A Survey on the Status of Equine Skin Tumors and Associated Epidemiological Factors in Iran

Objective: The purposes of the survey were to determine the incidence and the epidemiology of equine skin tumors in some areas of Iran. Materials and methods: The skin of 3709 urban, peri-urban and rural equids including horses, mules and donkeys in Tehran and East- Azarbaijan provinces was assessed between April 2006 and December 2008. Animals which had any cutaneous tumor or tumor-like lesions were selected. Their history and clinical findings as well as the lesion's specifications were recorded on the research sheets. Biopsies were performed on the affected animals and the samples of the cutaneous lesions were collected and fixed in 10% neutral buffered formalin for 24–72 hr. Fixed samples were dealcoholised after dehydration. Blocks were embedded in paraffin wax, sectioned at 5 mm, stained with hematoxylin and eosin and finally evaluated under a light microscope. Diagnoses of the lesions were taken on the basis of the clinical and histopathological examinations. Results: Among the assessed animals, 39 equids had tumor or tumor-like lesions. Histopathological examinations revealed 26 (66.6%) cutaneous tumors and 13 (33.4%) exuberant granulation tissues. From all of the 26 tumors, 15 (57.7%), 9 (34.6%) and 2 (7.7%) were observed in donkeys, horses and mules, respectively. the diagnosed tumors were 10 Fibromas (38.4%), 9 Sarcoids (34.8%), 3 Squamous cell carcinomas (11.5%), 3 Melanomas (11.5%) and 1 Papilloma (3.8%). Donkeys with 15 (57.7%) cutaneous tumors were the most affected animals with 8 Fibromas (53.3%), 5 Sarcoids (33.3%), 1 Squamous cell carcinoma (6.7%) and 1 Melanoma (6.7%). The tumors of 9 affected horses (34.6%) were 3 Sarcoids (33.4%), 2 Melanomas (22.2%), 2 Squamous cell carcinomas (22.2%), 1 Papilloma (11.1%) and 1 Fibroma (11.1%). In this study only 2 mules (7.7%) were observed with tumors, one of them had fibroma (50%) and the other one had sarcoid (50%). Absolute and relative frequencies of the tumor occurrences on the different areas of the body including limbs, neck - trunk, head and perineum – external genital organs were 11 (42.3%), 7 (26.9), 3 (11.5) and 5 (19.3%) respectively. the studied animals were between 1 and 15 years old ages with the mean of 8.5 years. With the increasing of the age, the incidence of the skin tumors at all, had been significantly increased also. More than 42% of the affected animals were between 10 and 15 years old and about 84% were between 5 and 15 years old. Fifteen animals were male (57.7%) and 11 were females (42.3%). The shape and form of the observed tumors varied from a simple, non ulcerative and single to ulcerative, verrucous and multiple ones. No species, breed, sex and coat color predispositions were observed. [...]