This article is from the Canine Medical Information FAQ, by Cindy Tittle Moore with numerous contributions by others.
Interdigital cysts are a common problem in short haired breeds of
dogs. Males do seem to be worse and Labs probably worst of all. There
are a number of differential diagnoses to consider such as demodex,
fungi, pyoderma secondary to atopy, dermoid cysts, etc. Dermoid cysts
are invaginations of the skin which forms a pocket of hair and misc.
junk. They are often infected and they always recurr unless surgically
Especially if the cysts are recurrent, a good option is to have the
cyst surgically removed and send it to a _dermatopathologist_, not a
regular pathologist. It is expensive but it will greatly reduce the
number of return trips to the vet. With that diagnosis, it will be
easier to deal with future recurrences.
Other treatment includes long-term antibiotic treatment... three to
six months may be required. Make sure the antibiotic choice and dosing
is appropriate. Culture & antibiotic sensitivity tests are
Also demodectic mange may be underlying the problem. Skin scrapes can
make the diagnosis, but false negatives are possible. Foot dips in
mitoban (diluted) followed by warm soaks in dilute chlorihexidine may
clear it up.
Fitting the dog with a rubber boot to protect the foot may help speed
recovery following the removal of the cyst.