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This article was published in 1978
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Ringworm in Pigs
E.A. Farleigh, B.V.Sc., Veterinary Inspector, Camden
It is desired to report on an outbreak of ringworm in pigs which has defied treatment over a period of approximately two years.
The piggery consists of approximately twenty breeding sows, - mostly of the Large White and Landrace cross. There are twenty five pens with concrete floors with the back half of the pens, which are under cover, being concreted to a half wall and the front half of the pens constructed with wooden battens. The drainage is by concrete drain running the whole length of the pens and watering is by individual nipples in steel bowls. The sows are run out on range in ten paddocks for about one month after weaning and are then mated. Each paddock consists of approximately one-tenth of an acre.
Over the last two years sows have averaged ten suckers per litter and the pigs are sold off as porkers at approximately twenty weeks of age.
The owner first noted, during December, 1975, a greasy appearance at the back of the pigs' ears but as he was late with his usual three monthly spraying for mange control with Nucidol (CibaGeigy) he was not unduly concerned and carried out a spraying programme of three sprays at ten-day intervals. However, the condition did not improve.
He noted in February, 1976 that one of the chemical firms was advertising for mange-infected pigs for experimental purposes and the firm was contacted and took some skin scrapings from some of the sows. However, it was reported that there was very little evidence of mange and the pigs were not suitable for experimental purposes.
About this time the typical circles of infection were starting to show on the bodies of the sows and ringworm was suspected. Another chemical firm was contacted and it was recommended that a proprietary line known as Wescodyne (Scott & Halladay) should be used. This consisted of scrubbing the pigs with a solution of 15 mls. to 10 litres of water and then treating the infected areas with neat Wescodyn for a period of three to five days, This also had no effect and the treatment was repeated, plus the use of Wescodyne solution at 60 mls. per 10 litres scrubbed into the affected parts. All the pens were sprayed at the same time with this solution.
A month later an application of one part Nucidol:30 parts water was scrubbed into the affected parts and surrounding areas on the pigs for 5 days. The owner also sprayed the pigs and pens with Nucidol at the recommended rate of one part to fifty, using distillate instead of water.
No improvement was noted and the firm was again contacted and one of the research personnel visited the property and took scrapings but later informed the owner that there was no evidence of lice or mange and they had not found anything else suggestive of ringworm and advised the owner to contact an official veterinarian. This was in June, 1976.
I first visited the property on 10th June, 1976 and noted that all pigs were in very good order, well housed and the property was kept in a very clean condition. Out of the twenty breeding sows approximately half were affected to a varying degree but only an occasional young porker showed any evidence of infection, mostly on the shoulders or on the back. A tentative diagnosis of ringworm was made. It has been noted that very few growing pigs showed any evidence of infection up to the time of marketing. The owner stated that apparently the infection had no effect on the market value of the pigs, as when they were scrubbed up prior to sale there was practically no evidence of any infection.
It was interesting to note that two saddleback sows showed no evidence of infection during the first twelve months the disease was known to be present, but did develop lesions later.
On inspection of the pigs it was quite evident that there was no alopecia or pruritus and skin scrapings were taken on the 10/6/1976, on 5/7/1976 and 4/8/1976 and Glenfield reported on each occasion that no evidence of ringworm organisms could be found.
The normal hygiene programme practised by the owner is for each shed to be spelled for a minimum of one week and usually up to four weeks between occupation by any sow or groups of young piglets. Each shed is hosed out with a pressure hose within 24 hours of the pigs vacating the pens and then each shed is sprayed with Chlormaine T at a disinfectant rate of 1 oz. to 2 gallons of water two days before restocking. All stock and sheds were sprayed with Nucidol at recommended rates with Chloramine T added, each three months, the spraying being carried out three times at ten-day intervals.
On 12/10/1976 skin biopsies were carried out on one sow, both from the centre and edge of a typical lesion and at the same time one piglet showing a lesion on the shoulder was taken to Glenfield for special treatment. Glenfield's report on the skin biopsy was that fungal elements were detected on PAS stain in the hyperkeratotic epithelium of the hair follicles and this was consistent with dermatomycosis infection in pigs.
The live piglet submitted on the 12/10/1976 showed a lesion which was roughly oval, measuring 9cm x 7 cm and well demarcated, had a dry scaly centre with an active erythematous periphery typical of ringworm. Fungal and bacterial cultures were taken. No significant bacteria were recovered from these cultures but a fungus was isolated and later identified as Fusarium species as a contaminant. No ringworm organisms were detected.
The first attempt at treatment was to apply Gentian Violet to half the lesion. On the 19/10/1976 the lesion was similar to the first report only much larger, measuring 11cm x 9cm. Gentian Violet was then applied b the whole area.
15 days later the lesion measured 15 cm x 13 cm, the Gentian Violet was washed off with soapy water and a scrubbing brush, resulting in surface scabs being scrubbed off leaving the underlying area red and inflamed.
On 4/11/1976 the area was still well demarcated and specimens were once again collected for bacterial and fungal cultures and the areas washed with Thiabendazole solution which was allowed to dry on. The area on the other side of the pigs was inoculated with the fungus previously isolated (Fusarium species) but no growth eventuated.
On 11/11/1976 the lesion appeared to be static, still measuring 15cm x 12 cm with a dry surface following the Thiabendazole applications.
On 15/11/1976 skin biopsy was taken for histopathological examination which revealed mild mononuclear cell infiltration into the epidermis with some acanthosis, although no fungal elements were seen.
Also, samples were taken for fungal culture with a yeast-like organism being recovered. This was later identified at the Australian National Reference Laboratory in Medical Mycology at the Royal North Shore Hospital as Trichosporum penicillatum, which is closely related to Trichosporum cutaeneum. This pig was finally post-mortemed on 23/12/1976 and on post-mortem the lesion appeared to have regressed, being dry and when the skin was washed down and the hair scraped, a clean underlying surface remained, suggesting the infection was only in the superficial epidermis, or the hairs themselves.
Glenfield reported that the fungi Trichosporum cutaeneum is considered to produce an infection known as White Piedra in man, although no reports of this condition could be found in the veterinary literature.
The on-farm treatments early in the outbreak included the use of Bordeaux mixture applied to a large number of sows on a number of occasions without any effect. Chloromycetin Tincture Aerosol (P.D. & Co.) was also used on one pig and Bradonit (Ciba) was tried on another pig, neither having any result.
During January, 1977 trial treatments were undertaken on the property with Fulcin 500 (Griseofulvin) given at the rate of 10 mg. per kilogram body weight orally for a minimum of seven days. This treatment was repeated on one sow a fortnight later but had no effect. Another sow was treated with the agricultural fungicide known as Captan (Lane's) used as a wash at the rate of 30 grams to 3 gallons of water. This also had no effect on the animal treated.
At the same time the pens were thoroughly sprayed with Formalin 5% solution using a power spray at 50 lbs./sq. in.
Further treatment was then experimented with, on the recommendation of the Director of Veterinary Research, using Whitfield's ointment on several pigs and also Cycloheximide as a wash which was applied with a paint brush, with two applications two days apart. Neither of these treatments had any effect in even controlling the spread of the infection on the pigs treated.
On 29th April, 1977, a second piglet 12 weeks of age was taken to the Glenfield Research Station, showing a lesion 15cm x 17cm covering the dorsal surface of the neck and being oval in shape. The lesion appeared dry, with dark scabs which brushed off an scraping, leaving a.reddened surface. Skin scrapings were taken at the Glenfield Research Station.
On 3rd May, the lesion was largely unchanged. Skin biopsies were taken with further skin scrapings.
On 12th May the mycology report confirmed ringworm and identified the organism as Microsporum nanum. Further skin scrapings were again taken and half the lesion was treated with tincture of iodine. The skin biopsy report stated that there was a mild hyperkeratosis with thickening of the stratum corneum which contained focal pockets of necrotic debris and some congestion with a moderate lymphocytic infiltration into the underlying dermis. No fungal elements were seen on H. & E. Stain. The skin scrapings did not show any ringworm organism. The Microsporum nanum was identified by the Royal North Shore Hospital Medical Mycology section.
The lesion was re-treated on 6 different occasions with tincture of iodine, mostly at one day intervals and then left for a week between 20th and 29th May. The following day further scrapings were taken from the treated side, which appeared cleaner with fewer crusty scabs. On the 6th June scrapings still confirmed the presence of Mycrosporum nanum which was recovered from lesions despite the iodine treatments. On 20th June, Nystatin (Mycostatin - Squibb) was applied to the right half of the lesion. This was repeated on the 13th and again on the 16th. There was some apparent improvement, with the absence of scabby crusts. On the 20th June, 1977 further scrapings were taken and the left half of the lesion treated with Malachite Green, with no apparent response.
On 7th June, the property was visited by Veterinary Research Officers from Glenfield Research Station and as the owner was now de-populating his piggery owing to the persistence of ringworm, a final attempt was made to collect specimens prior to the disposal of all pigs.
The remaining pigs were generally healthy, with two out of the fifteen weaners showing clinical ringworm and one sow having a greasy skin condition over the ears and neck. These three pigs, along with a sucker, were sampled and scrapings cultured directly into Sabourauds and Mycosel Agar. A later report from Glenfield stated that the large sow with the greasy skin condition covering the ears and neck showed a moderate contamination but a few Mycrosporum nanum colonies were evident, with a strong growth on subculture. The sucker with darkish lesions on the back showed a mixed growth of yeast organisms but no Mycrosporum nanum. The small pig (weaner) with a 25 cm diameter lesion on the rump showed a massive growth of Mycrosporum nanum. The slightly larger weaner with a dark circular lesion behind the ear and one on the back revealed a yeast growth with a few possible Mycrosporum nanum. So out of four samples, Mycrosporum nanum was only recovered from two pigs including the sow with the greasy skin condition.
Connole (1966) describes a condition in Queensland which appears very similar to the one on this piggery. However, he does state that treatment with Bordeaux mixture is usually successful and there was little trouble in clearing up the infection. This does not seem to be the case on this property.
Cameron (1975) also describes this condition. He claims that the disease is self-limited and treatment may not be necessary, but does suggest that Bordeaux mixture has been used successfully, but resolution may occur in pigs without any treatment. He describes the experimental infection carried out by Connole (1966) where pigs develop lesions within the first two or three weeks and resolution occurred in all pigs by nine weeks post inoculation. It can definitely be stated in this outbreak that even after eighteen months there is no evidence of any treatment being effective on the property and no evidence at all of any resolution of the condition in any pigs.
The investigations on this property reveal the following facts:—
1. The unreliability of skin scrapings as a guide to the diagnosis of ringworm.
2. The failure of accepted treatments of this condition. Contrary to the accepted treatments stated in the literature and the statement that most cases appear to resolve themselves, even without treatment, there is no evidence at all on this property over a period of approximately two years that any pig showed evidence of self-healing.
REFERENCES
Connole, M.D. & Boynes, I.D. (1966) Aust. Vet. J. 42:19-24
Cameron, R.D.A. (1975) Vet. Review No. 14., Uni, of Sydney. Post.-Grad. Foundation