Parvoviruses are single-stranded DNA viruses which are ubiquitous in nature and infect most animals among the order Carnivora. CPV particles measure 26 nm in diameter and consist of an icosahedral capsid that packages the ∼5-kb single-stranded DNA genome. CPV exploits the transferrin receptor type-1 genes that project from the 3-fold axes of capsid symmetry, and cells internalize the receptor-bound capsids by clathrin-dependent endocytosis. Capsids then penetrate endosomal compartments and deliver the viral genome to the nucleus to initiate replication.
After its re-emergence in the late 1970s (likely resulted from the re-adaptation of a parvovirus to the resistant receptor of multiple wild carnivore hosts), CPV-2 underwent a rapid re-evolution (mutation) which was clearly a variant of feline panleukopenia virus.
Within few years, new antigenic types termed CPV-2a and CPV-2b, completely replaced the original CPV-2. In 2001, an antigenic variant was reported in Italy. That variant has an amino acid substitution, Asp-426 → Glu, which occurs in a residue of the capsid protein that is considered important for the antigenic properties of CPV-2.
This variant (CPV-2/Glu-426 mutant), currently named as CPV-2c, has resulted in epizootic outbreaks across Italy, Spain, United Kingdom, and recently in Portugal, India, Brazil, France and Belgium.
The virus, which is very stable in the environment, is able to withstand wide pH ranges and high temperatures, has an incubation period of 3 - 8 days.
Transmission is by direct contact with infected dogs or contaminated feces (up to 3 weeks). Carrier dogs (and cats) which have recovered from acute parvoviral infections may also transmit infection periodically.
A breed predisposition has been reported in the Rottweiler, American Pit Bull Terrier, Doberman Pinscher and German Shepherd, with greater mortalities noted in non-vaccinated pure-bred dogs during summer months.
After ingestion, the virus replicates in lymphoid tissue of the oropharynx; from there, it spreads to the bloodstream. It attacks rapidly dividing cells throughout the body, especially those in the bone marrow, lymphopoietic tissue, and the crypt epithelium of the jejunum and ileum. Early lymphatic infection is accompanied by lymphopenia and precedes intestinal infection and GI signs. Replication in the bone marrow and lymphopoietic tissue causes neutropenia and lymphopenia, respectively. By 3 days after infection, rapidly dividing intestinal crypt cells are infected. Leucoencephalopathy has been reported rarely in dogs following parvovirus infection.
Viral shedding in the feces begins 3 - 4 days after infection and peaks when clinical signs appear. Viral shedding decreases rapidly and may no longer be detected 10 - 14 days after initial infection. Replication of the virus in the crypt epithelium of the gut causes collapse of intestinal villi, epithelial necrosis, and hemorrhagic diarrhea. Normal enteric bacteria, eg, Clostridium perfringens and Escherichia coli enter the denuded mucosa and may gain entry to the bloodstream, resulting in bacteremia.
Clinically affected dogs present with signs of gastroenteritis, including vomiting and a characteristic malodorous diarrhea, often 3 - 4 days after initiation of viral shedding in the feces.
Symptoms can be exacerbated by concurrent infections with Salmonella spp, Clostridium perfringens, Escherichia coli, Campylobacter spp, canine distemper virus and enteric parasites. Clinical disease is exacerbated by secondary infections, underlying stressors and environmental factors such as overcrowding.
The occurrence of myocarditis, once prevalent in puppies is now considered rare following the introduction of aggressive vaccination protocols of pregnant bitches.
Most dogs recover within a few days with appropriate supportive care; others can die within hours of the onset of clinical signs. A common complication is pulmonary edema or alveolitis.
Blood tests may reveal leucopenia, lymphopenia and thrombocytopenia, which in recovering dogs, usually begins to rise 24 - 48 hours post-treatment and in non-recovering dogs is usually depressed due to development of systemic inflammatory response syndrome.
Elevated blood levels of cardiac troponin-1, cortisol, creatine kinase, lactate dehydrogenase, AST, C-reactive protein, ceruloplasmin and haptoglobinare are associated with a poorer prognosis. A non-responsive lymphopenia and reduced thyroxine and cholesterol are also associated with a poorer prognosis.
Diagnosis is based on presenting clinical signs and ELISA based in-house tests. PCR assays are available, but are not usually required for clinical management of individual cases.
A differential diagnosis would include anticoagulant rodenticides, canine bocavirus, intestinal parasites (particularly Blastocystis spp, Giardia intestinalis, Toxocara canis, Isospora spp, Trichuris vulpis) and hemorrhagic gastroenteritis due to Clostridium spp.
Treatment is usually palliative and supportive with intravenous fluids, antiemetics such as metoclopramide (0.2 - 0.5 mg/kg parenterally ad lib) and broad-spectrum antimicrobials (e.g. cephalexins or enrofloxacin) if indicated.
The use of NSAIDs is not normally recommended due to promoting further gastrointestinal bleeding.
Adjunct therapies such as chicken egg yolk, immunostimulatory glucans, the antiviral drug oseltamivir (tamiflu) and the recombinant human granulocyte-colony stimulating factor show promise as possible alternative therapies.
Severe cases with hemorrhagic diarrhea may require blood transfusions.
Food and water should be withheld until vomiting has subsided, followed by a cooked chicken, egg and rice diet for 3 - 4 days. Contaminated areas should be thoroughly cleaned.
Vaccination is critical in the control of the disease and current vaccines protect dogs against all strains of the virus, which are numerous and vary geographically worldwide. Avoiding socializing puppies untill fully vaccinated is critical to minimize exposure to the virus.
Vaccines, both parenteral and intranasal, containing live attenuated canine parvovirus generally induce more effective immunity than inactivated virus vaccines, although not without risk due to constant CPV mutations and possible contamination of vaccine batches with feline retroviruses (most produced with Crandell-Rees feline kidney cell cultures). Newer DNA based vaccines appear less problematic.
Booster vaccinations do not give a significant increase in CPV-2 antibody titers.
- Animal Pet Doctor
- Zhao J et al (2011) Origin and evolution of canine parvovirus - a review. Wei Sheng Wu Xue Bao 51(7):869-875
- Parrish CR & Kawaoka Y (2005) The origins of new pandemic viruses: the acquisition of new host ranges by canine parvovirus and influenza A viruses. Annu Rev Microbiol 59:553–586
- Tsao J et al (1991) The three-dimensional structure of canine parvovirus and its functional implications. Science 251:1456–1464
- Kaelber JT et al (2012) Evolutionary reconstructions of the transferrin receptor of Caniforms supports canine parvovirus being a re-emerged and not a novel pathogen in dogs. PLoS Pathog 8(5):e1002666
- Hafenstein S et al (2007) Asymmetric binding of transferrin receptor to parvovirus capsids. Proc Natl Acad Sci USA 104:6585–6589
- Parker JS & Parrish CR (2000) Cellular uptake and infection by canine parvovirus involves rapid dynamin-regulated clathrin-mediated endocytosis, followed by slower intracellular trafficking. J Virol 74:1919–1930
- Harbison CE et al (2008) The parvovirus capsid odyssey: from the cell surface to the nucleus. Trends Microbiol 16:208–214
- Allison AB et al (2012) Role of multiple hosts in the cross-species transmission and emergence of a pandemic parvovirus. J Virol 86(2):865-872
- Stucker KM et al (2012) The role of evolutionary intermediates in the host adaptation of canine parvovirus. J Virol 86(3):1514-1521
- Parrish CR et al (1985) Natural variation of canine parvovirus. Science 230:1046–1048
- Buonavoglia C et al (2001) Evidence for evolution of canine parvovirus type-2 in Italy. J Gen Virol 82:3021–3025
- Martella V et al (2004) A canine parvovirus mutant is spreading in Italy. J Clin Microbiol 42:1333–1336
- Decaro N et al (2006) A minor groove binder probe real-time PCR assay for discrimination between type-2 based vaccines and field strains of canine parvovirus. J Virol Methods 136:65–70
- Decaro N et al (2007) Tissue disribution of the antigenic variants of canine parvovirus type 2 in dogs. Vet Microbiol 121:39–44
- Vieira JM et al (2008) Canine parvovirus 2c infection in central Portugal. J Vet Diagn Invest 20:488–491
- Parthiban S et al (2011) Isolation and Typing of Canine Parvovirus in CRFK Cell Line in Puducherry, South India. Indian J Microbiol 51(4):456-460
- Pinto LD et al (2012) Typing of canine parvovirus strains circulating in Brazil between 2008 and 2010. Virus Res 165(1):29-33
- Zicola A et al (2012) Fatal outbreaks in dogs associated with pantropic canine coronavirus in France and Belgium. J Small Anim Pract 53(5):297-300
- Clegg SR et al (2012) Canine parvovirus in asymptomatic feline carriers. Vet Microbiol 157(1-2):78-85
- Iris Kalli et al (2010) Factors affecting the occurrence, duration of hospitalization and final outcome in canine parvovirus infection. Res Vet Sci 89(2):174-178
- Ling M et al (2012) Risk factors for death from canine parvoviral-related disease in Australia. Vet Microbiol 158(3-4):280-290
- Brady S et al (2012) Canine parvovirus in Australia: the role of socio-economic factors in disease clusters. Vet J 193(2):522-528
- Schaudien D et al (2010) Leukoencephalopathy associated with parvovirus infection in Cretan hound puppies. J Clin Microbiol 48(9):3169-3175
- Pollock RV & Carmichael LE (1990) The Canine Parvoviruses. In: Tijssen P, editor. CRC Handbook of Parvoviruses. Vol. 2. Boca Raton: CRC Press, Inc. pp:113–134
- Schoeman JP et al (2013) Biomarkers in canine parvovirus enteritis. N Z Vet J Feb 15
- Goddard A et al (2008) Prognostic usefulness of blood leukocyte changes in canine parvoviral enteritis. J Vet Intern Med 22(2):309-316
- Mantione NL & Otto CM (2005) Characterization of the use of antiemetic agents in dogs with parvoviral enteritis treated at a veterinary teaching hospital: 77 cases (1997-2000). J Am Vet Med Assoc 227(11):1787-1793
- Kocaturk M et al (2012) Tei index (myocardial performance index) and cardiac biomarkers in dogs with parvoviral enteritis. Res Vet Sci 92(1):24-29
- Kocaturk M et al (2010) Prognostic value of serum acute-phase proteins in dogs with parvoviral enteritis. J Small Anim Pract 51(9):478-483
- Schoeman JP et al (2007) Serum cortisol and thyroxine concentrations as predictors of death in critically ill puppies with parvoviral diarrhea. J Am Vet Med Assoc 231(10):1534-1539
- Yilmaz Z & Senturk S (2007) Characterisation of lipid profiles in dogs with parvoviral enteritis. J Small Anim Pract 48(11):643-650
- Markovich JE et al (2012) Effects of canine parvovirus strain variations on diagnostic test results and clinical management of enteritis in dogs. J Am Vet Med Assoc 241(1):66-72
- Van Nguyen S et al (2006) Passive protection of dogs against clinical disease due to Canine parvovirus-2 by specific antibody from chicken egg yolk. Can J Vet Res 70(1):62-64
- Haladová E et al (2012) Immunomodulatory effect of glucan on specific and nonspecific immunity after vaccination in puppies. Acta Vet Hung 59(1):77-86
- Savigny MR & Macintire DK (2010) Use of oseltamivir in the treatment of canine parvoviral enteritis. J Vet Emerg Crit Care (San Antonio) 20(1):132-142
- Duffy A et al (2010) Hematologic improvement in dogs with parvovirus infection treated with recombinant canine granulocyte-colony stimulating factor. J Vet Pharmacol Ther 33(4):352-356
- Dodds WJ et al (2012) Immune plasma for treatment of parvoviral gastroenteritis. J Am Vet Med Assoc 240(9):1056
- Bragg RF et al (2012) Clinical evaluation of a single dose of immune plasma for treatment of canine parvovirus infection. J Am Vet Med Assoc 240(6):700-704
- Ju C et al(2012) Genome Sequence of Canine Parvovirus Strain SC02/2011, Isolated from a Puppy with Severe Diarrhea in South China. J Virol 86(24):13805
- Soma T et al (2012) Analysis of the VP2 protein gene of canine parvovirus strains from affected dogs in Japan. Res Vet Sci Oct 11
- Martella V et al (2005) Immunogenicity of an intranasally administered modified live canine parvovirus type 2b vaccine in pups with maternally derived antibodies. Clin Diagn Lab Immunol 12(10):1243-1245
- Decaro N et al (2008) Evidence for immunisation failure in vaccinated adult dogs infected with canine parvovirus type 2c. New Microbiol 31(1):125-130
- Yoshikawa R et al (2011) Contamination of infectious RD-114 virus in vaccines produced using non-feline cell lines. Biologicals 39(1):33-37
- Yoshikawa R et al (2012) Presence of infectious RD-114 virus in a proportion of canine parvovirus isolates. J Vet Med Sci 74(3):347-350
- Dahiya SS et al (2012) Immunogenicity of a DNA-launched replicon-based canine parvovirus DNA vaccine expressing VP2 antigen in dogs. Res Vet Sci 93(2):1089-1097
- De Cramer KG et al (2011) Efficacy of vaccination at 4 and 6 weeks in the control of canine parvovirus. Vet Microbiol 149(1-2):126-132
- Mitchell S et al (2012) Duration of serological response to canine parvovirus-type 2, canine distemper virus, canine adenovirus type 1 and canine parainfluenza virus in client-owned dogs in Australia. Aust Vet J 90(12):468-473
- Taguchi M et al (2012) Booster effect of canine distemper, canine parvovirus infection and infectious canine hepatitis combination vaccine in domesticated adult dogs. Microbiol Immunol 56(8):579-582