Ringworm PCR panel for dogs and cats
dog and cat assay data sheet
and differentiation of Microsporum and Trichophyton, common
causes of ringworm in dogs and cats, by real time PCR.
In cats, about 98% of ringworm (dermatophytosis) cases are caused by
Microsporum canis and almost
all of the other 2% by Trichophyton.
In dogs, ringworm is also usually caused by
Microsporum canis; but it is
caused by Trichophyton
mentagrophytes, and sometimes by other fungi, more frequently than
The most common clinical signs of these dermatophyte organisms include any combination
of hair loss, scaling, and erythema, with or without pruritus. Because
these symptoms overlap with skin diseases caused by a wide range of
non-dermatophytes, it is very difficult to identify the organism by clinical presentation alone.
Microsporum and Trichophyton dermatophytes is dependent on many factors including, but
not limited to, the amount of infective material, frequency of
exposure, general health of the animal, and physiological stress.
Dermatophyte fungi infect the hair shaft, follicle, and surrounding
skin. Infected hairs become brittle, and broken shafts can remain
infective in the environment for months. Direct contact with these
broken-off hair shafts represents the most common form of
Approximately 25% of human ringworm cases reported annually are attributed to animal
Microsporum is a genus of fungi
that infects mammals, and in humans causes ringworm, tinea capitis, tinea corporis, and other
dermatophytoses (fungal infections of the skin).
At least seventeen species of
Microsporum have been described, including
M. canis, M. distortum,
M. duboisii, M. equinum,
M. fulvum, M. gallinae,
M. langeronii, M. nanum,
M. praecox, M. ripariae
and M. rivalieri.
In 2016, a new classification scheme was proposed to limit the
Microsporum genus to just
three species: M. audouinii,
M. canis and
M. ferrugineum. The remaining geophilic and zoophilic species,
Microsporum species, are now proposed to be transferred to the
genera Lophophyton, Nannizzia and
Paraphyton. For example,
M. gypseum is now renamed as
Nannizzia gypsea and
now Nannizzia persicolor.
Among these Microsporum
species, M. canis
has worldwide distribution and
lives on both animals and humans. It is a frequent cause of ringworm in humans,
especially children. Cats and dogs are the main sources of human
M. canis infection.
M. ferrugineum is a species which
prefers living on human and can cause epidemic juvenile tinea capitis
in humans. The clinical features are similar to those of infections
M. audouinii, another species
which prefers living on humans, causing non-inflammatory infections of
the scalp and skin, especially in children. It had been the major
cause of tinea capitis in Europe and North America, but is now less
From a taxonomic point of view,
fusiform macroconidia with rough to echinulate walls differentiate
Microsporum species from
Microsporum species may form both macro- and microconidia, although
they are not always present. This makes identification of
Microsporum difficult by
Trichophyton is another genus of fungi
which causes opportunistic fungal
diseases in mammals. In humans, Trichophyton cause tinea, including athlete's foot, ringworm, jock itch,
and similar infections of the nail, beard, skin and scalp. The most common agent
of tinea capitis in North America is Trichophyton tonsurans whereas in much of Europe,
M. canis is a more common
cause of tinea capitis.
Trichophyton fungi are characterized by the development of
smooth-walled macro- and microconidia.
Sixteen species are now recognized in the genus; these include
T. equinum, T. benhamiae,
T. eriotrephon, T. erinacei,
T. quinckeanum, T. rubrum,
T. simii, T. soudanense,
T. verrucosum and T.
In horses, dermatophytosis is mainly caused by
Trichophyton equinum, but occasionally infection with
T. verrucosum may occur in horses having direct contact with
Identification and differentiation of these fungal infections by clinical symptoms
alone is very
difficult. Laboratory workup is required to differentiate these fungal
infections from other similar non-fungal diseases. Culture detection
has been used for a long time to identify these fungi but fungal
growth is very slow, and even if there is fungal growth, it is hard to
differentiate the different types of dermatophytes by culture.
Molecular detection by PCR, however, is fast, specific and sensitive,
and is now the method of choice for detecting and differentiating
Help confirm the disease causing agent
Shorten the time required to confirm a clinical
diagnosis of Microsporum
Help ensure that animal groups are free of these fungi
Early prevention of spread of these fungi
Minimize human exposure to these fungi
Verrier, J and Monod, M. (2017) Diagnosis of dermatophytosis using
molecular biology. Mycopathologia. 82:193-202.
Swab or sterile toothbrush run
deeply through hair and against skin for at least 30 seconds, or environmental surface swab.
Contact Zoologix if advice is needed to determine an appropriate specimen type for a specific diagnostic application. For specimen types not listed here, please contact Zoologix to confirm specimen acceptability and shipping instructions.
For all specimen
types, if there will be a delay in shipping, or during very warm
weather, refrigerate specimens until shipped and ship with a cold pack
unless more stringent shipping requirements are specified. Frozen
specimens should be shipped so as to remain frozen in transit. See
shipping instructions for more
2 business days
Qualitative real time PCR