{"id":8792,"date":"2022-01-28T18:36:36","date_gmt":"2022-01-28T18:36:36","guid":{"rendered":"https:\/\/tvn.tv-multi-theme.com.216-70-96-51.jvv2-rfnp.accessdomain.com\/?p=8792"},"modified":"2022-05-13T20:27:57","modified_gmt":"2022-05-13T20:27:57","slug":"pyoderma-in-the-dog","status":"publish","type":"post","link":"https:\/\/navc.sitepreview.app\/todaysveterinarynurse.com\/dermatology\/pyoderma-in-the-dog\/","title":{"rendered":"Pyoderma in the Dog"},"content":{"rendered":"

P<\/span>yoderma literally translates to \u201cpus in the skin\u201d and is the term used for bacterial infections, even when no pus is seen. The most common form of pyoderma in dogs is superficial bacterial folliculitis, which is also the primary reason for systemic antimicrobial use in small animal practice.1,2<\/sup> Although most staphylococcal bacteria are part of the normal flora of a dog\u2019s skin, several more aggressive (coagulase-positive) staphylococci are frequently associated with cutaneous disease. Most cases of superficial bacterial folliculitis are caused by Staphylococcus pseudintermedius<\/i>,3<\/sup> followed less frequently by Staphylococcus aureus<\/i> and Staphylococcus schleiferi.<\/i>4,5<\/sup><\/p>\n

Types of Pyoderma<\/h2>\n

Pyoderma can be classified as 1 of 3 types: surface, superficial, and deep (<\/b><\/span>FIGURE 1<\/span><\/strong>). Classification is important because it drives treatment choices. Each type of pyoderma can be primary or secondary. Patients with primary pyoderma have otherwise healthy skin, and specific antibacterial therapy is curative. Patients with secondary pyoderma have compromised skin, and treatment must also deal with the underlying, predisposing condition(s). <\/span><\/p>\n

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Figure 1. Illustrations of types of canine pyoderma.<\/p><\/div>\n

Surface Pyoderma<\/h3>\n

As the name suggests, surface pyoderma affects only the epidermis, specifically the layers between follicles. Surface pyoderma includes acute moist dermatitis (hot spots), skin-fold pyoderma (intertrigo), and microbial overgrowth.<\/span><\/p>\n

Acute moist dermatitis is largely self-inflicted as a result of an underlying pruritic problem (e.g., flea allergy, anal sac irritation, otitis, foreign body, arthritis). Clipping will often reveal a larger affected area with lesions ranging from erythematous papules to erosions and ulcers. Acute moist dermatitis is not considered a \u201creal infection\u201d unless self trauma has caused a deeper infection. <\/span><\/p>\n

Skin-fold pyoderma results from disruption of the outermost stratum corneum, caused by friction of skin against skin (<\/span>FIGURE 2<\/span><\/strong>). Irritation causes inflammation, which leads to increased heat and moisture, thereby providing the ideal environment for overgrowth of bacteria and\/or yeast. Cytology will typically yield elevated numbers of staphylococci and\/or yeast with few or no inflammatory cells. Microorganisms in the absence of inflammatory cells can indicate overgrowth of natural flora or an immune deficiency resulting in lack of an inflammatory response to infection. <\/span><\/p>\n

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Figure 2. Interdigital erythema\/pododermatitis. Courtesy Anthony Yu, V.A.D.E.R Clinic.<\/p><\/div>\n

Superficial Pyoderma<\/span><\/h3>\n

Superficial pyoderma involves the epidermis and\/or hair follicles. Types of superficial pyoderma include impetigo (puppy pyoderma), folliculitis, superficial spreading pyoderma, and mucocutaneous pyoderma. <\/span><\/p>\n

Impetigo is seen in prepubescent dogs. Nonfollicular pustules are often found in the axillae and inguinal region, and pruritus is uncommon. Impetigo is rare in adults and is usually secondary to an underlying condition (e.g., hyperadrenocorticism<\/a>, diabetes mellitus<\/a>, hypothyroidism<\/a>).6<\/sup> <\/span><\/p>\n

Folliculitis <\/b>is common in dogs and is often secondary to underlying allergies (<\/span>FIGURE 3<\/span><\/strong>). Folliculitis is also called \u201cshort-haired dog pyoderma\u201d and produces a moth-eaten appearance of the coat (<\/span>FIGURE 4<\/span><\/strong>). Folliculitis can be concurrent with superficial spreading pyoderma, appearing as papules, pustules, and epidermal collarettes. Plugged follicles (increased keratosis of hair follicles), also called comedones, can also lead to infection and are often seen secondary to long-term use of corticosteroids as well as with other conditions that compromise hair follicles (<\/span>FIGURE 5<\/span><\/strong>). <\/span><\/p>\n

\"FigureFigure 3. Pyoderma in an atopic dog. Courtesy Anthony Yu, V.A.D.E.R Clinic.<\/span><\/a><\/div>
\"FigureFigure 4. Moth-eaten appearance of coat. Courtesy Anthony Yu, V.A.D.E.R Clinic.<\/span><\/a><\/div>
\"FigureFigure 5. Epidermal collarettes (white arrows). Hyperpigmentation at the center with a torn circular edge gives the look of a \u201ctarget lesion.\u201d Note the cutaneous atrophy and comedones (black arrows) resulting from chronic corticosteroid administration to manage allergic symptoms. Courtesy Anthony Yu, V.A.D.E.R Clinic.<\/span><\/a><\/div>
<\/div><\/div>\n

Mucocutaneous pyoderma often affects the lips but can also affect other mucocutaneous junctions (<\/span>FIGURES 6 AND 7<\/span><\/strong>). Lesions include erythema, crusts, erosions, and ulcers. Should lesions be refractory to systemic antibiotics, biopsy samples should be collected to look for immune-mediated skin disease.<\/span><\/p>\n

\"FigureFigure 6. Periocular mucocutaneous pyoderma. Courtesy Anthony Yu, V.A.D.E.R Clinic.<\/span><\/a><\/div>
\"FigureFigure 7. Mucocutaneous pyoderma of lip fold. Courtesy Anthony Yu, V.A.D.E.R Clinic.<\/span><\/a><\/div>
<\/div><\/div>\n

Deep Pyoderma<\/span><\/h3>\n

Deep pyoderma is an infection that has penetrated down into the dermis and is accompanied by localized folliculitis and furunculosis, generalized deep folliculitis and furunculosis\/cellulitis, bacterial pseudomycetoma (i.e., botryomycosis), and acral lick dermatitis. Furunculosis involves ruptured <\/b>hair follicles that allow bacteria and keratin into surrounding tissues. Keratinous debris will cause a foreign body reaction, resulting in furuncles (boils) and then draining tracts. Exudate from deep pyoderma can contain small granules with microorganisms that are diagnostic for botryomycosis.<\/span><\/p>\n

Localized Deep Pyoderma<\/strong><\/p>\n

Deep pyoderma can be localized, often to the chin, muzzle, paws, and\/or pressure points. Folliculitis and furunculosis on the chin and muzzle are most common in adolescent dogs and are usually transient but sometimes persist, especially in Doberman pinschers, boxers, bulldogs, Great Danes, mastiffs, Weimaraners, and German shorthaired pointers.6<\/sup> Deep pyoderma can also progress to cellulitis. <\/span><\/p>\n

Callus or pressure point pyoderma affects contact areas such as elbows, hocks, stifles, and digits, most commonly in large breed dogs (<\/span>FIGURES 8 AND 9<\/span><\/strong>). Crusting or matting of hairs can mask ulceration and draining tracts. Underlying conditions that can contribute include inadequate bedding, poor circulation, and endocrine disease. <\/span><\/p>\n

\"FigureFigure 8. Deep pyoderma of elbow callus. Courtesy Anthony Yu, V.A.D.E.R Clinic.<\/span><\/a><\/div>
\"FigureFigure 9. Deep pyoderma at a pressure point over the hip of a German shepherd. Courtesy Anthony Yu, V.A.D.E.R Clinic<\/span><\/a><\/div>
<\/div><\/div>\n

Acral lick dermatitis is the result of tissue maceration from continual licking, often on the cranial aspect of a distal limb (<\/span>FIGURE 10<\/span><\/strong>). The erythematous plaque that forms is continually impregnated with oral microorganisms and progresses to a granuloma. Causes can be organic (e.g., ruptured hair follicles or foreign body reaction) or psychogenic. Always search for an underlying cause, including arthritis, before concluding that the problem is psychogenic. <\/span><\/p>\n

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Figure 10. Deep pyoderma of lick granuloma. Courtesy Anthony Yu, V.A.D.E.R Clinic<\/p><\/div>\n

Interdigital pyoderma can also lead to folliculitis and furunculosis (<\/span>FIGURE 11<\/span><\/strong>). Feet may be swollen with purulent discharge, along with paronychia, causing an abnormal gait, which can cause other hairs to be driven into the skin, fostering even more foreign body reactions. Underlying factors that can lead to severe pododermatitis and interdigital pyoderma include demodicosis, trauma from gait abnormalities, allergies (including contact reactions), dermatophytosis<\/a>, autoimmune diseases, endocrinopathy, immunodeficiencies, zinc-responsive dermatosis, and superficial necrolytic dermatitis (hepatocutaneous syndrome, necrolytic migratory erythema, metabolic epidermal necrosis).6<\/sup><\/span><\/p>\n

\"FigureFigure 11. Keratin causing a foreign body reaction, resulting in interdigital cysts. Courtesy Anthony Yu, V.A.D.E.R Clinic<\/span><\/a><\/div>
\"FigureFigure 11. Keratin causing a foreign body reaction, resulting in interdigital cysts. Courtesy Anthony Yu, V.A.D.E.R Clinic<\/span><\/a><\/div>
\"FigureFigure 11. Keratin causing a foreign body reaction, resulting in interdigital cysts. Courtesy Anthony Yu, V.A.D.E.R Clinic<\/span><\/a><\/div>
<\/div><\/div>\n

Generalized Deep Pyoderma<\/strong><\/p>\n

Generalized deep pyoderma causes furunculosis, nodules, and draining tracts that can affect much of the body. Patients may initially respond to treatment but later experience recurrence. There may be some genetic predisposition to deep pyoderma since German shepherds are overrepresented.6<\/sup> However, in the author\u2019s experience, this predisposition was more frequent years ago than it is today, perhaps reflecting a benefit of selective breeding. Other possible underlying conditions include allergies, endocrinopathies, demodicosis, ehrlichiosis, and immunodeficiencies. <\/span><\/p>\n

Diagnosis of Pyoderma<\/h2>\n

The diagnostic approach to pyoderma includes taking a thorough history, examining the skin for lesions and distribution patterns, and performing diagnostic testing consisting at a minimum of cytology. <\/span><\/p>\n

For patients with recurrent canine pyoderma, always look for the underlying cause(s). Factors that predispose a dog to pyoderma are numerous; therefore, unless the underlying cause is addressed<\/span>,<\/span> secondary pyodermas will continue to occur.6,7<\/sup> Predisposing factors to recurrence include the following:<\/span><\/p>\n