Vaccination

Vaccination exposes the immune system to a modified or inactivated pathogen (or its components), triggering an adaptive immune response that produces memory B cells and T cells. When the dog later encounters the actual pathogen, these memory cells mount a rapid, effective response — preventing disease or reducing its severity.

Core vs. Non-Core Vaccines

The American Animal Hospital Association (AAHA) classifies canine vaccines into two categories:

Core Vaccines (Recommended for All Dogs)

Vaccine	Disease	Why Core
Canine distemper virus (CDV)	Distemper	Fatal multisystemic disease; no treatment
Canine parvovirus (CPV-2)	Parvovirus	Fatal GI disease in puppies; highly contagious
Canine adenovirus-2 (CAV-2)	Infectious hepatitis	Severe liver disease; cross-protects against CAV-1
Rabies	Rabies	Fatal zoonotic disease; legally required

Non-Core Vaccines (Risk-Based)

Vaccine	When Recommended
Leptospirosis	Dogs with outdoor/water exposure; increasingly recommended broadly
Bordetella + parainfluenza	Dogs in boarding, daycare, dog parks
Lyme disease	Dogs in endemic tick regions
Canine influenza (H3N2/H3N8)	Dogs in social settings during outbreaks

Puppy Vaccination Schedule

Puppies receive maternal antibodies through colostrum that provide temporary protection but also interfere with vaccine response. The puppy series uses multiple doses to ensure protection as maternal antibodies wane:

• 6-8 weeks: first DHPP (distemper, hepatitis, parainfluenza, parvovirus)
• 10-12 weeks: second DHPP
• 14-16 weeks: third DHPP + rabies
• 12-16 months: first adult booster

The final puppy dose must be given at 16 weeks or later — earlier completion leaves a vulnerability window.

Adult Revaccination

AAHA guidelines (2022 revision) recommend:

• Core vaccines: every 3 years after the 1-year booster (evidence supports duration of immunity of 5-7+ years for CDV, CPV, CAV)
• Rabies: per local law (1-year or 3-year depending on jurisdiction and product)
• Non-core vaccines: annually (leptospirosis, Bordetella, Lyme, influenza — shorter duration of immunity)

Titer Testing

Serum antibody titer testing measures circulating antibodies against specific pathogens. For core vaccines (distemper, parvovirus, adenovirus), a positive titer indicates protective immunity — revaccination is unnecessary regardless of time since last vaccination.

Titer testing is particularly valuable for:

• Dogs with previous vaccine reactions
• Dogs with immune-mediated disease where vaccination may trigger flares
• Senior dogs where owners wish to minimize unnecessary medical interventions
• Dogs where vaccination history is unknown

A positive titer means the dog is protected. A negative titer means revaccination is indicated.

Over-Vaccination Concerns

The concept of over-vaccination — administering vaccines more frequently than immunologically necessary — has driven the shift from annual to 3-year core vaccine protocols. Documented concerns include:

• Vaccine-site reactions: injection-site sarcomas are well-documented in cats; rare but reported in dogs
• Immune stimulation: unnecessary immune activation in dogs with autoimmune tendencies
• Cost and stress: unnecessary veterinary visits and injections

The current AAHA guidelines represent a science-based balance between adequate protection and minimal unnecessary vaccination. Vaccination schedule optimization discusses this balance in detail.

Practical Recommendations

• Complete the full puppy series — incomplete vaccination is a leading cause of preventable puppy death
• Follow AAHA 3-year core vaccine guidelines for adult dogs
• Use titer testing when appropriate rather than defaulting to revaccination
• Discuss non-core vaccine needs based on your dog’s specific lifestyle and geographic risk factors
• Do not skip rabies vaccination — it is legally required and rabies is 100% fatal