study on cysts
Materials and methods
Twenty dogs were examined for staphylococcal deep
pyoderma at the Cornell University College of Veterinary
Medicine (Table 1). The dogs ranged from 4 mo to 11 y
of age, represented numerous breeds and a mongrel,
and consisted of 14 males and 6 females. Weights
ranged from 11 to 61 kg. Duration of clinical signs
ranged from 2 wk to 4 y. Thirteen dogs had received
prior antibiotic therapy and had recurrent infections. All
dogs had deep pyoderma involving the paws, pressure
points, face, or large areas of the body surface. Eight dogs
had previously diagnosed concurrent dermatoses
(Table 2) that may have been predisposing factors for the
development of deep pyoderma. The other 12 dogs had
no identifiable predisposing cause. Skin scrapings and
microscopic examination of pus from skin lesions were
performed on all dogs. Cytological examination of
pus expressed from draining tracts revealed pyogranulomatous inflammation, wherein the majority of neutrophils were degenerate and many contained phagocytosed cocci. Exudate collected from intact nodules and
plaques on all dogs was submitted for bacterial culture
and antibiotic susceptibility testing.
To be admitted into the study, all dogs had to have a
positive culture for S. intermedius that was tested for
in vitro susceptibility to clindamycin. In vitro susceptibility to clindamycin was determined by the broth
microdilution system, as recommended by the National
Committee for Clinical Laboratory Standards (28). All
plates were commercially prepared and tested by using
the Radiometer Sensitive system (Sensititre Microbiology
Systems, Radiometer America, Westlake, Ohio, USA).
In addition, informed consent had to have been obtained
from the dogs' owners. Clindamycin capsules (75 mg and
150 mg) were administered PO at 11 mg/kg BW, q24h.
Treatment with clindamycin was initiated at the time the
dogs were discharged from the clinic, before the results
of culture and in vitro antibiotic susceptibility testing
were known. Treatment was continued until all active
lesions had disappeared and then for another 7 d (1,29-31).
In 13 dogs, response to therapy was assessed by reexaminations at the College of Veterinary Medicine. In
7 dogs, response to therapy was assessed by reexaminations at the referring veterinarians' clinics and their
subsequent telephone conversations with one of the
authors. Reexaminations were performed every 2 to 3 wk.
The post-treatment follow-up period was 3 mo for all
Staphylococcus intermedius was isolated in pure culture
from all 20 dogs. Eighteen (90%) of the 20 isolates
were susceptible to clindamycin in vitro. The other 2 isolates were of intermediate susceptibility (case 16) or
resistant (case 3).
Twenty dogs were treated with clindamycin, and all
20 had excellent responses (complete resolution of their
infections). Treatment periods ranged from 21 to 91 d,
with an average of 45 d. Five dogs (25%) suffered recurrences within the 3-month posttreatment follow-up
period (Table 2). There did not appear to be any influence
of age, sex, duration of disease, concurrent dermatosis
(Table 2), or previous antibiotic therapy on the response
to clindamycin therapy. One dog (case 2) vomited when
the clindamycin was given on an empty stomach, but not
when it was administered with food.
Clindamycin produced an excellent result in 100% of