{"id":23164,"date":"2021-04-09T13:14:45","date_gmt":"2021-04-09T13:14:45","guid":{"rendered":"https:\/\/todaysveterinarypractice.com\/?p=23164"},"modified":"2022-04-29T14:20:51","modified_gmt":"2022-04-29T14:20:51","slug":"diagnostic-approach-to-the-pruritic-dog","status":"publish","type":"post","link":"https:\/\/navc.sitepreview.app\/todaysveterinarypractice.com\/dermatology\/diagnostic-approach-to-the-pruritic-dog\/","title":{"rendered":"Diagnostic Approach to the Pruritic Dog"},"content":{"rendered":"

Pruritus is one of the most common reasons why clients bring their dog to the veterinarian. Sometimes the cause of the pruritus is obvious (e.g., the dog is covered with fleas), and sometimes it is not so simple. The patient\u2019s primary condition may be exacerbated by secondary infections or development of (new) allergic skin diseases. If necessary, the veterinarian must be ready to \u201cpeel back\u201d diagnostic layers to get to the underlying cause\u2014or causes. This article provides a logical approach to the workup of the pruritic dog.<\/span><\/p>\n

Major Categories of Conditions Responsible for Pruritus<\/h2>\n

Although there are definitely exceptions, most conditions responsible for pruritus in the dog fall into 3 broad categories: infection, infestation\/ectoparasitism, and allergy (<\/span>TABLES 1-3<\/span><\/strong>).1-9<\/sup> Frequently, conditions in more than 1 category are present simultaneously (e.g., the patient with atopic dermatitis may also have fleas and a secondary yeast infection). Furthermore, the sensation of pruritus can be considered to be an additive phenomenon in which each condition builds on the discomfort generated by the other(s).<\/span><\/p>\n

Infection<\/h3>\n

The most common infectious conditions that can be associated with pruritus in the dog are staphylococcal pyoderma and yeast dermatitis (typically Malassezia<\/i>, although Candida<\/i> may also be seen, albeit rarely).9<\/sup> Dermatophytosis may also be associated with pruritus, although less commonly than bacterial and yeast disorders.9<\/sup> With the exception of dermatophytosis, infection is generally a secondary cause of pruritus.10<\/sup> However, any microbial overgrowth or invasion can trigger production of a nonspecific inflammatory response in the skin by activating and recruiting inflammatory cells, which subsequently release inflammatory and pruritogenic substances. Together, these events induce or enhance the sensation of pruritus.11<\/sup> <\/span>TABLE 1<\/span><\/strong> describes the most common infectious causes of pruritus and their distributions.<\/span><\/p>\n

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Figure 1. Brown discoloration on the claw of a dog with yeast pododermatitis.<\/p><\/div>\n

Infestation\/Ectoparasitism<\/h3>\n

Parasites typically associated with the development or perpetuation of pruritus in the dog can be classified into those infesting the skin surface, the superficial aspect of the skin (e.g., the stratum corneum and epidermis), or the deep portions of the skin (especially the follicles).6\u00a0<\/span><\/sup><\/span><\/p>\n