is a 6-month-old pug dog with a skin problem. His
caretakers, Forest and Sherry, have had him since he was
8 weeks old and noticed recently that he is developing
patches of missing hair on his body, some of which show
reddened skin. Hadley seems otherwise unaffected
although Sherry reports he does seem itchy. He has been
treated with a flea preventative and, according to
Forest and Sherry, he has no fleas.
absence of visible fleas does not rule out a skin
problem due to fleas. They can be very difficult to spot
and, in dogs with flea sensitivities, there may not be
any fleas on the dog, as they have chewed them all off.
That said, I do not think Hadley has fleas.
dogs such as Hadley can take time to develop a fully
competent immune system and, as a result, they can be
more susceptible to certain diseases. These diseases
would not affect a normal adult dog, but in a case in
which the immune system has not matured, they can
manifest. I suspect that is what is happening with
Hadley, that he has a case of mange.
is a collective term representing a skin disease caused
by different types of mites. Mites are in the arthropod
group of organisms and there are many different species
that can cause "mange" depending on the
species of animal. In dogs, we see predominately two
types of mites associated with mange — Sarcoptes
scabeii and Demodex sp.
Hadley’s case, I suspect he has a case of mange caused
by Demodex mites. These mites live in the hair follicles
of an infected dog and, as they increase, the hair
shafts fall from the follicles, creating patches of hair
loss as described in Hadley. This invasive process
causes an inflammatory response leading to reddening of
the skin. As one might imagine, these dogs can be itchy.
To definitively diagnose Demodex, Hadley needs to be
taken to a veterinarian.
diagnose Demodex, we use a simple diagnostic test called
a skin scrape. This is accomplished by scraping a
pinched ridge of skin in several affected areas of the
patient and examining the skin scrapings under a
microscope. It is important to scrape relatively
aggressively as these mites can be burrowed fairly
deeply into the hair follicles. Under the microscope the
Demodex mites appear very distinctive. They are cigar
shaped with three pair of stubby legs in the forward
third to half of their body. In a heavy case of Demodex
there will be large numbers of mites wiggling under the
I am correct in my diagnosis and Hadley has Demodex, he
will need to be treated. Sometimes Demodex can manifest
as a single lesion somewhere on the body and can simply
be treated topically in that one location or, in some
cases, not treated at all. In Hadley’s case, the
process sounds more generalized. For him, it is best to
treat his entire body. In the past this would involve a
topical therapy usually done in the veterinary hospital
and repeated multiple times until rechecked skin
scrapings are negative for the mite. Recently, a new
flea product Bravecto has shown great promise in
treating dogs with Demodex. It is an oral medication
given once every three months for flea prevention. In
the cases with which I have been involved using it
against Demodex, it took only one treatment to cure the
last point about Demodex is that it occurs on many dogs.
However, the mite population is kept in check by the dog’s
immune system. Patients with decreased or immature
immune systems, as in Hadley’s case, can break with
Demodex-associated mange. Adult dogs rarely get this
disease unless they are immune compromised.