“Homeopathic vaccines” called nosodes are prepared using high, serially agitated dilutions of infectious agents (i.e. infectious body fluids, vomitus, feces, or other tissue) which are administered to the animal orally for the purpose of protecting against later infection with the respective pathogen. Though some pet owners report efficacy of nosodes for protecting against infectious disease in their dogs, controlled clinical studies exploring the ability of nosodes to protect animals who are directly challenged with infectious disease indicate that nosodes are not effective for this purpose. In a clinical study by Larson and colleagues, nosodes administered to dogs completely failed to protect against death due to parvovirus when these dogs were administered nosodes of parvovirus-infected tissue over a period of time and then subsequently challenged with the pathogen. In another controlled clinical study by W.B. Jonas comparing efficacy of vaccination to nosode protection against infectious disease, though it was found that nosodes did increase the survival time following challenge with infectious disease, efficacy of protection was only 22% for nosodes compared to 100% protection with vaccination; that is, about 4 out of every 5 animals administered nosodes died from the infectious disease when challenged. This 22% efficacy is, in fact, the highest reported efficacy for nosode protection in any controlled clinical study to date.

In light of the data showing inefficacy of nosodes for protecting against infectious disease, why are some practitioners still promoting nosode use?  Proponents of nosode-use such as Jean Dodds, DVM and others in the field do not promote the use of nosodes in lieu of vaccination of dogs in general; they promote the use of vaccine alternatives like nosodes in dogs that have a suspected predisposition (certain bloodlines with genetic risk) or underlying health conditions (as those discussed above) that put these particular dogs at higher risk for developing adverse reactions to vaccines. As will be discussed in the next section, although nosodes do not provide the assurance of protection that vaccines do, nosodes may provide some benefits over not vaccinating these dogs at all. The wide-spread notion, however, of totally replacing vaccination with the homeopathic alternative of nosodes is purported rather by some in the field of alternative medicine who continually use the reports of Dr. Dodds and others out of the context in which they were initially written.

Are nosodes a viable alternative for protection against infectious disease in dogs that cannot be vaccinated due to health complications? Vaccination remains the single most effective method for protecting against infectious disease in healthy animals. In those dogs with higher risk for developing vaccine-associated complications, alternatives such as nosodes will not provide effective protection against infectious disease if the dog is exposed to a moderate- or high-dose of infectious pathogen sufficient enough to bring about active disease or in cases of infectious disease outbreak. If one considers low-dose exposure to a pathogen, however, it is conceivable that nosodes could possibly provide some protection in regard to reducing severity of the disease. Ironically, however, this nosode protection would only be most effective in the presence of a widely vaccinated population.

The current wide-spread use of vaccination in the dog population creates a condition known as “herd-immunity”. Herd-immunity occurs when vaccination of large numbers of individuals within a population decreases the occurrence of infectious disease within a population and thus actually protects those few in the population that may not be vaccinated from being exposed to and acquiring infectious disease. Though many vaccines do not prevent a carrier state (that is, a vaccinated dog that may be exposed to an infectious pathogen will be protected from disease but may still shed the pathogen in the environment), vaccination typically reduces the amount of pathogen and the duration of time that the pathogen is shed into the environment and thus decreases likelihood of exposure to and contamination of other dogs. Therefore, herd immunity alone does not assure freedom of risk from disease. In light of the Jonas’ finding that nosode treatment did provide some protection, albeit minimal, to treated animals as evidenced by longer survival times prior to succumbing to infection, administration of nosodes to dogs with high-risk for vaccine reactions may provide some marginal benefit in reducing risk of infectious disease but only in a population protected by herd-immunity and only if these nosode-protected dogs were to receive very low exposure to a pathogen. More controlled, clinical studies, and not anecdotal reports, in this area are clearly needed, however, before one can make any assumptions on the reliability of nosodes to effectively protect against low-grade infections. As more dog owners, however, turn to using nosodes in lieu of vaccinations based upon the unsubstantiated claims that vaccines are dangerous to all dogs in general, herd-immunity will decline and with it any hopes of using nosodes as a vaccine-alternative in dogs that are verifiably at higher-risk for vaccine side-effects.

Finally, in absence of controlled clinical studies to evaluate nosode protection in the face of low-grade infection and the improbability of assuring that an individual dog is only exposed to low levels of a particular pathogen, to date the safest alternative for reducing risk of secondary vaccine side-effects while also providing effective protection is the use of alternate types of vaccines (i.e. killed-vaccines, sub-unit vaccines or mono-valent vaccines) rather than multivalent vaccines in dogs with an underlying health condition, as those discussed above, or with a suspected predisposition to vaccine side-effects. For example, recent clinical studies have demonstrated that using vaccines with a lower valency (i.e. monovalent, tri-valent) significantly reduces adverse side-effects that frequently occur with multivalent vaccines while still providing effective protection against infectious disease