Case Study- Two Vaccinated Dogs Found to Lack Protective Antibodies

Introduction

Vaccination remains the most effective method of protecting dogs against the core viral diseases canine parvovirus (CPV), canine distemper virus (CDV), and canine adenovirus (CAV). In most dogs, vaccination induces long-lasting protective immunity. However, individual variation in immune response means that not every vaccinated dog develops or maintains protective antibody levels.

This case study presents two clinically healthy dogs that had been vaccinated according to accepted protocols but were later found to lack protective antibodies against one or more core pathogens. In both cases, antibody testing identified the gap in immunity, allowing revaccination and confirmation of protection.

Case 1: Zoey

Patient History

Date of birth: March 10, 2025
Vaccination history: Completed the puppy vaccination series at 15 weeks of age.
Clinical status: Healthy with no history suggestive of infectious disease.

At 1 year and 3 months of age, Zoey underwent routine antibody testing using VacciCheck to evaluate immunity against the canine core viruses.

Titer Results

Zoey demonstrated:

Canine adenovirus- positive
Canine parvovirus- negative
Canine distemper virus- negative

Although fully vaccinated as a puppy, Zoey lacked detectable protective antibodies against both CPV and CDV.

Clinical Management

Zoey was revaccinated with a core vaccine.

A follow-up VacciCheck performed after revaccination demonstrated protective antibody levels against all three core viruses.

Outcome

Following revaccination, Zoey tested positive for antibodies against:

Canine Parvovirus
Canine Distemper virus
Canine Adenovirus

The repeat test confirmed successful immunization.

Case 2: Tokyo

Patient History

Date of birth: March 27, 2025
Vaccination history: Received two core vaccinations while in a shelter on August 12 2025 and August 30 2025.
Clinical status: Healthy.

At 1 year and 3 months of age, routine antibody testing was performed using VacciCheck.

Titer Results

Tokyo demonstrated:

Canine adenovirus- postive
Canine parvovirus- positive
Canine distemper virus- negative

Despite receiving two documented vaccinations at 6 months of age, Tokyo lacked protective antibodies against canine distemper virus.

Clinical Management

Tokyo received a booster vaccination.

Follow-up antibody testing confirmed seroconversion to all three core viruses.

Outcome

Repeat VacciCheck testing demonstrated protective antibodies against:

Canine Parvovirus
Canine Distemper virus
Canine Adenovirus

Main Takeaway:

Although vaccination is highly effective, vaccination history alone does not guarantee that every individual dog has developed or maintained protective immunity. In both Zoey and Tokyo, antibody testing revealed gaps in protection that would otherwise have gone undetected despite documented vaccination. Following revaccination, both dogs developed protective antibody levels against all three core viruses. These cases highlight the value of serological testing as a tool to confirm immunity, identify the occasional dog that requires additional vaccination, and ensure patients are protected before natural exposure to potentially life-threatening diseases.

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