Deramatology

Question 1

What is a skin culture?

Answer 1

The inoculation of suitable media with material from the skin.

Question 2

What is the purpose of a skin culture?

Answer 2

1. To identify bacterial and fungal pathogens of the skin.

2. To determine the antibiotic sensitivity of bacterial skin pathogens.

Question 3

What equipment do you need for a skin culture?

Answer 3

• Cotton
• Culture Media
• Sterile 22-gauge needle or scalpel blade (for bacterial culture).
• Scalpel blad or hemostatic forceps (for fungal culture).
• 70% alcohol (for bacterial culture)

Question 4

Skin culture restraint & positioning?

Answer 4

An assistant restrains the animal in a position that affords access to the skin lesion(s).

Question 5

Bacterial Culture of a Skin Pustule

Procedure

Answer 5

1. Clip hair in square-inch area around pustule.
   * clipping must be done carefully to avoid rupturing the pustule.
2. Cleanse clipped area gently with cotton moistened with 70% alcohol.
   * Disinfection of the pustule w/70% alcohol removes surface contaminants that might invalidate the culture results.
3. Let skin air dry.
   * Do NOT collect material while skin is still moist because excess alcohol may be transferred to the swab.
4. Insert tip of swab into pustule after puncturing it w/sterile 22-gauge needle or after incising the pustule with point of no. 11 scalpel blade.
5. Inoculate material into suitable bacterial culture media.
   * The culture media can be inoculated directly, or the swab can be placed in transport medium.
6. Cleanse open pustule w/70% alcohol.

Question 6

Culture for Dermatophytes

Procedure

Answer 6

1. Cleanse edge of lesion w/cotton moistened w/water.
   * gentle cleansing w/water removes superficial debris but will not interfere with fungal culture.
2. Using scalpel blade or hemostat, scrape or pluck several hairs from edge of lesion.
   * Recovery of dermatophytes is most successful if visibly disease hairs from the edge of the lesion are cultured.
3. Inoculate dermatophyte culture medium w/hairs by forcing hairs below surface of medium.
   * Forcing of hairs below the surface of the medium ensures contact of dermatophytes on the hair w/culture medium.
4. Place cover on culture medium but do not close tightly.
   * Fungal growth may be enhanced by placing the medium in the dark.
5. Incubate at room temp & check daily for growth.
   * Dermatophyte organisms will cause a color change in DTM when minimal growth is visible.

Question 7

What is skin scraping?

Answer 7

A diagnostic procedure involving intention abrasion of a kin lesion with a scalpel blade.

Question 8

What is the purpose of a skin scraping?

Answer 8

To detect the presence of microscopic skin parasites.

Question 9

What is the possible complication of a skin scraping?

Answer 9

Minor hemorrhage.

Question 10

What equipment is needed for a skin scraping?

Answer 10

• Scalpel blade.
• Glass slides.
• Mineral oil or potassium hydroxide.

Question 11

Skin scraping restraint and positioning?

Answer 11

An assistant restrains the animal in a position that affords access to the skin lesions(s).

Question 12

Skin Scraping

Procedure

Answer 12

1. Place one drop of mineral oil on each of several glass slides.
2. Insert edge of scalpel blade into mineral oil on glass slide.
   * Moistening the scalpel blade w/mineral oil provides a sticky surface for collecting mites and ova during the scraping.
3. Select lesion(s) to be scraped, avoiding areas of severe…….
   * If sarcoptic mange is suspected, lesions on the ears, elbow, and…….
4. Pinch fold of skin & scrape surface until drops of capillary blood appear.
   * Pinching the skin helps to move the demodectic mites out of the deeper parts of the hair follicles. The normally deep location of demodectic mites w/in the skin necessitates scraping to the level of capillaries.
5. Transfer hair & epithelial debris collected from skin scraping into drop of mineral oil on glass slide by swirling or scraping material on slide edge.
   * Several scrapings should be made and the site of the scraping indicated on each glass slide. As many as 20 scrapings may be necessary to obtain sarcoptic mites.
6. Examine immediately.
   * If potassium hydroxide is used, waiting several minutes may result ins some clearing of the prepared specimens.
7. Note results of skin scrapings in animal’s medical record.
   * Note date, scraping sites, number of live and dead mites, larvae, and ova at each site. This is especially important in following the progress of animals being treated w/parasiticides.

Question 13

What is cellophane tape preparation?

Answer 13

It is used to collect material from the surface of the skin and hair coat.

Question 14

What is the purpose of the cellophane tape preparation?

Answer 14

To detect the presence of certain skin parasites, including flea larvae, lice, and mites.

Question 15

What equipment is need for the cellophane tape technique?

Answer 15

• Clear cellophane tape.
• Glass slides.
• Mineral oil.

Question 16

Cellophane tape technique restraint and positioning?

Answer 16

The animal is restrained in sternal recumbency or in a sitting or standing position.

Question 17

Cellophane Tape Technique

Procedure

Answer 17

1. Select site for sampling.
   * Choose an area in which seborrhea or black debris is present, usually along the dorsal midline.
2. Tear off a 1” to 2” piece of cellophane tape, attach one end to a glass slide, and double it back onto the slide so that the sticky side does not contact slide.
3. Part hair & touch sticky side of clear cellophane tape to hair and skin.
   * loose particles will adhere to the tape. The attached slide add rigidity to the tape and may improve collection of parasites.
4. Place a drop of mineral oil on glass slide and flip tape so that sticky side w/collected debris attaches to the slide and covers the oil.
5. Examine under microscope & note findings in animal’s medical record.
   * Note date, sampling site, number, and identity of parasitic organisms collected.

Question 18

Pruritus

Answer 18

Localized itching.

Question 19

Alopecia

Answer 19

Loss of hair.

Question 20

Erythema

Answer 20

Abnormal redness of skin.

Question 21

Dermatitis

Answer 21

Inflammation of the skin.

Question 22

Pediculosis

Answer 22

Infestation with lice.