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A Comparative Study of Protective Immunity Provided by Oral, Intranasal and Parenteral Canine Bordetella bronchiseptica Vaccines
Abstract
The present study was designed to determine if an oral live Bordetella bronchiseptica vaccine protects dogs from developing signs of respiratory disease after challenge with virulent Bordetella bronchiseptica. The study was also designed to compare the level of protection induced by the oral vaccine with the protection provided by an intranasal live vaccine and an injected killed vaccine. Forty 6-8 week old beagles, culture and antibody negative to Bordetella bronchiseptica, were randomly distributed to 4 groups. Group 1 (O) received a single dose of attenuated oral Bordetella vaccine at study day 14; Group 2 (IN) received a single dose of attenuated intranasal Bordetella vaccine at study day 14; Group 3 (SCu) received two doses of killed Bordetella vaccine administered subcutaneously at study days 0 and 14; and Group 4 (C) received saline both intranasally and subcutaneously. All dogs were challenged with virulent Bordetella bronchiseptica via nebulization chamber at study day 42. Blood and nasal swabs were collected weekly thru-out the study for serology and bacterial culture. After challenge, daily clinical assessments included body temperature and a weighted score of coughing and other respiratory disease signs. Severe signs of disease in the control group proved the validity of our challenge model. Results of this study showed that the oral Bordetella bronchiseptica vaccine protects dogs from challenge. This protection provided by the oral vaccine was equivalent to that induced by intranasal vaccine, and was superior to protection provided by the killed, subcutaneously administered vaccine.
... Use of orally administered Bb vaccines has gained momentum in veterinary practice in recent years due to individual preference for this route by some veterinarians and veterinary technicians. Bb vaccine studies have investigated the relative efficacy of different routes of administration (Ellis et al., 2001(Ellis et al., , 2002Larson et al., 2013) and have demonstrated that oral vaccination can provide protective immunity (Hess et al., 2011;Larson et al., 2013;Scott-Garrard et al., 2018). ...
... Use of orally administered Bb vaccines has gained momentum in veterinary practice in recent years due to individual preference for this route by some veterinarians and veterinary technicians. Bb vaccine studies have investigated the relative efficacy of different routes of administration (Ellis et al., 2001(Ellis et al., , 2002Larson et al., 2013) and have demonstrated that oral vaccination can provide protective immunity (Hess et al., 2011;Larson et al., 2013;Scott-Garrard et al., 2018). ...
... Previously published studies have demonstrated that parenterally administered killed and antigen extract Bb vaccines and live-attenuated intranasal Bb vaccines protected against severe clinical signs associated with Bb infection (Chladek et al., 1981;Glickman and Appel, 1981;Kontor et al., 1981;Shade and Rapp, 1982;Edinboro et al., 2004;Davis et al., 2007;Ellis et al., 2014;Ellis, 2015). In two live-attenuated Bb vaccine studies, the oral vaccine offered protection equivalent to that induced by intranasal vaccine (Larson et al., 2013;Scott-Garrard et al., 2018). In one study, it was demonstrated that both intranasal and oral Bb vaccines were disease-sparing after experimental challenge; however, the intranasal route of administration afforded superior clinical protection compared to the oral route (Ellis et al., 2016). ...
This experimental challenge study assessed immune protection 1 year after a single dose of live-attenuated oral Bordetella bronchiseptica (Bb) vaccine in dogs. Forty Bb-seronegative 7–9-week-old puppies were randomly assigned at Day 0 to receive a single oral dose of either Bb vaccine (n = 20; vaccinated group) or sterile water (n = 20; control group). Groups were housed separately until comingling 1 day pre-challenge (Day 365). Challenge with virulent aerosolized Bb occurred at Day 366. Clinical scores were obtained at Days 1–7, and 366–380. Bb microagglutination test (MAT) titers were obtained at Days −7, 0, monthly post-vaccination, and Days 358, 365, and 380. Nasal swabs were collected for microbiological assessment at Days −7, 0, 365, and 367–380.
Oral Bb vaccination was not associated with side effects. Pre-challenge, vaccinated dogs developed persistent Bb MAT titers and control dogs remained seronegative. Post-challenge, duration of cough was longer in control dogs (least square means [LSM], 8.6 days) than vaccinated dogs (LSM, 1.5 days; P < 0.0001), with more control dogs having cough on 2 or more consecutive days (control group, n = 17/19, 89.5%; vaccinated group, n = 3/19, 15.8%; P = 0.0011). Post-challenge, Bb shedding occurred in all control dogs and 5/19 (26%) vaccinated dogs. Average duration of Bb shedding was longer in the control group (11.9 days vs. 0.6 days; P < 0.0001) and nasal Bb loads were higher in the control group (P < 0.00001). Orally administered Bb vaccine stimulated immunity that was still protective against virulent Bb challenge after 1 year.
... Several studies, some comparative, have evaluated the efficacy of these vaccines against B bronchiseptica challenge with varying results. [1][2][3][4][5][6][7][8][9] The majority of the studies used a scoring system to assess the clinical signs after challenge, and intranasal vaccines tended to have better efficacy than vaccines administered by other routes. Intranasal vaccines have been noted to be difficult to administer, and injectable vaccines have the potential to cause injection site reactions. ...
... A particular advantage of oral vaccines is the ease of administration while maintaining the local mucosal immunity of an intranasal administration. 2 Since intranasal vaccines were most frequently observed to have the best efficacy, this study was designed to compare the efficacy of a newly developed oral vaccine with an established intranasal vaccine against a B bronchiseptica challenge seven days after vaccination. Rather than using a scoring system, the clinical signs in this study were evaluated as present or absent to provide the most stringent comparison of the vaccines. ...
... Bacterial growth on plates for each isolate was harvested and pooled in PBS. The challenge process was similar to that described by Hess et al 7 and Larson et al. 2 Dogs were randomised to challenge chamber with dogs from each group represented in each chamber. Dogs of different groups were comingled after challenge and were randomised to two pens so that each vaccination group was represented in each pen. ...
Three groups of approximately eight-week-old beagles were vaccinated once with 1 ml of placebo vaccine (oral, n=9), 1 ml of Recombitek® Oral Bordetella (oral, n=10) or 1 ml Nobivac® Intra-Trac3 (intranasal, 0.5 ml/nostril, n=10). Seven days after vaccination, the three groups were challenged with virulent Bordetella bronchiseptica via aerosolisation. Eight of nine dogs in the placebo group and no dogs in the Recombitek® Oral Bordetella or Nobivac® Intra-Trac3 vaccine groups developed spontaneous cough of two or more consecutive days (disease case definition). Dogs in the Recombitek® Oral Bordetella and Nobivac® Intra-Trac3 groups had a significantly lower incidence of disease (P<0.0001) with a 100 per cent preventable fraction. The study demonstrated that vaccination with either Recombitek® Oral Bordetella or Nobivac® Intra-Trac3 is effective in preventing disease seven days after vaccination when compared with dogs vaccinated with a placebo.
... Although published studies addressing this question do not always agree, the VGG is of the belief that, immunologically, vaccination via a mucosal route is more likely to generate relevant protective immunity (specifically the production of mucosal IgA and IgG antibodies as opposed to systemic IgG antibodies) for pathogens that infect via the same mucosae (Larson et al. 2013) [EB1]. Intranasal vaccination may have the added benefit of a rapid onset of immunity that may relate to a non-specific stimulation of innate immunity (via Toll-like receptor engagement and local cytokine/chemokine production) [EB4]. ...
... They may be given to puppies from 8 weeks of age and require annual revaccination. There is variation in the scientific literature as to whether the oral and intranasal Bb vaccines confer equivalent protection, or whether protection is better with intranasal products (Larson et al. 2013, Ellis et al. 2016a, Scott-Garrard et al. 2018 [EB1]. As to why these products are not available in LATAM, you would need to ask the manufacturers and regulatory authorities responsible for vaccine licensure. ...
Executive Summary
The World Small Animal Veterinary Association Vaccination Guidelines Group has produced global guidelines for small companion animal practitioners on best practice in canine and feline vaccination. Recognising that there are unique aspects of veterinary practice in certain geographical regions of the world, the Vaccination Guidelines Group undertook a regional project in Latin America between 2016 and 2019, culminating in the present document. The Vaccination Guidelines Group gathered scientific and demographic data during visits to Argentina, Brazil and Mexico, by discussion with national key opinion leaders, visiting veterinary practices and review of the scientific literature. A questionnaire survey was completed by 1390 veterinarians in five Latin American countries and the Vaccination Guidelines Group delivered continuing education at seven events attended by over 3500 veterinarians.
The Vaccination Guidelines Group recognised numerous challenges in Latin America, for example: (1) lack of national oversight of the veterinary profession, (2) extraordinary growth in private veterinary schools of undetermined quality, (3) socioeconomic constraints on client engagement with preventive health care, (4) high regional prevalence of some key infectious diseases (e.g. feline leukaemia virus infection, canine visceral leishmaniosis), (5) almost complete lack of minimal antigen vaccine products as available in other markets, (6) relative lack of vaccine products with extended duration of immunity as available in other markets, (7) availability of vaccine products withdrawn from other markets (e.g. Giardia vaccine) or unique to Latin America (e.g. some Leishmania vaccines), (8) accessibility of vaccines directly by pet owners or breeders such that vaccination is not delivered under veterinary supervision, (9) limited availability of continuing education in veterinary vaccinology and lack of compulsion for continuing professional development and (10) limited peer‐reviewed published scientific data on small companion animal infectious diseases (with the exception of leishmaniosis) and lack of support for such academic research.
In this document, the Vaccination Guidelines Group summarises the findings of this project and assesses in evidence‐based fashion the scientific literature pertaining to companion animal vaccine‐preventable diseases in Latin America. The Vaccination Guidelines Group makes some recommendations on undergraduate and postgraduate education and academic research. Recognising that current product availability in Latin America does not permit veterinarians in these countries to vaccinate according to the global World Small Animal Veterinary Association guidelines, the Vaccination Guidelines Group makes a series of “pragmatic” recommendations as to what might be currently achievable, and a series of “aspirational” recommendations as to what might be desirable for the future. The concept of “vaccine husbandry” is addressed via some simple guidelines for the management of vaccine products in the practice. Finally, the Vaccination Guidelines Group emphasises the global trend towards delivery of vaccination as one part of an “annual health check” or “health care plan” that reviews holistically the preventive health care needs of the individual pet animal. Latin American practitioners should transition towards these important new practices that are now well embedded in more developed veterinary markets.
The document also includes 70 frequently asked questions and their answers; these were posed to the Vaccination Guidelines Group during our continuing education events and small group discussions and should address many of the issues surrounding delivery of vaccination in the Latin American countries. Spanish and Portuguese translations of this document will be made freely available from the on‐line resource pages of the Vaccination Guidelines Group.
... In dog vaccination studies, routes of administration is highly debated topic and is often surrounded by controversies regarding the efficacy of parenteral, IN and oral Bordetella vaccination (18,21,(56)(57)(58)(59)(60). In one of the early studies (57), it has been shown that the dogs vaccinated subcutaneously with acellular Bordetella (aB) vaccines showed higher serum concentration of B. bronchiseptica reactive IgG when compared to IN vaccinated group in seropositive dogs. ...
... In one of the early studies (57), it has been shown that the dogs vaccinated subcutaneously with acellular Bordetella (aB) vaccines showed higher serum concentration of B. bronchiseptica reactive IgG when compared to IN vaccinated group in seropositive dogs. In later studies (18,59), this claim has been refuted and it was shown that the oral and IN route activates better salivary and serum immunoglobulin responses in seronegative dogs. In a recent study (60), it was shown that the previous history of infection (seropositive dogs) helps in a better and enhanced immune response in animals that are vaccinated subcutaneously with aB vaccine. ...
The Bordetella species are Gram-negative bacterial pathogens that colonizes mammalian respiratory tract causing respiratory diseases in humans and animals. B. bronchiseptica causes clinical conditions in many mammals including immunocompromised humans. Using the dog model of respiratory infection, it has been shown in this study that a newly developed B. bronchiseptica Bacterial Ghost (BbBG) vaccine exhibited significant protection in the face of a severe pathogenic bacterial challenge in seronegative dogs. The protein E-specific lysis mechanism was used to produce BbBGs. Bacterial Ghosts (BGs) are the empty cell envelope of Gram-negative bacterium. They are genetically processed to form a microscopic hole in their membrane, through which all the cytoplasmic contents are expelled leaving behind intact empty bacterial shells. Due to the intact surface structures of BGs, they offer the safety of inactivated but efficacy of live attenuated vaccines. In this study, seronegative dogs were vaccinated subcutaneously (s/c) with two different doses of a newly developed BbBG vaccine [lower 10∧5 (BbBG – 5) and higher 10∧7 (BbBG – 7)] on day 0 and 21. The animals were challenged (by aerosol) with virulent live B. bronchiseptica strains 41 days after first vaccination. The dogs vaccinated s/c with BbBG – 7 vaccine had significantly lower spontaneous coughing scores (P = 0.0001) than dogs in negative control group. Furthermore, the tested BbBG – 7 vaccine was equivalent to the positive control vaccine Bronchicine CAe in terms of safety and efficacy. For the first time, we report the successful use of liquid formulated BGs vaccines in animal studies. Earlier reported studies using BGs vaccines were performed with resuspended freeze-dried BGs preparations.
... The challenge process was similar to that described by Hess and others 7 and Larson and others. 3 For the challenge phase, dogs from both groups were commingled and housed with littermates in three rooms. ...
Background
Very few studies have evaluated the duration of immunity of Bordetella bronchiseptica vaccines in dogs, and to date, no studies have been published on the duration of immunity of oral canine Bordetella bronchiseptica vaccines. This study was designed to determine the effectiveness of a single dose of an oral B bronchiseptica vaccine in dogs when challenged 13 months after vaccination.
Methods
Two groups of approximately eight-week-old beagles were vaccinated once with 1 ml of placebo vaccine (oral, n=17) or 1 ml of Recombitek Oral Bordetella (oral, n=17). Thirteen months after vaccination, both groups were challenged with virulent B bronchiseptica via aerosolisation.
Results
Thirteen of 17 dogs in the placebo group (76.5 per cent) and no dogs in the Recombitek Oral Bordetella vaccine group (0.0 per cent) developed spontaneous cough of two or more consecutive days (disease case definition). Dogs in the Recombitek Oral Bordetella group had a significantly lower prevalence of disease with prevented fraction of 1 (100 per cent prevention). In addition, the number of days coughing, duration of cough and prevalence of tracheal and nasal shedding were significantly lower for dogs vaccinated with Recombitek Oral Bordetella.
Conclusions
The study demonstrated that vaccination with Recombitek Oral Bordetella is effective in preventing disease and reducing shedding 13 months after vaccination when compared with dogs vaccinated with a placebo.
... Vaccines best considered against Bb infection in other species are live attenuated by intranasal or oral application: they induce both local immunity at nasal level (IgA) and seroconversion (IgG), only one application is needed to produce longtime immunity, effective immunity is achieved rapidly (up to 72 hours) and do not provoke local reactions [23][24][25][26][27][28][29][30][31]. Local nasal immunity (IgA) appears to be of crucial importance in respiratory infectious diseases, particularly if Bordetella spp. is implicated [17,23,32,33]. ...
Bordetella bronchiseptica causes severe respiratory disease in guinea pigs and it has been associated with stillbirths, abortions, infertility and infections of the reproductive system and tympanic bullae. Disease caused by Bordetella bronchiseptica in pet guinea pigs is mostly a poor understood disease; studies about this pathogen has been conducted mostly in laboratory guinea pigs. The objective of this review is to condense published information about the disease caused by Bordetella bronchiseptica in guinea pigs for the veterinarian who attends pet guinea pigs, with special emphasis on the prevention of this disease. The author concludes that vaccination in pet guinea pigs against Bordetella bronchiseptica needs to be considered for future studies.
Canine infectious respiratory disease (CIRD) typically presents as a self‐limiting, mild to moderate upper respiratory disease of dogs. A presumptive diagnosis of an uncomplicated case of CIRD is based on key clinical signs: a hacking, paroxysmal cough, and a mild to moderate nasal discharge with or without mild pyrexia. Clinical diagnosis of CIRD is based on clinical signs, a history of recent exposure, and response to therapy. Pathogens traditionally associated with CIRD are most commonly spread in aerosolized droplets from coughing and sneezing and through contact with fomites such as hands, clothing, and cleaning tools. Housing design can aid in preventing CIRD outbreaks. Balancing biosecurity with behavioral enrichment, including interactions with people and conspecifics, is important for shelter animal welfare. For veterinarians working with cases of individual dogs with CIRD, a discussion of medical treatment is primarily concerned with the administration of appropriate pharmaceuticals at an effective dose and duration.
This chapter covers aspects of immunity in relation to individuals, as well as populations of animals within the shelter, and addresses special concerns regarding the immunity of juvenile animals. Specific vaccines for dogs and cats are discussed in the context of vaccination programs designed for optimal effectiveness in the shelter environment. The chapter describes the use of serology for the evaluation of immunity. It covers diagnostic tests that may be affected by vaccination. Many of the significant, potentially deadly viral diseases, such as canine distemper virus, canine parvovirus, and feline parvovirus, are “vaccine‐preventable” if animals are effectively immunized prior to exposure to the pathogen. Animals entering shelters are either: immunologically naïve and thus susceptible to infection and development of disease if exposed to pathogens; already immune as a result of natural immunization or previous vaccination; or already infected.
The canine infectious respiratory disease complex (CIRDC) is an endemic worldwide syndrome involving multiple viral and bacterial pathogens. Traditionally, Bordetella bronchiseptica (Bb), canine adenovirus type 2 (CAV-2), canine distemper virus (CDV), canine herpesvirus (CHV) and canine parainfluenza virus (CPiV) were considered the major causative agents. Lately, new pathogens have been implicated in the development of CIRDC, namely canine influenza virus (CIV), canine respiratory coronavirus (CRCoV), canine pneumovirus (CnPnV), Mycoplasma cynos and Streptococcus equi subspecies zooepidemicus. To better understand the role of the different pathogens in the development of CIRDC and their epidemiological relevance in Europe, prevalence data were collected from peer-reviewed publications and summarized. Evidence of exposure to Bb is frequently found in healthy and diseased dogs and client-owned dogs are as likely to be infected as kennelled dogs. Co-infections with viral pathogens are common. The findings confirm that Bb is an important cause of CIRDC in Europe. CAV-2 and CDV recovery rates from healthy and diseased dogs are low and the most likely explanation for this is control through vaccination. Seroconversion to CHV can be demonstrated following CIRDC outbreaks and CHV has been detected in the lower respiratory tract of diseased dogs. There is some evidence that CHV is not a primary cause of CIRDC, but opportunistically re-activates at the time of infection and exacerbates the disease. The currently available data suggest that CIV is, at present, neither a prevalent nor a significant pathogen in Europe. CPiV remains an important pathogen in CIRDC and facilitates co-infection with other viral and bacterial pathogens. CnPnV and CRCoV are important new elements in the aetiology of CIRDC and spread particularly well in multi-dog establishments. M. cynos is common in Europe and is more likely to occur in younger and kennelled dogs. This organism is frequently found together with other CIRDC pathogens and is significantly associated with more severe respiratory signs. S. zooepidemicus infection is not common and appears to be a particular problem in kennels. Protective immunity against respiratory diseases is rarely complete, and generally only a reduction in clinical signs and excretion of pathogen can be achieved through vaccination. However, even vaccines that only reduce and do not prevent infection carry epidemiological advantages. They reduce spread, increase herd immunity and decrease usage of antimicrobials. Recommending vaccination of dogs against pathogens of CIRDC will directly provide epidemiological advantages to the population and the individual dog.
Since first emerging in the North American canine population in 2004, canine influenza virus (CIV) subtype H3N8 has shown horizontal transmission among dogs, with a high level of adaptation to this species. The severity of disease is variable, and coinfection by other respiratory pathogens is an important factor in the degree of morbidity and mortality. The first influenza vaccine for dogs, an inactivated vaccine containing CIV subtype H3N8, was conditionally approved by the U.S. Department of Agriculture (USDA) for licensure in May 2009 and fully licensed in June 2010. This study evaluates the efficacy of this vaccine to reduce the severity of illness in dogs cochallenged with virulent CIV and Streptococcus equi subsp. zooepidemicus.
A placebo-controlled field trial was conducted to compare the effectiveness of intranasal (IN) vaccines containing Bordetella bronchiseptica and canine-parainfluenza virus, with (IN-BPA) or without (IN-BP) canine-adenovirus type 2, for prevention of kennel cough at a humane shelter. Dogs were examined on admission to the shelter and those without respiratory signs of disease were assigned daily, on a rotating basis, to receive one of three vaccines. We enrolled 972 healthy dogs. Dogs were monitored for up to 30 days post-vaccination for coughing and other clinical signs of respiratory disease. Thirty-three (10.7%; 95% confidence interval (CI): 7.2%, 14.2%) dogs in the IN-BP group, 36 (10.2%; CI: 7.0%, 13.4%) [corrected] dogs in the IN-BPA group, and 42 (13.5%; CI: 9.7%, 17.3%) [corrected] dogs in the IN-P group coughed spontaneously for > or = 1 day within 30 days of vaccination (P = 0.37). The IN-BP and IN-BPA vaccines were 20.7 and 24.4% effective, respectively, in reducing coughing compared with a placebo vaccine. The strongest prognostic factor for coughing (regardless of vaccine group) was the number of days spent at the shelter, with each additional day increasing the risk of coughing by 3% (95% CI: 1.01, 1.06) [corrected] The low incidence of coughing in the shelter during this study precluded observation of differences in vaccine effectiveness. No differences in vaccine-associated adverse events (coughing, sneezing, nasal or ocular discharge) were noted during the first 3 days post-administration or thereafter.
Infectious tracheobronchitis (ITB), also known as the kennel cough, is a respiratory syndrome of dogs and usually appears to be contagious among dogs housed in groups. Etiologic agent of ITB is multiple and sometimes complex. In the present study, 68 household dogs showing clinical signs of respiratory infection were examined, and 20 dogs (29.4%) were found to be positive for either of following agents. Bordetella bronchiseptica (B.b.) was most frequently detected from nasal and oropharynx sites of 7 dogs (10.3%). Among the viruses examined, canine parainfluenza virus (CPIV) was detected with the highest frequency (7.4%). Other pathogens included in the order of frequency group 1 canine coronavirus (4.4%), canine adenovirus type 2 (2.9%), group 2 canine respiratory coronavirus (1.5%), and canine distemper virus (1.5%). Only 2 cases showed mixed infections. Neither influenza A virus nor canine bocavirus (minute virus of canines) was found in any dogs examined. These results indicate that both B.b. and CPIV are likely to be the principal etiologic agents of canine ITB in Japan, and they may be considered as the target for prophylaxis by vaccination.
Beta-defensins are cationic peptides which form part of the innate immune response of the respiratory epithelium. Due to their antimicrobial properties and immunostimulatory activity, beta-defensins are potential tools for the treatment and prevention of respiratory disease. In dogs, infectious respiratory disease is a common problem, particularly in housed animals. This study aimed to assess the presence of four beta-defensins in the canine respiratory tract and to use quantitative real-time PCR to determine mRNA levels following microbial challenge. Three beta-defensins, CBD1, CBD103 and CBD108, were detected in respiratory cells. All three defensins were also readily expressed in skin samples, while their expression in lymphoid tissues and the kidney was low and inconsistent. Treatment of primary tracheal epithelial cells with lipopolysaccharide (LPS) or infection with canine respiratory coronavirus led to decreased expression of CBD103 and CBD108, while cells infected with canine parainfluenza virus had lower levels of CBD1 and CBD108. Furthermore CBD103 was demonstrated to have antimicrobial activity against the respiratory pathogen Bordetella bronchiseptica.
Three groups of healthy dogs with low antibody titers to Bordetella bronchiseptica (Bb), canine parainfluenza virus (CPI), and canine adenovirus type 2 (CAV-2) were used in this study. One group was vaccinated with a single dose of monovalent attenuated Bb vaccine and one group with a trivalent vaccine containing attenuated Bb, CPI, and CAV-2; dogs were vaccinated intranasally with a single dose of the respective vaccines. The third group served as unvaccinated controls. All vaccinated dogs subsequently developed serum antibody titers to Bb that persisted for at least 1 year. Following Bb challenge 1 year after vaccination, all vaccinated dogs, regardless of group, showed significantly fewer clinical signs and shed significantly fewer challenge organisms than unvaccinated controls. These results demonstrate that intranasal administration of a single dose of monovalent attenuated Bb vaccine or trivalent vaccine containing attenuated Bb, CPI, and CAV-2 provides 1 year of protection against Bb.
The association of Mycoplasma cynos with canine infectious respiratory disease is increasingly being recognised. This study describes the strain typing of 14 M. cynos isolates cultured from trachea and bronchoalveolar lavage samples of six dogs with respiratory disease, from two separate kennels in the United Kingdom. The genetic similarity of the isolates was investigated using pulsed-field gel electrophoresis (PFGE) and random amplified polymorphic DNA (RAPD). Most of the isolates from four dogs housed at a re-homing kennel were genetically similar and some isolates from different dogs were indistinguishable by both PFGE and RAPD. These isolates were cultured from dogs with non-overlapping stays in the kennel, which may indicate maintenance of some strains within kennels. A small number of isolates showed much greater genetic heterogeneity and were genetically distinct from the main group of M. cynos strains. There was also a high degree of similarity of the M. cynos type strain (isolated from a dog with respiratory disease in Denmark in 1971) to at least one of the United Kingdom isolates using PFGE analysis, which may suggest possible conservation of pathogenic strains of M. cynos.
Bordetella bronchiseptica produced tracheobronchitis when administered in aerosol to specific pathogen-free dogs. Clinical signs appeared to be directly
related to numbers of bacteria in the trachea. Electron microscopic examination revealed that each bacterium was close to
one or more tracheal cilia and that a fibrillar material was radiating from the bacterial cell wall. B. bronchiseptica required 14 weeks to be cleared from the tracheas of infected dogs; in contrast, other organisms commonly isolated from the
respiratory tracts of dogs were cleared within one to three days. Strains of high and low in vitro passage and strains representing
three different morphotypes were of equal pathogenicity. Local immunity was observed after infection and appeared to be of
primary importance in recovery from the infection. Presumably this reponse involves prevention of bacterial attachment and
reattachment to cilia.
During the autumn of 1988 an outbreak of canine infectious tracheobronchitis, which seemed to be more infectious than usual, occurred throughout Scandinavia. Paired serum samples and bacterial swabs were collected from 52 dogs with clinical signs of infectious tracheobronchitis in three districts of Norway. The results revealed a fourfold or greater rise in the titre of antibodies against canine parainfluenza virus in 79 per cent of the cases, strongly suggesting that the virus was of aetiological importance in the outbreak. Bordetella bronchiseptica was not isolated from the diseased dogs, and they showed no rise in the titres of antibodies against influenza virus, reovirus or adenovirus.
The effect of Bordetella bronchiseptica upper airway colonization on the clinical, radiographic, serologic, pathologic, and pulmonary function changes caused by canine parainfluenza-2 virus (CPIV-2) infection was studied in 24 purebred Beagle pups (10.5 +/- 1.4 weeks old). Eight control dogs (group I) were not colonized or inoculated with CPIV-2. Of the 12 noncolonized dogs inoculated with CPIV-2 (group II), 9 developed antibody titers to CPIV-2 and 10 had clinical signs of infectious canine tracheobronchitis (kennel cough). Group I and group II dogs did not differ in radiographic findings or pulmonary function. Four group II dogs necropsied 1 to 5 days after clinical signs developed had laryngotracheobronchitis and bronchiolar inflammation not present at necropsy on 2 group I dogs. Four dogs had B bronchiseptica upper airway colonization and were inoculated with CPIV-2 (group III). All 4 group III dogs developed positive antibody titers, had clinical signs of kennel cough, and had radiographic changes. Pulmonary dynamic compliance was lower in group III than in group I or group II animals. Respiratory rate and tidal volume did not differ among the 3 groups. The 1 group III dog that was necropsied had changes similar to group II dogs with the addition of lobar bronchopneumonia. The present study indicates that asymptomatic B bronchiseptica colonization may effect the clinical, radiographic, and pulmonary function changes produced by CPIV-2 respiratory tract infections.