Current Findings in the Regional Veterinary Laboratories
March 2007
Cattle
Salmonella typhimurium was isolated from a number of foetuses submitted to
Athlone from one farm. Advice was given regarding the zoonotic implications of this
pathogen. Bacillus licheniformis was isolated by Limerick from two bovine foetuses
from one farm. There were gross lesions of fibrinous pericarditis and pronounced
heart enlargement. Athlone diagnosed thyroid hyperplasia (suggestive of iodine
deficiency) in two calves from a farm with a history of stillborn and weak calves.
All laboratories reported an increase in the number of neonatal calf submissions. A
two-day old calf, with a history of breathing difficulty since birth and an
unwillingness to suckle, was submitted to Kilkenny. Post-mortem examination
revealed a diaphragmatic hernia, with the small intestine and part of the abomasum
located in the thoracic cavity. Six neonatal calves were submitted to Athlone from one
herd. Amongst the conditions seen were pneumonia, enteritis and navel ill, but
common to all was evidence of hypoglobulinaemia. It transpired that colostrum
feeding was being restricted as part of a Johnes Disease control programme.
Colisepticaemia associated with hypoglobulinaemia was diagnosed in a three-day old
calf submitted to Dublin. The zinc sulphate turbidity (ZST) test result of six units
indicated little to no absorption of colostrum antibodies. Similar cases were also
recorded in Cork, Dublin, Limerick and Sligo.
A congenital heart malformation was diagnosed by Cork in a one-month old calf with
a short history of dyspnoea. The liver had “nutmeg” lesions associated with
congestive heart failure. Salmonella dublin was isolated from a one-month old calf
which was presented to Athlone with terminal dry gangrene. Meningoencephalitis due
to gram-negative bacterial infection was diagnosed in a one-month old calf submitted
to Cork with a history of nervous signs.
Kilkenny diagnosed enzootic pneumonia in three to four-week old housed calves. All
of the farms investigated had mixing of age groups within the same airspace, and
sick animals were not routinely removed from the house. Concern was expressed
that the modern tendency towards building larger animal houses did not allow for the
isolation of sick animals in a separate air space. A four-month old Montbelliard heifer
presented to Sligo was also diagnosed with enzootic pneumonia and was positive for
BVD virus. There had been ongoing animal health problems on the farm, which
involved high mortality rates, stunted growth and ill thrift. Overcrowding was
considered to be an important contributory factor. Three three-month old calves were
presented to Sligo with a history of sudden death. The herd has a history of high
mortality rates in housed calves over a number of years. Two of the calves showed
evidence of pneumonia at gross post mortem examination. Mannheimia haemolytica
was isolated from these two calves. Salmonella dublin was isolated from two of the
three calves. The farm was visited. The affected calves were housed in a creep area of
a wide-span shed, with access to the dams. Overcrowding was considered to be a
factor. As a result of assessment of air movements the ventilation in the creep area
was considered to be poor. Advice was given on ways to correct this and a Salmonella
dublin vaccination programme was also recommended.
Dublin diagnosed concurrent copper and magnesium deficiency in a group of suckler
calves with a history of intermittent periods of weakness and collapse. The affected
animals tended to recover from these episodes, but some died following epileptiformtype seizures. The herd was known from previous years to suffer from a severe
copper deficiency. Gross post-mortem and histopathological examination of tissues
was unremarkable. There were virtually undetectable levels of copper in the liver and
magnesium levels in vitreous humor were markedly decreased. Correction of both the
copper and magnesium deficiencies was recommended with follow up blood sampling
to confirm that adequate supplementation had been achieved.
Sheep
Three aborted lambs submitted to Cork from one flock were found to have
histopathological lesions consistent with protozoal infection (toxoplasmosis).
Toxoplasmosis was also suspected by Dublin as a cause of abortion in a flock in
which 20 ewes out of 400 aborted over a period of ten days. All age groups were
affected. Multifocal necrosis with dystrophic calcification was seen in foetal
membranes. Campylobacter spp was isolated by Cork from stomach contents from an
aborted foetus. Meningitis, perivascular focal encephalitis, suppurative pneumonia
and hepatitis were seen on histopathology.
Kilkenny identified mismothering/starvation as the cause of death in several neonatal
lambs. Post mortem examination of a five-week old lamb in Athlone showed
impaction of the stomach with soil. It transpired that the concentrate being fed was
spread on the ground rather than in troughs. This meant that some lambs were eating
too much soil and this resulted in the impaction seen at gross. Altogether three lambs
died.
A six-week old lamb was submitted to Athlone from a flock in which coccidosis was
considered to be a problem. Deaths, mostly of single lambs were described.
Following gross and histopathological examination, nephrosis was diagnosed. There
were no coccidial oocysts detected in the faeces of the lamb. Nephrosis was also
diagnosed on histology of the kidney from a hogget, which presented to Athlone
following sudden death. Kilkenny found urolithiasis with rupture of the urethra at the
sigmoid flexure in two seven-week old lambs. One of the lambs had been found dead
and the other was observed to have difficulty in urination.
Pigs
Seven weaned 33-day old piglets that died following a short vague illness were
submitted to Dublin. On gross examination some pigs had purple ear tips and purple
hind leg extremities. Overt evidence of septicaemia with bacterial colonies in the
blood vessels of lung and liver was seen. Other indicators of septicaemia were seen in
other pigs i.e. increased inflammatory cell numbers in the hepatic sinusoids and acute
interstitial pneumonia. Haemolytic colonies of Escherichia coli O149 were cultured
from the tissues of these pigs, including from small intestinal contents and meninges.
The farmer had been vaccinating against E. coli but had just recently stopped this
practice. Kilkenny also isolated E. coli O149 from the viscera and intestines of two
two-week old piglets that were reported with scour and rapid death.
Porcine dermatitis and nephropathy syndrome was diagnosed by Kilkenny in a pig
herd where there were a number of animals with dermal purpurea and enlarged lymph
nodes (figure 1). Porcine
immunohistochemistry.
circovirus
type
2
was
not
identified
on
Other Species
Kilkenny isolated Streptococcus equi subspecies equi from a swab submitted from a
horse with suspect strangles. Rhodococcus equi was isolated from an abscess in the
lung of a donkey presented to Limerick. The animal was in very poor condition and
was also suffering from parasitism.
Yersinia pseudotuberculosis was isolated by Dublin from pyogranulomatous
hepatitis (white spot liver) lesions of a three-week-old kid goat, which had a
history of chronic illthrift (figure 2).
Avian aspergillosis was diagnosed in a wild mallard duck presented to Dublin.
Multifocal nodular lesions were seen in the lungs, from which Aspergillus spp. was
isolated, and fungal hyphae were seen on histopathological examination. Kilkenny
identified hepatitis consistent with a herpes viral infection in an emaciated
sparrow hawk (Accipiter nisus).
Kilkenny diagnosed infectious canine hepatitis in an eight-week old greyhound
with a history of lethargy and inappetance for 24 hours. It had swollen tonsils and a
tender abdomen. Limerick examined a dog that had died shortly after a visit to a
public park. This dog was one of a number that died with similar symptoms and
similar histories after visiting this park. This particular dog began frothing from the
mouth, became diarrhoeic and weak and went into convulsions within a short time of
leaving the park. Death occurred within an hour. Post-mortem examination showed
generalised hyperaemia, with pulmonary, hepatic and splenic congestion. As
poisoning was suspected the stomach contents were sent to the Pesticide Control
Laboratory in Backweston. Multi-residue screening analyses revealed very high
levels of carbofurans. Carbofurans belong to the carbamate group of organic
compounds and their toxicity is similar to the organophosphate group i.e. they cause
cholinesterase inhibition by inactivating the enzyme acetylcholinesterase. Carbofurans
are widely used as systemic pesticides on field crops. It has, however, one of the
highest acute toxicities to humans of any the most widely used insecticides. One ml.
can be fatal. In granular form one grain can be fatal to birds. Carbamates are also
used as insecticides in veterinary medicine, particularly for flea control in small
animals. Anecdotal evidence suggests that this compound is being illegally used for
vermin control, and the gardai are investigating the incident.
CAPTIONS FOR PHOTOS
Figure1
“Skin lesions in a pig with porcine dermatitis and nephropathy syndrome – photo
Donal Toolan”
Figure2
“Pyogranulomatous hepatitis in a goat associated with Yersinia pseudotuberculosis
infection – photo William Byrne”