Trueperella (formerly Arcanobacterium) pyogenes (11 cases) and infectious bovine rhinotracheitis (five cases).
A six-week-old calf had a reported history of being stiff on its hindlegs for three to four days, but otherwise was bright and alert. There was no report of any respiratory signs in this animal nor in any of its cohort. It was subsequently euthanased after being found collapsed. Grossly, at postmortem examination, there was an extensive fibrinous pleuritis and pericarditis from which M haemolytica was isolated in profuse culture (Fig 1).
Of 5086 blood samples that were tested for bovine viral diarrhoea virus (BVDV) by virus isolation or ELISA antigen capture, 345 (6.8 per cent) were positive. In addition, six of 511 (1.2 per cent) submitted tissues and nasal mucus samples were positive by immunofluorescence. Three cases of mucosal disease were confirmed at postmortem examination during this period.
The pathogens identified in neonatal bovine faecal samples during the quarter are shown in Table 1. Overall, Cryptosporidium species and rotavirus were the most common pathogens identified.
Other enteric conditions
Parasitic ova found in ruminant faeces samples submitted during the period are shown in Table 2.
Examination for Mycobacterium avium subspecies paratuberculosis (MAP) was carried out by microscopic examination, with Ziehl-Neelsen staining, on 248 bovine faecal samples. Thirteen samples (5.2 per cent) contained acid-fast organisms typical of MAP. Of 10,322 bovine blood samples that were tested for antibodies to MAP, 763 (7.4 per cent) were positive.
Reproductive and mammary diseases
Specimens from 187 bovine abortions and stillbirths were examined during the first quarter. Significant pathogens were detected in 91 cases (48.7 per cent). Of these, Bacillus licheniformis (28 cases, 15.0 per cent) was the most commonly identified pathogen. Other pathogens identified included Trueperella pyogenes (18 cases, 9.6 per cent), Neospora caninum (12 cases, 6.4 per cent), Escherichia coli (eight cases, 4.3 per cent), Leptospira Hardjo (eight cases, 4.3 per cent) and BVDV (five cases, 2.7 per cent).
A total of 517 bacterial isolates were cultured from milk samples submitted from acute and chronic mastitis cases. Fifty-six (10.8 per cent) samples yielded cultures of more than two organisms and were considered to be potentially contaminated. No bacteria were cultured in a further 133 samples. E coli was the most frequently isolated organism and accounted for 20.9 per cent of isolates cultured. Other frequently identified organisms included Streptococcus uberis (14.7 per cent), Staphylococcus aureus (8.7 per cent), coagulase-negative Staphylococcus species (6.8 per cent), Streptococcus species (5.8 per cent), alpha-haemolytic streptococci (5.6 per cent), Streptococcus dysgalactiae (5.6 per cent) and Pseudomonas species (4.6 per cent).
Twelve bovine skin samples were examined for ectoparasites in the first quarter. Two were positive for mites, five were positive for lice and two were positive for ringworm.
A three-day-old female crossbred beef calf was submitted with skin lesions. The lesions were irregularly shaped, up to 10 cm across and consisted of full-thickness epidermal loss with a distribution over the distal limbs and around the ears and eyes, on the basis of these signs and histological findings, a diagnosis of epidermolysis bullosa was made (Fig 2). There had been no previous reports of this condition on the farm.
Idiopathic haemorrhagic diathesis
Cases of bovine neonatal pancytopenia continue to be recorded, with 11 cases diagnosed in the first three months of 2013. Of these,10 were between one to two weeks old, and one case was three weeks old.
During a routine TB test, a batch of three- to four-month-old calves was held in a yard which contained a footbath filled with formalin. Approximately two hours later two calves died and two more became recumbent. Postmortem examination revealed acute abomasitis and enteritis, with copious amounts of fibrin in the abomasal lumen and adhered to the intestinal mucosa. Abomasal contents had a strong odour of formalin. Accidental ingestion of the formalin footbath was considered the most likely cause of death.
A heifer weighing 414 kg was found dead with no premonitory signs. At postmortem examination an abscess was present in the muscles caudal to the left shoulder. Another abscess measuring approximately 10 cm in diameter was also present in the free wall of the right ventricle. The lesion bulged into the ventricular lumen, greatly reducing the ventricular space (Fig 3). A pure growth of T pyogenes was grown on culture.
Respiratory disease was identified in 28 ovine postmortem submissions during this quarter. Jaagsiekte (12 cases), M haemolytica (seven cases), P multocida (two cases), laryngeal chondritis (two cases) and fibrinous pleurisy (two cases) were the most common diagnoses.
Thirteen ovine faecal samples were examined microscopically using Ziehl-Neelsen staining for MAP. A single sample (7.7 per cent) contained acid-fast organisms typical of MAP. Eight ovine blood samples were tested for antibodies to MAP, one (12.5 per cent) of which was positive.
Specimens from 281 ovine abortions and stillbirths were examined during the first quarter. Significant pathogens were detected in 182 cases (64.8 per cent). Pathogens identified included Toxoplasma gondii (57 cases, 20.3 per cent), Chlamydophilia species (47 cases, 16.7 per cent), E coli (22 cases, 7.8 per cent), Campylobacter (18 cases, 6.4 per cent), Leptospira species (14 cases, 5.0 per cent) and B licheniformis (10 cases, 3.6 per cent).
A ewe gave birth to twins, one of which was healthy while the other consisted of a roughly spherical mass of tissue with two attached partially formed limbs. There was an absence of normal internal organs. Connective tissue was very oedematous and freely oozed fluid on cut surface.
Thirty-eight ovine skin samples were examined for ectoparasites in the first quarter. Four were positive for mites, two were positive for lice and 12 were positive for ringworm.
One hundred and fifty-seven swabs were examined for the presence of Taylorella equigenitalis during this quarter, all of which were negative. Two swabs were cultured from horses with a history suggestive of strangles, both of which were negative.
Twenty-one equine skin samples were examined for ectoparasites in the first quarter. Four were positive for ringworm.
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