LAS VEGAS — In the late 1970s, demodicosis was regarded as one of the most persistent diseases in dogs and cats, said Stephen E. Waisglass, BSc, DVM, CertSAD, DACVD, veterinary dermatologist at North Toronto Animal Clinic in Ontario, Canada.
"Today, the prognosis for generalized demodicosis has improved dramatically," he said here at the Western Veterinary Conference. "Approximately 90% of cases can be cured, and I believe we're entering an era when things may get even easier."
New diagnostic techniques and treatments have made it easier to recognize and treat demodicosis, but success still depends on the ability to find mites on the pet, Waisglass said.
A skin scrape is necessary. "We have always taught students to give the skin a good squeeze before doing a skin scrape, but someone recently asked where that [technique] came from," he said. "The consensus among dermatologists was that we had no idea. However, we all do it and we all teach it, so squeeze the skin if you want. Just be sure to get good, deep scrapings."
Waisglass recommended scraping many locations for samples, particularly areas with alopecia or a lot of comedones, or blackheads, because they often are teeming with mites.
He also warns owners before the appointment that the dog will look bad after skin scrapings, but the pain is minimal — equivalent to a skinned knee. "You want a nice, bloody sample," he explained. "Put a lot of mineral oil on it, cover it with a coverslip that will minimize oil slicks and look under the microscope."
One tip for spotting Demodex, Waisglass said, is to lower the condenser on the microscope to achieve more contrast, which can make it easier to identify mite motility.
For young dogs with generalized demodicosis, Waisglass conducts a fecal examination and evaluates the dog's diet to ensure it is getting good nutrition. If an older dog presents with generalized demodicosis, he runs a full immunologic and biochemical profile, including heartworm status. He may also add abdominal ultrasonography. "I will look for things that may be immunosuppressing the dog," he said.
"An older dog with late-onset demodicosis will usually present with an underlying disease within 6 months of diagnosing generalized demodicosis. The [underlying] disease could be anything from cancer to hypothyroidism."
For more information
Waisglass SE. Demodicosis update: some considerations to increase your success. Presented at: The Western Veterinary Conference. Las Vegas; Feb. 15-19, 2009.
