Causes and Diagnosis of Common Dog Skin Diseases

Causes and Diagnosis of Common Dog Skin Diseases

1. Overview of canine skin diseases

Canine skin diseases occur in various time periods, and there are many types and causes. Compared with other types of diseases such as infectious diseases, skin diseases have a higher incidence and are one of the more common diseases. However, because skin diseases have little impact on dogs themselves

2. The cause of the disease

There are many etiologies of canine skin diseases, including non-pathogenic and pathogenic factors.

2.1 Pathogenic factors

The parasitic skin diseases among the pathogenic factors are roughly divided into lice, mites, fleas, etc. The mites are caused by parasitic mites in the hair follicles and sebaceous glands of dogs and cats in the stratum corneum of the cortex.

2.2 Non-pathogenic factors

Non-pathogenic factors include skin diseases such as seborrheic dermatitis caused by genetic factors caused by different dog breeds; lack of trace elements caused by insufficient nutrition in dog food; poor self-sanitation of dogs or long-term dark and humid conditions.

3. Symptoms and Diagnosis

3.1 Clinical symptoms

3.1.1 Fungal skin diseases

The main symptoms of fungal skin diseases are increased dandruff, the formation of large and small irregular hair loss areas locally or on the whole body, and occasional severe itching, etc.

3.1.2 Bacterial skin diseases

Bacterial skin diseases are generally accompanied by pyoderma, which is characterized by inflammatory exudation under the skin [3], the surface of the lesions is shed, and the exudation forms crusts on the surface.

3.1.3 Parasitic skin diseases

Parasitic skin diseases are characterized by hair loss, itching, and scratching and biting in sick dogs. Parasites such as Demodex can also cause scabs and pyoderma.

3.1.4 Seborrheic skin disease

Dogs with seborrheic dermatosis will emit a strong oily smell, incomplete skin keratinization, and many white bran-like dander or tawny oil-like dander between the hairs [4].

3.2 Diagnostic methods

3.2.1 Diagnosis of fungal skin diseases

For fungal skin diseases, local or whole body hair loss areas and a large number of dandruff can be found in the clinical examination, and then the Wood's lamp is used to examine in the dark, and the fungal infection can be determined by the fluorescence reaction displayed.

3.2.2 Diagnosis of parasitic skin diseases

Parasitic skin diseases can be obtained by scraping the affected area of ​​the dog until there is slight oozing of blood. The scraped dog skin tissue and hair can be examined by microscopy. If the microscopic examination shows adult mites or larvae or egg feces, the diagnosis can be made.

3.2.3 Diagnosis of bacterial skin diseases

Bacterial skin diseases need to observe the diseased part of the dog, and judge by its manifestations such as papules, pustules, etc.

3.2.4 Diagnosis of seborrheic skin disease

Usually, dogs with seborrhea have a special smell, and the seborrheic characteristics are obvious in the coat skin, and the greasy feeling is heavy.

For the skin disease investigation in Wuxi Anmei Pet Hospital, about 50 cases of dogs were investigated successively. First, the pets were clinically examined for canine skin disease. After finding that the examination could not fully reflect the real cause, fluorescence reaction and skin scraping microscopy were carried out.

Table 1 Investigation and analysis results of infection rate and infection types of canine skin diseases

Canine skin disease types

Number of dogs (only)

Infection rate (%)

Fungal skin disease



Bacterial skin diseases



Parasitic Skin Disease






4. Investigation and analysis of the causes of canine skin diseases

I have diagnosed many cases of skin diseases and found that there are many reasons for canine skin diseases, which are mainly divided into the following reasons: fungal skin diseases caused by spores; bacterial skin diseases caused by Staphylococcus aureus;

During the internship in the pet hospital, the skin disease examination of dogs generally includes ultraviolet fluorescence reaction, skin scraping sampling examination, etc.

Table 2 Types of canine skin diseases and the results of investigation and analysis

Types of canine skin diseases (number of dogs)


Contact with sick dogs (only)

Grass Infection (only)

Lots of meat (only)

Other (only)

Fungal skin diseases (11)





Bacterial skin diseases (4)





Parasitic skin diseases (7)





Seborrhea (3)





4.1 Types and disease characteristics

4.1.1 Fungal skin diseases

At the time of the onset, the dog's coat fell off, forming obvious ringworm spots, small red spots on the surface, severe itching, and the sick dog kept scratching until the skin oozing, as shown in Figure 2.3.1

4.1.2 Bacterial skin diseases

Bacterial skin disease manifests skin swelling, swelling, crusting and hardening; parasitic skin disease, milder hair loss, severe skin papules, skin and tissue nodules, and pustules

4.1.3 Parasitic skin diseases

During the onset of parasitic skin disease, the hair on the lesion will fall off, the skin will appear keratinized, and the dandruff will increase as shown in Figure 2.3.3.

4.1.4 Seborrheic skin disease

Seborrheic skin disease has a special smell, the smell of oil is very serious, and the texture of the coat is also relatively greasy.

Figure 2.3.5, Figure 2.3.6

Figure 2.3,1 Fungal skin disease

Causes and Diagnosis of Common Dog Skin Diseases

Fig. 2.3,2 Parasitic skin diseases

Figure 2.3,3 Demodex

Figure 2.3,4 Demodex

Fig. 2.3,5 Seborrhea

Fig. 2.3,6 Seborrhea

5. Summary

Generally speaking, the main skin diseases of dogs are roughly divided into four categories, parasitic skin diseases, seborrheic skin diseases, bacterial skin diseases, and fungal skin diseases.