Animal Allergy and Dermatology
Center of Central Texas
There are many different species of ectoparasites that can live in the hair follicles of your canine or feline companion. These conditions can have very similar symptoms, yet require very unique methods of treatment. Dr. Nichols will identify the particular species and develop a specific, effective treatment customized to your pet. Examples of common ectoparasites are as follows:
Sarcoptic Mange (Scabes) is caused by the mite Sarcoptes scabiei var. canis. Mites live in the superficial layers of the skin where they burrow, breed, and lay eggs. Scabes mites do not live for prolonged periods without the host, so they are generally passed by direct contact with other dogs. The hallmark of the disease is intense pruritus (itching). Classic scabies will manifest as red papules (bumps) to the chest, abdomen,and as time progresses, as a thick scale on the ears, elbows, and hocks. Fever, lymph node enlargement, and weight loss with secondary bacterial infection may occur. To definitively diagnose this disease, the mites must be seen microscopically on skin scraping or fecal exam.
Demodectic Mange (Demodex) is a type of mite that is present in small numbers in most healthy dogs. However, in some dogs, the mites live, reproduce, and overpopulate, leading to infection and hair loss. It is believed that some dogs have a defect in their immune system that allows the mites to reproduce. Diagnosis is made by microscope examination of scrapings of the skin and hair follicles and/or impression smear of the crusts.
Dermatophytosis (Ringworm) is a fungal infection of the hair, superficial skin, and occasionally nails. There are no worms involved, despite the name. Three species of ringworm cause the majority of infections - Microsporum canis, Microsporum gypseum, and Trichophyton mentagrophytes. The most common sources of infection are other infected pets, rodents, contaminated environments, and occasionally, the soil. The most common clinical signs of infection are hair loss, broken hairs, and increased pigmentation of the skin. Other signs may include red bumps, itching, crusting, scaling, and occasionally, pus. Some animals may act as carriers of the disease with no visible lesions. People who come in contact with infected animals are at risk of developing ringworm. Diagnosis is based on fungal cultures and/or skin biopsy.