Download May 2005

Current Findings in the Regional Veterinary Laboratories
May 2005
Cattle
A one-day old Charolais calf with congenital cleft palate, inability to straighten flexed forelimbs
and medial deviation of hindlimbs at the fetlock joints was presented to Dublin (figure 1). Postmortem examination revealed dysplasia of the hip (a relatively flat articular surface without proper
femoral head formation), stifle (patella running in intercondylar groove of distal tibia), shoulder and
elbow (deep intercondylar groove), supporting a diagnosis of congenital arthrogryposis. Tests for
BVD virus gave negative results. In a separate investigation, a high incidence of congenital
arthrogryposis with associated cleft-palate was seen in a beef suckler herd. Out of five Charolaiscross calves examined from a herd with twenty-five spring-calving sucklers, four had congenital
arthrogryposis, two of which also had cleft-palate. An inherited genetic defect was considered as a
possible cause in this case.
A calf submitted to Kilkenny from a farm with losses in two to three-week old calves showed
severe lesions of pneumonia. Haemophilus somnus, Arcanobacterium pyogenes and Salmonella
dublin were isolated. Cork had several cases of pneumonia in calves but causal agents were not
identified in most. However, one calf aged one month, had the pathognomonic histological lesions
of parainfluenza virus (PI3) infection, and another aged ten months had evidence of both infectious
bovine rhinotracheitis (IBR) and PI3 involvement. Cork found that a two-week old calf that died
with respiratory distress had a congenital pleuroperitoneal hernia. Post-mortem examination
revealed a congenital pleuroperitoneal hernia (10cm diameter ring) with the abomasum
protruding into the thoracic cavity, very thin diaphragm, misshaped liver and hypertrophic
myocardium. A three-month old Charolais heifer calf and a five-week old Friesian heifer calf were
submitted to Dublin from two different herds with a similar history of sudden death. Both calves
had lesions of serofibrinous pleuritis and bronchopneumonia with the Friesian heifer also having
pericarditis. In both cases Mannheimia (formerly Pasteurella) haemolytica was isolated from
affected tissue. Limerick identified IBR in a yearling bullock with lesions of acute tracheobronchitis.
Kilkenny identified BVD virus in a weanling with ulcerative lesions in the oral cavity and a watery
scour. The condition had progressed slowly with no response to treatment. Another weanling in the
same herd had already died with similar symptoms.
Kilkenny diagnosed lead poisoning in a two-month old calf with a history of sudden death. Two
farmers had lost two calves each in adjoining fields over a few days. Sligo also diagnosed lead
poisoning in a group of recently turned out calves. Limerick encountered a number of lead
poisoning outbreaks in calves and cows. Discarded batteries were found in all cases investigated. In
one case, cows had unearthed a battery on the bank of a river, and in another case, the battery had
been lying in a shed that had been broken into by a number of calves.
Sligo diagnosed chronic fasciolosis in an 11-month old Galloway calf from an organic farm. The
cows and calves had been set-stocked and had not been dosed.
Limerick reported an outbreak of ragwort poisoning in a cattle herd. The presenting signs varied
from wasting and tenesmus to acute nervous signs. Sligo encountered a number of outbreaks of
babesiosis coinciding with the seasonal rise in tick activity.
Athlone diagnosed peritonitis in a cow from a herd where four other deaths had occurred. In this
case the condition appeared to have developed from a chronic necrotic cystitis. This cow was a
few weeks calved and her uterus was normal. The cause of the cystitis was not determined.
A biopsy was submitted to Sligo from an annular lesion obstructing the oesophageal juction with
the rumeno-reticulum in a seven year-old cow. This tissue was sampled during the rumenotomy of
the cow with a history of dyspagia and projectile vomiting. Histopathology confirmed that the
lesion was a squamous cell carcinoma. The animal's grazing history included long-term exposure
to bracken.
Athlone reported malignant catarrhal fever in a cow. Prior to death the cow had shown nervous
signs and was the fourth to die under similar circumstances in the herd. The presence of the
causative herpesvirus was detected by PCR. Twenty-five other cattle were blood sampled in the
herd, one of which was positive for the virus. This animal had begun to show clinical signs.
Sheep
Cork examined a one-month old lamb that had died following clinical signs of dyspnoea. It was
found to have multifocal areas of necrosis in the lungs and liver. Fusobacterium necrophorum
was isolated on culture and histopathological lesions were consistent with the presence of this
pathogen. Disseminated infection with Fusobacterium necrophorum is usually secondary to a
primary focus such as navel ill or necrotic stomatitis, but no such lesions were found in this case.
Kilkenny examined a five-week old lamb with a history of pneumonia. Hydrothorax, extensive
pleuritis and pericarditis were present. Mannheimia haemolytica was isolated. Athlone also isolated
Mannheimia haemolytica from a ewe with lesions of pneumonia.
Sligo reported an increase in the incidence of louping ill in sheep, coinciding with the seasonal
surge in tick activity.
Ovine pulmonary adenomatosis (Jaagsiekte) was diagnosed by Athlone in a ewe from a 500-ewe
flock presented with a history of sudden death. Jaagsiekte is a disease caused by a retrovirus. It is
spread laterally and, because of its long incubation period, clinical signs are usually seen in sheep
from three or four years of age. Mortality due to the disease on a flock basis is usually between two
and eight per cent. It causes weight loss, cough/pant after exercise, moist rales and a frothy nasal
discharge. Culling of sheep at the onset of clinical signs as well as culling of the progeny of affected
sheep are the recommended control procedures.
Pigs
Streptococcus suis type II was isolated by Cork from joint fluid, meninges and lung of a threeweek old piglet with clinical signs of ataxia and swollen joints. Histopathology showed a diffuse
leptomeningitis. Kilkenny isolated Haemophilus parasuis from the lungs of a two-month old piglet
with pleuritis and swollen joints.
Poultry
Cork dealt with production drop and poor egg quality, but with very low mortality, in a freerange flock. The flock consisted of two houses with over 2000 hens in each. The problem was
confined to one house even though only a single wire fence separated the runs. The clinical signs,
gross lesions, histopathological lesions and the subsequent response to therapy all supported a
diagnosis of avian vibrionic hepatitis (AVH) (figure 2). However, no bacterial pathogen could be
demonstrated on culture, a historical problem associated with this disease. AVH was documented
extensively in the decade from 1965 in both Europe and USA, but then largely disappeared. The
Cork laboratory has only ever dealt with one other apparent AVH outbreak. This was six years ago
(Irish Veterinary Journal (2000) 53: 78) and was in the same flock and house as this current
outbreak!
Cork had a submission of pheasant eggs that had failed to hatch. Of eighty eggs incubated only
two chicks pipped. Several of the eggs were grossly contaminated. Findings of mixed growth of
bacteria suggested that spread of infection within the incubator participated in some of the deaths
but other management factors may also have been involved as many chicks which had no evidence
of infection died three to four days before pipping.
Other Species
Limerick investigated high mortality in an aviary. Examination of two zebra finches showed
multifocal abscessation of the liver, spleen and mesentery from which Yersinia pseudotuberculosis
was isolated.
A Fota Island Halley-Mandril monkey that died shortly after birth had a severe interstitial
pneumonia with histopathological changes suggestive of a viral aetiology.
CAPTIONS FOR PHOTOS
Figure 1 “Charolais calf with athrogryposis- photo William Byrne”
Figure 2 “Numerous small necrotic lesions seen in the liver of a hen with suspect Avian Vibrionic
Hepatitis- photo Pat Sheehan”