EPIDEMIOLOGIC ASPECTS OF CATTLE DIGITAL DERMATITIS IN TWO DAIRY FARMS IN THE STATE OF GOIAS STATE, BRAZIL

Abstract

From November of 2000 until October 2003 some epidemiologic aspects related to digital dermatitis were evaluated in 7,752 cattle, from two farms in the cities of Jataí and Orizona, Goiás state, in both the wet and dry seasons of the year. Management, age, sex and reproductive status were considered as intrinsic variables of the farm. On the other hand, the introduction of animals without podal examination, cattle transiting on foot or in trucks, access of strangers to the farm, the presence of digital dermatitis bearers in the surrounding properties, and daily visiting of milk transport trucks were considered extrinsic factors to the property. The chi-square test (?2), at 5% of significance, was used to compare the frequency of the condition between age ranges. The comparison between wet and dry seasons of the year associated to intensive and extensive managements was done by diagnosing the condition in the periods and considering the management, and then calculating the association coefficient (j) to quantify the intensity of the variables considered. The odds ratio (OR) was calculated for the two variables: season of the year and management system. The Spearman coefficient was used to correlate the many associated factors for the disease. Digital dermatitis was diagnosed on 161 (3.85%) animals from farm A (Jataí), and in 95 (2.66%) animals from farm B (Orizona). There was a difference (p<0.01) on the occurring of the condition among the ages considered, with lower association in farm A (p<0.001) (j=0.13) and moderate association (j=0.41) in farm B. No matter the age ranges, the greater occurrence was diagnosed in the dry season, when the animals were confined. This points to a relative influence from the season in the development of the condition, mainly in farm B, where there was an association (j=0.07). Rainfall and the introduction of new animals in the farm did not correlate positively with the disease. Intensive management presented a greater number of cases compared to extensive management, and the greatest occurrence happened in the three-to-six-year-old group. Recently calved cows presented a greater amount of lesions, and most of cases inspite of age happened on the dry season of the year. 
KEY WORDS: Associated factors, bovine, hoof, podal lesion.