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). Post-mortem 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 Charolais-cross 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 tracheo-bronchitis.

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 three-week 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 free-range 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”