Seroepidemiology of respiratory (group 2) canine coronavirus, canine parainfluenza virus, and Bordetella bronchiseptica infections in urban dogs in a humane shelter and in rural dogs in small communities

This prospective study evaluated seroepidemiologic features of canine respiratory coronavirus (CRCoV), canine parainfluenza virus (CPIV), and Bordetella bronchiseptica infections in dogs in an urban humane shelter and in rural/small community dog populations in western Canada. Seroprevalence of CRCoV and CPIV was low compared with other countries; seroprevalence of B. bronchiseptica was moderate to high in most populations examined. Rural dogs were 0.421 times (P ≤ 0.0001) less likely to be positive for CRCoV than dogs admitted to the shelter. There were no statistical differences in prevalence of antibodies to B. bronchiseptica and CPIV between urban and rural populations. Dogs from Fort Resolution, NWT were significantly (P < 0.05) less likely to have moderate or high antibody titers to the 3 agents than dogs in the shelter. Seroconversion to CRCoV was common in dogs in the shelter, but was not associated (P = 0.18) with respiratory disease. Antibodies to CRCoV, CPIV, or B. bronchiseptica on arrival were not significantly (P > 0.05) associated with disease-sparing after entry into the shelter.     

北京地区犬呼吸道冠状病毒感染状况的监测与分析

本研究旨在分析犬呼吸道冠状病毒（canine respiratory coronavirus,CRCoV）的感染情况和在北京地区的流行病学状况。采用RT-PCR方法,对自2015年12月—2017年3月于中国农业大学动物医院采集的487份犬咽鼻拭子进行了CRCoV检测,同时,对部分样本进行了犬副流感病毒（canine parainfluenza virus,CPIV）、犬腺病毒II型（canine adenovirus type 2,CAV-2）、犬瘟热病毒（canine distemper virus,CDV）等病毒的混合感染情况调查。结果表明：CRCoV的阳性率为21.36%（104/487）;CRCoV与CPIV、CAV-2、CDV的混合感染率分别为3.43%（11/321）,0%（0/156）和3.85%（6/156）。在所有呼吸道症状记录完整的455例样本中,无呼吸道症状的犬CRCoV携带率为27.19%（31/114）;呈轻度呼吸道症状（鼻液、咳嗽）的犬CRCoV感染率为19.73%（59/299）;呈中至重度呼吸道症状（肺炎）的犬CRCoV感染率为14.28%（6/42）。对2016年11月―2017年3月采集的146例样本进行CRCoV与CPIV、CAV-2、CDV混合感染情况调查,CRCoV带毒犬混合感染率为12.50%（1/8）;呈轻度呼吸道症状的CRCoV感染犬混合感染率为41.18%（7/17）;呈中至重度呼吸道症状的CRCoV感染犬混合感染率为100.00%（2/2）。454例不同年龄段犬的CRCoV阳性率为15.56%~22.97%;除7月份CRCoV检出率高外,较冷的冬春季节检出率高于夏秋季节。结果提示：CRCoV的致病力较弱,单一感染犬常表现为无或轻度呼吸道症状,与其他呼吸道病毒（CPIV、CAV-2、CDV）混合感染时多出现轻度或中至重度呼吸道症状。该病毒在冬春季节更易流行;其感染率和年龄无显著关系。     

Duration of serologic response to five viral antigens in dogs

OBJECTIVE: To determine whether vaccinated dogs either remained seropositive or responded serologically to revaccination for 5 key viral antigens after extended periods since their last vaccination. DESIGN: Serologic survey. ANIMALS: 322 healthy client-owned dogs. PROCEDURE: Dogs were > or = 2 years old and vaccinated against canine distemper virus (CDV), canine adenovirus-1 (CAV-1), canine adenovirus-2 (CAV-2), canine parainfluenza virus (CPIV), and canine parvovirus (CPV). On day 0, dogs were revaccinated with a vaccine from the same vaccine line as they had historically received. Antibody titers were measured in sera collected at day 0 (prevaccination titer) and 5 to 7 days later (postvaccination titer). Dogs were considered to have responded serologically if they had a day-0 serum neutralization titer to CDV > or = 1:32; a serum neutralization titer to CAV-1, CAV-2, or CPIV > or = 1:16; a hemagglutination inhibition titer to CPV > or = 1:80; or a > or = 4-fold increase in antibody titer after revaccination. RESULTS: The percentage of dogs that had titers at or greater than the threshold values or responded to revaccination with a > or = 4-fold increase in titer was 98.1% for CDV, 98.4% for CAV-1, 99.0% for CAV-2, 100% for CPIV, and 98.1% for CPV. CONCLUSIONS AND CLINICAL RELEVANCE: In most dogs, vaccination induced a response that lasted up to and beyond 48 months for all 5 antigens. Although not equivalent to challenge-of-immunity studies as a demonstration of efficacy, results suggest that revaccination with the same vaccine provides adequate protection even when given less frequently than the traditional 1-year interval. The study provides valuable information for clinicians to help determine appropriate revaccination intervals.     

Serosurvey of ex situ giant pandas (Ailuropoda melanoleuca) and red pandas (Ailurus fulgens) in China with implications for species conservation.

Conservation strategies for the giant panda (Ailuropoda melanoleuca) include the development of a self-sustaining ex situ population. This study examined the potential significance of infectious pathogens in giant pandas ex situ. Serologic antibody titers against canine distemper virus (CDV), canine parvovirus (CPV), canine adenovirus (CAV), canine coronavirus (CCV), canine herpesvirus, canine parainfluenza virus (CPIV), Toxoplasma gondii, Neospora caninum, and Leptospira interrogans were measured in 44 samples taken from 19 giant pandas between 1998 and 2003 at the Chengdu Research Base of Giant Panda Breeding in Sichuan, China. Seroassays also included samples obtained in 2003 from eight red pandas (Ailurus fulgens) housed at the same institution. All individuals had been vaccinated with a Chinese canine vaccine that included modified live CDV, CPV, CAV, CCV, and CPIV. Positive antibody titers were found only against CDV, CPV, and T. gondii. Sera were negative for antibodies against the other six pathogens. Results indicate that the quality of the vaccine may not be reliable and that it should not be considered protective or safe in giant pandas and red pandas. Positive antibody titers against T. gondii were found in seven of the 19 giant pandas. The clinical, subclinical, or epidemiologic significance of infection with these pathogens via natural exposure or from modified live vaccines in giant pandas is unknown. Research in this area is imperative to sustaining a viable population of giant pandas and other endangered species.     

Association between cancer chemotherapy and canine distemper virus, canine parvovirus, and rabies virus antibody titers in tumor-bearing dogs.

OBJECTIVE: To determine the association between cancer chemotherapy and serum canine distemper virus (CDV), canine parvovirus (CPV), and rabies virus antibody titers in tumor-bearing dogs. DESIGN: Prospective study. ANIMALS: 21 client-owned dogs with various malignancies and 16 client-owned dogs with lymphoma. PROCEDURE: In study A, serum antibody titers were measured by use of hemagglutination inhibition (CPV titers) or serum neutralization (CDV titers) before and at least 1 month after initiation of chemotherapy. Baseline values were compared with values obtained from a control population of 122 healthy dogs seen for routine revaccination. Titers were considered protective at > or = 1:96 for CDV and > or = 1:80 for CPV. In study B, serum IgG titers were measured by use of immunofluorescent assay (CDV and CPV titers) and rapid fluorescent focus inhibition test (RFFIT, rabies titers) at baseline and again at weeks 5, 8, and 24 of a standard chemotherapy protocol for treatment of lymphoma. An IgG titer of > or = 1:50 was considered protective for CPV and CDV. An RFFIT titer of > or = 0.5 U/ml was considered protective for rabies virus. RESULTS: Significant changes were not detected in CDV, CPV, and rabies virus titers following chemotherapy in tumor-bearing dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that established immunity to CDV, CPV, and rabies virus from previous vaccination is not significantly compromised by standard chemotherapy used to treat tumor-bearing dogs.     

成都地区宠物犬感染犬瘟热病毒和犬呼吸道冠状病毒的分子流行病学调查

为了解成都地区宠物犬犬瘟热病毒（canine distemper virus,CDV）和犬呼吸道冠状病毒（canine respiratory coronavirus,CRCoV）的感染情况,本试验应用RT-PCR对采自成都地区8家动物医院共计420份出现呼吸道症状的宠物犬鼻腔棉拭子样本进行分子检测。结果发现,从420份样本中,检出213份CDV阳性,检出率为50.71%;检出247份CRCoV阳性,检出率为58.81%;CDV和CRCoV混合感染的检出率为41.19%。表明成都地区宠物犬感染CDV和CRCoV较为严重,且二者混合感染率较高。宠物犬CDV和CRCoV的检出率与年龄、性别、品种、季节和免疫状况等因素的关系存在不同程度的差异。其中,1~3月龄幼犬检出率最高,分别为74.40%和79.20%;纯种犬的检出率较其他犬种高,分别为59.37%和62.22%;春季CDV的检出率较高,为56.19%,而冬季CRCoV的检出率较高,为67.59%;未免疫犬的检出率较高,分别为64.42%和63.46%。该研究丰富了成都地区宠物犬CDV和CRCoV的流行病学资料,为该地区宠物犬CDV和CRCoV的诊断及防控提供了基本数据。     

Factors associated with development of Canine Infectious Respiratory Disease Complex (CIRDC) in dogs in 5 Canadian small animal clinics

This study investigated the association between presence of respiratory pathogens and development of Canine Infectious Respiratory Disease Complex (CIRDC) in dogs in 5 Canadian small animal clinics. In total, 86 dogs were tested using a commercial PCR respiratory panel; 64 dogs were considered as cases and 22 were control dogs matched by veterinary clinic. No control animals (0/22) were positive for canine parainfluenza virus (CPIV), whereas 27/64 (42%) CIRDC cases were positive. Furthermore, 81% of case dogs tested positive for Mycoplasma cynos, compared with 73% of control dogs. Canine respiratory corona virus (CRCoV) was detected in no control dogs compared with 9.4% of clinical dogs. No animals were positive for any influenza virus type A present in the diagnostic panel. Presence of CPIV was associated (P < 0.01) with the occurrence of CIRDC after adjustment for demographic factors and presence of CRCoV (P = 0.09).     

Clinical use of serum parvovirus and distemper virus antibody titers for determining revaccination strategies in healthy dogs

OBJECTIVE: To assess whether serum canine parvovirus (CPV) and canine distemper virus (CDV) antibody titers can be used to determine revaccination protocols in healthy dogs. DESIGN: Case series. ANIMALS: 1,441 dogs between 6 weeks and 17 years old. PROCEDURE: CPV and CDV antibody titers in serum samples submitted to a commercial diagnostic laboratory were measured by use of indirect fluorescent antibody (IFA) tests. On the basis of parallel measurements of CPV and CDV serum antibody titers in 61 paired serum samples determined by use of hemagglutination inhibition and serum neutralization methods, respectively, we considered titers > or = 1:5 (IFA test) indicative of an adequate antibody response. RESULTS: Age, breed, and sex were not significantly associated with adequate CPV- or CDV-specific antibody responses. Of 1,441 dogs, 1,370 (95.1%) had adequate and 71 (4.9%) had inadequate antibody responses to CPV, whereas 1,346 of 1,379 (97.6%) dogs had adequate and 33 (2.4%) had inadequate responses to CDV. Vaccination histories were available for 468 dogs (468 for CPV, 457 for CDV). Interval between last vaccination and antibody measurement was 1 to 2 years for the majority (281/468; 60.0%) of dogs and 2 to 7 years for 142 of 468 (30.3%) dogs. Interval was < 1 year in only 45 of 468 (9.6%) dogs. CONCLUSIONS AND CLINICAL RELEVANCE: The high prevalence of adequate antibody responses (CPV, 95.1%; CDV, 97.6%) in this large population of dogs suggests that annual revaccination against CPV and CDV may not be necessary.     

Application of a dot enzyme-linked immunosorbent assay for evaluation of the immune status to canine parvovirus and distemper virus in adult dogs before revaccination.

A growing body of literature has been published indicating that the current practice of annual vaccination of dogs may not be beneficial and in some cases may even be harmful. A number of publications have proposed assessing the immune status of dogs before annual revaccination. In this study the usefulness of a commercially available dot-ELISA kit was evaluated to determine the duration IgG antibody titers to canine parvovirus (CPV) and canine distemper virus (CDV) in 158 dogs vaccinated at least one year ago. Overall, the percentage of dogs with protective antibody titers to both CPV and CDV was 84%. The percentage of dogs with borderline antibody titers was 11% for CPV and 10% for CDV. Four percent of the dogs had no detectable antibody to CPV and 6% had no antibody to CDV. The results reported here are in good agreement with other studies measuring IgG antibody levels. It is concluded that the kit offers veterinarians the opportunity of determining antibody titers and revaccinating only those pets whose antibody titers to specific diseases have waned.     

Serum antibody response to canine parvovirus, canine adenovirus-1, and canine distemper virus in dogs with known status of immunization: study of dogs in Sweden

Serum antibody titers to canine parvovirus (CPV), canine adenovirus-1 (CAV-1), and canine distemper virus (CDV) were measured in dogs with known immunization status. The dogs represented 3 groups: nonvaccinated dogs less than 12 months old; vaccinated dogs less than 12 months old; and adult dogs greater than 12 months old. For practical reasons, the population from which the specimens were obtained could be considered as free from natural infection with CAV-1 and CDV. In nonvaccinated dogs less than 12 months old, antibodies against all 3 viruses were measured at the time the dogs were given their first vaccination. Altogether, 50.7% of the dogs had titer greater than or equal to 1:10 to CPV, and 26.1 and 46.2% had titer greater than or equal to 1:8 to CAV-1 and CDV, respectively. The concentration of maternal antibody seemed to be of major importance for failure of immunization with use of inactivated CPV vaccine, but not with CAV-1 and CDV vaccination. In dogs less than 12 months old and vaccinated against CPV infection with inactivated virus, only 11.5% had titer greater than or equal to 1:80. In dogs vaccinated against infectious canine hepatitis and canine distemper, 63.2 and 78.3%, respectively, had titer greater than or equal to 1:16. In adult dogs greater than 2 months old and vaccinated against CPV infection, less than 50% had titer greater than or equal to 1:80, regardless of time after vaccination. There was no significant difference in titer between vaccinated and nonvaccinated dogs.(ABSTRACT TRUNCATED AT 250 WORDS)     

Three-year duration of immunity in dogs following vaccination against canine adenovirus type-1, canine parvovirus, and canine distemper virus

A challenge-of-immunity study was conducted to demonstrate immunity in dogs 3 years after their second vaccination with a new multivalent, modified-live vaccine containing canine adenovirus type 2 (CAV-2), canine parvovirus (CPV), and canine distemper virus (CDV). Twenty-three seronegative pups were vaccinated at 7 and 11 weeks of age. Eighteen seronegative pups, randomized into groups of six dogs, served as challenge controls. Dogs were kept in strict isolation for 3 years following the vaccination and then challenged sequentially with virulent canine adenovirus type 1 (CAV-1), CPV, and CDV. For each viral challenge, a separate group of six control dogs was also challenged. Clinical signs of CAV-1, CPV, and CDV infections were prevented in 100% of vaccinated dogs, demonstrating that the multivalent, modified-live test vaccine provided protection against virulent CAV-1, CPV, and CDV challenge in dogs 7 weeks of age or older for a minimum of 3 years following second vaccination.     

Prevalence of antibodies to four major canine viral diseases in dogs in a Liverpool hospital population

To determine the prevalence of antibodies to four major canine viruses, serum samples were obtained from 190 dogs presented to the Small Animal Hospital at the University of Liverpool. Antibodies to canine coronavirus (CCV), canine distemper virus (CDV), canine parvovirus (CPV) and rotavirus (RV) were assayed using serum neutralisation (CCV and CDV), haemagglutina-tion inhibition (CPV) and indirect fluorescent antibody (RV) techniques. Overall 54 per cent of dogs were seropositive to CCV, 84 per cent to CDV, 70 per cent to CPV and 86 per cent to RV, The antibody titres obtained were analysed with respect to a number of different parameters including: age, sex, breed, vaccination status, exercise regime, diet, Liverpool district in which the dog resided and the presence of diarrhoea, The prevalence and titres of antibodies to CCV, CDV and RV appeared to be influenced by age, CDV by vaccination status, and CCV by the presence of diarrhoea; no other influencing parameters were found.     

Assessment of serum antibody titers against canine distemper virus, canine adenovirus type II, and canine parvovirus in Alaskan sled dogs before and after a long-distance race

OBJECTIVE: To determine serum antibody titers against canine distemper virus (CDV), canine adenovirus type II (CAV-2), and canine parvovirus (CPV) in trained sled dogs prior to and after completion of a long-distance race. DESIGN: Prospective cohort study. ANIMALS: 195 Alaskan sled dogs (from 18 kennels) that participated in the 2006 Iditarod Trail Race. PROCEDURES: All 1,323 dogs participating in the race had been vaccinated against the 3 viruses at 19 to 286 days prior to initial blood sample collection (obtained within the month preceding the race). Within 12 hours of race completion, blood samples were collected from 195 dogs (convenience sample) and matched with each dog's prerace sample. Serum antibody titers (90% confidence intervals [CIs]) were determined via serum neutralization assays. RESULTS: After racing, geometric mean titers against CDV and CPV were significantly higher (2,495 [90% CI, 321 to 16,384] and 6,323 [90% CI, 512 to 32,768], respectively) than prerace values (82 [90% CI, 11 to 362] and 166 [90% CI, 32 to 1,024], respectively). Sixty-one of 194 (31.4%) dogs had > or = 4-fold increases in anti-CPV antibody titers after racing. Prerace serum antibody titers against CDV, CPV, and CAV-2 varied significantly by sled team but were not associated with time since vaccination. CONCLUSIONS AND CLINICAL RELEVANCE: Postrace increases in serum anti-CDV and anti-CPV antibody titer might reflect exposure of dogs to these agents immediately before or during racing. Dogs had no clinical signs of CDV-, CAV-2-, or CPV-associated disease; therefore, the clinical importance of these titer changes is uncertain.     

Obesity,expression of adipocytokines,and macrophage infiltration in canine mammary tumors

Obesity influences the development, progression and prognosis of human breast cancer and canine mammary cancer (MC) but the precise underlying mechanism is not well-documented in the fields of either human or veterinary oncology. In the present study, the expression of major adipocytokines, including leptin, adiponectin, and leptin receptor (ObR) in benign (n = 28) and malignant (n = 70) canine mammary tumors was investigated by immunohistochemistry and on the basis of the subject's body condition score (BCS). To evaluate the relationship between obesity and chronic inflammation of the mammary gland, macrophages infiltrating within and around tumoral areas were counted.The mean age of MC development was lower in overweight or obese dogs (9.0 ± 1.8 years) than in lean dogs or optimal bodyweight (10.2 ± 2.9 years), and the evidence of lymphatic invasion of carcinoma cells was found more frequently in overweight or obese group than in lean or optimal groups. Decreased adiponectin expression and increased macrophage numbers in overweight or obese subjects were significantly correlated with factors related to a poor prognosis, such as high histological grade and lymphatic invasion. Leptin expression was correlated with progesterone receptor status, and ObR expression was correlated with estrogen receptor status of MCs, regardless of BCS. Macrophage infiltration within and around the tumor may play an important role in tumor progression and metastasis in obese female dogs and may represent a prognostic factor for canine MCs.     

Accuracy of a point-of-care ELISA test kit for predicting the presence of protective canine parvovirus and canine distemper virus antibody concentrations in dogs

Canine parvovirus (CPV) and canine distemper virus (CDV) are highly infectious and often fatal diseases with worldwide distributions, and are important population management considerations in animal shelters. A point-of-care ELISA test kit is available to detect serum antibodies to CPV and CDV, and presumptively to predict protective status. The aim of this study was to determine the diagnostic accuracy of the test compared to CPV hemagglutination inhibition titers and CDV serum neutralization titers determined by a reference laboratory, using sera collected from dogs housed at animal shelters. The ELISA test was used under both field and laboratory conditions and duplicate specimens were processed using an extra wash step. The test kit yielded accurate results (CPV: sensitivity 92.3%, specificity 93.5%; CDV: sensitivity 75.7%, specificity 91.8%) under field conditions. CDV sensitivity was improved by performing the test under laboratory conditions and using an optical density (OD) meter (laboratory performed 94.0%; OD 88.1%). Point-of-care ELISA testing for serum CPV and CDV antibody titers was demonstrated to be a useful tool for determining antibody status when making decisions regarding the need for CPV and/or CDV vaccination and also in animal shelters for population management.     

Prevalence of positive antibody test results for canine parvovirus (CPV) and canine distemper virus (CDV) and response to modified live vaccination against CPV and CDV in dogs entering animal shelters

Canine parvovirus (CPV) and canine distemper virus (CDV) infections are relatively common in animal shelters and are important population management issues since the immune status of incoming dogs is usually unknown. This study aimed to determine the prevalence of positive antibody test results for CPV and CDV in incoming dogs aged ≥ 4 months and to measure antibody response over 2 weeks following vaccination with a modified live vaccine (MLV). Dogs aged 4-24 months entering an adoption-guarantee shelter (Shelter 1, n=51) and aged ≥ 4 months entering a limited admission shelter (Shelter 2; n=51) were enrolled. Dogs from Shelter 1 had been vaccinated with MLV at a municipal shelter 5 days before enrollment, whereas dogs from Shelter 2 had no known history of vaccination at enrollment. Sera were obtained on day 1, immediately prior to CPV/CDV MLV, and tested using an in-clinic ELISA kit to detect CPV/CDV antibodies. Dogs negative for CPV and/or CDV were retested at day 6-8 and those dogs still negative at day 6-8 were retested at day 13-15. Prior to CPV/CDV MLV on day 1, more dogs tested positive for CPV (Shelter 1 - 68.6%; Shelter 2 - 84.3%) than for CDV (Shelter 1 - 37.3%; Shelter 2 - 41.2%). On day 1, prior to MLV, all spayed/neutered animals tested CPV antibody-positive (n=17/102) and CPV antibody-positive dogs were older than serologically negative dogs (Shelter 1, P=0.0029; Shelter 2, P=0.0042). By day 13-15, almost all dogs were CPV antibody-positive (Shelter 1 - 97.9%; Shelter 2 - 100.0%) and CDV antibody-positive (Shelter 1 - 93.8%; Shelter 2 - 97.8%). MLV induces protective antibody titers against CPV/CDV in almost all dogs after 13-15 days.     

同时检测犬瘟热病毒和犬细小病毒双重PCR方法的建立

为建立可以同时检测犬瘟热病毒(CDV)和犬细小病毒(CPV)的双重PCR方法,本研究根据GenBank登录的CDV N蛋白序列和CPV NS基因保守序列,设计合成2对特异性引物。通过优化反应条件,对CDV阳性病毒株反转录后的cDNA模板和CPV的DNA模板进行双重PCR扩增,同时得到2条与试验设计相符的669 bp(CDV)和392 bp(CPV)特异性条带,建立了同时检测CDV和CPV的双重PCR方法。实验结果表明:在同一PCR反应体系中可以同时检测这2种病毒,而对犬腺病毒Ⅰ型、犬腺病毒Ⅱ型、狂犬病毒检测均为阴性;CDV和CPV的最低检出限分别为101.8TCID50和101.4TCID50。采用该方法对在黑龙江省不同地区所采集的30份犬病料样品进行检测,CDV阳性率为30%;CPV阳性率为23.33%,表明建立的PCR方法可以用于临床诊断。     

犬副流感病毒单克隆抗体的研制及其特性鉴定

为研制犬副流感特异性诊断试剂,我们以犬副流感病毒(CPIV)免疫8周龄BALB/c小鼠,采用淋巴细胞杂交瘤技术获得4株稳定分泌针对CPIV的单克隆抗体(MAb)细胞株,分别命名为4F386、584C9、4G7F4和4C9D8.4株MAb腹水针对CPIV的间接ELISA抗体效价达1:10~5～1:10~6,与犬瘟热病毒(CDV)和犬细小病毒(CPV)均不发生交叉反应.MAb 4F386和4C9D8为IgG,5B4C9和4G7F4为IgM.Western blot检测表明,4F386与CPIV的F蛋白发生特异性反应,4G7F4与CPW的HN蛋白发生特异性反应,而584C9和4C9D8不与变性的CPIV蛋白发生反应.4株MAb均具有中和病毒活性,间接免疫荧光检测均呈为阳性.本研究为进一步研制CPIV特异性诊断和治疗制剂创造了条件.     

Antibody titers for canine parvovirus type-2, canine distemper virus, and canine adenovirus type-1 in adult household dogs

Serum antibody titers for canine parvovirus type-2 (CPV-2), canine distemper virus (CDV) and canine adenovirus type-1 (CAV-1) were investigated in 1031 healthy adult household dogs (2 to 18 years old) given an annual inoculation in the previous 11 to 13 months. The number of dogs retaining significant titers of antibodies against CPV-2, CDV, and CAV-1 were 888 (86%), 744 (72%), and 732 (71%), respectively. There were no differences between males and females in antibody titers against the 3 viruses. Antibody titer for CPV-2 was significantly higher in younger dogs than in older dogs, CDV antibody was significantly higher in older dogs than in younger dogs, and CAV titer was not associated with age.     

Three-year rabies duration of immunity in dogs following vaccination with a core combination vaccine against canine distemper virus, canine adenovirus type-1, canine parvovirus, and rabies virus

Thirty-two seronegative pups were vaccinated at 8 weeks of age with modified-live canine distemper virus (CDV), canine adenovirus type-2 (CAV-2), and canine parvovirus (CPV) vaccine and at 12 weeks with a modified-live CDV, CAV-2, CPV, and killed rabies virus vaccine. An additional 31 seronegative pups served as age-matched, nonvaccinated controls. All test dogs were strictly isolated for 3 years after receiving the second vaccination and then were challenged with virulent rabies virus. Clinical signs of rabies were prevented in 28 (88%) of the 32 vaccinated dogs. In contrast, 97% (30 of 31) of the control dogs died of rabies infection. These study results indicated that no immunogenic interference occurred between the modified-live vaccine components and the killed rabies virus component. Furthermore, these results indicated that the rabies component in the test vaccine provided protection against virulent rabies challenge in dogs 12 weeks of age or older for a minimum of 3 years following vaccination.