In this report a serological survey was carried out in search for antibodies to canine distemper virus (CDV) and canine parainfluenza virus (CPIV) in 173 sera from dogs withdraw in kennels of the municipalities of Novo Hamburgo (n=82) and Porto Alegre (n=91), RS, Brazil. Neutralizing antibodies were evaluated against two CDV strains used for vaccine production (Rockborn and Snyder Hill) as well as one strain of CPIV (V660). Search for anti-CDV neutralizing antibodies revealed that 95.9% of sera were negative for antibodies to CDV Snyder Hill and 90.7% were negative for antibodies to CDV Rockborn. Among the positive sera (n=20; 11.6 %) only three of those had neutralizing antibodies to both CDV strains, indicating a low degree of cross reactivity between those. As regards CPIV, neutralizing antibodies to V660 were detected in 51.4% of sera. These findings suggest that the majority of the dogs from the populations examined in the present study had not previous contact with CDV, either by natural infection or by previous immunization. CPIV, on its turn, seem to be widespread within these populations, most likely by natural exposure to the virus.37411781181APPEL, M.J.G., ROBSON, D.S., A microneutralization test for canine distemper virus (1973) American Journal of Veterinary Research, 30, pp. 1167-1182APPEL, M.J.G., BINN, L.N., Canine infectious tracheobronchitis short review: Kennel cough (1987) Virus infections of carnivores, pp. 201-211. , APPEL, M.J.G, ed, Amsterdan: Elsevier ScienceAPPEL, M.J.G., SUMMERS, B.A., Canine distemper: Current status (1999) Recent advances in canine infectious diseases, p. 6. , CARMICHAEL, L.E, Ithaca,NY, International Veterinary Information ServiceBAUMGÄRTNER, W.K. Canine parainfluenza virus. In: OLSEN, R.G. et al. Comparative pathobiology of viral diseases. Boca Raton: CRC, 1985. V.2, p.77-83BELLINI, W.J., Matrix genes of measles virus and canine distemper virus: Cloning, nucleotide sequence, and deduced amino acid sequences (1986) Journal of General Virology, 58, pp. 408-416BLIXENKRONE-MØELLER, M., Studies on manifestations of canine distemper virus infection in an urban dog population (1993) Veterinary Microbioloy, 37, pp. 163-173COLLINS, P.L. et al. Parainfluenza Viruses. In: FIELDS, B.N. et al. Fields virology. 3.ed. Philadelphia: Lippincott- Raven, 1996. p.1205-1241DAMIÁN, M., Immunohistochemical detection of antigens of distemper, adenovirus and parainfluenza viruses in domestic dogs with pneumonia (2005) Journal of Comparative Pathology, 10, pp. 1-5EK-KOMMONEN, C., Outbreak of canine distemper in vaccinated dogs in Finland (1997) Veterinary Record, 141, pp. 380-383ERLES, K., Longitudinal study of viruses associated with canine infectious respiratory disease (2004) Journal of Clinical Microbiology, 42 (10), pp. 4524-4529FORD, R.B.VANDEN, S.L. Canine infectious tracheobronchitis. In: GREENE, C.E. Infectious diseases of the dog cat. 2.ed. Philadelphia: Saunders, 1998. p.33-38GEMMA, T., Epidemiological observations on recent outbreaks of canine distemper in Tokio area (1996) Journal of Veterinary Medical Science, 58, pp. 547-550GOUVEIA, A.M.G., Cinomose canina: Ocorrência em animais vacinados e distribuição por faixa etária (1987) Arquivo Brasileiro de Medicina Veterinária e Zootecnia, 39, pp. 539-545HEADLEY, S.A.GRAÇA, D.L. Canine distemper: epidemiological findings of 250 cases. Brazilian Journal of Veterinary Research and Animal Science, v.37, n.2, p.00-00, 2000. Acessado em 12/06/2006. On line. Available from World Wide Web: http://www.scielo.br/scielo.phpHSIUNG, G.D., Parainfluenza-5 virus. Infection of man and animals (1972) Progress in Medical Virology, 14, pp. 241-274KRAMPS, J.A., A simple, specific, and highly sensitive blocking enzyme-linked immunosorbent assay for detection of antibodies to bovine herpesvirus (1994) Journal of Clinical Microbiology, 32, pp. 2175-2181RIJSEWIJK, F., (1998), Report on the study: validation of CPI-5 challenge. Lelystad: Academic, 15p, ID-DLO report 98.014ROCKBORN, G., Further studies on viraemia and neutralizing antibodies in naturally acquired distemper in dogs (1958) Archive fur die Gesamte Virusforshung, 8, pp. 500-510STETTLER, M., Determinants of persistence in canine distemper viruses (1997) Veterinary Microbiology, 57, pp. 83-93SUMMERS, B.A., APPEL, M.J.G., Aspects of canine distemper virus and measles virus encephalomyelitis (1994) Neuropathology and Applied Neurobiology, 20, pp. 525-534TIPOLD, A., Diagnosis of inflammatory and infectious diseases of the central nervous system in dogs: A retrospective study (1995) Journal of Veterinary Internal Medcine, 9, pp. 304-314TIZARD, I., Risks associated with use of live vaccines (1990) Journal of the American Veterinary Medical Association, 196, pp. 1851-1858