A 9-year-old spayed female large mixed-breed dog was presented to NCSU for evaluation of progressive skin lesions of eight
At the time of lesion onset, the dog's monthly topical flea and tick prevention had been changed from Frontline (Merial) to
ProMeris. Since then, the owner had observed crusts between the shoulder blades within days of each ProMeris application,
starting with the first one. The lesions were initially restricted to the application site and always resolved within two
days without any treatment. However, with each subsequent application, the affected area grew in size, and, eventually, it
was no longer confined to the interscapular region.
Within hours after the seventh application, the patient became lethargic and anorectic, was chewing at its paws, and had extensive
crusting between the shoulder blades. The dog was subsequently hospitalized at an emergency clinic for two days of intravenous
fluid therapy. After initial improvement of the lethargy, the patient developed a fever of 104.9 F (40.5 C) and became lethargic
again; this time, the patient was also lame on all four legs. The skin lesions spread to involve the ventral abdomen, flank
regions, paws, and pinnae.
The primary-care veterinarian prescribed a four-day course of oral antibiotics and administered an intravenous injection of
dexamethasone (0.16 mg/kg). This combination resulted in improvement of the lethargy and resolution of the lameness; however,
the skin lesions remained, and the dog was referred to NCSU.