Current Findings in the Regional Veterinary Laboratories
January 2005
Common abortefacients in Cattle
High concentrations of Cryptosporidia in two month old calves
Ringworm in a yearling
A salmonellosis outbreak in a large 120-cow dairy herd.
Deaths and blindness in a ewe flock
Hypocalcaemia in ewes
Salmonella typhimurium from the lungs of first and second-stage weaners
Blackhead (Histomonas meleagridis) in peacock chicks
Deer with a very severe lungworm infestation
Active fascioliasis in a goat - Triclabendazole resistance
Tuberculosis in a herd of Alpaca.
Cattle
Bacillus licheniformis, Arcanobacter pyogenes, Salmonella dublin, and Neospora
caninum were amongst the most common abortefacients identified in all RVLs
during the month. Cork found that the percentage of Salmonella dublin isolates
showed an increase over January 2004. This maintained the higher seasonal pattern
for 2004-2005 when compared to 2003-2004.
Sligo reported that Bacillus licheniformis was isolated from the abomasal contents of
several bovine foetuses, including three submitted from an abortion storm in Donegal
(15 abortions to date). Traditionally thought of as urinary tract commensal that
caused occasional, sporadic abortions, this agent seems to be increasing in importance
as an abortefacient.
Cork and Kilkenny both found Bovine Virus Diarrhoea (BVD) antigen in a small
number of the foetal submissions received.
Foetal anomalies noted by Limerick during the month included scoliokyphosis in a
seven-month foetus and foetal anasarca in a near full-term foetus.
Athlone reported neonatal enteritis in a three-day old calf and a three-week old calf
due to concurrent E.coli and rotavirus infections.
Kilkenny carried out a post-mortem examination on a three-day old calf that had been
very weak and unwilling to suck since birth. A diagnosis of patent ductus arteriosus
was made.
Two month old autumn-born calves with diarrhoea were diagnosed by Cork as having
high concentrations of Cryptosporidia species in their faeces. No other pathogen
was identified. In Ireland cryptosporidiosis is generally a condition of calves in the
second and third weeks of life.
Sligo reported that a four centimetre ventricular septal defect was found at the
necropsy of a weanling that had survived until the age of 6 months. The history
described marked growth retardation/illthrift and multiple episodes of pneumonia
(recovering with intensive therapy each time) before the animal succumbed to chronic
pneumonia and fibrinous pleurisy. Experience suggests that it is quite rare for an
animal with such a severe congenital cardiac defect to live so long.
Kilkenny examined the carcass of a heifer that had been euthanased following a
period of recumbency. An abscess at C6-C7 level of the spinal column was found to
have caused spinal cord compression. No pathogen was isolated from a swab taken
from the lesion.
Sligo reported that a yearling heifer that died after a short episode of inappetance,
weight loss and haematuria had a severe purulent cystitis and pyelonephritis.
Arcanobacter pyogenes was isolated from the bladder and kidney.
Ringworm caused by Trichophyton verrucosum was diagnosed by Cork from skin
and hair samples submitted from a yearling bullock. What made the diagnosis
unusual was that, while this animal was almost totally bald from the infestation, the
companions had no clinical signs of the condition whatsoever. An
immunosuppressive condition was suspected. A blood sample tested for BVD virus
was negative. The animal eventually died and was not necropsied.
Limerick RVL diagnosed spermatic granuloma in one of two samples of vas deferens
tissue submitted by a practitioner for histological confirmation of effective vasectomy
of a bull. The samples were obviously taken from near the head of the epididymis
rather than the more usual ductus deferens. The lesion was unilateral, with the right
side only affected. Spermatic granulomas occur following extravasation of
spermatozoa. Congenital anomalies, trauma or infection are the usual causes. The
literature suggests that, if congenital in origin, the lesion is usually unilateral, with the
right side more commonly affected.
Athlone reported diffuse subcutaneous cellulitis in a two-year old heifer. The
condition was remarkable because of its diffuse nature. While the predisposing factors
and the aetiology are frequently difficult to establish, this condition may be associated
with the use of contaminated needles.
Investigations were carried out by Kilkenny into a salmonellosis outbreak in a large
120-cow dairy herd. A number of cows became seriously ill, resulting in seven cow
deaths, ten abortions and one weanling death at the time of this report. Salmonella
typhimurium was isolated from a number of samples submitted. Intensive fluid
therapy was successfully applied in some of the cases. One family member has been
hospitalised with salmonellosis, the type of which has not yet been confirmed.
Cork examined submissions from a dairy herd where there was a history of suboptimal milk yield and diarrhoea. The cows were “wagon-fed” and, occasionally, fruit
was obtained from an importer and added to the wagon. The fruit, which could
comprise a variety of types (bananas, grapes, melons etc.), was never spoiled, but
would often be approaching its best-before date. No adjustment in the proportions of
other ingredients was made when the fruit was added to the wagon mix. The problem
was considered to be nutritional in origin and the herd owner was advised to consult a
dairy nutrition advisor.
Sheep
Athlone reported that abortion and mortality in a ewe flock was due to pregnancy
toxaemia, gastro-intestinal and liver parasitism.
Kilkenny isolated Salmonella dublin from aborted lambs on two separate farms.
Athlone investigated deaths and blindness in a ewe flock. The ewes had been
outside on beet tops and silage until late December. At that stage they were housed
and given some nuts in increasing amounts. Lambing was due to start in late January.
The problem was noticed soon after the change of diet. Post-mortem examinations
and raised serum beta-hydroxybutyrate (βHB) levels lead to a diagnosis of twin lamb
disease. It was suggested to the flockowner that the change of diet had lead to an
energy deficit, predisposing to the development of the condition. Sligo also diagnosed
several cases of pregnancy toxaemia, based on serum βHB levels in samples
submitted from periparturient ewes.
Sligo has diagnosed several cases of hypocalcaemia in ewes, including one large
outbreak involving 15 ewes that were outwintered. This outbreak occurred during a
period of wet, cold, windy weather, and some of the affected ewes had calcium levels
as low as 0.2 mmol/l (normal range: 2.1-3.0 mmol/l).
Sligo diagnosed the first case of acute fasciolosis in January - a remarkably late date.
Cork received blood samples from ewes in a flock in which “ringwomb” (uterine
inertia/failure of cervix to dilate fully at lambing) was an annual problem. A
metabolic/mineral profile of a selection of in-lamb ewes showed insufficient current
energy intake and low inorganic phosphorus concentrations. The sheep were getting
clover-rich silage. It was postulated that if the clover had a high oestrogenic
concentration this may have contributed to the ringwomb problem.
Two ewes submitted to Sligo from different flocks had died from haemorrhage from
the middle uterine artery. In one case, the ewe had prolapsed repeatedly, despite
treatment each time, and was found dead after the last reduction and suturing of the
prolapse. In the other case, the ewe had suffered a severe uterine torsion.
Pigs
Limerick RVL isolated Salmonella typhimurium from the lungs of first and
second-stage weaners submitted from a herd with a history of pneumonia.
Poultry
Sligo reported an outbreak of blackhead (Histomonas meleagridis) in peacock
chicks kept with other species (hens, turkeys, guinea fowl) and, on a separate farm,
ulcerative enteritis in chickens, caused by Clostridium colinum.
Other Species
Gross post-mortem examination of a deer carried out in Athlone showed a very
severe lungworm infestation, with the bronchi and bronchioles packed with
lungworms. The faecal strongyle egg count was also high. Histopathological
examination showed bronchitis with hypertrophy of the bronchial epithelium, peribronchial cuffing and evidence of larvae in the bronchi. It was the 5th deer to die in
the herd.
Sligo diagnosed chronic active fascioliasis in a goat that died three weeks after being
treated with triclabendazole at twice the recommended dose. The adult flukes present
appeared to be fresh and intact, i.e. as if they had died at around the same time as the
goat. This suggested that the drug treatment had not been effective (Figure 1).
Triclabendazole resistance in liver flukes is well established in the northwest, but
this appears to be the first case reported in a goat. Fluke eggs from this case have
been supplied to a research project in the University of Bristol studying drug
resistance in liver flukes, with a view to determining the drug resistance status of the
parasites. There were no sheep on the farm and triclabendazole was the only product
used for fluke control.
Athlone reported a serious outbreak of tuberculosis in a herd of Alpaca. The area
around the farm was known to be a bovine TB blackspot.
Sligo diagnosed rabbit haemorrhagic disease in a rabbit submitted from a colony
where there had been multiple sudden deaths. Interestingly, while virtually all of the
adult rabbits died, many young rabbits survived the outbreak without showing any
clinical signs.
A glaucous gull (Larus hyperboreus), a very large seagull that breeds in Iceland and
visits the Irish coast in small numbers in winter, was submitted to Sligo for necropsy.
It had been found dead on a beach in west Sligo by a local ecologist, after a severe
storm. There were no external marks or injuries and the carcass was very fresh. The
remarkably dense and thick plumage, an adaptation to survival in a harsh climate,
completely disguised the very poor body condition of the bird, which had virtually no
intestinal contents, no adipose depots and showed severe muscle atrophy, especially
obvious in the pectoral muscles. No other lesions were noted and no pathogens were
isolated. Death was presumably due to starvation (Figure 2).
Sligo reported that septicaemia (due to Staphylococcus aureus) and parasitism (very
high strongyle egg count) had caused the deaths of two Irish hares (Lepus timidus
hibernicus) whose carcasses were submitted to the laboratory by a wildlife ranger
from the National Parks and Wildlife Service.
CAPTIONS FOR PHOTOS
Figure 1 “Chronic fascioliasis in a goat – photo Michéal Casey”
Figure 2 “Glaucous Gull (Larus hyperboreus) – photo Michéal Casey”