A Hematologic and Electrophoretic Study in Puppies Vaccinated Against Canine Distemper Virus and Canine Parvovirus

Background: Canine distemper is a contagious multisystemic viral disease that affects canines and others carnivores. Canine parvovirus infection is one of the most important viral diseases in young dogs. Side effects of vaccine generally include fever, lethargy and local inflammation. Complementary exams are important to evaluate the strenght of immungenic stimulation. This study was aimed at evaluating hematological and electrophoretic alterations in puppies after inoculation of live attenuated vaccine against canine distemper virus and canine parvovirus. Materials, Methods & Results: Five non-breeding newborn dogs of the same litter were used. Animals received three subcutaneous injection of 1mL (at days 0, 21 and 42). Blood was collected at day 0 (day of vaccination) and for three times for each dose: at days 7, 14 and 21 (first dose); at days 28, 35 and 42 (second dose); and at days 49, 56 and 63 (third dose). Blood containing ethylenediaminetetraacetic acid as anticoagulant was used for hematological evaluation. The total serum protein were determined by the biuret method, using commercial reagent, according to fabricant instructions. Serum was used for protein fractionation by using cellulose acetate strip electrophoresis. A decrease in platelet count was observed at days 7 and 28 post-vaccination. Lymphocyte number increased 88.4%, as well as the level of the protein fractions alpha-1 globulin (68%) and alpha-2 globulin (41.4%) at day 7. Moreover, a 5-fold increase in the fibrinogem concentration and in the number of eosinophils was observed at day 14. Thereafter, the platelet count decreased by 27.3% and the number of monocytes increased 5-fold at day 28. Discussion: Mild to moderate thrombocytopenia is often observed in dogs 3-5 days post-vaccination with live attenuated vaccines, mainly those against CDV and CPV. Besides the platelet damage caused by the CDV per se, infected animals showed secondary immune-mediated thrombocytopenia and decreased platelet production due to direct viral megakaryocyte infection. The increase in alpha-1 globulin may be related to the augment in the synthesis of alpha-1 antitrypsin, the main protein of the alpha-1 globulin region, in response to the vaccine-induced acute inflammatory process. The alpha-2 globulin region includes haptoglobin, alpha-2 macroglobulin and ceruloplasmin, and the increase observed in this fraction suggested that both haptoglobin and ceruloplasmin levels were augmented, following acute inflammatory response pattern. Fibrinogen is a soluble plasma glycoprotein that is converted by thrombin into fibrin during blood clotting. Despite the increase in fibrinogen concentration be the best indicator of inflammation in large animals, the hyperfibrinogenemia observed suggests that the inflammatory process was adequate to stimulate synthesis of this acute phase protein (P < 0,05). Absence of lymphocytosis observed at days 49, 56 and 63 associated to the progressive increase of the gamma globulin fraction, although not statistically significant, suggested an augment of B lymphocytes. The eosinophilia was observed in highlighting the presence of inflammation. Moreover, an increase in monocyte count indicating the presence of subacute or chronic inflammation after the second dose of the vaccine.