Canine babesiosis is world-wide tick-borne disease characterized by erythrocyte destruction, haemolysis and inflammatory response, with increased serum concentrations of positive acute phase proteins and a decrease in negative acute phase proteins. Some of the negative acute phase proteins function as carriers of thyroid hormones, so the goal of this study was to determine the non-thyroidal illness syndrome in dogs with babesiosis. The study included 60 dogs with babesiosis and 26 healthy dogs. Serum concentrations of thyroxine, thyrotropin and transthyretin were determined using ELISA methods, while albumin concentrations were measured using spectrophotometric methods. Statistical analysis of the data demonstrated a significant decrease in thyroxine, transthyretin and albumin in dogs with babesiosis, while thyrotropin concentrations were did not differ significantly in comparison with healthy dogs. The results obtained indicate the presence of a non-thyroidal illness. Decreased albumin and transthyretin probably represent one of the mechanisms which contribute to this syndrome in canine babesiosis. Key words: dogs; babesiosis; nonthyroidal illness; transthyretin Babezioza je cesta bolest pasa. Obiljezava je razaranje eritrocita te upalni odgovor pracen porastom serumske koncentracije pozitivnih akutnofaznih proteina i padom serumske koncentracije negativnih akutnofaznih proteina. Neki od negativnih akutnofaznih proteina imaju funkciju nosaca hormona stitnjace, stoga je cilj istrazivanja bio utvrdivanje sindroma netireoidne upalne bolesti kod pasa oboljelih od babezioze. U istrazivanje je bilo ukljuceno 60 pasa kod kojih je u eritrocitima potvrdena prisutnost parazita B. canis te 26 zdravih pasa. Imunoenzimskim testom u serumu pasa izmjerene su koncentracije tiroksina, tirotropina i transtiretina, a koncentracija albumina izmjerena je spektrofotometrijskom metodom. Statistickom obradom podataka dokazano je statisticki znakovito smanjenje koncentracije tiroksina, transtiretina i albumina u serumu pasa oboljelih od babezioze, dok se koncentracija tirotropina nije znakovito razlikovala u odnosu na kontrolnu skupinu. Dobiveni rezultati upucuju na prisutnost sindroma netireoidne bolesti, pri cemu je pad koncentracije albumina i transtiretina vjerojatno jedan od mehanizama nastanka ovoga sindroma kod babezioze pasa. Kljucne rijeci: pas; babezioza; sindrom netireoidne bolesti; transtiretin