Symptoms Diagnosis and Treatment of
Ringworm on Dogs
"
Ringworm on Dogs is actually a group of fungal diseases, caused by
three
different fungal species called dermatophytes which are referred to
as Microsporum, Epidematophyton
and Trichophyton. Dog ringworm, in other words is also called
“Dermatophytosis”. Dermatophytes usually grow in keratinized tissues,
causing skin problems in growing hairs, where “Keratin”, the
protein is found. Dog ringworm is characterized by a weakened or
broken hair base, alopecia (hair loss), circular patches and scales on
the skin and
in severe cases, folliculitis (infection at the skin opening the
encloses hair) and generalized infection is noted.
Taking a fungal culture is the best way to diagnose canine
ringworm, along with
the clinical appearance of a ring or circular patches on the skin. In
most
cases, dog ringworm is self-resolving, but use of Anti–fungal drugs
hastens the recovery, and also helps to prevent the spreading
the
disease. "
Cause of Ringworm on Dogs:
As described, dog ring worm is also called “Dermatophytosis”,
which is caused by a fungal species termed “Dermatophytes”. In dogs
three types of
dermatophytes have been identified as causative agents of dog ring
worm. These are Microsporum, Trichophyton and Epidematophyton.
Microsporum; M. canis and M. gypseum are two species
reported as causative agents for dog ring worm. These are generally
single cell, spindle shaped fungus, ranging 100–160 um in size. These
are highly transmissible species of fungi, and may also infect cats and
humans too. 70% of all dog ring worm cases reported are caused by M.
canis, while 20% of those are caused by M. gypseum.
Trichophyton; In dogs, 10% of all cases of ring worm are
caused by the
specie of Trichophyton, called T. mentagrophytes. Trichphytons are
generally spherical shaped dermatophytes, ranging 8–50 um in
size.

Picture of Dog Ringworm
Picture
Signs and Symptoms of Ringworm on Dogs:
Clinically, dog ringworm is characterized by circular or ring shaped
scaly hair loss. The appearance on the skin gives the
condition its name - “Ring–Worm”. Broken
hair, weakened hair base, hair loss, mild irritation, scales
and
distributed patches on the skin are common signs of dog ringworm. In
severe
conditions, inflammation of hair follicles and generalized
patchy
skin can be seen, with severe irritation. There can also
be signs of a generalized
illness such as fever, weakness and lethargy.
Picture of Ringworm on
Dog Face
Source: Washington State University
Diagnosis of Ringworm on Dogs:
Clinical signs are very helpful in identifying dog ring worm. Ring like
appearances of hair loss on the body, especially on the abdomen and
lateral sides, usually results in a ringworm diagnosis.
In order to confirm and differentiate dog ring worm from bacterial
folliculitis, dermatitis and demodecosis, usually a fungal culture is
required. Samples are collected from the base of the hairs and are
cultured in the laboratory for confirmation. The test requires
12–24 hours to complete.
Treatment of Ringworm on Dogs:
Most cases of dog ringworm resolve on their own;
therefore, a treatment plan is only used to speed up the
recovery and also
to prevent the transmission and spreading of the disease to other dogs,
cats and humans. Shampooing affected dogs with quality
product containing “Enilclonazole” or lime-sulfur is considered
effective, though
there are some controversies related with whole body topical
applications of anti–fungal agents. One lime-sulfur based
shampoo and rinse to consider that is available without a prescription
is
Dermisil
for Pet Ringworm.
There is also a natural homeopathic product available for dogs called
Ring-Ex
that is made specifically to help dogs with ringworm. It
contains well
known and highly regarded ingredients that also promote longer term
skin health. The
product contains Tee Tree Oil (soothes the skin), Neem (natural product
to make skin worm resistant and soothes the skin), Marigold (skin cell
regeneration) and Whitchhazel (supports skin cell regrowth).
See the manufacturers site via the above link for more
information and clinical support.
In chronic or severe cases, use of griseofulvin is recommended at dose
rates of 25–100mg/Kg B.W. The formulation of grisofulvin is usually
referred, per oral tablets and administered for 3–4 days.
Some side effects of grisofulvin, such as gastrointestinal upset
are possible in sensitive dogs, thus Terbinafine at dose rates of 30
mg/Kg B.W or Itraconazole at dose rates of 5–10 mg/Kg B.W can be
administered as alternatives for dogs.
Removing Ringworm Fungal Spores from Your Home -
A Necessary
Step
Is ringworm contagious? Ringworm is highly contagious and can spread
from pet to human (the
most common zootonic disease - one that spreads from pet to human).
The spores can spread from the dog and scatter throughout the
home and stay in carpets, bedding, furniture and even your home's air
filtration system. The spores can live up to 18 months.
For this reason, it is a smart move to clean the home as well.
This includes removal of any air filters in the heating/air
conditioning system, thorough vacuuming and the use of a disinfectant
designed to kill ringworm spores such as
Benzarid.
Have A Question About a Dog Ringworm Problem For Our Editors or a Suggestions to Share?
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We will do our best to get back to you quickly (it depends on how many questions we receive each day). If you do require an immediate response we suggest using this online dog veterinary service that is available now.
References:
The
Merck Veterinary Manual
M. C Sharma, ET all. Dogs:
Breeding,
Nutrition & Health Management (C.B.S Publishers, India. 2005)
Revised Ed.