What is ringworm?
Ringworm in cattle is a dermatophyte (fungal) infection of skin and hair. Trichophyton verrucosum is responsible for most ringworm infections in cattle. Under optimal conditions, fungal spores are able to survive for many months in the environment. Control of ringworm is important as it causes not only production losses but can also be transmitted to people working with infected cattle.
What economic impact does it have on farm?
The economic costs of ringworm are:
- Scarring of hides: Damage is readily visible on leather after tanning. Even healed skin lesions reappear after tanning
- Reduced growth rate: Growth rates of affected cattle are reduced in the active stage of infection and there is an increased risk of debilitating disease
- Loss of stock: Severely affected animals may have to be euthanized for welfare reasons
Are cattle on my farm at risk of developing ringworm?
Several factors increase the risk of ringworm on farm:
- Age: Young animals are very susceptible to infection. It is common in young calves between two and seven months of age. This is due to poor immunity and lack of previous exposure
- Intensive management systems: Especially if there is overcrowding of young animals
- Low immunity: Poor nutrition, concurrent disease such as BVDV, mineral deficiencies
- Environmental factors: hot, humid climates; calves kept indoors or exposed to foggy weather with little or no sunlight
How does it spread?
The environment is the major source of infective fungi.
Spores can be spread by:
- clinically infected animals – main source of infection
- asymptomatic carriers
- fomites (e.g. brushes, gates, feed carts)
What signs indicate that my cattle may have ringworm?
- Ringworm lesions are usually easy to recognise. The disease is self-limiting but scarring leads to damaged hides. Cattle present with:
- Characteristic circular lesions with a grey colour and ash like surface
- Size ranges from 3-5 cm to large confluent lesions
- Lesions seen mainly on the head and neck but may be anywhere on the animal
- Pruritus (Scratching) is usually mild or absent
- In most cases, ringworm is self-limiting. The period between infection and the appearance of lesions is 1 to 4 weeks and the duration of disease ranges from 1 to 4 months. Scarring and collagen deposits damages hides even after lesions have healed
- Ringworm lesions are usually easy to recognise, however your vet may want to take some hair plucks or skin scrapings to send to the laboratory to confirm the diagnosis
What can I do to control ringworm on the farm?
Farm premises should be disinfected between batches of calves and wooden surfaces treated with effective chemicals. Animals should be handled with gloves. Bought in calves or other animals should be screened for skin lesions on arrival and separated and treated until all lesions have gone. Spores may still be present in the environment from previously infected animals. Trichophyton verrucosum spores are very resistant to ordinary cleaning and require heavy specialist disinfection for complete eradication. Up to 4% chlorine in the disinfectant has been recommended. Spores last longer than a year in sheds and will survive after the cattle have departed. In very aggressive outbreaks potentially in-contact animals can be vaccinated. Only one vaccination is available for the treatment and prevention of ringworm and advice on its use should be sought from your vet.