Section 3 Clostridial disease
- Maresa Sheehan
- Senior Research Officer, Kilkenny Regional Veterinary Laboratory, DAFM, Leggatsrath, Hebron Road, Kilkenny, Ireland
Clostridial spp. cause significant disease in both sheep and cattle and are encountered regularly in post mortem room submissions. They also cause disease in other species including goats and pigs. Typically, clostridial disease presents as acute disease or sudden death and mortality approaches 100% in most cases.
3.1 Blackleg
Blackleg is the most frequently diagnosed clostridial disease in bovine submissions; it is commonly, but not exclusively, associated with detection of Clostridium chauvoei (Table 3.1 and Figure 3.3). The pathogenesis of this disease requires pre-existence of bacteria in tissue that, in conjunction with favourable circumstances such as trauma, establish anaerobic conditions which allow bacterial proliferation and toxin production, the latter causes severe local necrotising myositis (Figure 3.1) and systemic toxaemia. Cases encountered in post-mortem rooms frequently have a typical rancid butter odour and affect muscles of the limbs, tongue and heart.
Figure 3.1: Blackleg lesion (severe necrotising myositis) in the hindquarters of a bullock. Photo: Maresa Sheehan.
| Disease | No. of Cases | Percentage |
|---|---|---|
| Blackleg | 40 | 45.5 |
| Botulism | 21 | 23.9 |
| Malignant Oedema | 14 | 15.9 |
| Enterotoxaemia | 10 | 11.4 |
| Black Disease | 3 | 3.4 |
3.2 Botulism
Botulism is the second most frequently diagnosed bovine clostridial disease. Clostridium botulinum toxin typically results in affected animals lying in sternal recumbancy with the head on the ground or turned into the flank, similar to a cow suffering from post parturient hypocalcaemia/milk fever. However, a range of clinical signs can be detected within an affected group, likely reflecting levels of toxin ingested, these can include restlessness, inco-ordination and knuckling. The association of this disease with the spread of poultry litter has resulted in Codes of Practice being established for disposal of such material. The laboratory service has been involved in the investigation of a number of cases where a direct link with poultry litter was not established, carrion and forage associated botulism could not be ruled out in these cases.
3.3 Malignant Oedema
Malignant oedema can be caused by a number of Clostridial spp. including C. septicum, chauvoei, sordellii and novyi. Epidemiology and pathogenesis of this disease differs from blackleg in that bacteria is introduced through a wound and causes focally extensive skin gangrene and oedema of the sub-cutaneous and intra-muscular connective tissue, there is less frequent involvement of underlying muscle.
Figure 3.2: Perivascular oedema in the brain associated with vascular compromise due to Epsilon toxin-Pulpy kidney. Photo: Maresa Sheehan.
Figure 3.3: Clostridial disease diagnosed in Bovine carcasses in 2018 (n= 88 ).
3.4 Enterotoxaemia
Enterotoxaemia is a disease caused by Clostridium perfringens that causes significant losses in both cattle and sheep (Table 3.2) and Figure 3.5). This micro-organism can be a normal inhabitant in the intestine of most species inlcuding humans. When intestinal environment is altered by sudden changes in diet or other factors, C. perfringens proliferates in large numbers and produces several potent toxins that are absorbed into the general circulation or act locally with usually devastating effects on the host. Enterotoxaemia diagnosis presents a diagnostic challenge as this bacteria is a normal inhabitant of the gut, therefore, demonstration of toxins is essential. However, as some of the toxins can be present in small amounts in clinically normal animals, presence of concurrent gross lesions and histopathological changes is desirable.
Figure 3.4: Fibrin clot in pericardial sac associated with clostridial enterotoxaemia. Photo: Maresa Sheehan.
| Disease | No. of Cases | Percentage |
|---|---|---|
| Pulpy Kidney Disease | 38 | 37.6 |
| Enterotoxaemia | 36 | 35.6 |
| Malignant Oedema | 12 | 11.9 |
| Abomasitis- emphysematous | 8 | 7.9 |
| Black Disease | 6 | 5.9 |
| Braxy | 1 | 1.0 |
In lambs, C. perfringens type A produces a rare form of acute enterotoxemia known as yellow lamb disease, clinically characterised by depression, anemia, icterus and hemoglobinuria (Uzal and Songer 2008). In cattle, it has been associated with haemorrhagic enteritis, indistinguishable from that caused by Types B and C. It has also been proposed as a cause of acute deaths in calves due to clostridial abomasitis and of jejunal haemorrhage syndrome in adult cows. The latter is a disease entity sporadically diagnosed in the veterinary laboratory service and, consequently, no definitive conclusions on its aetiology can be made (Van Kruiningen et al. 2009,Songer and Miskimins (2005)).
Clostridium Perfringens Type B and C can cause sudden death, with or without haemorrhagic enteritis, in lambs and calves, and struck in adult sheep. Clostridium perfringens Type D produces epsilon toxin, which causes vascular endothelial damage (Figure 3.2) resulting in typical lesions of Focal Symmetrical Encephalomalacia (FSE) and pulpy kidney. In the PM room, detection of fibrin clots in fluid of the pericardial sac (Figure 3.4) is a strong indicator of epsilon toxin involvement.
3.5 Black Disease
Black Disease is a less frequently diagnosed cause of acute or sudden death in cattle and sheep. Clostridium novyi proliferates in anaerobic conditions, typically associated with liver damage due to Fasciola hepatica migration. Multifocal areas of hepatic necrosis are observed at post mortem. Pathogenesis of bacillary haemoglobinuria is similar, although in addition to multifocal hepatic necrosis and vascular damage, the organism also produces an haemolytic toxin which causes haemoglobinuria. Clostridium haemolyticum should be included in the list of differentials for haemoglobinuria, which also includes Babesiosis, periparturient hypophosphataemia, copper poisoning in sheep and brassica poisoning amongst others.
Figure 3.5: Clostridial diseases diagnosed in Ovine carcasses in 2018 (n= 101 ).
3.6 Braxy
Braxy is caused by Clostridium septicum and is typically seen in animals submitted after grazing frozen/snow covered pasture. It causes necrosis, ulceration, congestion and emphysema of the abomasal wall.
3.7 Clostridial abomasitis
Abomasitis caused by Clostridium sordellii has a similar post mortem presentation. Histopathology will reveal a severe necrotising abomasitis (Figure 3.6) with intra-lesional bacilli. It is essential that gross signs and histopathology concur with isolation/FAT detection of bacteria, as C. sordellii and septicum are normal inhabitants of the gut.
Figure 3.6: Haemorrhagic and emphysematous abomasitis associated with Clostridium sordellii. Photo: Maresa Sheehan.
3.8 Clostridial Vaccination
Vaccination using a multivalent vaccine is recommended for protection of animals against clostridial diseases. Due to the ubiquitous nature of agents involved, vaccination should be considered an essential component of herd/flock management. However, in a recent study into sheep mortality by regional veterinary laboratories, fifteen flocks that reported vaccinating against clostridial disease recorded a clostridial disease diagnosis. This finding is not wholly unexpected as vaccination of flocks does not infer sterile immunity, nor does detection of a pathogen on postmortem necessarily infers causation. Without data on vaccine storage, administration frequency or checks to validate that all submitted animals actually received the vaccine, it is impossible to be more specific about the reasons for these findings. However, it can be speculated that at least some clostridial disease in lambs may be due to insufficient maternal transfer of immunity to newborn lambs or waning of passive immunity in older lambs. Uzal and Songer (2008) and Songer and Miskimins (2005) reported that, although widely used, there can be variations in individual responses or manufacturer’s vaccine quality, when determining the response of sheep flocks to multivalent clostridial vaccination (Murray et al. 2019).
References
Uzal, Francisco A, and J Glenn Songer. 2008. “Diagnosis of Clostridium Perfringens Intestinal Infections in Sheep and Goats.” Journal of Veterinary Diagnostic Investigation : Official Publication of the American Association of Veterinary Laboratory Diagnosticians, Inc 20 (3): 253–65. doi:10.1177/104063870802000301.
Van Kruiningen, Herbert J, Carol A Nyaoke, Inga F Sidor, Jaroslaw J Fabis, Lynn S Hinckley, and Kevin A Lindell. 2009. “Clostridial Abomasal Disease in Connecticut Dairy Calves.” The Canadian Veterinary Journal = La Revue Veterinaire Canadienne 50 (8): 857–60.
Songer, J. Glenn, and Dale W. Miskimins. 2005. “Clostridial Abomasitis in Calves: Case Report and Review of the Literature.” Anaerobe 11 (5): 290–94. doi:https://doi.org/10.1016/j.anaerobe.2004.12.004.
Murray, Gerard M, Seamus Fagan, Denise Murphy, John Fagan, Colm Ó Muireagáin, Rebecca Froehlich-Kelly, Damien J Barrett, et al. 2019. “Descriptive Analysis of Ovine Mortality in Sentinel Sheep Flocks in Ireland.” Veterinary Record 184 (21). British Medical Journal Publishing Group: 649–49. doi:10.1136/vr.105291.
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