Controlling Ringworm in Livestock
It is funny how veterinarians sometimes have to squeeze information out from farmers when they are reporting their sick animals. Imagine it is over the phone and distances away in the villages but you have to keep on asking “what else?”, so that you can get a picture of the disease or to make the right diagnosis.
But then, there are those diseases that are so obvious that farmers just know how to describe it. One such disease is Ringworm in cattle and occasionally sheep and goats. The farmer would tell you “My animal has patches of skin that has slough off, but they are mostly in round circles”.
I’m sure the minute you read that we are going to talk about “Ringworm”; you will condition yourself to hear about those squeamish creatures “worms”. But in this case, the disease surprisingly has nothing to do with worms. Thus, for this week, let’s discuss what Ringworm is all about and how farmers can treat and prevent the occurrence of the disease in their livestock.
Ringworm is a contagious skin disease caused by a fungus such as Trichophytom verrucosum among other, and has nothing to do with worm. These fungi are spore forming and when the spores germinate or grow, that’s when they tend to spread and infect the skin and hair. This type of fungus can also infect people.
An animal is infected with the fungus when in close contact with infected animals. Usually, you will notice the disease after you have bought or introduced new animals into your herd. The Ringworm causing spores are very hardy and can survive and remain alive for years in a dry environment and the disease occurs in all parts of Namibia. That’s why it can be carried from farm to farm by animals, equipment, hands and on clothes without a problem.
Ringworm lesions typically occurs around the eyes, ears, nose, neck and backs of young animals and can spread to the legs and chest in adult cattle and sheep.
The typical signs that the farmer will notice are circles or rings of a grayish-white skin with an ash like surface that is spattered with raised lesions. The size of lesions are very variable and can be small or big (about 2-5 cm in diameter) or even appear in double-rings. Sometimes, an animal can become extensively affected, and all you will see its skin with patches and patches of the round skin that had sloughed off all over the body. The lesions start as small areas of crust and scales, which become round bare patches after the hair has fallen off. This is why it is typically called “Ringworm” (although up to know I still fail to understand why they had to refer to the disease as “worm”).
Since the signs of Ringworm are typical, it is not usually necessary to take samples for laboratory confirmation. However, the type of fungi can be confirmed at the veterinary laboratory from hair and scales taken from the edge of the lesions.
Ringworm is usually quite treatable and some cases heal without treatment.
However, to clear the herd might take up to a few months. The common treatment that farmers try is applying topical wound dressing (wound oil or salve) directly onto the lesions. But most often this is not sufficient as medication might not penetrate the crust of the Ringworm lesions. I would advise that before applying the wound dressing, it is better to wash and scrap or brush the affected areas with an antiseptic solution such as Betadine®, just to remove much of the crusts and scales as well as dirt. The mistakes that most farmers do is to only treat the affected animal once, but I can’t stress enough that Ringworm lesions should be treated at least every day the first two days and then twice, three to five days apart. It is important to collect and burn the crusts in order to avoid contaminating the premises.
An alternative is to use an iodine tincture from our local veterinary drug supplier (or use that yellowish liquid iodine that we get cheap from super market/pharmacy in a small bottle that is used by people). What you do is mix equal parts of iodine tincture with glycerin or liquid paraffin (even normal Vaseline® or baby oil will do) and apply it directly on the bare patches in the same manner you would wash and apply the wound dressing above.
Another effective treatment that was commonly used in Namibia for stubborn cases of Ringworm is griseofulvin, which is an anti-fungal drug that can be given orally. Unfortunately, griseofulvin is no longer approved for use in food-producing animals in most countries. Thus, we only use it under strict veterinary supervision where the withdrawal period is adhered to. Hence, we should also use other alternative antifungal drugs that are recommended for limited lesions, such as to use 3-5 percent thiabendazole paste, a miconazole cream or a clotrimazole cream, applied once or twice daily on the lesions. Any fungicide used to treat athlete’s foot in man can also be applied in livestock to treat Ringworm.
For prevention of Ringworm, it is important to not to introduce animals with signs of recent ringworm infection onto the farm. Even those animals with healed lesions may be carrying infectious fungi as well. You should also isolate any affected animals until new wool/hair is growing on old lesions so that other animals are not infected. Always wear gloves when dealing with Ringworm cases or washing equipment used in such cases. Adhering to strict hygiene in the environment is also important.
Fortunately, Ringworm does not spread fast between animals and that’s the main reason you will notice that only few animals from your herd will be affected at a particular time. Although Ringworm disease causes little permanent damage to the affected animal, it is quite unpleasant to look at. I mean, who would want to see his beautiful animal full of round patches and patches of bare skin, right?