Parasitic and Fungal Skin Disorders
A parasite is any living thing that lives in, on, or with another living thing, known as the host, and that depends on the host for its food and shelter. Some Parasites depend on a host for their entire lives, while others depend on the host only during a part of their life. Many worms are parasites that infect dogs, cats, horses and other animals. Some of these worms may also infect people. Here are a few examples of parasitic worms found in dogs.
Dracunculus insignis is a species of round worm found mainly in the connective tissue beneath the skin of the legs. They are known to infect racoons, minks, and other animals, including dogs, in North America. Female worms can reach up to ten feet in length. Male worms are tiny in comparison, being only about 0.6 inches long. These worms can produce skin ulcers on their host. When the ulcers touch water the worms stick their heads out of the wounds in order to lay the thin-tailed larvae. The larvae then develop inside another host, the water flea. Dogs can also become infected when they drink contaminated water or eat another host, such as a frog. Signs of D. insignis worm infestation include snake like, swollen tracks under the skin and crater like red ulcers on the skin?s surface. These infections are rare but have occasionally been found in dogs that have been around small lakes and shallow, stagnant water. Veterinarians treat the infection by carefully and slowly extracting the parasites. Antiparasitic drugs of the miridazole or benimidazole classes can also be useful.
Pelodera dermatitis is a rare skin worm infestation that causes a short term skin infection. The condition is caused when larvae of roundworms known as Pelodera strongyloides invade the skin. These larvae are widespread in decaying organic matter, such as damp hay, and on or near the surface of moist soil. They are only occasionally parasitic. In most cases, animals are exposed to the larvae through direct contact with infested materials, such as damp, filthy bedding. Animals with healthy skin are not usually at risk for infection. The sores usually only appear on parts of the body that contact the infested material, such as legs, groin, abdomen, and chest. The affected skin is red and partially or completely hairless. In addition, there may be bumps in the skin, lumps filled with pus, crusts or ulcers. Often but not always, there is severe itching causing the animal to scratch, bite, or rub the affected area. A definitive diagnosis can be made by your veterinarian by examinating skin scrapings under a microscope to check for worm larvae. Animals with Pelodera dermatitis can be treated in the same manner as other skin worm infestations.
Ringworm ( Dermatophytosis ):
Ringworm is an infection of skin, hair and claws caused by a type of fungus. In dogs about seventy percent of ringworm cases are caused by the fungus Microsporum canis, twenty percent by Microsporum gypseum, and ten percent by Trichophyton mentagrophytes. The infecting fungus is spread easily in the environment. People can easily be infected with these fungi. Most cases of ringworm are spread by contact with infected animals or contaminated objects such as furniture or grooming tools. Broken hairs with associated spores are important sources for spread of the disease. Contact does not always result in infection. Whether infection is established depends on the fungal species and on host factors including age, health, condition of exposed skin surfaces, grooming behavior, and nutrition. Infection leads to short-lived resistance to reinfection. Under most circumstances dermatophytes grow only in the dead cells of the skin and hair, and infection stops on reaching living cells or on inflamed tissue. As inflammation and host immunity develop, further spread of infection stops, but this process may take several weeks. Infected dogs develop bald, scaly patches with broken hairs in ring-like whirls. The most common sites affected by ringworm are the face, ear tips, tail, and feet. Ringworm is diagnosed by fungal cultures, examination with an ultraviolet lamp, and direct microscopic examination of hair and skin scales. Fungal culture of hairs and scrapings from the affected areas is the most accurate method. Direct microscopic examination of hairs or skin scrapings may allow early diagnosis. Ringworm infections can sometimes clear up on their own without treatment, but I wouldn?t risk it. Talk to your veterinarian to find out the best way to determine diagnosis, and what the best treatment method may be.