Predictive Assessment (Odds Ratio) of Relapse Presentation in Canine Leishmaniasis
*Dpto. Patología Animal-Medicina Veterinaria - Facultad de Veterinaria de León, Campus de Vegazana s/n
Few studies deal in depth with the prognostic value that certain clinical, biochemical or hematological variables may have on the relapse presentation, in dogs that have achieved clinical remission after specific therapy for canine leishmaniasis. The aim of this study is to assess the possible influence these variables (particularly antibody titre, serum protein electrophoretogram, CBCc, urea and ALT) might have on the probability of relapse presentation after remission achievement. The multiple regression analysis is capable to select and quantify the influence of those variables that may act as risk factors for relapse presentation.
48 dogs of both sexes, different breeds and ages, diagnosed with leishmaniasis by IFAT, were included in the present study. All these animals achieved clinical remission after one or more courses of treatment with meglumine antimoniate SQ (150 mg/kg/day, 10 days-10 days free-10 days) associated with allopurinol PO (10 mg/kg/12h, 45 days). After clinical remission dogs were checked-up every 3 months in order to detect a possible relapse. Relapse presentation were considered when at least two of the following events occurred: reappearance of clinical signs, protein electrophoretogram disturbances and/or increase of antibody titre. The BMDP statistical programme was used to analyze the effect of the blood parameter values obtained at diagnosis and remission. The relative probability or odds ratio (O.R.) of relapse presentation versus no relapse presentation is represented by the equation: O.R.= ea0+a1x1+a2x2+...+apxp.
Seventeen of the 48 dogs relapsed (13.9 months average), while 31 dogs remained in remission during the whole follow-up period (17.7 months average). The values at diagnosis and remission of the various variables of these dogs were considered to calculate the probability of relapse. When the moment of diagnosis alone was considered for predicting the relapse presentation, the only variable selected was the lymphocyte count (p<0.01): O.R.=Pyes/Pnot=e-2.503+0.0009xlymphocytes. When the moment of remission was considered, the lymphocyte count was once again selected (p=0.030), followed by the alfa-globulin concentration (p=0.048): O.R=Pyes/Pnot=e-4.642+0.0006xlymphocytes+3.019xalfa-glo. Considering both moments (diagnosis and remission) jointly, the multiple regression analysis selected the lymphocyte count at diagnosis (p<0.01) and the hemoglobin concentration at remission (p=0.039): O.R=Pyes/Pnot=e4.942+0.00104xlymphocytes-0.5004xHb.
A low lymphocyte count has been related to a cellular response impairment and thus to a poor post-therapeutic response. Nevertheless, this study demonstrate a highly significant direct relationship between the probability of relapse and the lymphocyte count of the patients, both at diagnosis and at remission: dogs that relapsed were those with the highest lymphocyte mean values. Further studies are needed to determine the role of the various leukocytes lines, and to characterize the population of lymphocytes present in circulating blood, not only during the course of the disease, but also throughout the post-therapeutic period.