Vaccines and Outbreaks in Small Animals

Outbreak vaccination

Modification of routine vaccination protocols to rapidly protect animals in a high-risk population

Seven considerations when developing an outbreak vaccination protocol

1.) Vaccine type

2.) Route

3.) Starting age

4.) Frequency

5.) Time to protective immunity

6.) Timing relative to exposure

7.) Risks

Primary priority in shelter medicine

Population health over individual animal health

Why do shelter vaccination protocols differ from routine GP protocols?

Animals have unknown vaccination histories, frequent movement, close contact, and increased exposure to infectious diseases

Main goal of vaccination during an outbreak

Establish protective immunity as quickly as possible to limit disease transmission

Three major differences between routine GP and shelter juvenile vaccination

1.) Earlier starting age

2.) Shorter vaccination intervals

3.) Later final dose

Routine GP juvenile vaccination interval

Every 3-4 weeks

High-risk shelter juvenile vaccination interval

Every 2 weeks

Why are vaccination intervals shortened in shelters?

To minimize the time animals remain susceptible in a high-exposure environment

Feline panleukopenia (FPV)

A highly contagious viral disease of cats that can cause severe illness and death, especially in kittens

Three pathogens covered by FVRCP:

1.) Feline herpesvirus-1

2.) Feline calicivirus

3.) Feline panleukopenia virus

Three feline populations requiring an updated shelter vaccination protocol:

1.) Kittens

2.) Adult cats

3.) Pregnant queens

Recommended FVRCP vaccine for shelter kittens

Modified-live (MLV), SQ

Earliest recommended age to begin FVRCP in high-risk shelter kittens

4 weeks

Recommended FVRCP frequency in shelter kittens

Every 2 weeks

Age through which shelter kittens should continue receiving FVRCP

20 weeks

Recommended timing of initial FVRCP in shelter kittens

Immediately at intake, if age-appropriate

Why begin shelter kitten vaccination at 4 weeks instead of 8 weeks?

To establish protection as early as possible in a high-risk population

Why continue shelter kitten vaccination through 20 weeks?

Some kittens retain interfering maternal antibodies through approximately 16 weeks; since age at intake is unknown continuing to vaccinate until 20 weeks eliminates potential maternal antibody interference

Most important factor when determining completion of a juvenile vaccine series

Timing of the final vaccine, not the total number of doses

Why is the number of vaccines administered less important than their timing?

Multiple early doses may be ineffective if maternal antibodies are still interfering

Shelter kitten FVRCP protocol (all together)

SQ MLV vaccine beginning at 4 weeks, repeated every 2 weeks through 20 weeks; vaccinate at intake

Recommended FVRCP vaccine for adult shelter cats

SQ modified-live

Assumption regarding an adult shelter cat with unknown vaccination history

Assume it has never been vaccinated

Recommended initial FVRCP protocol for adult shelter cats with unknown history

First dose at intake, second dose approximately 2 weeks later

Two major risks of modified-live FVRCP vaccination during pregnancy

1.) Abortion

2.) Fetal abnormalities, including cerebellar hypoplasia

Routine GP recommendation for modified-live FVRCP in pregnant queens vs shelter outbreak setting

In GP, generally avoid giving modified live vaccines to pregnant animals (instead do killed vaccines)

However, in shelter situation, use MLV despite reproductive risks because protecting the shelter population is more important

Main disadvantage of killed FVRCP during an active outbreak

Protection develops more slowly because an initial dose and booster are required

Approximate time to protective immunity with killed FVRCP

7-14 days after the second dose

Why may killed FVRCP be inadequate for a heavily pregnant queen during an outbreak?

She may give birth before protective immunity develops

Alternative management option for pregnant queens discussed in lecture

Spay-abort followed by vaccination, depending on shelter policy

Three FVRCP formulations/routes

1.) MLV SQ

2.) MLV IN

3.) Killed SQ

Preferred FVRCP route for preventing feline panleukopenia

Subcutaneous

Why is SQ FVRCP preferred over IN for panleukopenia?

It provides more effective systemic protection against FPV

Approximate time to protective immunity for the initial SQ MLV FVRCP series

7-14 days after the second dose

Three groups in which SQ MLV FVRCP is generally avoided or used cautiously in routine GP

1.) Pregnant cats

2.) Kittens younger than 4 weeks

3.) Retroviral-positive cats

Primary benefit of IN FVRCP

Rapid and local protection against respiratory disease

Why does IN vaccination stimulate local respiratory protection?

It stimulates mucosal immunity at the site where respiratory pathogens enter

Major antibody associated with local mucosal immunity

IgA

Major limitation of IN FVRCP

Less effective against panleukopenia than SQ vaccination

Possible adverse effect of IN FVRCP

Transient upper respiratory signs

When might IN and SQ FVRCP be used simultaneously?

During an outbreak when both respiratory and systemic FPV protection are desired

Two patient populations in which killed FVRCP is generally considered safer

1.) Pregnant cats

2.) Retroviral-positive cats

Major disadvantage of killed FVRCP compared with MLV during an outbreak

Requires a booster and takes longer to establish protection

FVRCP formulations (all together)

-MLV SQ: preferred for FPV

-MLV IN: rapid respiratory protection

-killed SQ: safer for certain high-risk individuals but slower protection

Recommended timing of shelter vaccination relative to intake

Immediately upon arrival; ideally before entering the shelter population

Five core feline vaccines/pathogens discussed

1.) FHV-1

2.) FCV

3.) FPV

4.) Rabies

5.) FeLV in cats younger than 1 year

Three non-core feline vaccines:

1.) FeLV in cats older than 1 year

2.) Chlamydia felis

3.) Bordetella bronchiseptica

Why are non-core vaccines used selectively in shelters?

Animals may be adopted before the initial series has time to establish protection

Two circumstances that may justify additional non-core vaccines in a shelter

1.) Active outbreak

2.) Increased individual or population risk

Approximate time to protective immunity for many non-core vaccines discussed

10-14 days after the second dose

Feline leukemia virus (FeLV)

A retrovirus that can cause immunosuppression and other serious diseases in cats

Why should FeLV prevention be considered in shelters?

Cats and kittens frequently enter with unknown histories and may introduce infection into the population

Primary route of FeLV transmission

Close contact involving infected saliva

Three activities that can facilitate FeLV transmission

1.) Mutual grooming

2.) Nose-to-nose contact

3.) Sharing food/water bowls

Two FeLV vaccine types

1.) Recombinant canarypox-vector

2.) Killed

Required step before FeLV vaccination

Test for FeLV infection

FeLV vaccination classification in cats younger than 1 year

FeLV vaccination classification in cats older than 1 year

Core vaccine

Risk-based/non-core

Earliest recommended age for FeLV vaccination

8 weeks

Initial FeLV vaccination series

Two doses, 2-4 weeks apart

Approximate time to FeLV protective immunity

7-14 days after the second dose

Timing of first FeLV revaccination after the initial series

12 months after the final initial dose

FeLV vaccination protocol (all together)

Test first; begin at 8 weeks; two doses 2-4 weeks apart; revaccinate after 12 months, then according to risk

Two rabies vaccine types

1.) Killed/inactivated

2.) Recombinant canarypox-vector

Approximate time to protective immunity after a cat's first rabies vaccination

28 days

Initial rabies vaccination requirement compared with most killed vaccines

Only one initial dose is required

Protection following subsequent rabies boosters, as described in lecture

Immediate recognized protection, even if overdue

What determines rabies revaccination frequency?

Local laws and vaccine labeling

Recombinant rabies vaccine

A non-adjuvanted vaccine using a canarypox vector to deliver rabies antigen

Four major risks/challenges of shelter outbreak management

1.) Vaccination risks

2.) Movement restrictions

3.) Communication

4.) Financial/reputational consequences

Movement restriction during an outbreak

Limiting animal transfers and adoptions to reduce disease transmission

Why might animal movement need to be stopped during an outbreak?

To prevent infectious animals from spreading disease to other populations

Four negative consequences of prolonged movement restrictions

1.) Reduced adoptions

2.) Increased stress

3.) Increased secondary illness

4.) Increased housing costs

Why is rapid outbreak control particularly important in shelters?

It allows normal animal movement and adoptions to safely resume

Main concern in the boarding/daycare scenario

Dogs developing upper respiratory infections after attending the facility

Four major updates recommended for the boarding/daycare protocol

1.) Clarify vaccine requirements

2.) Add influenza/lepto

3.) Require vaccination before entry

4.) Improve screening/isolation

Major flaw in allowing dogs to receive vaccines on the day of boarding

Protective immunity has not had time to develop

Recommended general vaccination planning window before boarding

Approximately 3 weeks before entry

Recommended waiting period following the final required vaccine/booster

Approximately 2 weeks before daycare entry

Why is vaccination status alone insufficient for determining boarding eligibility?

An animal may have received its vaccines but not yet developed protective immunity

DAPP vaccine

Combination vaccine protecting against canine distemper, adenovirus, parvovirus, and parainfluenza

Four pathogens covered by DAPP

1.) Distemper

2.) Adenovirus

3.) Parvovirus

4.) Parainfluenza

Recommended DAPP vaccine type and route

Modified-live, SQ

Recommended age for the final puppy DAPP vaccine

16-20 weeks

Why is requiring at least three DAPP vaccines before daycare insufficient?

All three may have been administered too early to overcome maternal antibody interference

Most important consideration when evaluating a puppy's DAPP history

Whether the final dose was given at an appropriate age (16-20 weeks)

Recommended waiting period after the final puppy DAPP vaccine before daycare

Approximately 2 weeks

Two acceptable vaccination histories for adult dogs in the lecture's boarding protocol

1.) Completed puppy series + adult booster

2.) Appropriate initial adult series

Recommended approach for an adult dog with unknown vaccination history in the lecture

Administer an appropriate initial two-dose series

DAPP requirements for boarding (all together)

Puppies: final dose at 16-20 weeks

adults: appropriate completed series/booster history; allow time for immunity before entry

Bordetella bronchiseptica

bacterium associated with canine infectious respiratory disease complex (kennel cough)

Three Bordetella vaccination routes:

1.) Subcutaneous

2.) Oral/oral transmucosal

3.) Intranasal

SQ Bordetella vaccine type

Killed

Initial requirement for SQ Bordetella

Initial dose followed by a booster

Approximate time to protection with SQ Bordetella

2-3 weeks

Major disadvantage of SQ Bordetella in boarding facilities

Slower protection and reduced efficacy compared with preferred mucosal options

Oral Bordetella vaccine type

Modified-live

Oral transmucosal (OTM) vaccination

Administration intended to maintain vaccine contact with the oral mucosa

Respiratory pathogen not included in the oral Bordetella formulation discussed

Parainfluenza

Preferred Bordetella vaccination route for the boarding scenario

Intranasal