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This article was published in 1962
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INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.
Infectious Rhinitis in Pigs
K. F. OPFERKUCH, B.V.Sc., Veterinary Inspector, Condobolin
Infectious Rhinitis was first recognised in Australia in South Australia in 1959. This disease in that State appeared as an acute epidemic which has abated since to the chronic form, which now apparently is recognised only in piggeries where management is poor or some other disease is active.
The South Australian outbreak has been well described by Cameron-Stephen (1961), and he divides infections into two types:—
(a) The initial onslaught with heavy economic loss;
(b) The second phase, in which previously affected animals were themselves producing young pigs and the economic loss was relatively small.
Type (a), with symptoms of sneezing, typical nasal and ocular discharge and difficult breathing, well described by Cameron-Stephen, has not been seen in the Condobolin district; whereas the chronic form described as Type (b), has been encountered commonly. However, Condobolin Type (b) has included the chronic emaciation and deaths associated with the acute initial onslaught.
This then is the reason for the presentation of this paper. The typical disease described by overseas and interstate authorities has not been seen. There was no clear-cut epidemic such as one would expect in a pig population which had had no previous contact with the disease. None of the outbreaks seen had any inter-connection. The initial acute outbreak with sneezing and nasal involvement was not present usually; and on two properties where young pigs were sneezing, there was very little economic loss. Both these piggeries were under excellent management.
The acute type seen was rather one in which loss of condition of young pigs was followed by emaciation and death of a big percentage of suckers. The secondary type described by Cameron-Stephen, i.e., with losses only in badly fed and badly managed pigs, was the most common in our experience, and this type of infection usually was associated with other diseases.
Some typical outbreaks of Rhinitis are described; and from them it will be seen that management and good feeding eventually will clear up an outbreak, after a small initial loss. In other cases, good management and feeding will mask an outbreak so that the only symptom noted is a small set-back to young suckers which is apparent for a short time only.
Pneumonia is the most common complication of Rhinitis in our experience, and it is possible that many outbreaks of contagious pneumonia are set of by an initial Rhinitis infection.
The disease the writer has described as Glasser's disease: i.e., peritonitis with pleurisy and sometimes pneumonia, may be due to some other cause. Cameron-Stephen mentions postmortems of pigs with typical Infectious Rhinitis, showing pathology of: Fibrinous pericarditis, multiple pleuritic adhesion without pneumonia; as well as these associated with pneumonia.
It is noted also that brain lesions similar to those seen in Swine Fever do occur in cases which appear to be due to Infectious Rhinitis.
The following observations are made on outbreaks which have occurred in the Condobolin district:—
OUTBREAK "A"
This was investigated on 22/2/61. The history was that in 1960 the owner purchased 4 sows to increase the number of his breeders to 10. No trouble had been experienced prior to that time. The 10 sows were mated and farrowed in November and December, 1960. From the farrowings only 34 pigs were reared to the age of 2-3 months. The young pigs thrived until about one month old, then rapidly lost condition, stopped growing and, although eating well, either died or were destroyed by the owner. The pigs showed no other symptoms except unthriftiness and scaly skins, with loss of hair. Post-mortem revealed emaciation only.
Infectious Rhinitis was diagnosed on histological examination of the turbinates of the sows which lost their litters were re-mated and the subsequent litters were affected in a similar manner.
The owner has marketed very few pigs and the young pigs at present on the property - some eight months old are retarded in growth and poor in condition; and are not an economic proposition to feed.
The owner states that his loss on his pig farming enterprise is about £400 so far this year. If the sows which are to farrow do not produce healthy litters he will be forced out of pig-raising.
The standard of feeding and housing is reasonable. Green grazing has been available over some of the period and Vitamin A supplement has been fed. Meatmeal and wheat have been fed ad. lib. over the period but no response has been obtained.
OUTBREAK "B"
Investigated on 2/9/60. About 150 pigs were run on this property, where grazing was good and pigs were fed a supplement of crushed wheat. At the time of inspection, the pigs were in excellent condition; except the sick ones which were affected only recently.
Eight young pigs 2-3 months old had died and several of the same age were sick. Some sick pigs were coughing, but others appeared unthrifty only and were dopey and depressed.
Post-mortem of a typically affected pig revealed a fibrinous peritonitis and pleurisy. The lungs were adherent to the chest wall and the condition appeared chronic. About half of each lung was consolidated. Another pig showed pneumonia only.
Infectious Rhinitis was diagnosed by histological examination of the turbinate bones. No significant bacteria were recovered from the pipettes from lung, blood and kidney.
In this case, control consisted of slaughter of the worst cases and isolation of all pigs which appeared off-colour. These sick pigs were all treated with sulphamezathine by intramuscular injections and appeared to recover.
The subsequent history of this outbreak is that no further pigs were affected except one sow which died suddenly three months later. On post-mortem this sow showed the same peritonitis and pleural adhesions as seen in the original cases. The other pigs have continued to thrive and no difficulty has been encountered.
The standard of management on property "B" did not appear much better than property "A", except that more green grazing on better class pasture was available. The pigs on property "A" had green oats; whereas on "B", clover and grasses were available for grazing.
OUTBREAK "C"
The owner of this piggery has had trouble with sick pigs for some years. The original trouble showed a scouring which affected young pigs in an old dirty yard. He then built new concrete floored pens which were kept scrupulously clean. Feed is good; consisting of grain and meatmeal with mineral and vitamin supplement. Scours occurred in 3 piglets 10 days old, but this symptom responded to iron therapy. However, some pigs appeared dull and unthrifty. One died on 1/6/1961. This pig was 4-5 months old and had been running on lucerne and oats with grain supplement.
Post-mortem revealed many pleural adhesions and some strands of fibrin in the abdominal cavity; with deposits of fibrin on the omental surfaces.
Infectious Rhinitis was diagnosed on histological examination.
Further history of this piggery is that two additional pigs became sick and were treated with sulphamezathine; and recovered. These pigs were fed ad. lib. on grain, had excellent grazing and when seen six weeks after the initial mortality were very healthy and in fat condition.
COMMENT
The interesting observation in these outbreaks is that at no time was sneezing or nasal discharge seen in any of the affected pigs. Even in outbreak "A", where no other lesions were seen, there did not appear to be any nasal involvement. In "B" and "C" the picture is that of Glasser's Disease as a secondary invader; without which attention would not have been drawn to the Infectious Rhinitis. It would appear that "B" and "C" are the chronic condition, which occurs when control of other diseases and good management mask completely the effects of Rhinitis. The outbreak "A", on the other hand, appears to be a more acute type; causing a mortality in the absence of other diseases, and in spite of good management.
The condition described above as Glasser's Disease is seen frequently in this District, and is responsible for a few deaths. There is no further mortality or morbidity and affected pigs appear to respond to sulphamezathine if treated as soon as symptoms appear.
SUMMARY:
1. A disease diagnosed as Inclusion Body Rhinitis is well established in swine in the Condobolin area.
2. Where management, particularly feeding, is good, no major economic losses occur if no other disease is present, this disease may trigger of other infectious diseases; particularly pneumonia.
3. The presence of this disease may trigger off other infectious diseases; particularly pneumonia.
4. The presence of this virus disease may complicate diagnosis of other virus diseases, such as Swine Fever, due to the brain lesions it produces.
Reference
- Cameron-Stephen, I. D. (1961) — Aust. vet. J., 37: 87