How to recognise ringworm in dogs and cats? Treatment, signs and diagnosis
You see the classical circular bald spot….eek it looks like ringworm. Ringworm is more common than we think, and can affect all animals – humans included! In this article, we will discuss ringworm treatment, signs and diagnosis.
What Is Ringworm?
Why ringworm is called ringworm is kind of bizarre, as there are no worms involved. The name occurred due to the ringlike appearance of lesions.
Ringworm is a fungal infection caused by a fungus known as dermatophytosis. There are different species of ringworm, the most common culprit we see is Microsporum canis.
Ringworm is common in cats, dogs, horses and cattle. The most common dermatophytes isolated according to species are:
Cats: Microsporum canis, Trichophyton mentagrophytes, M. gyspeum
Dogs: Microsporum canis
Horses: Trichophyton equinum, Microsporum canis, Trichophyton veruccosum
Cattle: T. veruccosum
Ringworm often occurs in the very young, the very old and the immunocompromised.
What are the signs of ringworm?
The classic appearance of ringworm is a circular area of hair loss. It may be crusty and scaling. Generally, the area is not itchy or painful, just unsightly.
Initially, we often see a raised area, and the hair can be ‘plucked out’ easily leaving a bald (alopecia) area. Sometimes these areas are reddened. This redness often resolves quickly.
Some animals, particularly cats, can harbour ringworm and show relatively few signs, resulting in massive contamination of the environment if an affected cat enters a colony.
How is ringworm diagnosed?
Ringworm diagnosis is not particularly tricky, although it can mimic bacterial or parasitic disease (Demodex). It is worthwhile getting a formal diagnosis due to the zoonotic nature (can affect humans).
In the case of breeding operations and animal rescue centres (particularly cats), it is absolutely imperative that diagnosis of any suspicious lesion is performed, as this skin disease can result in unmanageable outbreaks, excessive costs, and euthanasia due to its potential to spread to people (zoonosis).
The initial test that most vets will perform is the examination of the lesion with a Wood’s Lamp. Although not a perfect diagnostic test due to the relatively high frequency of false negative results, a Wood’s lamp – correctly used – can be a helpful and cost-effective screening tool. A negative Wood’s lamp exam does not, of course, rule out infection and suspicious lesions should always be cultured.
How is ringworm treated?
Treatment and management of ringworm need to go hand in hand when there is an outbreak of ringworm. Whether you are treating dogs, cats, horses or other species the principles are the same.
It’s also important to understand that ringworm can infect people (zoonosis) especially those that may be immunocompromised. For this reason it is essential that you treat any animals with signs of this infection.
Topical treatment of ringworm
Lime Sulphur – 8%
- Safe in kittens and puppies (be sure to keep warm)
- Apply twice weekly to cats and dogs. Horses can be a daily application initially, and then move to twice weekly in the second week.
- Apply powder then spray with water. (Don’t pre-wet). Wipe paste over facial areas (nose, ears etc).
- Leave to soak in, no need to rinse off.
- Continue treating until you have two consecutive negative fungal cultures a week apart. (It is common for cats especially to appear ‘cured’, when in fact they are still highly contagious).
Chlorhexidine – is not effective.
Systemic treatment of ringworm
Antifungals are often used in a situation to speed up time of resolution. They cannot be used in pregnant animals and often need to be compounded to get the small dose required in kittens and puppies. These drugs work better when given with a fat, like butter.
Environmental treatment of ringworm
Ringworm can survive in the environment for years. It is important to clean all surfaces with a bleach solution (1:10) applied twice, allowing for complete drying between applications. Grooming equipment is either bleach cleaned multiple times or thrown out and burned.
Have you ever had an animal suffer from ringworm? Tell us below how you managed and treated for it.