Red wolf vaccination study at PDZA

We have a guest blogger this week, Dr. Kadie Anderson, DVM at Point Defiance Zoo & Aquarium!  Dr. Anderson has graciously blogged for us previously on reproductive research that is ongoing through the Red Wolf Species Survival Plan (RWSSP) and Point Defiance Zoo & Aquarium (PDZA). 

Just like our pets, red wolves require routine and preventive care.  Most animal health programs recommend vaccinating for certain infectious disease and the veterinary arm of the RWSSP is no different.  Red wolves in the RWSSP and wild populations’ are vaccinated to protect these endangered animals against disease such as parvovirus, distemper, and rabies. 

As the field of zoo and wildlife medicine continues to advance, veterinarians often have to extrapolate treatment and management plans from models developed in similar domestic species, e.g. dogs, and apply them to non-domestic canids.   Red wolves have been vaccinated for parvovirus, canine distemper, adenovirus, and rabies on an annual basis without evidence that the vaccines conveyed adequate immunity and how long the vaccines would last.  Recent research showing that domestic dogs could maintain protective titers to distemper and parvovirus for longer than one year (and as long as 3 years) sparked the RWSSP’s interest in determining the efficacy and duration of these vaccines in non-domestic canids such as the red wolf.    

To understand this study, a brief review of how vaccines cause protective immunity is warranted.  It may come as a surprise that the first dose of many vaccines is not protective against disease.  The first dose of vaccine primes the immune system to begin developing a response to the antigen, or disease agent.  This initial response generates antibodies but usually not in sufficient quantities to generate a protective response or titer (amount of antibody).  The second and third boosters of vaccine again stimulate the immune system to generate a larger amount of antibody with each dose, eventually reaching an endpoint (for most animals) which is considered protective.  These antibodies, called IgG, circulate in the immune system for an unknown length of time waiting to react to an infection.

In 2007, PDZA received funding from PDZA’s Conservation Committee to begin a multi-year study to determine whether the vaccination interval could be increased from one year to three years for canine distemper and parvovirus vaccine products.  Facilities from around the nation participated in the study, with the majority of study animals coming from PDZA’s off-site breeding facility.  A total of 32 animals entered the study.  In order to enter the study, wolves must have completed a neonatal series of vaccines and received their annual booster vaccination.  Serology was performed to determine endpoint titers for parvovirus, distemper, and adenovirus on an annual basis.  A positive endpoint titer (considered protective) was extrapolated from that which was considered positive in domestic dogs.  While results of adenovirus protection were unclear due to varying vaccination histories and products used, 100% of wolves developed and maintained a protective titer over three years to distemper virus and ~97% of wolves developed and maintained a positive titer to parvovirus over the three year study. 

Approximately 8 week old pup receiving first series of vaccinations.
Photo: W. Waddell/PDZA

Pup receiving third vaccination at around 12 weeks of age.
Photo: W. Waddell/PDZA

These findings have changed the preventive medicine guidelines for red wolves in the RWSSP, to align with recommendations for domestic dogs, where the initial vaccination series occurring in neonates is followed with a booster at 1 year of age then triennially thereafter.  Increased vaccination intervals reduce handling and associated stress in the wolves, and minimize the risks associated with vaccination.  It is hoped that this information can also be utilized to aid in the management and risk reduction for wild red wolves, to minimize potential losses to infectious disease.