The diagnosis of solitary solid nodules is mainly based on clinical symptoms and fungal examination. Mycological examination is mainly by Wood′s lamp: Microsporum canis and Microsporum gypsum-like emit greenish-yellow or bright green fluorine. Microscopic examination is also possible: scrape off the skin flakes on a slide, add 10% sodium hydroxide or potassium hydroxide, heat slightly, and place under a low or high magnification microscope for observation. When dogs show suspicious symptoms in fungal endogenous infection, diagnosis can be made by doing chest X-ray fluoroscopy, serum complement binding test, agar diffusion test, pathological histological examination, etc. 1, fungal exogenous diseases Fungal exogenous diseases in dogs are mainly manifested as dermatophytosis or surface fungal diseases, which are fungal diseases of fungal infestation of the epidermis and its appendages (hair, horns, paws). There are many types of pathogenic fungi, but the main cause of canine dermatophytosis is Microsporum canis; to be exact, about 70% is caused by Microsporum canis, 20% by Microsporum gypsum-like, and 10% by Trichophyton spp. Most of the pathogenic fungi that can cause dermatophytosis are often prevented from growing properly by the defensive barrier of healthy dog skin and simply adhere to the skin or coat, co-existing with other fungi and bacteria that do not cause skin infections on the body surface. The epidermis, coat, air and these attached microorganisms together constitute the microenvironment of the body surface. Since microorganisms and even fungi and bacteria live in a changeable environment, they promote each other, antagonize each other or are symbiotic. As the external environment changes, it can cause the occurrence of fungal diseases to have certain effects. When the external environment changes, resulting in the canine organism infected with pathogenic bacteria, fungal spores in the epidermal cuticle multiply, gradually in the hair follicle mouth to form a large number of mycelium, mycelium into the hair follicle, and then into the hair root, deep into the upper part of the hair bulb keratin formation area, and later in the hair or peri-hair branching division to form tight spores or segmented mycelium, causing hair lesions and skin inflammation and produce symptoms. Clinical symptoms are mainly manifested as the appearance of papules, pustules, scales, hair loss. 2, endogenous infection Endogenous infection mainly includes histoplasmosis, coccidioidomycosis, bacteriophage, cryptococcosis, sporotrichosis, candidiasis, etc.. Among them, the pathogen of histoplasmosis is Histoplasma capsulatum, which grows in the soil and is mainly infected through the respiratory tract. Sick dogs mainly present persistent and incurable persistent cough and diarrhea. Anorexia, emaciation, irregular fever, vomiting, dermatitis, and enlarged mesenteric lymph nodes are often found on palpation of the abdominal wall. Ulceration of the buccal mucosa and enlarged tonsils are sometimes seen in chronic cases. The pathogen of coccidioidomycosis is Coccidioides, which is mainly infected through the respiratory tract. The lungs and bronchial or mediastinal lymph nodes of the sick dog develop granulomas, and the sick dog shows elevated body temperature, cough, dyspnea, loss of appetite, emaciation and diarrhea. When the joints are attacked, lameness and muscle atrophy are observed. The etiology of budding bacteriosis is Bacillus dermatitidis. The disease can be divided into two types: systemic and cutaneous. The systemic type mainly manifests as a disease of the lungs, with the sick dog being depressed, feverish, anorexic, emaciated and coughing. On autopsy of the dead dog, there are nodules and abscesses in all lobes of the lungs, and the lungs appear grayish or reddish mottled with focal or diffuse sclerosis. Necrosis occurs in the center of the granulomatous nodules but is not calcified. When the lesion spreads peripherally, it may cause enlargement and suppuration of bronchial and mediastinal lymph nodes, and even pleurisy. Cutaneous budding bacteriosis presents as solitary or multiple cutaneous granulomas that eventually liquefy and necrosis and ulcerate in the center. The pathogen of cryptococcosis is Cryptococcus novelis, which mainly affects the brain, meninges, paranasal sinuses, as well as lungs, spleen, muscles, joints, and skin, causing dysmotility, circling movement, abnormal behavior, lameness, and nasal leakage in sick dogs. On autopsy, there were small foci of suppuration in the paranasal sinuses, turbinate, nasal cavity, and brain, and mucopurulent inflammation of the meninges. Subcutaneous granulomas were seen in the ears, eyelids, and feet. The possibility of cryptococcosis should be considered when unexplained respiratory and central nervous system signs are found clinically in sick dogs. The causative agent of cryptococcosis is C. schenckii. Infection is via trauma. The lesions mainly invade the skin, often at the extremities, and spread along the lymphatic vessels, forming a typical banding swelling. The primary site is a firm, inelastic, movable, non-pressure nodule or granuloma. After the nodule part is shed by the hair, it can be seen with exudate, and after drying, it forms nodules, and some nodules can form abscesses and ulcers after breaking down. Candidiasis whose pathogen is Candida albicans. Often present in the digestive tract of healthy animals. Young and weak, especially animals fed antibacterial additives for a long time or treated with antibiotics for a long time, are susceptible to the onset of infection. The clinical features of the disease in dogs are the formation of a large or several small raised soft spots on the mucosa of the mouth and esophagus, which are covered with a yellowish-white pseudomembrane and peeled off to reveal a congested surface that bleeds easily. Treatment measures combining antibacterial and anti-inflammatory with improvement of skin resistance and nutritional status are taken to enhance skin resistance after skin temperature, blood circulation, nutritional supply and immune function are all improved. In addition, several inspections, repeated medication and several times of environmental disinfection are required. 1, antifungal topical drugs (1) clotrimazole (triamcinolone imidazole): antibacterial agent, can selectively bind to the lipids of the cytoplasmic membrane, thus affecting the structure and function of fungal cells. (2) Econazole: This product is one of the derivatives of imidazole, it is compared with other imidazole derivatives (such as dibenzimidazole, clotrimazole and isobizole), broad antibacterial spectrum, strong antibacterial power, high efficacy, has a certain effect on Candida and Aspergillus, effective for superficial fungal infections, and ineffective for invading deeper layers of various fungi. Topical topical doses of 1% cream and 1% suspension, applied to the wound 2 to 3 times a day. (3) ketoconazole: white or light brown, odorless and tasteless mucilage, effective for all kinds of Candida surface and deep infection. Commonly used 1% ketoconazole solution (prepared with 2% dilute hydrochloric acid) or 1% suspension applied to the trauma, the efficacy is better than econazole. (4) Other topical drugs: including mycoplasma aqueous suspension or Phellodendron, Santoprene, etc. 2, systemic and local application of antifungal drugs (1) mycoplasma: oral action only on the gastrointestinal tract fungus, not absorbed, excreted from the feces, 50 ~ 1 million u, 4 times a day. Trigomycin 200 to 400,000 u daily, divided into 4 oral doses. (2) Ketoconazole: wide antibacterial spectrum, strong antibacterial activity, good oral absorption, 0.2~0.4 times a day, divided into two oral doses. (3) Amphotericin B: broad-spectrum antifungal drug, oral absorption is low and unstable, must be administered intravenously, the side effects are more serious, the administration should be gradually increased from 1-5mg per day to 1mg/kg body weight. To alleviate the side effects, flumethasone 5mg or hydrocortisone 25mg can be added intravenously at the same time. In general, we pay attention to the cleanliness and hygiene of the dog’s skin in the daily feeding management of the dog, and frequently check the coat for ringworm spots and scales. Strengthen the management of dogs, find sick dogs to isolate and treat them in time, and avoid contact between healthy dogs and sick dogs. In addition, while treating, special attention should be paid to the disinfection of kennel apparatus and training equipment. You can use 2% to 3% sodium hydroxide solution, 5% to 10% bleach solution, 1% peroxyacetic acid, 0.5% chlorhexidine solution, etc., all have a good effect of killing fungi. There are also dog feed pay attention to cleanliness and hygiene, it is strictly prohibited to use moldy feed to feed the dog.