Solitary solid nodule

Introduction Necrosis occurs in the center of the granulomatous nodule, but it is not calcified. When the lesion spreads around, the bronchial and mediastinal lymph nodes can be swollen, purulent, and even cause pleurisy. Skin-type germination is characterized by a single or multiple skin granuloma, and finally liquefaction necrosis and ulceration occur in the center. The pathogen of cryptococcosis is Cryptococcus neoformans, which mainly invades the brain, meninges, paranasal sinuses, lungs, spleen, muscles, joints, skin, etc., causing movement disorders, circling movements, abnormal behavior, lameness, and rhinorrhea. At the time of necropsy, there were small suppurative lesions in the paranasal sinus, nasal turbinates, nasal cavity and brain, and there was mucous purulent inflammation in the meninges. Subcutaneous granuloma can be seen in the ear, eyelids and feet.

Cause

The pathogenicity of fungi can be divided into exogenous or endogenous infections, allergies, toxin poisoning or tumorigenicity. Fungi can cause different diseases in various animals through different forms. Some fungi have parasitic pathogenic effects, some are conditional pathogenic effects, and some produce toxins to poison animals. Among them, pathogenic fungal infections, mainly exogenous fungal infections, can cause skin, subcutaneous and systemic infections. Since dermatophytes have a keratinocyte, local inflammation and lesions are caused by mechanical stimulation and metabolites after extensive local reproduction of the skin. Deeply infected fungi are phagocytosed by phagocytic cells and can be killed without causing tissue chronic granulomatous inflammation and tissue necrosis.

Conditional pathogenic fungal infections, some endogenous fungi such as Candida, Aspergillus, Mucor, etc., are not pathogenic, but only after the body's immunity is reduced or long-term use of antibiotics, hormone therapy, will cause infection. Fungal allergic diseases, some fungi can cause allergic reactions, but not pathogenic. However, when Alternaria, Aspergillus, Fusarium and the like pollute the kennel air, it may cause diseases such as contact dermatitis. Fungal poisoning, a fungus that grows in feed and causes acute or chronic poisoning after consumption by an animal. The main cause of poisoning is the toxin produced by fungi. The poisoning caused by fusarium can cause the kidney, liver, heart muscle and brain tissue of the animal to produce lesions. The aflatoxin of aflatoxin and the variegated toxin of variegated fungi can cause animals. Liver damage, citrinin of Penicillium citrinum can cause damage to the glomerulus, leading to acute or chronic kidney disease. Tumor-causing, some fungal products are closely related to the occurrence of tumors, of which aflatoxin is very toxic, and small doses have a strong carcinogenic effect.

an examination

Related inspection

Mammography X-ray examination chest CT examination

It is mainly diagnosed based on clinical symptoms and mycological examination. Mycological examinations were mainly performed with Wood's lamps: Microsporum canis, gypsum-like microspores emit greenish yellow or bright green fluorescence. Can also be examined by microscopy: scrape off the dandruff on the slide, add 10% sodium hydroxide or potassium hydroxide, slightly heated, placed under low magnification or high magnification. When a dog has a suspicious symptom of a fungal endogenous infection, it can be diagnosed by performing chest X-ray, serum complement fixation test, agar diffusion test, histopathological examination, and the like.

Differential diagnosis

(1) Exogenous diseases of fungi

The fungal exogenous disease of dogs mainly manifests as dermatophytosis or surface fungal disease, which refers to fungal diseases in which the fungus infects the epidermis and its accessory structures (hair, horn, claw). There are many types of pathogenic fungi, but the main cause of canine dermatophytosis is Microsporum canis. Specifically, about 70% is caused by canine microspores, 20% of gypsum-like microspores and 10% of Trichophyton. Most pathogenic fungi that can cause fungal skin diseases are often blocked by healthy dog skin and cannot grow normally. They simply adhere to the skin or coat and are shared with other fungi and bacteria that do not cause skin infection. Exists in the body surface. The epidermis, coat, and air together with these attached microorganisms constitute the surface microenvironment. Because microorganisms and even fungi and bacteria live in a changeable environment, they promote each other, antagonize or symbiosis. As the external environment changes, it will cause certain effects on the occurrence of fungal diseases. When the external environment changes, causing the canine body to infect the pathogenic bacteria, the fungal spores multiply in the stratum corneum of the epidermis, gradually forming a large number of hyphae in the hair follicle mouth, the hyphae extending into the hair follicle, and then entering the hair root, deep into the horny formation of the upper part of the hair bulb The area, later splitting in the hair or the hairy branches to form tight spores or segmented hyphae, causing hair lesions and skin inflammation to produce symptoms. The main clinical symptoms are papules, pustules, scales, and hair loss.

(2) Endogenous infection

Endogenous infections mainly include histoplasmosis, ball parasitic disease, blastomycosis, cryptococcosis, sporotrichosis, candidiasis and the like. Among them, histoplasmosis is a capsular histoplasm, which grows in the soil and is mainly infected by the respiratory tract. The sick dog mainly presents persistent cough and diarrhea that are not easy to cure. Affolated dogs with anorexia, weight loss, irregular fever, vomiting, dermatitis, abdominal wall palpation often found enlarged mesenteric lymph nodes. Chronic cases sometimes show ulceration of the buccal mucosa and enlargement of the tonsils. The pathogen of coccidioidomycosis is Coccidioides, which is mainly infected by the respiratory tract. The dog's lungs and bronchus or mediastinal lymph nodes develop granuloma, and the dog presents with elevated body temperature, cough, difficulty breathing, loss of appetite, weight loss and diarrhea. When the joint is invaded, it exhibits lameness and muscle atrophy. The pathogen of blastomycosis is dermatitis buds. The disease can be divided into two types: systemic type and skin type. The whole body type is mainly characterized by lung diseases, and the dog is depressed, feverish, anorexia, weight loss and cough. When the dog was dissected, the lungs had nodules and abscesses, and the lungs were grayish-white or reddish-striped with focal or diffuse hardening. Necrosis occurs in the center of the granulomatous nodule, but it is not calcified. When the lesion spreads around, the bronchial and mediastinal lymph nodes can be swollen, purulent, and even cause pleurisy. Skin-type germination is characterized by a single or multiple skin granuloma, and finally liquefaction necrosis and ulceration occur in the center.

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