Diagnostics and Therapy in Veterinary Dermatology. Группа авторов
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Название: Diagnostics and Therapy in Veterinary Dermatology
Автор: Группа авторов
Издательство: John Wiley & Sons Limited
Жанр: Биология
isbn: 9781119680635
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Scale: loose fragments of cornified cells that accumulate on the skin surface
Hyperpigmentation: darkening of skin color
Hypopigmentation: lightening of skin color
Lesion Distribution
In addition to lesion type, distribution on the patient’s body contributes to differential diagnosis list formation. For example, pustules and crusts present on the face, ears, and limbs of a dog are suggestive of pemphigus foliaceus. Erosions, ulcerations and draining tracts in the inguinal region of an overweight cat suggest infection with rapid‐growing mycobacteria (Figure 2.7). Feline mosquito bite hypersensitivity is characterized by papules, plaques, and crusts on the bridge of the nose, pinnae, and paw pads. Perianal erythema can be a sign of food allergy (Figure 2.8).
In addition to anatomic location, lesion distribution on different colors of the coat or skin can be important. These changes are often more subtle and can take practice to recognize. In cases of solar dermatitis, affected areas of white skin will be thickened, erythematous, and even infected, while adjacent pigmented skin will be normal (Figure 2.9). In cases of black hair follicular dysplasia, diffuse alopecia and broken hairs will be seen in black‐haired areas, while white‐haired areas will be normal.
Figure 2.7 Ulcerations, draining tracts, and scarring in the inguinal region of a cat with rapid‐growing mycobacteria.
Figure 2.8 Perianal erythema in a dog with food allergy.
Recording Results
While a complete dermatologic examination is important, much of its value is in its recording. As many students are taught in veterinary school, if something isn’t documented, it didn’t happen. Too often the details of the exam don’t make their way into the medical record, which can make it difficult to reassess patients and their response to therapy. Additionally, patients frequently see multiple doctors within a practice. The more information that is provided to the next veterinarian, the better they will be able to adjust therapeutic and diagnostic plans. Details such as the percentage of stenosis of an inflamed horizontal ear canal, tail head distribution of a bacterial folliculitis, or location and size of perianal fistulae can help the next clinician, or even someone several months or years in the future.
Figure 2.9 Dog with chronic solar dermatitis. Multifocal areas of erythema and erosions with purulent exudate. The white‐skinned areas feel thickened and rough, while the black‐skinned areas palpate normally.
Much like the exam itself, there are different options for recording dermatologic findings. Many medical record systems include body map images of animals that can be marked to denote the location of different lesions. The body map can provide a quick way to assess lesion distribution and help to formulate differential diagnoses. It is also important to include a description of the different lesions, not just their location.
Another option for recording dermatologic exam findings is through written descriptions. These can be particularly helpful in complex cases with a variety of lesions. Finally, today’s electronic systems make it relatively easy to include photographs as part of the patient’s medical record. Pictures can enable a more reliable measure of improvement and can make it easier for new doctors to manage a case that has previously been treated.
3 New Diagnostic Tools and Tests for Dermatology
Amelia White
KEY POINTS
Traditional in‐house dermatologic diagnostics require the technical expertise of the technician or clinician to provide accurate results.
New laboratory diagnostic techniques can give more accurate information without the need for in‐house expertise.
New diagnostic techniques can provide quicker results, but may be more costly.
If possible use laboratories that have independent studies verifying the specificity, sensitivity, and accuracy of their tests.
The Importance of Diagnostic Investigations in Dermatology
Changes in the skin and hair coat of animals frequently signal the presence of a primary disease process. These primary conditions create inflammation and changes in the protective skin barrier function. Alteration of the normal mechanisms maintaining cutaneous microbial homeostasis permits bacteria and fungi residing here to flourish. It is important to consider these secondary infections when diagnosing and treating dermatologic conditions, especially because they complicate the diagnosis of the primary disease. Oftentimes, these secondary diseases must be treated prior to further investigation of the primary disease process. Utilization of multiple diagnostic tools in these cases is common because many dermatologic conditions, both primary and secondary, visually appear identical.
Traditional diagnostic procedures continue to provide effective and reliable methods of achieving the correct dermatologic diagnosis. These include otic and skin cytology, fine needle aspiration, skin scraping, trichography (hair plucking), diascopy (a test performed by applying pressure to the skin with a glass slide to observe for blanching), Wood's lamp examination, tissue and hair cultures, and histopathology. These diagnostics have many benefits including affordability, low technical complexity, and easy accessibility. However, results are largely dependent on technical skill, correct lesion selection, and appropriate sample size.
More recently, a transition toward more expensive, rapid, and sensitive testing methodologies using molecular diagnostics has begun. Molecular diagnostic testing uses many different techniques to study the genetic variations in biologic markers found in individual genomes and proteomes. Techniques such as polymerase chain reaction (PCR) or enzyme‐linked immunosorbent assay (ELISA) allow for the detection of microbial DNA from a small sample of skin, even if fungal and bacterial cultures from the same skin were negative.
Molecular diagnostics provide insight into how an individual organism expresses its genetic code, which can dramatically enhance our knowledge of why and how diseases occur. Comparing the genetic code alterations between diseased and normal animals provides a deeper understanding of the pathophysiology of many primary dermatologic diseases. Similarly, assessing changes within СКАЧАТЬ