Historically, piggeries have been common on the north coast of NSW because they were undertaken in conjunction with the large dairy industry. Although there are no longer many commercial piggeries, there are still approximately 11,000 pigs on 140 holdings. Increasingly pig producers are required to meet quality assurance standards. This can be difficult for smaller piggeries. This case study is an example of the North Coast Livestock Health and Pest Authority (NCLHPA) working with private veterinarians to help producers meet quality assurance, increase production and improve welfare outcomes.
In September 2012, a private veterinarian contacted the Lismore District Veterinarian of the NCLHPA about severe lameness and sudden death in four weaners owned by one of his clients. The NCLHPA contacted the pig producer and a property visit was undertaken.
The pig producer does not breed pigs himself and simply purchases weaner pigs from a range of other farms to grow out. Pigs are kept in similar age groups of about ten in concrete pens. Grower feed is purchased from a local mill and is medicated with 'Dox R Pan' (Olaquindox 25g/tonne). The farm has previously had whipworm (Trichuris sp.) and salmonellosis diagnosed in introduced pigs. On arrival at the farm, all weaners are medicated with 0.3mls of Dectomax injectable (Doramectin).
Four weaners that had been purchased from a piggery in the Grafton district became acutely lame and unable to stand two weeks after arrival. One of these weaners was found dead two days later. Post-mortems on three weaners were carried out and samples sent for laboratory testing.
The three most severely affected weaners had been moved into a sick pen and on examination were found to be in lateral recumbency with pyrexia (39.7C), pale mucous membranes and swollen joints hot to the touch. One weaner had open-mouth breathing. One weaner that was not in the 'sick pen' was non-weight bearing lame on its right forelimb.
The three most severely affected weaners were euthanized and post-mortems carried out. Dark, yellow joint fluid was found within the elbow, stifle, hip and hock joint cavities of all three weaners. There was moderate swelling and oedema around the hock joints. One weaner had multifocal randomly distributed areas of white discoloration of its liver surface. Large amounts of dark yellow pleural and pericardial effusion and yellow, fibrinous material adherent to both lung surfaces was found in one weaner.
A fine needle aspirate was taken of the joint fluid and a smear made. Cytology of the smear revealed a moderate increase in inflammatory cells and scattered medium-sized bacilli. A range of tissues was submitted for histopathology. The lung and myocardium histopathology revealed moderate amounts of fibrinous exudate and numerous neutrophils consistent with pleuritis and pericarditis of a bacterial cause. Histopathology of the liver, spleen, ileum, jejunum and spiral colon samples were unremarkable. A worm egg count performed on manure was zero eggs per gram. Haemophilus parasuis PCR performed on fresh lung tissue was positive.
Disease on this piggery was diagnosed as "Glassers disease" or polyserositis caused by the bacteria Haemophilus parasuis. These organisms are normal flora of the nasopharynx of pigs. In young, weaned pigs, organisms can invade the mucosal barrier of the oropharynx and enter the bloodstream resulting in septicemia and localisation in serosal and synovial cavities. Most affected animals develop a serofibrinous serositis such as pleuritis, pericarditis, peritonitis, arthritis and/or meningitis (Buddle, 2000; Hodgson et al., 2010). All of these conditions were noted in this case except for meningitis, as brain samples were not collected. Death most likely occurs due to endotoxic shock caused by Disseminated Intravascular Coagulation (DIC).
Stress such as weaning, transport, management stress and overcrowding are believed to play a role in the disease, which strikes within days of the stressful event (Hodgson et al., 2010). The pigs in this case had been through weaning and were transported a significant distance two weeks prior to the pig producer contacting the District Veterinarian.
Hodgson et al. (2010) describes the clinical signs of Haemophilus similar to what was seen in this case (fever, inappetence, respiratory distress and lameness) but also includes convulsions and discoloration of the skin, which were not noted in this case.
The NCLHPA reported the findings of their disease investigation to the private veterinarian who took responsibility to prescribe an appropriate antibiotic. He advised the pig producer to treat the remaining weaners with penicillin as H. parasuis is susceptible to this drug. The piggery manager reported no further lameness or sudden death cases in his piggery when the District Veterinarian followed the case up 5 days after the initial visit.
This case was an example of the collaboration that can occur between the NCLHPA and local private veterinarians.