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July/August 2014 today's Veterinary Practice 75 Vital Vaccination: Kennel cough ReVisited | tvpjournal.com Vaccines should only be administered to healthy animals. For example, administering a live, avirulent B bronchiseptica vaccine (intranasal or oral) to a dog concurrently receiving an antibiotic may exert an an- tibacterial effect on the vaccine antigen, resulting in reduced to no immunity. Factors Applicable to Selection While manufacturer advertisements and claims of vaccine efficacy can lead to confusion regarding vaccine selection; veterinarians recommending vaccination against CIRD must base selection on several factors: 1. Age Intranasal vaccines can be administered as a single dose as early as 3 to 4 weeks of age (see manufacturer label instructions) because maternally derived antibody (IgG) does not interfere with mucosal immune respons- es (secretory IgA). Although impractical among individ- ual household pets, puppies housed in high-risk envi- ronments (animal shelters) may benefit from early vacci- nation (ie, at 3–4 weeks of age). In this case, intranasal vaccine may need to be repeated at 2 to 4 week intervals until 12 weeks of age. It is not known whether the oral B bronchiseptica vac- cine, which also induces local immunity, has efficacy in puppies less than 8 weeks of age. The parenteral B bron- chiseptica vaccine requires 2 initial doses, at a minimum interval of 2 weeks, with the first dose administered to dogs 8 weeks of age or older. 2. Exposure Risk Assessment of exposure risk is particularly important when selecting a vaccine. For dogs with limited risk for exposure, administration of any combination of parenteral, oral, or intranasal vaccines is indicated. In high-risk environments, however, administering either the oral or parenteral B bronchiseptica vaccines alone limits the scope of pro- tection to B bronchiseptica; neither product contains vac- cine against CPiV or CAV-2. 3. Onset of Immunity Following a single dose of intranasal B bronchiseptica vaccine, dogs have shown protection against aerosol chal- lenge by 48 to 72 hours. 11,12 Vaccination with oral B bron- chiseptica vaccine is expected to induce rapid-onset mu- cosal immune response similar to the intranasal vaccine. 13,14 Dogs initially vaccinated with parenteral B bronchisep- tica vaccine are not expected to derive protective immu- nity until 5 to 7 days following administration of the sec- ond dose, that is, not earlier than 19 to 21 days following administration of the first dose. 4. Ease of Administration Reports from veterinarians indicate that parenteral and oral vaccines are easiest to administer and best tolerated by individual dogs. A small number of dogs will aggres- sively resist intranasal vaccination; resistance to intrana- sal vaccination may warrant changing to oral or parenteral administration (see Change of Administration Route). 5. Route of Vaccination The most recent studies (see Studies on B bronchisep- tica Vaccine Administration, page 76) assessing routes of administration center on B bronchiseptica vaccination. These studies highlight the role of mucosal immunity in protecting dogs against exposure to B bronchiseptica. Similar comparative studies assessing the quality of pro- tection derived from intranasal versus parenteral CPiV and CAV-2 vaccine administration have not been published. Administration Considerations 1. Vaccine Loss Following Administration Following intranasal administration of vaccine to dogs, subsequent sneezing and head shaking is likely to result in a small volume of vaccine dose being expelled from the nose; however, it is unlikely that this degree of vaccine loss reduces efficacy due to: • High antigen concentration per dose • Affinity of avirulent live B bronchiseptica for respira- tory epithelium. 2. Reduction of Diluent Volume to Reduce Volume/Dose When administering intranasal vaccine to small breeds, particularly small brachycephalic breeds, the volume of diluent may be arbitrarily reduced when reconstituting lyophilized vaccine antigen. Doing so reduces the volume of vaccine that reaches the nasopharynx without reducing antigen concentration or vaccine efficacy. 3. Vaccine Mixed with Food Due to the absence of published studies, administering a dose of oral B bronchiseptica vaccine by mixing the dose with food is not recommended. Doing so may result in sig- nificantly reduced antigen contact with mucosal surfaces and, thus, ineffective immunization. 4. Change of Administration Route When administering an intranasal vaccine, veterinarians may encounter sufficient resistance in some dogs to war- rant switching to a parenteral or oral vaccine. Switching from Intranasal to Parenteral. Intranasal vaccination may not consistently result in significant levels of serum IgG. Therefore, administration of 2 parenteral doses, 2 to 4 weeks apart, is recommended, regardless of the dog's age when the dosing route is changed. The dog may be revaccinated annually thereafter. Switching from Intranasal to Oral. If switching from intranasal to oral vaccination, a single oral dose is indicat- ed to effectively protect against B bronchiseptica infection. 5. Inappropriate Route of Administration Vaccines indicated for protecting dogs against CIRD must be