Erysipelas in pigs: detection, treatment and prevention

Erysipelas is a bacterial infection of pigs that usually causes red lesions on the skin, fever, depressed appetite and in some cases, arthritis, reproductive issues and septicemia.

Quick and effective treatment can lead to full recovery though, so knowing the signs and acting fast is key.

Gemma Thwaites, vet and director of Garth Pig Practice, talks through the key points surrounding the disease and explains how to minimise the risk of infection on a pig unit.

What is erysipelas?

It is a serious disease and can be potentially fatal. It is very common and found in most, if not all, pig farms. The bacterium involved is Erysipelothrix rhusiopathiae. 

It usually only affects pigs above 12 weeks as maternal immunity protects then until that age.

How is it contracted?

The bacterium alone can cause disease but outbreaks often follow a concurrent disease such as PRRS (Blue Ear) or Swine Influenza. The pig is infected orally by ingesting contaminated material. The bacterium can survive in soil or muck for six months or more and can be carried by birds and rodents, especially mice.

Is it contagious?

The bacterium is excreted in saliva, faeces or urine so is easily passed from pig to pig, but it is also present in the environment, so a single pig can contract the disease without any contact with others.

What are the clinical symptoms?

There are various presentations of the disease.

1. Pre-acute disease – septicemia resulting in sudden death.

2. Acute – this is the classic form of the disease when raised red diamond-shaped lesions appear on the pig’s skin.  The pig will usually have a fever and be depressed and off their food. The lesions may slough off in the recovered pig.

These lesions are not always seen and these pigs can develop an endocarditis which is a bacterial build-up inside the heart (cauliflower heart) which results in death a few days later despite apparent recovery.

3. Arthritis – the lesions are not present but the pig develops a very severe lameness, usually in the hind legs.  If treated very early damage can be minimised but often the damage is too great once the gait is severely affected and pigs require euthanasing on welfare grounds.

4. Reproductive problems – sometimes classical diamonds are seen, sometimes not, followed by increased abortions and/or return to service. Affected boars can be rendered infertile for six to eight weeks following the fever caused by the disease.

See also: A guide to African Swine Fever

Are there long-term effects on pig performance/health?

Pigs that are treated very quickly can recover completely.

Lesions can sometimes result in skin loss, especially the ears and scrotum. Any pigs sent to slaughter with any remnant of the diamond lesions are likely to be skinned, resulting in financial losses.

Arthritis and endocarditis may develop and cause more chronic problems for the pig. If a pig survives with endocarditis then it may well be condemned at slaughter.

Can you prevent it?

There are commercially available vaccines that work against serotypes 1 and 2 and these are very effective.

Erysipelas vaccination is routinely used in breeding animals and can also be used in growing pigs on units where the disease has been a problem.

The vaccine is given to breeding animals twice a year following a primary course and usually only once to growing pigs at around 10-12 weeks of age. This then lasts through the growing period.

In very rare cases a strain not covered by the vaccine may be involved and in these circumstances an autogenous vaccine can be produced under a special licence. This would be discussed by your veterinary surgeon where appropriate.

How do you minimise the risks?

It is impossible to completely eliminate the disease on a commercial unit but ensuring the pigs are not subject to any extra stress will reduce the risk. 

These ‘stresses’ are usually environmental, for example chilling through insufficient bedding up during cold weather periods.

Minimising exposure to the organism where possible by good vermin control and preventing access of birds by covering feeders for example reduces the risks.

As previously mentioned, very effective commercial vaccines are available and discussion with your vet will result in a very effective control programme. The vaccines available are not expensive and are very cost-effective, regardless of herd size.

Good hygiene is critical and thorough cleansing and infection between batches when feasible would always be advised.

How do you treat it?

The acute disease can be treated with penicillin-based antibiotics. NSAIDs (non-steroidal anti-inflammatory drugs) can be given concurrently to reduce the fever.

These are usually given by injection but can be water-based in extensive outbreaks. Your veterinary surgeon will be able to advise the most appropriate method for your unit.

Talk to your veterinary surgeon regarding managing other pigs in the group and subsequent control programmes.

If suspected, how is it diagnosed?

Clinical picture and post-mortem examination by your veterinary surgeon. The bacteria is easily grown in the laboratory, confirming diagnosis. Due to the ubiquitous nature of Erysipelas single blood samples are of limited value.

Can humans catch it?

Erysipelas can cause local skin lesions but this is very rare. The Erysipelas described in people is actually caused by a streptococcal infection rather than infection with this bacterium.

Is there any system that is more or less likely to see erysipelas?

Erysipelas is often more evident in ‘high-welfare’ systems. These would include large straw-based yards where pigs have access to solid muck and potential mouse contamination and contact with bird faeces.

It is also commonly seen in small populations, backyard and pet pigs.  Again these animals often have access to areas that can be accessed by birds and rodents and the bacterium persists in the soil. 

In a mixed smallholding there are often other birds and sheep, which may have common access.

Units running ‘all in-all out’ systems with thorough cleansing and disinfection between batches minimise exposure.

More information on the disease is available on the NADIS website.