Clinically, there are many causes of cat skin diseases. Skin parasitic mites, fleas, fungi or allergies, as well as other endocrine disorders and nutritional disorders, can cause some skin abnormalities such as hair loss and dermatitis. In order to clarify the cause of the disease and prescribe the right medicine, the diagnostic technology of skin diseases is very important. Diagnosis not only requires thorough understanding of all aspects of the consultation, but also requires detailed examination and laboratory methods to assist in inferring the condition.

1. Consultation

Mainly consult the owner about the cat’s performance in the early stage of the disease, what medicine has been used, how the symptoms are after taking the medicine, whether it is relieved or worsened, the cat’s living environment, whether there are carpets and mats, whether it has been in contact with other sick cats and dogs, and what kind of washing is used Hair lotion, how to use shampoo and how and how often to bathe. Is it itching, etc.?

2. General inspection

Partial observation of the skin: whether the coat is standing upright, whether it is shiny, whether it is shedding, whether the hair is bilateral, the elasticity, stretchability, thickness of the local skin, whether there is pigmentation, etc.

Lesions: location, size, shape, several or scattered, unilateral or symmetrical, condition, smooth or rough, wet or dry, hardness and color, etc. ​​​​​​

3. Laboratory technology

Hair collection: pluck hairs and place them on clean transparent tape and stick them on a glass slide or drop paraffin oil and place them under a coverslip. Check for signs of breakage or damage to the tips, and for sudden, stiff or frayed ends instead of the normal tapering tips. These lesions indicate gnawing or excessive licking by animals, and diseased hair shafts also occur in dermatophytosis. Examine the hair roots to assess whether the hair is in the anagen phase (ball-shaped roots) or the telogen phase (barb-shaped or damaged rod-shaped roots). The number of anagen and telogen hairs can estimate the number of primary and secondary hairs present. Abnormalities in hair structure are found in cases of congenital coat defects, dysplasia, and genetic defects. Blackheads and follicular casts may also be detected, which means that the extracted hair roots are wrapped.

The hair-plucking test can detect Demodex mites, especially on the toes and the skin around the eyes. The detection rate of the hair-plucking test is higher than that of scraping. When a ringworm infection is suspected at the same time, hair plucking can also be done for microscopic examination and fungal culture.

Transparent tape method: It is very practical to use transparent tape to sample the skin surface. After sampling, stick it on a glass slide for microscopic examination of ectoparasites and eggs. This method is ideal for areas of small mammals that are difficult to scrape sample. Samples from the shaved skin surface can also be stained (Diff-Quick or Gram) for microscopic examination to look for microorganisms such as Malassezia.

Smear of hair follicle extrusions: This is a very effective method of collecting Demodex mites from hair follicles. Squeeze the skin and spread the extrudate on a clean glass slide for staining and microscopic examination. It is also possible to collect the extrudate into a scalpelon, and then transfer to a glass slide. Without staining, drop a little mineral oil (or liquid paraffin) and cover with a coverslip.

Smear of ear wax or ear secretions: Debris from the external auditory canal is usually collected with a cotton swab and smeared onto a glass slide. Ear mites and their eggs can be detected through microscopic observation. Moisten the swab with liquid paraffin to help the secretions adhere to it. You can also drop it on the slide to separate the sample from the swab, and then cover it with a coverslip.

Skin scrapings: Skin scrapings are mainly used to diagnose Demodex (deep scraping) and scabies (large-scale shallow scraping). In cases of Demodex, samples should be taken from the blackheads. For scabies cases, the main lesions and areas without ulcers should be taken. Sampling from multiple locations is necessary. Papules or scabs at the edge of the lesion are the best sites for sampling. Cut off the coat and use a blunt scalpel to collect the sample.

Ringworm: If ringworm is suspected, we should take samples from the edge of a newer lesion, including hair plucking and skin scraping. The ringworm element is best found in potassium hydroxide solutions; in paraffin oil the hair becomes opaque and loses structure due to fungal infection. Mycelium can be found in broken hair shafts and in scales. The spores may be within the hair (Entratrichophyton spores) or more often in the hair shaft (Extrichia trichophyton spores). By placing a drop of blue-black ink or lactophenol cotton blue on a glass slide, the structure of the ringworm can be seen more clearly.