Atrophic Rhinitis Vaccine (Bordetella / Pasteurella)

Atrophic rhinitis vaccines are bacterin-toxoid preparations designed to protect swine against the destructive nasal disease caused by Bordetella bronchiseptica and toxigenic strains of Pasteurella multocida. These two organisms act synergistically to damage the turbinate bones within the nasal passages of young pigs, producing a spectrum of disease ranging from mild, self-resolving turbinate inflammation to severe, permanent destruction of nasal architecture with visible snout deformation. Vaccination programs targeting these pathogens represent the primary immunological control measure for atrophic rhinitis in commercial and seedstock swine operations worldwide.

The disease exists in two clinically and pathologically distinct forms that reflect the involvement of different organisms. Non-progressive atrophic rhinitis is caused by Bordetella bronchiseptica alone and produces mild to moderate turbinate atrophy that typically resolves as the pig matures, with limited long-term impact on growth performance. Progressive atrophic rhinitis, the far more economically damaging form, requires infection with toxigenic Pasteurella multocida, specifically strains producing dermonecrotic toxin (DNT), which causes severe and permanent turbinate destruction that does not resolve with age. Bordetella bronchiseptica frequently acts as a predisposing agent by colonizing the nasal mucosa and creating conditions favorable for subsequent Pasteurella multocida establishment, making dual-agent vaccines the standard approach to comprehensive atrophic rhinitis prevention.

The vaccine formulations contain killed Bordetella bronchiseptica whole cells (bacterin) combined with inactivated Pasteurella multocida dermonecrotic toxin (toxoid). The bacterin component stimulates antibodies against Bordetella surface antigens that reduce nasal colonization in exposed piglets. The toxoid component, which is the more critical element for preventing progressive disease, stimulates antitoxin antibodies that neutralize the dermonecrotic toxin responsible for osteoclastic destruction of the turbinate bones. The relative importance of the toxoid component reflects the central role of Pasteurella dermonecrotic toxin in the pathogenesis of progressive atrophic rhinitis - without this toxin, the severe form of the disease does not occur regardless of bacterial colonization levels.

The primary vaccination strategy for atrophic rhinitis is maternal immunization of sows and gilts, which generates high concentrations of protective antibodies in colostrum that are passively transferred to piglets during the first hours of life. This maternal antibody approach is preferred because the critical window of susceptibility to turbinate damage is during the first weeks of life when the turbinate bones are actively growing and most vulnerable to toxin-mediated destruction. Piglets cannot mount an effective active immune response quickly enough through direct vaccination to protect themselves during this vulnerable neonatal period, making colostral passive immunity the practical mechanism for early-life protection.

Understanding the pathogenesis of atrophic rhinitis is essential for appreciating why vaccination is structured the way it is and why timing matters so critically. The disease process begins when Bordetella bronchiseptica colonizes the nasal mucosa of young piglets, typically within the first days to weeks of life through direct contact with colonized sows or pen-mates. Bordetella adheres to the ciliated epithelium of the nasal passages using fimbrial adhesins and produces a range of virulence factors including cytotoxins, adenylate cyclase toxin, and lipopolysaccharide that damage the mucosal surface, impair ciliary clearance mechanisms, and create an inflammatory environment that predisposes the nasal mucosa to secondary colonization by other bacteria.

Toxigenic Pasteurella multocida, the agent responsible for progressive disease, colonizes the Bordetella-damaged nasal mucosa and produces dermonecrotic toxin, a 145-kilodalton protein that is the principal virulence factor driving turbinate destruction. Dermonecrotic toxin acts directly on osteoblasts and osteoclasts within the turbinate bones, inhibiting osteoblastic bone formation while stimulating osteoclastic bone resorption. The net effect is a dramatic shift from bone synthesis to bone degradation that progressively destroys the delicate scroll-shaped turbinate structures within the nasal cavity. In severe cases, the nasal septum itself is affected, leading to the characteristic lateral deviation of the snout that is the most visible clinical sign of advanced progressive atrophic rhinitis.

The age-dependent susceptibility to turbinate damage explains why neonatal protection through maternal antibodies is the logical vaccination target. Turbinate bones in young piglets are actively growing through endochondral ossification, a process that involves rapid cell division and bone remodeling activity. This metabolically active state makes the turbinates highly susceptible to the disruptive effects of dermonecrotic toxin. As pigs mature and turbinate growth slows, the bones become increasingly resistant to toxin-mediated destruction, and by the time pigs reach market weight, even active Pasteurella colonization produces minimal additional structural damage. The practical consequence is that turbinate damage sustained during the first four to eight weeks of life is largely irreversible and determines the pig's lifetime nasal architecture and respiratory function.

The vaccine rationale follows directly from this pathogenesis: deliver neutralizing antitoxin antibodies to the piglet through colostrum before the animal encounters toxigenic Pasteurella during the vulnerable neonatal period. Maternal antibodies absorbed from colostrum circulate in the piglet's bloodstream and are present in tissue fluids including those bathing the nasal mucosa. When dermonecrotic toxin is produced by colonizing Pasteurella, circulating antitoxin antibodies bind and neutralize the toxin before it can reach turbinate bone cells and initiate the destructive cascade. The antibacterial component targeting Bordetella provides an additional layer of protection by reducing the initial mucosal colonization that predisposes to Pasteurella establishment.

The primary indication for atrophic rhinitis vaccines is the vaccination of breeding swine - sows and gilts - to stimulate the production of colostral antibodies that protect their piglets against turbinate atrophy caused by Bordetella bronchiseptica and toxigenic Pasteurella multocida. This maternal vaccination approach is the standard of practice in commercial swine operations where atrophic rhinitis is endemic or where the economic consequences of uncontrolled disease justify preventive vaccination. The vaccines are not therapeutic - they cannot reverse turbinate damage that has already occurred and do not treat active clinical disease.

In herds with a history of progressive atrophic rhinitis, vaccination of all breeding females is the foundational control measure. Sows that have been previously vaccinated and boosted maintain their ability to produce high-quality colostral antibodies with each subsequent farrowing, provided they receive pre-farrowing booster doses according to the product schedule. Gilts entering the breeding herd for the first time require a primary two-dose vaccination series to establish baseline immunity before their first farrowing, as they have no prior antigenic exposure to generate the robust colostral antibody levels needed for piglet protection.

Some vaccine products are additionally labeled for direct vaccination of piglets at one to three weeks of age, providing active immunization to complement the waning maternal antibodies received through colostrum. Piglet vaccination is not a substitute for sow vaccination because the piglet's active immune response develops too slowly to protect against turbinate damage during the critical first weeks of life. Rather, direct piglet vaccination serves as a secondary measure that extends protection beyond the period covered by maternal antibodies, potentially reducing the degree of turbinate damage in pigs that encounter heavy pathogen challenge after colostral immunity has declined.

Boar vaccination is included in some herd protocols, not because boars themselves are at significant risk of atrophic rhinitis, but because Bordetella bronchiseptica colonization in boars can serve as a reservoir of infection that is transmitted to sows and subsequently to piglets through the sow. Reducing the overall nasal bacterial load in the breeding herd through comprehensive vaccination of all adults - sows, gilts, and boars - contributes to lower environmental pathogen pressure in farrowing facilities where neonatal exposure occurs.

In seedstock operations, atrophic rhinitis vaccination carries additional significance because breeding stock sold to commercial producers must be free of clinical disease and ideally have low nasal pathogen colonization levels. Purchasers of gilts and boars expect animals with normal snout conformation and no history of respiratory disease. Seedstock herds implement rigorous vaccination programs as part of their health assurance protocols, often combined with strategic antimicrobial use in piglets and environmental management of farrowing facilities to minimize the risk of producing animals with subclinical turbinate damage that could affect their market value.

The standard dosing protocol for atrophic rhinitis vaccines in sows and gilts involves a two-dose primary series followed by pre-farrowing booster doses for each subsequent pregnancy. The primary series for gilts consists of two intramuscular injections of 2 mL each, with the first dose administered approximately six to eight weeks before the expected farrowing date and the second dose given two to four weeks later, approximately two to four weeks before farrowing. This timing ensures that the sow's immune response has been fully boosted and that peak antibody concentrations in the blood coincide with the period of colostrum formation in the mammary gland, maximizing the transfer of protective antibodies into the colostrum that piglets will consume.

For previously vaccinated sows, a single 2 mL booster dose administered two to four weeks before each subsequent farrowing is sufficient to restimulate the anamnestic (memory) immune response and elevate circulating antibody levels for colostral transfer. The booster schedule should be incorporated into the standard pre-farrowing sow processing protocol alongside other routine vaccinations and management procedures. Consistent adherence to the pre-farrowing booster schedule is essential because skipping a booster dose results in lower colostral antibody concentrations and reduced piglet protection for that particular farrowing.

When piglet vaccination is included in the protocol, the typical schedule involves a 2 mL intramuscular injection at one week of age with a second dose at three to four weeks of age. The first piglet dose is administered while maternal antibodies are still present, and while maternal antibody interference may partially blunt the active immune response, priming of the piglet's immune system still occurs. The second dose provides the booster stimulus that drives antibody levels above protective thresholds as maternal immunity wanes. Not all vaccine products are labeled for piglet use, and producers should verify that their specific product includes piglet vaccination in its labeled indications.

The route of administration for all atrophic rhinitis vaccines is intramuscular injection. The preferred injection site in sows and gilts is the neck musculature behind the ear, a location that avoids carcass-valuable tissue and provides adequate muscle mass for intramuscular deposition of the 2 mL dose volume. In piglets, the neck is also the preferred site, though the small muscle mass of neonatal pigs requires careful needle selection - typically a 20-gauge, half-inch to five-eighths-inch needle - to ensure intramuscular rather than subcutaneous placement without penetrating through the muscle into deeper structures.

Vaccine handling during administration sessions requires attention to cold chain maintenance and aseptic technique. The vaccine should remain refrigerated at 2 to 8 degrees Celsius until immediately before use and should not be exposed to direct sunlight or freezing temperatures. Multi-dose vials should be shaken thoroughly before withdrawing each dose to ensure uniform antigen distribution. Needles should be changed frequently during large-group vaccination sessions to maintain sharpness and minimize injection site trauma that could increase local reactions or introduce contamination.

Atrophic rhinitis vaccines are generally well tolerated in swine when administered according to label directions, though as with all bacterin-toxoid products containing adjuvants, local and occasionally systemic reactions can occur. The adjuvant systems used in these vaccines - typically aluminum hydroxide, oil-in-water emulsions, or proprietary adjuvant complexes - are necessary to stimulate a robust and durable immune response but inherently provoke localized inflammatory reactions at the injection site. Understanding the normal range of post-vaccination responses helps producers distinguish expected reactions from adverse events warranting veterinary attention.

Local injection site reactions are the most commonly observed side effects and include transient swelling, firmness, and mild soreness at the injection site. These reactions typically appear within 24 to 48 hours of vaccination and resolve progressively over one to three weeks without treatment. The severity of local reactions varies between vaccine products, with oil-adjuvanted formulations generally producing larger and more persistent injection site granulomas than aluminum-adjuvanted products. In sows vaccinated repeatedly over multiple parities, injection site fibrosis may develop in the neck region if the same injection location is used at every vaccination, though rotating injection sites between left and right sides of the neck mitigates this accumulation.

Systemic reactions including transient fever, reduced feed intake for 12 to 24 hours, and mild lethargy can occur following vaccination, particularly after the first dose in naive gilts that have no prior immunological experience with the vaccine antigens. These systemic responses reflect the general immune activation triggered by the vaccine and are typically self-limiting. In pregnant sows vaccinated during the pre-farrowing period, systemic reactions should be monitored carefully because high fever during late gestation can adversely affect fetal viability and piglet birth weights. Products formulated with reduced-reactivity adjuvants are available specifically to address the concern of adverse systemic effects in late-gestation sows.

Anaphylactic reactions are rare but possible with any injectable biological product. Signs of anaphylaxis in swine include acute respiratory distress, cyanosis, vomiting, collapse, and in severe cases death within minutes of injection. Epinephrine should be available at the vaccination site for emergency treatment of anaphylaxis. The risk is highest at the time of injection and during the subsequent 30 minutes, and animals showing any signs of acute hypersensitivity require immediate attention. Individual animals that experience anaphylaxis should not be revaccinated with the same product.

Precautions specific to atrophic rhinitis vaccines include avoidance of vaccination in clinically ill animals, as the immune response may be suboptimal and the stress of handling and injection may worsen existing health conditions. Concurrent administration with other injectable vaccines at the same injection session is common practice in commercial swine operations, but producers should be aware that simultaneous administration of multiple adjuvanted products can increase the incidence and severity of local reactions. When multiple vaccines are given at the same processing event, they should be administered at separate injection sites. Withdrawal times for atrophic rhinitis vaccines are typically 21 days for slaughter, though specific product labels should be consulted as withdrawal periods vary between manufacturers.

The efficacy of atrophic rhinitis vaccines is measured by their ability to reduce turbinate lesion scores, decrease the incidence of snout deviation, and maintain growth performance in vaccinated litters compared to unvaccinated controls. Field trials and controlled challenge studies have consistently demonstrated that sow vaccination with combined Bordetella-Pasteurella bacterin-toxoid products significantly reduces the severity and prevalence of turbinate atrophy in their piglets when compared to progeny of unvaccinated sows. The degree of protection varies between products, challenge conditions, and farm management factors, but well-implemented vaccination programs typically reduce turbinate lesion scores by 50 to 80 percent and snout deviation incidence by 60 to 90 percent.

The antitoxin component of the vaccine, directed against Pasteurella multocida dermonecrotic toxin, is the primary determinant of efficacy against progressive atrophic rhinitis. Studies correlating colostral antitoxin titers with piglet protection have established that higher maternal antibody levels at birth correspond to lower turbinate lesion scores at slaughter. This dose-response relationship underscores the importance of proper vaccination timing relative to farrowing to maximize colostral antibody concentrations. Sows that receive their booster dose too early (more than six weeks before farrowing) or too late (less than two weeks before farrowing) produce colostrum with suboptimal antitoxin levels, reducing the margin of protection for their piglets.

Vaccination does not prevent nasal colonization by Bordetella bronchiseptica or Pasteurella multocida. The organisms can still establish themselves on the nasal mucosa of vaccinated piglets, but the presence of circulating antitoxin antibodies prevents the toxin-mediated turbinate destruction that constitutes the clinically and economically important disease. This distinction between colonization prevention and disease prevention is important for interpreting surveillance results: culture-positive nasal swabs from piglets born to vaccinated sows do not indicate vaccine failure if the pigs have normal turbinate architecture and no clinical signs of atrophic rhinitis.

Field performance of atrophic rhinitis vaccines is influenced by factors beyond vaccine quality that determine the level of pathogen challenge and the robustness of passive immunity in individual piglets. Farrowing house hygiene directly affects neonatal pathogen exposure levels - piglets born into heavily contaminated environments encounter higher bacterial doses earlier in life, potentially overwhelming the protection afforded by maternal antibodies. Colostrum intake adequacy varies among piglets within a litter, with piglets that nurse poorly or are displaced by larger littermates receiving insufficient antibody transfer. Environmental stressors including temperature extremes, overcrowding, and poor ventilation increase disease susceptibility and reduce the effective duration of passive protection. Vaccination is most effective when implemented as one component of a comprehensive atrophic rhinitis control program that also addresses environmental management, sanitation, and piglet husbandry.

Long-term herd-level benefits of sustained vaccination programs extend beyond individual litter protection. Consistent vaccination over multiple production cycles progressively reduces the overall nasal pathogen load within the breeding herd, as vaccinated sows carry lower levels of Bordetella and Pasteurella in their nasal passages and shed fewer organisms to their piglets. This population-level effect creates a positive feedback cycle in which decreasing pathogen pressure enhances the effectiveness of the vaccine-mediated protection, and some operations that have maintained rigorous vaccination programs for years report turbinate lesion scores near zero across their production flow.

Atrophic rhinitis vaccination does not operate in isolation but functions as one element within the broader swine herd health program that addresses multiple respiratory, reproductive, and enteric disease challenges simultaneously. In commercial farrow-to-finish and farrow-to-wean operations, the pre-farrowing sow processing protocol typically includes vaccination against atrophic rhinitis alongside vaccines for Escherichia coli scours, Clostridium perfringens type C enteritis, porcine parvovirus, leptospirosis, erysipelas, and in some programs, porcine circovirus type 2 and Mycoplasma hyopneumoniae. Coordinating the timing and administration of multiple vaccines requires a structured schedule that balances immunological effectiveness with practical labor and handling considerations.

Strategic antimicrobial use in young piglets complements vaccination in herds where atrophic rhinitis remains a clinical concern despite vaccination. Some operations administer injectable antibiotics effective against Bordetella and Pasteurella to piglets during the first week of life to reduce early nasal colonization during the period before vaccine-derived maternal antibodies have reached maximum concentration in the piglet's circulation. This combined approach targets both the bacterial colonization step (antimicrobials) and the toxin-mediated tissue damage step (passive antitoxin immunity) simultaneously. The choice of antimicrobial, if used, should be guided by susceptibility testing of isolates from the specific herd, as antimicrobial resistance patterns in Bordetella and Pasteurella vary between herds and regions.

Environmental management in farrowing facilities directly impacts the success of vaccination programs by controlling the bacterial challenge level that piglets face during the critical neonatal period. All-in/all-out farrowing room management with thorough cleaning and disinfection between groups reduces the accumulation of bacterial contamination that builds up in continuously occupied facilities. Temperature management to maintain the thermal comfort zone for neonatal piglets supports immune function and reduces respiratory stress. Adequate ventilation provides fresh air exchange without creating drafts at piglet level. These environmental factors do not replace vaccination but determine whether the level of protection provided by maternal antibodies is sufficient to prevent disease given the actual pathogen challenge present in the farrowing environment.

Monitoring the effectiveness of atrophic rhinitis control programs requires systematic assessment of turbinate integrity in production pigs. Slaughter check programs, in which a representative sample of market-weight pig heads from the herd are cross-sectioned at the level of the second premolar to score turbinate morphology, provide the definitive assessment of program effectiveness. Turbinate scoring on a standardized scale from zero (normal) to four (complete turbinate atrophy with septal deviation) allows quantitative tracking of disease status over time and comparison between production groups or management changes. Herds with effective vaccination programs should maintain average turbinate scores below one, with minimal to no snout deviations observed in the sampled population.

The economic justification for atrophic rhinitis vaccination rests on the documented relationship between turbinate lesion severity and growth performance. Pigs with moderate to severe turbinate atrophy grow approximately 5 to 15 percent more slowly than pigs with normal nasal architecture, translating to increased days to market weight and higher feed costs per unit of gain. In severe cases, the respiratory compromise caused by turbinate loss predisposes to secondary pneumonia caused by other respiratory pathogens including Actinobacillus pleuropneumoniae, Mycoplasma hyopneumoniae, and porcine reproductive and respiratory syndrome virus, compounding production losses beyond the direct effects of atrophic rhinitis alone. The cost of a comprehensive sow vaccination program is modest relative to the production losses prevented in herds with documented atrophic rhinitis challenges.

Proper storage of atrophic rhinitis vaccines is essential for maintaining antigen potency and adjuvant integrity throughout the product's shelf life. Vaccines must be stored under continuous refrigeration at 2 to 8 degrees Celsius (35 to 46 degrees Fahrenheit) from the time of manufacture through administration. Exposure to temperatures outside this range - either freezing or ambient warmth above 8 degrees Celsius - can irreversibly damage the vaccine. Freezing disrupts the physical structure of adjuvant-antigen complexes, causing aggregation and sedimentation that reduce both immunogenicity and injectability. Excessive heat accelerates protein denaturation and can inactivate the toxoid component, rendering the vaccine incapable of stimulating protective antitoxin responses.

During vaccination sessions, vaccines removed from refrigeration should be used within a reasonable timeframe and protected from direct sunlight and temperature extremes. In warm weather, transporting vaccines to the barn in an insulated cooler with ice packs maintains appropriate temperature during the time between removal from the refrigerator and completion of the vaccination session. Multi-dose vials that have been opened and partially used should not be returned to storage for future use if significant time has elapsed or if aseptic withdrawal technique was not maintained, as bacterial contamination of the remaining vaccine can cause injection site abscesses in subsequently vaccinated animals.

Regulatory oversight of atrophic rhinitis vaccines in the United States falls under the jurisdiction of the USDA Center for Veterinary Biologics (CVB), which licenses veterinary biological products based on demonstrated purity, safety, potency, and efficacy. Manufacturers must maintain compliance with 9 CFR (Code of Federal Regulations) standards for production, testing, and labeling. Products carry USDA establishment and product license numbers that identify the manufacturing facility and the specific approved formulation. Producers should verify that vaccines purchased from distributors carry valid USDA license numbers and have not exceeded their labeled expiration dates.

Withdrawal time requirements for atrophic rhinitis vaccines vary by product and should be verified on the specific product label before vaccinating animals approaching slaughter weight. Most products specify a 21-day slaughter withdrawal period, during which vaccinated animals must not be sent for processing for human consumption. This withdrawal period allows resolution of injection site reactions and clearance of adjuvant-associated tissue changes that could cause carcass trim or condemnation at inspection. For sow-level vaccination programs, withdrawal times are rarely a practical concern because breeding females are not approaching slaughter at the time of vaccination, but in operations that vaccinate piglets or that cull recently vaccinated sows, observance of the labeled withdrawal period is a food safety and regulatory compliance requirement.

Record keeping for vaccination programs should document the product used (name, manufacturer, serial number, expiration date), the date of administration, the animals or groups vaccinated, the dose administered, the route and site of injection, and the identity of the person who performed the vaccination. These records support quality assurance programs, enable investigation of suspected vaccine reactions or failures, and demonstrate compliance with withdrawal time requirements. In operations participating in the Pork Quality Assurance Plus (PQA Plus) program, systematic documentation of all treatments including vaccinations is a program standard that supports the industry's commitment to responsible animal care and food safety.