February RVL Monthly Report
February saw a seasonal increase in the number of calf submissions to the laboratory service, and infectious disease such as salmonellosis was important among the diagnoses made. Kilkenny isolated Salmonella Dublin from a five-day-old calf with peritonitis, while Kilkenny also diagnosed Salmonella Dublin septicaemia in a one-day-old calf with peritonitis which had been born one week prematurely. Salmonella abortion in the herd had already been confirmed and this herd had several neonatal calf mortalities recently. Salmonella Dublin was isolated from a four-day-old calf, which had suffered from pyrexia and respiratory distress ante mortem. Ten other calves from the herd of origin were similarly affected. Limerick diagnosed salmonellosis in a 12-day-old-calf with a history of sudden death and which presented with hepatomegaly, splenomegaly and diffuse pulmonary oedema on necropsy. Salmonella Dublin was isolated from tissues. Kilkenny isolated Salmonella Dublin from a three-week-old calf with terminal dry gangrene and Limerick suspected salmonellosis in a two-month-old calf with terminal dry gangrene (Figure 1) while Sligo also saw a similar case. Salmonella Dublin was isolated in another calf submitted to Sligo from the same herd; this latter calf had developed diarrhoea.
Figure 1: Terminal dry gangrene in the leg of a two-month-old calf. Photo: Alan Johnson.
Colisepticaemia in young calves was also seen by the laboratory service in February; such diagnoses were usually accompanied by a finding of hypogammaglobulinaemia highlighting the importance of adequate colostrum intake in early life. Limerick reported a finding of colisepticaemia in several submissions of young calves during February; a low zinc sulphate turbidity (ZST) test suggestive of poor immunoglobulin intake was a consistent finding with these cases. Sligo saw much infectious disease in young calves in February which included peritonitis, navel infection, joint ill and scour, again evidence of low immunoglobulin intake was a consistent finding. A one-week-old calf submitted to Kilkenny was found to have severe pericarditis and changes consistent with congestive heart failure. Hypogammglobulinaemia was found and Escherichia coli was isolated from several organs. Kilkenny also saw a lot of enteritis in young calves, and aetiological agents identified in these cases included rotavirus, Cryptosporidium spp. and Salmonella spp. Rotavirus was the agent most commonly identified. Dublin detected Cryptosporidium ssp. and rotavirus in the faeces of a ten-day-old calf which had pale watery scour ante mortem. Hot power washing of accommodation when empty was advised as Cryptosporidium oocysts in particular are very resilient in the environment.
A number of congenital defects in young calves were seen in February. Dublin diagnosed a large interventricular septal defect in a nine-day-old calf which was found dead (Figure 2). Kilkenny found that the heart of a stillborn calf was dilated, the interventricular septum was entirely absent while the conjoined pulmonary artery and aorta arose from the right side of the heart. Kilkenny also investigated the case of a one-day-old calf which was depressed ante mortem, polycystic kidneys were found on post mortem examination (Figure 3). A one-day-old calf with a history of inability to defecate was submitted to Athlone. A diverticulum of the terminal ileum was found on post mortem examination, this diverticulum was filled with meconium while the contents of the large intestine were scant, the diverticulum acted as a bowel obstruction seriously compromising the viability of the calf. Kilkenny diagnosed atresia coli in two calves that had failed to pass faeces, one of the calves had also developed an intusseception in the small intestine. The RVL network is currently participating in a collaborative study of congenital bowel defects in calves with Teagasc Moorepark and the submission of all suspect cases of abnormal bowel development such as atresia ani, or atresia coli is encouraged.
Figure 2: Large interventricular septal defect in a nine-day-old calf. Photo: William Byrne.
Figure 3: Polycystic kidneys in a one-day-old calf. Photo: Donal Toolan.
Other cases seen in February included a three-day-old calf with a history of sudden death submitted to Athlone. Gross examination of tissues revealed patchy pallor of the myocardium and skeletal muscle. Histopathology confirmed myocardial necrosis. Cardiomyopathy was diagnosed in this case. The most likely cause was nutritional and though selenium levels were normal, hypovitaminosis E could also contribute to such pathology. Limerick also investigated a sudden death case in a one-month-old calf, where mesenteric root torsion was found on necropsy. Athlone diagnosed coccidiosis in a ten-day-old calf with a history of bloody scour ante mortem, and haemorrhagic enteritis was evident on post mortem examination. Detection of coccidial oocysts in faeces confirmed the diagnosis. Coccidia have a pre-patent period of three weeks, so the oocysts must have originated from coprophagia rather than from the calf itself. Nevertheless, it is clear that this calf was subjected to a very heavy coccidial challenge in its environment. It seems likely that prepatent coccidiosis caused the gross lesions observed. Bovine Viral Diarrhoea Virus (BVDV) infection was found in two separate cases submitted to Kilkenny. In one case persistent infection with BVDV was detected in a four-month-old calf suffering from ill-thrift while in the second case persistent BVDV infection was confirmed in the case of an eight-month-old calf that was suffering from ill thrift and diarrhoea. Dublin also detected BVDV in the tissues of a two-month-old calf with diffuse chronic bronchopneumonia, immunosuppression due to BVDV infection is likely to have predisposed to the pneumonia. Kilkenny also confirmed a case of Bovine Neonatal Pancytopaenia (BNP) in a two-week-old calf while the same laboratory was awaiting confirmation of a separate suspect case of BNP from a different herd. Athlone necropsied a five-day-old calf which was found to be recumbent and paddling ante mortem. ZST results showed poor colostral transfer of maternal immunity and histopathology revealed a suppurative encephalitis consistent with listeriosis. Listeriosis was also suspected in the case of a ten-month-old heifer which was ill for two days ante mortem. Clinical signs included repeated banging of the head against a wall. Necropsy of this case revealed chronic suppurative valvular and mural endocarditis and brain swelling on gross examination, while suppurative meningoencephalitis was evident on histology. Athlone also necropsied a three-month-old Belgian blue calf that was recumbent prior to death. Post mortem examination revealed abscessation and bone necrosis in the fourth cervical vertebra (Figure 4). Leptomeningitis and wallerian degeneration were found along the spinal cord caudal to the abscess while Arcanobacterium pyogenes was isolated from the abscess – Salmonella Dublin has been more commonly associated with this syndrome in the past. The localisation in the mid-cervical vertebrae may be related to the relatively poor perfusion of these vertebrae.
Figure 4: Bone necrosis and abscessation (see arrows) of the fourth cervical vertebra from three-month-old Belgian Blue calf with a history of recumbency ante mortem. Photo: John Fagan.
Limerick investigated the death of a six-year-old Montbéliarde cow with a history of severe respiratory difficulty for a few hours before death. Post mortem examination revealed fibrinous pleuritis and pneumonia, and histology showed a fibrinous pleuropneumonia. Mannheima haemolytica was isolated from the affected tissues. Athlone detected TB lesions in the mammary gland of a tuberculin test-reactor cow which was submitted from a herd where a number of calves were also found to have TB. The farmer used a system of pooled feeding of milk to calves which was likely to have contributed to the spread of infection. The farm family had fortunately ceased to consume raw milk produced on farm a mere two years previously.
Pathogenic isolates from bovine foetuses submitted to Kilkenny included Arcanobacterium pyogenes, Salmonella Dublin and Bacillus licheniformis. Kilkenny also found bilateral rib fractures in a full-term calf with a history of dystocia. PCR testing of tissues in a stillborn calf submitted to Limerick yielded a positive result for bovine herpesvirus 1 (IBR). This was the third such stillbirth in a herd of 85 cows and the dam was described as being depressed before delivering the calf. Sligo also reported submission of stillborn calves; dystocia was diagnosed in most of these cases.
There was a seasonal increase in the submission of lambs in February. Limerick diagnosed colisepticaemia in a one-day-old lamb with a history of weakness and depression. Cryptosporidial oocysts were also found in the faeces. Athlone necropsied a four-day-old lamb with a history of diarrhoea. It was the eight lamb to be lost from the flock, and the intestinal contents were yellow and watery; E. coli K99 was identified in faeces. E. coli K99 vaccination and a review of lambing hygiene were recommended. Athlone also saw two five- week-old lambs submitted from the same flock. Septic peritonitis due to perforated abomasal ulcer was diagnosed in one, and large numbers of coccidia oocysts were found in intestinal contents. The second lamb bore evidence of enteritis while high urea levels found in peritoneal fluid were consistent with nephrosis. Nephrosis when it occurs in lambs is frequently idiopathic, but is sometimes associated with coccidiosis or nematodirus. In a separate case Athlone isolated Mannheima haemolytica from the lungs of a three-month-old lamb with a history of acute pneumonia. A number of such losses had occurred in the flock. Sligo saw several cases of death due to shock in ewes with uterine prolapses, in which loops of intestine were incarcerated within the prolapse. Large foetal size in association with small dam stature was considered contributory to the problem. Sligo also diagnosed several cases of pregnancy toxaemia (twin lamb disease). Concurrent parasitism was also frequently found in these cases. Athlone investigated the deaths of two 2.5 year old ewes form the same flock. Grain was found in the ingesta in both while a low pH in ruminal fluid in both cases was indicative of ruminal acidosis.
Limerick isolated Campylobacter fetus fetus from aborted triplet lambs which were two weeks premature, while in a separate case Limerick detected high antibody titres to Toxoplasma gondii in aborted lambs submitted from a flock with no history of vaccination. Ovine abortifacients detected by Kilkenny included Toxoplasma gondii, Campylobacter fetus fetus and Salmonella Dublin, while Sligo found that Toxoplasma gondii was the most common abortifacient detected there. Dublin found placentitis and endometritis associated with in utero death in the case of one of two very large foetal lambs in a Suffolk ewe which had suffered vaginal prolapse and had not survived prolapse replacement. The ewe was in good condition and had fatty infiltration of the liver.
Dublin observed diffuse exudative glomerulonephritis in a section of kidney tissue collected from a fattening pig suspected of having Porcine Dermatitis and Nephropathy Syndrome (PDNS). Glomerulonephritis is a pathological finding that is consistent with a diagnosis of PDNS in fattening pigs that also have multifocal dermatitis.
Athlone found multiple torsion, thrombosis and haemorrhage of the umbilical cord in a submitted equine foetus and placenta. The placenta appeared otherwise normal and testing for infectious equine abortifacients proved negative. Umbilical cord torsion was identified as the cause of death.
Athlone necropsied a wild duck with multifocal pale lesions in pectoral muscles, liver and mesentry. Histopathology revealed these lesions to have arisen as a result of parasitic invasion. The aetiological agent was identified as Sarcocystis rileyi, a parasite of muscles often found in wild ducks.