The skin is the largest organ of the body that has many functions. Canine dermatology remain a challenging field that requires a variety of knowledge as dermatological problems are reported to be the most common health problem in small animal practice. Blood, skin and biopsy samples were collected from 50 dogs of different breeds and sexes. The present study is designed for identification of the different etiological agents causing skin diseases in dogs, evaluation of some hematological and biochemical parameters in diseased dogs and histopathological examination of selected cases using skin biopsy. These dogs were grouped into two groups, the first one was the control group (n=10) apparently healthy dogs and the second group (n=40) diseased dogs presented with different skin ailments where 12 out of 40 dogs were suffered from demodicosis, dermatophytosis (6 cases), pyoderma (8 cases) , mixed infection (10 cases) and canine atopic dermatitis (4 cases). Evaluation of the hematological parameters revealed presence of anemia and leukocytosis with apparent neutrophilia in dogs with pyoderma and eosinophilia in the other groups. Biochemical parameters lied within the reference range in all diseased groups. Staphylococcus spp. was the most common bacterial isolate in canine pyoderma. With respect to histopathological picture, results indicated presence of large focal area of epidermal liquefactive necrosis associated with dense neutrophils infiltration. Severe dermatitis, folliculitis, perifollicular and perivascular inflammatory cells infiltration, all these changes associated with cases of pyoderma. Demodicosis cases demonstrated as heavy mite infestation in different developmental stages in the stratum conium of the epidermis and in the follicles. Laminar orthokeratotic hyperkeratosis, vacuolated epidermal prickle cells, acanthosis and vaculation of keratinocytes of the infundibula. Dermatitis characterized by moderate to marked inflammatory infiltration. Necrosis of adnexa, folliculitis and perifollicultis were also recorded in demodecosis infected dogs. Fungal dermatosis showed pronounced laminar orthokeratotic hyperkeratosis and acanthosis. Vacuolar degeneration of keratinocytes and fungal Hyphae were seen in dermatophytosis infected dog. Ulcerative dermatitis in form of focal extensive area of epidermal necrosis and ulceration associated with inflammatory cells infiltration, acanthosis and spongiosis of prickle cell layer were noticed in mixed infection infected dogs. The most common infectious skin problems during our study were pyoderma, red mange and dermatophytosis. The predominant pathogen in pyoderma affected dogs was Staphylococcus spp. Histopathological examination was very useful in our study as they provide accurate diagnosis in a short period of time and help in clear visualization of the clinical picture.