Piglet diarrhoea - don t let disease score. IDT Biologika GmbH Am Pharmapark D Dessau-Rosslau, Germany Tel

Transcription

1 01/ Piglet diarrhoea - don t let disease score IDT Biologika GmbH Am Pharmapark D Dessau-Rosslau, Germany Tel

2 The piglet s intestine is the key to sucess The intestine of a piglet is not just merely a simple digestion pipe. Each section of the intestinal tract is dedicated to perform specific and diverse tasks. A healthy digestive tract, good feed and good management is the key to maximising the piglet s growth and performance. Intestinal diseases which cause diarrhoea (scouring) during the early stages of the piglet s development have an enormous impact on the animal s later development and the overall economics of the farm.

3 Scouring is the symptom, but not the problem. Time is money - each day the piglets are scouring means another day of reduced profitability. Today s piglet producer is not only a farmer, but also a businessman. Optimum levels of productivity can only be reached by running the farm as efficiently as possible. Regular visits from the vet are important to maintain animal s health or to restore productivity of the farm through accurate diagnosis of a problem and speedy implementation of corrective therapy. The common goal for the farmer and veterinary surgeon s work being to produce a positive financial result for the piglet producing unit. Reduction of hard and soft costs: Scouring doesn t necessarily mean that animals die, however a piglet that has suffered from diarrhoea will be affected in its later development and will hardly ever achieve its full potential (in particular, weight at weaning, daily weight gain and feed conversion rate etc). These factors can easily be extrapolated as profit derived from sellable piglets per sow per year. However, the factors vary markedly depend on the causative agents (see later). Quite often this type of calculation does not consider so called soft costs. Each litter that suffers from diarrhoea has to be treated by the vet and the farmer in order to minimise the losses. The measures which have to be taken to address the hard and the soft costs will be addressed in this brochure. What causes Scouring? The causes of scouring are many and varied. Scouring is merely a symptom, but not the final diagnosis of the problem. The most common causes are infections of certain pathogens, including viruses, bacteria and parasites. The following table gives an overview of the most common infectious agents in the field of piglet rearing. This brochure does not address factors caused by management (feeding, stress etc). The piglet s intestine plays a major role in disease prevention and healthy growth! Disease Causative organism Course of disease Percentage of herd affected Mortality rate* Incubation period Rotavirus diarrhoea Rotavirus peracute to acute up to 100% up to 100% 1 2 Days TGE Porcine Coronavirus peracute to acute up to 100% up to 100% 1 4 Days Viral Vomiting and Wasting Disease Hemagglutinating Encephalomyelitis-Virus acute to chronic up to 10% 10 50% 4 6 Days Necrotic enteritis Clostridium perfringens Typ C peracute to chronic up to 50% up to 100% 1 3 Days Bacterial Clostridial diarrhoea Clostridium perfringens Typ A acute to chronic up to 50% % Less than 1 Day Coli dysentery Hemagglutinating E. coli peracute to chronic up to 100% up to 100% 1 3 Days Coccidiosis Isospora suis acute to chronic up to 100% up to 50% 2 3 Days Parasitic Cryptospirosis Cryptosporidium parvum chronic up to 50% up to 10% 2 10 Days Strongyloides Strongyloides ransomi acute to chronic up to 100% up to 50% 1 Day *without treatment

4 Not all organisms are pathogens... The digestive tract of a pig is never free of microorganisms. On the contrary! Numerous useful microorganisms live there (bacteria, fungi, yeasts etc). There are an estimated 100 billion bacteria in the intestine - this is more than the whole number of body cells in the pig. These microorganisms constitute the microflora, which are useful helpers to cope with life supporting processes (e.g. provision of nutrients in the gut mucosa, breaking down of feed components). Unlike the intestine of adult pigs, the young piglet is highly susceptible to disruptions of any kind. The process of birth catapults the piglet from the protective womb, into an environment with completely different external conditions. While the animal was previously supplied via the umbilical cord with all necessary nutrients, it now has to organise its own feed intake via the sow s milk, or any alternative feed supply provided by the farmer. In this early phase of life, the piglet s intestinal microflora hasn t established itself completely and its intestine is forced to adapt rapidly to the new situation described above. Obviously this sensitive inner balance can be upset by the smallest disturbances. As mentioned earlier, diarrhoea is merely a symptom. If scouring appears on a farm the very first step is to identify the causes. The veterinary surgeon will send samples off for laboratory analysis (e.g. faecal samples), or conduct post mortems on dead animals to identify the causes of the problem. Once these have been identified, a suitable treatment plan can be established. Here we have to differentiate between acute therapeutic measures (e.g. antibiotics, electrolyte solutions) and medium to long term preventative measures (vaccine and/or management changes). It s self explanatory that the goal must be to prevent scouring rather than to treat it. This is where vaccination is valuable. What can be achieved through vaccination? Vaccination of very young piglets against scouring is not practical and so the sow vaccination has been developed to provide the piglet passive protection. The sow is vaccinated prior to farrowing in accordance with the vaccine manufacturer s instructions. The immune system of the sow is stimulated to produce certain defensive substances (antibodies) against the proffered pathogens (antigens) that are contained in the vaccine. These antibodies will circulate in the blood of the sow and will accumulate in the first milk after farrowing (colostrum). Colostrum provides the new born piglet with both, essential nutrients as well as protective antibodies. This explains why it is so important that newborn piglets suckle without delay. In the first hours of life, the piglet s intestine has not been fully separated from its blood stream and during this time extremely small particles (namely the antibodies) can still pass this barrier and reach the blood stream of the piglet. Other antibodies do not need to pass this barrier but instead attach to the intestinal wall of the piglet. If the piglet is then confronted by microorganisms that cause scouring, it has a passive protection against this infection (locally in the intestine and systemically in the bloodstream) because the attacking pathogens can be confronted immediately. The major prerequisites for good immunisation of piglets are: > Sufficient uptake of colostrum > High antibody levels in the sow s milk or colostrum > Healthy teats of the sow Most microorganisms in the piglet s intestine are useful and important. But just after birth, the digestive tract is particularly sensitive to agents that cause disease. Once scouring occurs, the farmer needs to involve the vet, identify the cause of scouring and take corrective measures. 8 / 8

5 Bacteria Prevention rather than treatment Coli Dysentery (Diarrhoea) Causative agent More than 1000 different representatives (so called serotypes) are known to date for the bacterium Escherichia coli (E. coli). Only those that can attach to the gut epithelium and are able to build toxins at the same time primarily represent the strains that can cause scouring. These strains are known as enterotoxic E. coli (ETEC). After ingestion of the E.coli organisms and subsequent passage through the stomach, the disease complex is characterised by three phases: > Rapid multiplication of organisms in the gut > Adhesion of the organisms to the gut wall > Release of poisonous substances (enterotoxins) The toxins are transported into cells of the gut wall where they cause increased release of liquid into the gut lumen and simultaneously block the absorption of electrolytes by the cells. This reversion of the natural flow of body liquids, i.e. from the body into the gut, results in the animals losing large amounts of water and minerals. The intestinal mucosa may not be visibly damaged, but the process will lead to dehydration of the animals and often to its death. Common sources of infection are dirty and humid housing, faeces of the sow as well as excretions of siblings that already suffer from scouring. Short information Coli dysentery > Primary diarrhoea-causing strains are known as ETEC > Dehydration of the animals can often lead to death > Protection through sow vaccination possible Clostridium perfringens (C. perfringens) infections Causative agent The genus of clostridia contains 82 species, however only those that produce toxins are pathogens. Amongst the clostridial toxins are the strongest known biological poisons (e.g. Botulinum toxin and Tetanus toxin). Infection of piglets with clostridia occurs after oral ingestion of the bacteria from the faeces of the sow. Certain substances in the sow s milk protect vital antibodies provided via the colostrum from natural inactivation through digestive processes in the piglet s gut. Unfortunately, they also prevent inactivation of damaging toxins and therefore increase the piglet s susceptibility to clostridial toxins. Obviously the problem disappears as soon as the piglets are weaned. In this context, Clostridium perfringens is the main causative agent of interest. Course of disease Following ingestion of C. perfringens Type C, the microorganisms infect the mucosa of the small intestine and produce toxins. Clostridia produce a poison that not only affects the function of the intestine, but may also affect and completely destroy the sensitive intestinal tissue and its deeper mucosal layers (see schematic diagramme below). Destruction of intestinal tissue through Clostridium perfringens Type C toxins toxins 1 2 Course of disease Piglets that appear perfectly healthy may fall ill within the first hours of life. Usually the whole litter is affected; the piglets show severe light coloured watery/creamy diarrhoea. The flanks of the animals become sunken. The piglets are weak and lethargic in the stall. Without immediate treatment and liquid replacement mortality is very high. villi intestinal cells outer intestinal layer blood vessel defence cells Treatment As the infection is attributable to high infection pressure and absence of colostral antibodies, the introduction of sow vaccination and improvements in hygiene should be considered. Pre-farrowing vaccination of sows with a vaccine containing the most commonly occurring E. coli strains is the most effective measure. Modern commercial vaccines that are able to provide immunisation against cell wall antigens, adhesin antigens and toxins are particularly effective. Production of an autogenous vaccine is indicated if exotic E. coli strains have been identified which are not included in commercially available products. Following oral infection, toxins are released into the intestine. Destruction of intact intestinal tissue 3 The toxins damage the sensitive intestinal tissue. Local inflammation of intestinal tissue occurs as a consequence of the natural defence reaction of the host. red blood cells 4 In the acute phase, administration of electrolyte solutions and antibiotics is indicated. Antibiotics will stop bacteria from multiplying however they are not effective against toxins that are already present. These measures will help prevent the worsening of the animal s condition, but cannot correct the damage which has already taken place and should therefore be restricted to emergency use only. The toxic effect suffices to cause decay of the intestinal tissue. Eventually, the damage encroaches on the blood vessels that nourish the intestine. As a consequence, blood seeps into the intestinal lumen. From: Sieverding E (2000)

6 Course of disease (continued) Three different courses of disease can be seen in a herd: Table 2: Overview of clinical infection grades with Clostridium perfringens Type A Peracute: Sudden death without any typical symptoms of diarrhoea Acute Subacute/Chronic Acute: The damage to the intestinal mucosa leads to blood entering the intestine. This results in watery, brown/red bloody granular diarrhoea of the piglet. This clinical picture is called necrotic enteritis, the general condition is highly disturbed, animals appear depressed and refuse feed, in some cases vomiting may be observed. Without treatment up to 100% of piglets may die. Day of life 1 st to 14t h Day from 1 st Day Chronic: Foamy, bad smelling, grey/yellowish diarrhoea with granular texture may be observed. Piglets primarily die through water and electrolyte loss than because of the presence of bacterial toxins. Table 1: Overview of clinical infection grades with Clostridium perfringens Type C Clinical Diarrhoea Dehydration Potential death of frail piglets or death in conjunction with mixed infections (E. coli, rotavirus, coccidia) Diarrhoea (yellow, with gas bubbles) Dehydration Runting-stunting Peracute Acute Subacute/Chronic Day of life Birth to 2 nd Day 2 nd to 5 th Day 5 th to 10 th (14 th ) Day Pathological findings (Post mortem) Catarrhal to haemorrhagic enteritis Serous to catarrhal enteritis Clinical No food intake Circulation problems No diarrhoea Diarrhoea (brown-red) Bloated piglets due to blood loss over the intestine Dehydration Diarrhoea (grey-yellow with gas bubbles) Dehydration Runting-stunting Treatment Sows can be vaccinated as a prophylactic measure against C. perfringens Type C with commercially available vaccines, in addition, combination products are marketed that protect piglets simultaneously against both, dysentery and necrotic enteritis. In the acute phase, clostridial infections can also be treated with antibiotics. The damage to the intestine of survivors is irreversible and performance of the animals will be reduced lifelong. Pathological findings (Post mortem) Haemorrhagic to necrotic enteritis Necrotic enteritis At the moment no licensed vaccine for sows against C. perfringens Type A is available that would protect piglets from infection. However, autogenous vaccines can be made from gens isolated from the affected farm and from which an individually tailored vaccine can be patho- produced. The frequency of isolation of certain Clostridium perfringens species has shifted over the past few years. Towards the end of the 1990s, the predominant species was Type C, nowadays C. perfringens Type A is most frequently isolated. The different Clostridium perfringens species differ from each other in the type of toxin produced. In direct comparison, infections caused by C. perfringens Type A result in milder forms of diarrhoea than those by C. perfringens Type C. In very rare cases piglets will die within 48 hours. More typically, piglets will develop watery, slimy, yellowish diarrhoea in the first seven days of life. Toxins from C. perfringens Type A cause liquid exudate from neighbouring cells into the gut lumen as well as causing inflammation of these cells. Unlike toxins from C. perfringens Type C, the intestinal tissue will not be completely destroyed. Hence indirect losses through runting-stunting and reduced daily weight gain are points of major concern to the piglet producer. Short information Clostridium perfringens Type A > Milder disease than with C. perfringens Type C > Indirect losses through runting-stunting > Protection through sow vaccination possible Short information Clostridium perfringens Type C > Irreversible damage to the lining of the intestine (intestinal mucosa) > Characteristic bloody diarrhoea > Protection through sow vaccination possible

7 Rota- and Corona viruses Ride out the storm Parasites Who goes there? Friend or foe? Rota- and corona viruses are about 100 times smaller than bacteria, are unaffected by antibiotics and to date cannot be prevented by immunising the piglets with a commercially available vaccine. The only therapy available is to ensure an adequate supply of liquids to prevent the piglets from dehydrating. Other than that, the only option is to ride out the storm. As the infection spreads through the herd, some animals may survive and subsequently develop a solid immunity.. Rotavirus Rotaviruses are not particularly host-adapted and can also cause disease in calves and dogs. Infections with rotaviruses are considered as multi-factorial diseases. The severity of the disease will also be determined by housing conditions, hygiene, temperature and the humidity of the stall. The faeces will appear greasy to fatty and of white to yellowish colour. In healthy pigs, the mucosa of the intestine is densely covered by minute finger-like structures called villi which increase the surface area of the gut, thus assuring optimal uptake of nutrients from the feed. During the course of a rotavirus-infection the layer of villi in the small intestine will be completely destroyed. This is accompanied by a rapid and significant loss of liquids and cases of death. Coronavirus Another viral intestinal disease is the so-called Transmissible Gastro-Enteritis (TGE), caused by a coronavirus. As the descriptive name of the problem (TGE) already indicates, the disease is highly contagious and can affect animals of all ages. If piglets younger than two weeks are affected, mortality may often reach up to 100%. The disease mainly occurs in winter, as the virus is highly sensitive to heat and sunlight. Some countries have a surveillance system in place and cases or suspected cases of TGE have to be notified so the government is in a position to act rapidly to avoid spreading and to enforce disease control measures. In pens with suckling piglets, typical disease symptoms are very severe and sudden watery diarrhoea and vomiting. The speed at which the infection spreads, even when animals have no direct contact to each other is an indication for it s ability to spread via the air. The important role of airborne spreading must be kept in mind. The changes in the gut epithelium (villi) is comparable to those described for a rotavirus infection. Coccidial infection Causative agent Scouring can also be caused by parasites. Coccidia are single celled organisms that infect the gut epithelium. The only commercially important species of coccidia affecting pigs is Isospora suis. Coccidial infections cause long lasting damage of the gut epithelium, resulting in poor performance and runting-stunting. Course of disease Suckling piglets would usually fall ill at 5 to 10 days of age. They would have been infected immediately after birth through ingestion of so-called oocysts (a specific development stage of the parasite) from the environment. The parasite invades the intestinal cells and remains there through several phases of its life-cycle. Finally, a non-sexual multiplication phase occurs after which the cell bursts, releasing vast numbers of the parasites that in turn attack new cells within the intestinal wall. The extensive depletion of healthy intestinal cells obviously leads to a serious disruption of feed absorption and an imbalance of the body s liquid management. Cells lose water into the gut lumen; consistency of faeces varies from temporarily pasty to profuse, yellowish-watery diarrhoea. Treatment Coccidia, like viruses cannot be treated with normal antibiotics, but do respond to orally administered pharmaceuticals given during the first few days of life. These effectively control coccidiosis in piglets and thus avoid the outbreak of disease. Short information Coccidia > Settle in the intestinal mucosa > Litters grow at different rates > Respond to treatment with pharmaceuticals Short information Rota- and Coronavirus > Antibiotics do not work against viruses > Coronavirus infection is particularly common in winter > No commercial vaccines available

8 Short and Sweet at one glance Scouring can have various causes and but always means extra costs, is always time consuming and unnerving. To develop a suitable strategy to combat and prevent disease, it is necessary to identify the underlying reason and the causative agent. This approach enables the piglet producer and the veterinarian to work together on defining, implementing and executing a specific and tailor-made strategy. Highly effective vaccines are available to control infectious diseases. Prevention measures will keep the life stock healthy and save money in the long term. Ask your veterinarian for commercial and autogenous vaccines from IDT Biologika GmbH. Literature References: Jungnitz, S: Wenn Colis und Co. den Ferkeln zu schaffen machen. In: top agrar, issue 6/1999, S4 S7. Krueger, M, S Schwieger and W Schroedl: Die Magen-Darm-Flora (MDF) des Schweins ein Überblick. In: Tieraerztliche Umschau. 63. Jg. 2008, issue 4, 208 Ritzmann, M and K Heinritzi: Durchfallerkrankungen beim Schwein. In: Tieraerztliche Praxis. 2006, issue 34, 411 Roesch, H and S Springer: Clostridium perfringens Infektionen beim Saugferkel. In: Der Praktische Tierarzt. 90. Jg. 2009, issue 1, 78 Rolle, M and A Mayr: Medizinische Mikrobiologie, Infektions- und Seuchenlehre. 8th edition, Stuttgart 2006, 245 Sieverding, E: Handbuch Gesunde Schweine. 1 st edition, Osnabrueck 2000, 192 Einlegelasche 16 / 16