Adrienne is a certified dog trainer and former veterinarian assistant who partners with some of the best veterinarians worldwide.
Hairless patches the size of a quarter may be descriptive enough of ringworm, but not always. To make things more complicated, ringworm does not necessarily always show as round patches and may appear as large hairless areas or irregular shapes and sizes. There are many skin conditions that may share the same symptoms, so veterinarians often have a hard time coming to a diagnosis based on looks alone.
It's very likely that your vet will take a skin scraping and send it out to a laboratory. Since it may take some time for the results to come in, sometimes veterinarians will prescribe anti-fungal creams right away if they suspect ringworm is the culprit.
What Is Ringworm?
The first time dog owners hear the word ''ringworm'' they very likely think they are dealing with some sort of parasite. The word is misleading as ringworm is caused by a fungus. There are theories that the word ''ringworm'' may have originated from the past belief that the patchy circular areas were caused by a worm.
What Is the Ringworm Fungus?
The fungus behind the unsightly patches can belong to different families: Microsporum canis (the most common), Microsporum gypseum, and Trichophyton mentagrophytes.
This fungus is highly contagious to other dogs, cats, and people, so you will want to keep your dog away from your other dogs and pets, disinfect common areas, and wash your hands thoroughly after handling him.
How to Tell if Your Dog Has Ringworm
You groom your dog one morning and you find a hairless patch the size of a quarter. Later you find another one and then another one. Concerned about these unsightly spots, you take your dog to the vet for a diagnosis: "Ringworm."
Use Ultraviolet Light to See Ringworm
Owners may try to find out if their dog has ringworm by using an ultraviolet light or black light. About 50% of ringworm cases will cause the lesion to glow. A bright apple green fluorescence found on the hair shafts may help diagnose the dog. However, if the lesion does not glow consider that it does not necessarily mean the dog does not have ringworm. Many veterinarians will perform this test in their offices.
Consider Exposure to Other Dogs With Ringworm
Another way to tell if your dog has ringworm is if he has been exposed to other dogs with this condition. If your dog has frequented a dog grooming center, a kennel or has been in contact with other dogs or stray cats, then he may have picked up this skin disorder from these places and these animals. Consider that the incubation time, that is the time between when your dog was in contact with the potential cause and the time the first symptoms arise, may be around 10 to 12 days.
Check Your Environment
Consider though that at times dogs can pick up the disease from an infected environment. This means all it takes is exposure to infected materials such as bedding, carpets, hair clippers, combs and even dirt. Even exposure to other dogs that appear healthy may cause ringworm as some dogs may be carriers of the skin disorder without showing any signs of actual disease.
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What to Do if You Think Your Dog Has Ringworm
If you suspect ringworm in your dog, your best bet is to have your dog see your vet. Your vet can only prescribe the most effective treatment and confirm or rule out this annoying skin condition. Even though ringworm eventually clears up on its own, prescription medications will shorten the course of the disease lessening the amount of time your dog may be contagious.
This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.
© 2010 Adrienne Farricelli
Adrienne Farricelli (author) on September 23, 2018:
Ringworm is generally found in young animals and the hair would be broken off. The round, hairless areas are often the size of coin. A hot spot is oozy of serum and is red and raw and painful.
Angie Mayo from Victoria Australia on September 15, 2018:
How can you tell the difference between a ringworm and a hot spot?
jandee from Liverpool.U.K on July 24, 2010:
Scary ! Lot's of poor stray cats hang around my gate as the man next door feeds them and now I'm worried,jandee
bayoulady from Northern Louisiana,USA on July 16, 2010:
I 've had dogs all my life. You taught me something.(I thought I knew all about dog's skin issues by now......) I'm lucky I'm following you! I'll make sure to keep my dog Sweetie Pie away from cats with ringworm.Thanks.
Dallas W Thompson from Bakersfield, CA on July 14, 2010:
Informative hub. Take care of your pet and they take care of you!