Pigs are susceptible to a number of diseases within Australia. We’ll cover pig diseases on this page.

Boar Taint

Studies from many Australian farms have consistently found that approximately 20% of boars at current slaughter weights are highly tainted.

This level of boar taint is one of the key factors limiting the eating quality of pig meat in Australia.

Internationally more than 95% of all male pigs are castrated before weaning to control boar taint. While castration is effective in controlling boar taint it is at the expense of reduced feed efficiency.

Barrows are fatter than entire boars, need more feed and suffer higher losses due to the stress of castration.

E. coli scours in Pigs

Piglets are exposed to Escherichia coli, a common bacterium of the gut, within minutes of birth. A number of strains of this common bowel bacterium are pathogenic for pigs.

Unless the piglet receives adequate supplies of maternal colostrum, which is rich in antibodies to, these E. coli strains, then infection may occur.

Good hygiene and temperature control in the farrowing crates are essential in controlling and preventing E.coli scours.

Vaccination of sows with E. coli pilus antigens stimulates them to produce protective antibodies that are passed to the piglets via the colostrum. These antibodies coat the intestinal lining and prevent pathogenic E. coli from attaching to the gut wall and causing disease.

Erysipelas

Erysipelas is a bacterial infection caused by the bacterium Erysipelothrix rhusiopathiae.

It is commonly know as “diamond skin disease”.  Significant production losses may result from erysipelas in pigs causing deaths, abortion, ill-thrift and rejection of carcasses at the abattoir. The economic losses due to slow growth and chronic illness can be greater than those resulting from acute outbreaks. For example, in the grower herd a 10 gram per day reduction in growth rate equates to a reduction in returns per sow of around $30.

Although erysipelas is widespread across the pig industry, outbreaks of acute disease are less common than chronic infections.

Erysipelas in pigs may present as either an acute, sub-acute or chronic infection. The clinical symptoms vary.

Because the organism can survive for long periods in the environment, a continuing preventative vaccination program is recommended.

Leptospirosis in Pigs

Leptospirosis is a bacterial infection that colonises the kidneys and genital tract of the host.

The disease can be spread to humans and other animals when leptospires are shed in the urine and from the reproductive tract into the surrounding environment.

L. tarassovi and L.pomona are usually the most common types found in pigs.

Clinical signs of leptospirosis in pigs can include abortion, weak or stillborn piglets, which can all affect the productivity and profitability of the herd.

Symptoms in humans range from profound fatigue and headaches to muscular aches and vomiting. Usually, infected people return to work within 3 to 4 weeks, however continuing relapses can occur. The disease is a significant occupational health and safety issue for pigs, producers and the most important method of prevention is vaccination of the herd.

Porcine Parvovirus

Porcine Parvovirus (PPV) infection typically causes returns to service, small litters, mummified foetuses, stillbirths or abortion.

PPV occurs either as an endemic infection resulting in a continual low level of reproductive loss that will erode profitability or as an epidemic infection involving larger numbers of animals. Epidemic infections can be financially devastating.

PPV is a very tough, resistant virus that can survive in the environment for many months, therefore making eradication virtually impossible. Routine preventative vaccination against PPV is recommended worldwide.

Integrated Parasite Management

The increasing incidence of chemical resistance detected in pest populations has led to a new way to target internal and external parasites.  Integrated pest management (IPM) is a method of controlling parasites in a population of animals by using a combination of chemical and non-chemical methods. IPM approaches have been in use for some time to control pests in cropping and horticultural systems and have been successfully used to manage the risk of chemical resistance and improve overall pest control outcomes.  Non-chemical methods to combat internal parasites in livestock species includes providing “safe pastures” for young, vulnerable stock (such as weaners), and ensuring adequate nutrition so that stock can develop immunity to these parasites. The use of treatment thresholds below which treatment is not undertaken is also a key strategy in IPM.

Safe pastures are those pastures that have a low level of larval pasture contamination.  Preparation of safe pastures requires good planning so that young stock can be rotated onto a new pasture every few months.  These pastures can be prepared in a number of ways, including spelling paddocks over a hot, dry season, cropping cereals, hay and silage production, rotational grazing (short-term spelling) and alternating grazing pastures between sheep and cattle.  All of these methods have different levels of effectiveness, but the ultimate goal is to minimise the larval challenge to younger stock.

Worm egg counts (WECs) are a useful way of determining whether production losses may be occurring in livestock associated with worms. Use of chemicals to control internal parasites should be carried out after undertaking WECs to determine whether a need for a drench exists, and a drench that is known to be effective on the worm population should be used.  The most appropriate way to determine which is the best drench to use on your property and if you have any existing resistance among the worms on your farm is to conduct a Faecal Egg Count Reduction Test (FECRT).  Additionally, the correct dose and the correct method of administration should be used for any drench.  Timing of drenches throughout the year vary from region to region.

IPM can also be used to help control external parasite and pest populations, including buffalo fly and cattle tick.  Examples of this include utilising dung beetles to break down faecal pats to reduce the eggs laid by fly populations, the use of a specialised fly trap to remove buffalo flies from cattle by exploiting the natural behaviour of the flies to move towards light, and the detection of natural predators or diseases (viruses and fungi, for example) which can be used to reduce the pest population.  Breeding hardier populations of animals – such as breeding sheep with a bare breech to combat fly strike – is a long term solution.  Other methods include monitoring pest populations and only using chemical methods of control when economic losses are occurring, as well as rotating the active chemicals used to slow the development of resistant populations.

By reducing a reliance on chemicals, the long term effectiveness of these chemicals can be sustained as well as reducing the risk of residues.

Anthrax

Overview

Anthrax is an acute, rapidly fatal disease caused by the bacterium Bacillus anthracis.  It can affect all classes and ages of livestock including cattle, sheep, goats, pigs and horses and can result in significant losses during an outbreak situation.

Disease Epidemiology

The bacteria are present world-wide. The disease was first seen in Australia in 1847 and spread widely soon after introduction due to the absence of appropriate controls. In Australia, a recognised zone known as the “Anthrax Belt” runs through central NSW and into northern Victoria.  Most cases of anthrax occur within this region because the soils are favourable for long term survival of spores and the area has become infected with spores due to previous outbreaks of anthrax. Occasionally outbreaks occur outside this area within NSW and isolated cases have occurred in Queensland and Western Australia with no known links to the anthrax endemic area. Anthrax spores are able to exist in deep alkaline soil for many years, but if the spores are close to the surface and are exposed to wind, rain, sunlight and acidic conditions, their survival time will be reduced to around 18 months.

Anthrax is not spread directly from animal to animal. The most common route of infection of livestock is by ingestion of spores that have been present in the soil on a property. Anthrax was often spread from one place to another by animals picking up the disease at one location and then being moved to another area while incubating the infection and subsequently dying of anthrax at that location. Livestock can be infected by contact with the carcass and its discharges. Prior to control programs being in place for anthrax in Australia, spores were often spread via contaminated stockfeed or blood and bone used as fertilizer, that had been made from animals that died of anthrax.

Anthrax bacteria are present in fluids that ooze from a carcase, and when exposed to the environment, these bacteria produce the highly resistant spores which can exist deep in soil for many years.  When spores are brought to the surface, usually through soil disruption (for example, after heavy rainfall, erosion or earthworks), livestock may ingest them while grazing.   Once inside the animal, they develop into the vegetative organism and multiply rapidly releasing lethal toxins, which cause oedema and tissue damage, resulting in death from shock and organ failure. The most common sign of anthrax is a dead animal without signs of a struggle prior to death. Blood which has failed to clot may be seen to be oozing from body orifices, however this may not always occur.  There is usually an absence of rigor mortis (stiffness) in the infected carcass.

In dairy cattle, early signs of infection, such as a fever, milk drop and depression, may be seen prior to death, but progression of signs is invariably rapid.

Anthrax in Humans

Humans can also be infected by Bacillus anthracis.  The most common type of human anthrax seen in Australia is cutaneous anthrax, otherwise known as “Woolsorter’s Disease”.  This disease can occur when handling stock or carcasses infected with anthrax, with the spores entering the skin through cuts and abrasions.  Although not recently recorded in Australia, it is also possible to ingest or inhale spores, resulting in a potentially fatal infection.

Diagnosis and Treatment of Anthrax

Anthrax is a notifiable disease.  Anthrax should be a suspected cause of the sudden death of an animal, particularly if unclotted blood is seen oozing from orifices.  If suspected, it is important not to touch or move the carcase, and to contact a government veterinary officer or district veterinarian as soon as possible, who will advise on appropriate steps to reach a diagnosis.   Diagnosis can be conducted by examining blood smears to confirm the presence of B. anthracis bacteria. Other confirmatory tests are also available. 

Treatment of the disease in live animals is usually futile due to the rapid onset of clinical signs and death.  Some antibiotics are useful in treating infected animals if diagnosed and treated in the early stages of the disease.

Anthrax Vaccination

A highly effective vaccine is available which contains a live, avirulent (ie does not cause disease) strain of anthrax.  Use of the vaccine is highly regulated and permission from the Chief Veterinary Officer in each state is required to obtain this vaccine.  In order to purchase the vaccine, contact your government veterinary officer or district veterinarian.

It is important that antibiotics are not used at the same time as the vaccine, as this may interfere with the development of protective immunity within the animal.

Disposing of Carcasses

Extreme care must be taken when disposing of infected carcasses to, firstly, prevent human disease and secondly, to minimise the risk of spores from the infected carcass contaminating the environment.  Any direct contact with the carcass must be avoided and appropriate personal protective equipment must be worn.

Please contact your local government veterinary officer or district veterinarian for information on carcass disposal and decontaminating affected areas.

Further information on anthrax and its control within Australia is available from the following web sites:

For NSW click here

National control strategy: click here

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