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Porcine Dermatitis and Nephropathy Syndrome - By Jake Waddilive MA, VetMB, MRCVS
Porcine Dermatitis & Nephropathy Syndrome

Porcine Dermatitis & Nephropathy Syndrome (PDNS) was fist described in the U.K. in 1993 as a sporadic condition affecting individual finisher pigs. At that stage it was a sporadic condition affecting individual pigs. It has been described in many parts of the world, but more recently it has caused increasing problems apparently associated or closely related to Porcine Multisystemic Wasting Syndrome (PMWS). Under these circumstances it has changed to a more significant condition affecting large numbers of pigs. It is frequently seen as a complexed problem with PMWS and at times chronic cases of the two syndromes can be difficult to separate.

It is important to note that PDNS and PMWS can occur together, following each other or independently of each other.

What Is PDNS?

PDNS is mainly a condition of grower and finisher pigs. It has been reported from 8-18 weeks of age, but is mainly seen in pigs 11-14 weeks of age.

The most obvious signs are red-purple blotches on the skin. These are often slightly raised. They tend to be most obvious on the hind legs, loin, scrotum and ears, but can extend over the abdomen, flanks and fore legs eventually covering the whole body. Over a few days the lesions become crusty and brown. Eventually, providing the pig survives, they fade away. Most pigs with skin lesions die, although some may only do so slowly.

In the early stages temperatures of up to 41?C have been reported. Pigs are lethargic and acute cases have swollen legs leading to lameness. Respiratory distress and/or scouring can be seen.

Pigs that survive tend to lose weight and slowly waste away.

Why Is PDNS Important?

Obviously the losses caused by PDNS can amount to relatively high levels. Over a period of one month mortality rates of 60% have been reported in individual batches. More typically ongoing mortality of 2-6% above the Farm's normal mortality can be seen. This may persist for several months.

In spite of this mortality is not the most important feature of this disease. The biggest problem is its very close clinical similarity to Classical Swine Fever (CSF or Hog Cholera) and to African Swine Fever (ASF). This leads to a serious problem differentiating it from these diseases. This is perhaps best illustrated by the CSF outbreak in the U.K. in 2000 when there were 16 cases of CSF but several hundred farms were reported as possible CSF - most of which were in fact PDNS.

What Is The Cause Of PDNS?

The cause of PDNS is unclear at present. It appears to be an immune complex mediated disease. Work in Scotland suggests that this is related to a strain of Pasturella multocida and other bacteria have been suspected as being possibly involved. At the same time Porcine Circovirus type 2 (PCV2) has been strongly implicated - this is the organism that is believed to be an important part of the cause of PMWS. It may be that the newer outbreak form of PDNS is triggered by PCV2.

The risk factors for PDNS appear to play an important part in development of the syndrome. These include continuous flow production, failure to apply good biosecurity measures, mixing of different sources of pigs at/or soon after weaning and herds with high stock turnovers. Farm size seems less important as the syndrome can occur in anything from the smallest to the largest farms. Interestingly it seems that if we mix pigs from known affected and unaffected source farms at over 30-40 kg the disease does not appear to spread between the two categories.

How is PDNS Spread?

As we do not know the precise cause it is difficult to be accurate about the method of spread. It appears that the disease is spread between herds by movement of pigs but it also seems likely there are other methods of spread.

Diagnosis Of The Syndrome Is Important

As stated above the syndrome is very similar clinically to CSF and ASF. Accurate diagnosis cannot be based solely on clinical assessment and post-mortem and histological examinations are essential.

Is There Any Treatment?

Once the syndrome has developed in a group of pigs treatment is largely ineffective. There is some indication that treating pigs from 15-40 kg with Chlortetracycline in feed may reduce the subsequent development of the syndrome. (This is probably related to depression of the bacterial component of this disease).

So How Do We Control PDNS?

At present there are no vaccines available so control measures are based on generic management changes targeted at reducing disease challenge and the important risk factors of the disease.
  1. Where possible purchase pigs from known free sources. (This can be difficult and in some parts of the world nearly impossible. Freedom can only be assessed by lack of clinical signs in progeny from the source).
  2. Decrease stocking densities.
  3. Adopt strict all-in, all-out, policy at least by room but preferably by building or even site. This is important from weaning onwards even if signs are not being seen until well into the finishing period.
  4. Ensure strict biosecurity measures during and between batches. It is essential to use an appropriate disinfectant with these. See below.
  5. Do not mix pigs of different age groups in one air space. This is especially important in the post-weaning period.
  6. Do not mix pigs from different sources (co-mingling). Again this is most important in the post-weaning period.
  7. Reduce environmental stressors (e.g. temperature variation, draughts and challenge with noxious gasses).
  8. Control concurrent infections. This is of less benefit than in PMWS cases.
  9. Ensure the herd has as stable and immune status as possible. Here isolation and integration of incoming stock are very important.

What Is An Effective Cleaning Programme to Reduce Spread of PDNS Between Batches?

As PCV2 is believed to be an important part of this syndrome it is essential for us to control this. For the all-in, all-out policy that is a major part of control of PDNS to work we must have a disinfectant that works against PCV2. The Central Veterinary Laboratory, MAFF, Weybridge has produced specific data showing that Virkon S (Antec International) is effective against Circoviruses at a dilution of 1 in 250. Independent work at Iowa State University, U.S.A showed Virkon S to be the most effective of the commercially available disinfectants against PCV2. In this trial Virkon S was tested and its standard dilution of 1 in 100. Therefore institute a terminal biosecurity programme between batches using this product. For the best activity thorough cleaning before disinfection is essential and here the heavy-duty detergent Biosolve (Antec International) is recommended.

Virkon S should also be used in foot-dips, wheel dips and similar in continuous biosecurity programmes to prevent possible lateral spread about the unit and on to the unit. Its use in the water system may be particularly important as this is a known method of spread of other Circoviruses.

How Do We Prevent PDNS?

As the study of the aetiology and epidemiology of this disease is in its infancy prevention of PDNS can only be based on sound biosecurity principles.
  1. Always purchase stock from a source with a high quality health control programme that includes rigorous biosecurity on its farms. The source farm should be free from clinical signs of PDNS (as described above) but until precise details of the disease are worked out it is not possible or realistic to specify that purchased stock should be free from PCV2 or other potential causative agents.
  2. Maximise external biosecurity measures. These will include the control of visitors, deliveries and vehicles. Wheel dips and washes plus foot-dips should be filled with Virkon S. Details can be seen in the Pig Biosecurity Programme from Antec International.
  3. Control access of other animals.
  4. Have an effective rodent and bird control programme.
  5. Ensure there is no unauthorised access to the unit.
  6. Adopt management procedures that will minimise the effects of PDNS if it enters the herd. Again this will be concentrated on all-in, all-out, production especially in the post-weaning period.

To Summarise

Porcine Dermatitis & Nephropathy Syndrome is important because it can cause considerable mortality in affected herds and it also complicates the diagnosis of Classical Swine Fever and African Swine Fever. Although the disease can occur at low sporadic levels in pig herds, certain parts of the world have experienced considerable outbreaks with large economic impacts.

The syndrome can persist on farm for many months and there is no specific vaccination or treatment protocol to prevent it. For the above reasons control must be based on good management and a high level of biosecurity measures. All-in, all-out, pig production and the use of high activity broad-spectrum disinfectants (such as Virkon S) to prevent the spread of the syndrome are highly important in controls. The activity of Virkon S against some of the organisms associated with/or secondary to this syndrome is shown below.

Agent Virkon-S Activity Test Country









Streptococci spp




1:100(~H. somnus)


Salmonella spp.















Jake Waddilove MA, VetMB, MRCVS - 28th March 2001

NOTE: Reference to commercial products or trade names within information provided by does not constitute an endorsement by the and does not imply discrimination against any other similar products.

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