No efficacy comparison studies between itraconazole and terbinafine have been done. Some dogs may have hepatotoxicity with terbinafine, but cats do not.Ī study showed that terbinafine therapy combined with a weekly lime-sulfur dip resolved ringworm in cats in three weeks.1 I have been impressed with the efficacy and ease of administration of the new formulation, Itrafungol (Elanco). Generic and compounded itraconazole are not recommended. In healthy patients, spontaneous resolution may occur within three months.ĭogs and cats: 5 mg/kg orally, once a day for seven days, then stop for seven days repeat pattern three timesĪlanine aminotransferase and serum alkaline phosphatase activities may rise without liver disease signs, although hepatotoxicity is rare. Treatment duration is variable and may take between 14 days and six months. Continue treatment until you obtain two or three negative cultures. ![]() To monitor treatment progress, perform a repeat culture one to three weeks after beginning therapy and every one to three weeks thereafter. This means that you, your team and the owners will all need to work together. Treating ringworm requires a combination of systemic or topical therapy and environmental management. These discrepancies could've been caused by differences in sampling, but for now, we are performing both ringworm PCR and fungal cultures. I've recently seen several cases of ringworm in which the fungal PCR result was negative and the DTM result was positive. Use a Wood's lamp to identify appropriate hair samples to help decrease the possibility of a false positive result. Submit nail bed scrapings or clippings in a sealed fungal envelope or sterile container.įalse positive results are possible when monitoring during ringworm treatment since the PCR is sensitive enough to pick up spores from environmental contamination. Pluck hair with follicles, lift or remove crusts, or perform skin scrapings from the active border of a suspect lesion, and then place the collected items in a red top tube. Use a soft-bristle toothbrush to comb the suspect lesion, then submit the toothbrush in a plastic, reusable storage bag. You have a few options for submitting samples. Results are available in one to three working days, so it may be helpful for diagnosis in patients you want to start treating immediately. The Ringworm RealPCR Panel (Idexx Laboratories) includes Microsporum and Trichophyton species real-time PCR tests and performs with greater than 95% sensitivity and 99% specificity. Plates should be kept for at least 14 days, but 21 days is preferable.Ĭollect a tape sample from suspicious colonies, stain with lactophenol cotton blue or the purple modified Wright's stain (Diff-Quik-Dade Behring), and then examine at 10x magnification and then 40x to look for macroconidia. Most ringworm species will grow and sporulate within seven to 10 days, but Trichophyton species cultures often take up to 21 days. Ringworm growth will appear white or buff-colored (never dark) and will develop a red color around it as it grows. ![]() Ideally, incubation temperature should remain between 75 F (23.9 C) and 80 F (26.7 C), and you should check the plates daily for fungal culture growth. Then gently stab the bristles or press the gauze over the entire surface of the culture plate. Be sure to sample near the eyes, in the ears and between the toes. ![]() You can also use the Mackenzie brush technique, in which you rub a new toothbrush or clean gauze over the entire affected site until hair is clearly visible in the brush bristles or on the gauze surface. To grow ringworm species in a DTM, grasp individual, grossly abnormal hairs (or Wood's lamp-positive hairs) in the direction of growth and tug gently, trying to get the root bulb. Sab-Duet from Hardy Diagnostics showing positive growth for M. However, a Wood's lamp examination or direct examination of hairs can help you identify and manage ringworm cases. These animals can be chronic carriers of a fungus even though they may not show any signs of infection themselves.Ī fungal culture (using a dermatophyte test medium ) or fungal polymerase chain reaction (PCR) test is needed to determine the species of ringworm that is infecting your patient. Cats, especially longhaired breeds, have a more generalized form of infection than dogs. In dogs, there is often a clearly defined border of affected versus nonaffected skin. Ringworm can be more extensive, causing well-demarcated alopecia, erythema, pruritus and scale. The face, ears, feet and tail are the most commonly affected areas. These lesions result from an inflammatory reaction to the fungus. ![]() Note the border between affected and normal skin.Clinical signsĭermatophytosis has come to be called ringworm because of the characteristic circular area of hair loss with a red, raised outer rim. A pit bull with generalized dermatophytosis.
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