Information Sheet
Vaccination

Table of Contents

Introduction
Dog Vaccines
Cat Vaccines
Types of Vaccines Available
Which Vaccines should a shelter use?
Which animals should be vaccinated?
When should the vaccine be given?
What should the revaccination (booster) schedule be?
Proper Vaccine Handling and Administration
Proper locations of vaccine injections
Vaccine reactions
Adverse effects of vaccines given by incorrect route
Vaccine failures
Other Sources of Information

Introduction

This protocol was developed for use in shelters, rescue groups, or any other facility housing more than 5 animals at one time, This is not the correct protocol for use in private homes. If you are interested in viewing UC Davis' recommendations for vaccination of privately owned animals please visit the VMTH's vaccine guideline site.

Strategies for vaccination in a shelter or other high-turnover small animal population are different in many ways from those for a privately owned pet. The likelihood of exposure to disease is often very high, and the consequences of infection potentially severe for both the affected animal and the shelter population. A well designed vaccine program can be a life saving tool to keep shelter animals healthy. Some vaccines provide protection within a few days or even a few hours of administration, and can drastically reduce the frequency of life-threatening disease in the shelter. Other vaccines, while less impressive, can reduce the frequency and severity of disease both within the shelter and after release to adopters or rescue groups. This can help the shelter's repuation and facilitate increased adoptions and improved relations with rescues, conferring a benefit well beyond the vaccine itself.

Of course, vaccination is not a magic bullet for disease prevention. Even the best vaccintes take some time to provide protection, and animals may enter the shelter already incubating disease. In addition, vaccination does not provide protection to 100% of vaccinates under the best of circumstances, and animals entering shelters stressed and malnourished may not respond optimally. Finally, vaccines are not available for all diseases of importance in shelters, and do not provide complete protection for some diseases even when there is a vaccine available. Vaccines can help but are never a substitute for good overall animal husbandry.

Questions to consider

As with a private pet, the vaccination strategy should reflect the needs of the particular shelter population. While some generalities can be made, to some extent the vaccine program depends on the prevalent diseases in the area, population characteristics ( e.g.... low versus high turnover, animal control versus adoption facility, mostly owner surrendered versus mostly stray animals) and shelter resources and philosophy. Ultimately, establishing the ideal vaccine protocol for a particular shelter may require some trial and error. It is important to monitor disease levels before and after trying a new vaccine protocol. Once the level of disease is understood, shelters should consider the questions and answers addressed in this document which apply to most situations.

What pathogens should we vaccinate against?

Core vaccines are vaccines indicated for virtually all shelter animals, and include vaccines against those agents which are very likely to be a threat and for which vaccines are at least somewhat protective. Limiting vaccines to core components reduces cost and incidence of adverse reactions.

Dog Vaccines

Core Vaccines for dogs in shelters

• Distemper (CDV)
• Adenovirus-2 (CAV-2/hepatitis)
• Parvovirus (CPV)
• Parainfluenza (CPiV)
• Bordetella bronchiseptica

The first four antigens are often grouped into one vaccination (DA2PP or DHPP) administered by a single injection given under the dog’s skin (subcutaneously/ SQ.).Puppies should be vaccinated starting at 4-6 weeks of age and revaccinated every 2-4 weeks until 16-18 weeks of age (earlier end of age range and shorter interval when infectious disease risk is high). Adult dogs should be vaccinated once at intake. If resources permit, a second vaccination 2-4 weeks later may be beneficial if poor health prevented an optimal response to the vaccine given on intake.

Vaccines for Bordetella bronchiseptica are available with or without canine parainfluenza and canine adenovirus-2. A recent study showed modest benefit even in a shelter where dogs were likely exposed to high levels of disease early in the shelter stay. [Edinboro, 2004 #762] In general, intranasal vaccination is recommended due to the demonstrated rapid onset of immunity (3-5 days) and the potential benefits of local IgA derived protection. Additionally, this vaccine can be used in puppies as young as 2-3 weeks of age, and may provide local immunity even in the face of maternal antibody.

Quasi-core vaccine:

• Rabies: Rabies vaccination may be given at the time of adoption or by the adopter’s new veterinarian, depending on local legal requirements, shelter philosophy and resources. Shelters which house dogs long term may consider vaccinating for rabies at intake.

Vaccines not generally recommended ( because of undemonstrated efficacy and/or low risk of disease transmission within shelter.)

• Canine coronavirus.
• Giardia
• Vaccines for diseases which pose minimal infectious risk within the shelter (e.g. leptospirosis, Lyme disease) are generally not indicated until after adoption, when the dog’s individual risk profile can be assessed.
  

Cat Vaccines

Core Vaccines for cats in shelters

• Feline herpesvirus-1 (feline viral rhinotracheitis/FHV-1)
• Feline calicivirus (FCV)
• Feline panleukopenia (FPV)

Feline vaccinations are usually grouped into one vaccination (FVRCP). Modified live subcutaneous vaccination is generally recommended because of demonstrated rapid onset of protection and good efficacy in the face of maternal antibody. Kittens should be vaccinated starting at 4-6 weeks of age and revaccinated every 2-4 weeks until 18 weeks of age (earlier end of age range and shorter interval when infectious disease risk is high). Adult cats should be vaccinated once at intake. If resources permit, a second vaccination 2-4 weeks later may be beneficial if poor health prevented an optimal response to the vaccine given on intake.

Cat vaccines occasionally recommended:

Use of these vaccines should be reserved only for shelters in which infection has been confirmed by laboratory diagnostics as an ongoing problem.

• Chlamydophila felis (C. psittici): The efficacy of the vaccine is low, disease is generally infrequent and adverse reactions may be relatively common. This vaccine should be considered when disease has been confirmed by laboratory diagnostics and/or very suspicious clinical signs. The need for this vaccine should be periodically re-assessed.
  
• Bordetella bronchiseptica: Vaccination does not have proven benefit in shelters and may cause mild signs of URI in some vaccinates. This vaccine should be considered when disease has been confirmed by laboratory diagnostics. The need for this vaccine should be periodically re-assessed.

• Rabies: Rabies vaccination may be given at the time of adoption or by the adopter’s new veterinarian, depending on local legal requirements, shelter philosophy and resources. Shelters which house cats long term may consider vaccinating for rabies at intake.

 

Vaccines not generally recommended ( because of undemonstrated efficacy and/or low risk of disease transmission within shelter.)

• Feline coronavirus (“FIP vaccine”) : There is currently only one vaccine available for feline coronavirus, a modified live intranasal product labeled for use in cats > 16 weeks of age, to be given as a series of two vaccines 3-4 weeks apart. Results of studies regarding the efficacy of this vaccine have been variable, some showing no efficacy and others showing limited efficacy under certain circumstances. One study showed a significantly decreased risk of FIP for cats that were seronegative at the time of vaccination. Although there may be some benefit to giving the vaccine to cats that have never before been exposed to a multi-cat environment (and are therefore relatively likely to be seronegative), most shelter cats will have long since been exposed by the time the recommended booster vaccine can be administered.
• FeLV
• FIV
• Giardia

Types of Vaccines Available

Each type of vaccine has advantages and disadvantages. In shelters, the most important aspects of each vaccination choice are outlined here. In the vast majority of cases, modified live or recombinant vaccines are the preferred choice in shelters.

Advantages of modified live vaccine (MLV):

• Provides a relatively rapid onset of immunity (5-7 days for antibody development, significant protection within hours to days for some vaccines.)
• A single dose of MLV vaccine can offer protection.
• Better able to overcome maternal antibody interference.
• Prevents shedding as well as disease from some agents (e.g. parvo), providing better population protection.
• Produces mucosal immunity when given by appropriate route (important for prevention of some respiratory diseases.)

Disadvantages of modified live vaccine (MLV):

• Can produce mild signs of disease indistinguishable from natural infection.
  • Can create complacency and failure to isolate ill animals (“it’s just a vaccine reaction”).
  • Can overburden isolation areas and cause longer stays for affected animals.
  • Can lead to euthanasia for vaccine induced sneezing; however, shelters that must euthanize mildly sneezing cats generally are overwhelmed with healthy adoptable animals. Thus, euthanasia for vaccine induced sneezing may not lead to an overall increase in euthanasia, and may afford significant population protection.
• Can cause shedding of antigen which may be indistinguishable from field strain on diagnostic tests.
• May establish infection and carrier state with vaccine strain virus.
  • This can occur with the feline respiratory viruses
  • Once carrier state is established, virus may be continually shed into the environment, increasing the possibility of reversion to virulence.
• Some vaccines (e.g. distemper) can produce significant disease in severely immunosuppressed animals. “Everyday” immunosuppression associated with such things as stress, poor nutrition, surgery have not been shown to increase vaccine induced disease. Genetic immune deficiency, chemotherapy, or parvoviral infection are more significant risk factors. [Greene, 1998; Miyamoto, 1995]. Animals so severely immunosuppressed that vaccination poses a meaningful risk are unlikely to survive exposure to the many pathogens in a shelter; a rule of thumb is that an animal not healthy enough to vaccinate should not remain in a shelter except under strict isolation.
• Some MLV (e.g. feline panleukopenia, parvovirus) may cause death or disease of fetuses and very young animals (< 4 weeks).
• MLV vaccines can be inactivated by incorrect storage or handling.
• May produce significant disease when given by the incorrect route ( e.g. parenteral FVRCP given intranasally, intranasal Bordetella bronchiseptica given parentally.

Using Killed Vaccine:

The advantages and disadvantages of killed vaccines reflect the flip side of those listed for modified live vaccines. Killed vaccines will not cause shedding of antigen nor cause disease even in pregnant or very young animals, and are much more tolerant of variations in storage and handling. The most significant disadvantage of killed vaccines is that protection will not be acquired until 1-2 weeks after a booster vaccine is given (2-3 weeks after initial vaccination). This means naïve animals will not be protected for up to five weeks after vaccination! In a shelter the animal almost certainly will have been exposed to disease long before the vaccine can provide protection For all their advantages of safety and store-ability, then, this single problem greatly limits the usefulness of killed vaccines in the shelter environment.

Other Vaccine types

Other types of vaccines containing synthetic or genetically engineered antigen have been developed. For example, a recombinant vaccine for canine distemper is available. While recombinant vaccines may offer good protection with minimal side effects, purified or recombinant products often require the same booster schedule and time to onset as a killed vaccine. Recombinant vaccines are also generally more costly than traditional MLV or killed. These factors limit use of recombinant products in shelters. However, a recombinant vaccine for canine distemper (Merial) has been shown to provide rapid protection similar to standard MLV vaccines, and better efficacy in the face of maternal antibody (Larson, 2006). In the future, attenuated products may be produced using selective deletion or vectored delivery systems with the advantages of a modified live vaccine and the safety of a killed vaccine. Stay tuned!

So which vaccine should shelters use?

For diseases which are a serious threat and for which vaccine protection is good, a modified live or recombinant vaccine is clearly preferred. For canine core vaccines, most available vaccines are modified live combination products which include distemper, canine adenovirus 2, parvo and parainfluenza (DA2PP or DHPP). If Bordetella bronchiseptica vaccine is used (with or without adenovirus 2 or parainfluenza), a modified live intranasal product is generally indicated due to the more rapid onset of protection. The simultaneous use of both parenteral and IN vaccination for kennel cough may provide some additional protection, though this may not justify the extra cost. [Ellis, 2001] Additionally, the subcutanous vaccine used in this study is no longer available; it is unknown whether the currently available subcutaneous product, which is an antigen extract as opposed to a whole cell killed bacterin, would have the same effect. For more information on vaccination for canine infectious respiratory disease complex, please see our canine infectious respiratory disease information page.

For cats, the core vaccines are available as killed or modified live combination products (feline viral rhinotracheitis, calicivirus and panleukopenia, FVRCP). In recent years, feline panleukopenia has re-emerged as a near-ubquitous threat. Vaccine-induced protection against FPV is excellent. Routine use of a modified live parenteral vaccine containing panleukopenia will provide optimal protection against outbreaks of this devastating disease.

The case for modified live versus killed vaccine against feline respiratory viruses is less clear cut. Vaccines against these viruses provide only partial protection at best, making the risk/benefit ratio less obvious than with FPV. Feline respiratory vaccines do not protect against infection or development of a carrier state, and resistant strains of feline calicivirus are common. [Pedersen, 1995; Weigler, 1997] [Lauritzen, 1997] [Dawson, 1993] Some cats will experience mild signs of URI such as sneezing or mild oral inflammation after modified live vaccination. This is more common with intranasal vaccines but may occur with parenteral vaccines as well. For shelters with no ability to isolate or monitor sneezing cats, this can present a significant problem. Killed products are also preferred for shelters or mobile operations without the ability to correctly store modified live vaccines. Unfortunately, there is no product currently available that offers the ability to give killed URI components and modified live panleukopenia virus. Therefore the choice must be made to give either all killed components (e.g. Fel-o-vax®, Fort Dodge), all modified live (many brands available), or a killed multivalent FVRCP with a single antigen MLV panleukopenia vaccine (e.g. Felocell-FPV®, Pfizer) in addition.

Intranasal vaccines for cats are modified live, and are available as bivalent products containing only the respiratory viruses, or trivalent containing the respiratory viruses and feline panleukopenia. Because intranasal vaccination is not as reliably effective to protect against feline panleukopenia, all cats should be vaccinated with a parenteral MLV panleukopenia vaccine, regardless of whether or not IN respiratory vaccines are used. One study suggested that giving an intranasal vaccine in addition to the parenteral vaccine provides extra protection against feline URI. [Edinboro, 1999]

Vaccinating kittens as young as 2 weeks old (with the bivalent product only!) provides some protection, although keeping these vulnerable babies out of the shelter is of greatest importance. Shelters which have used the intranasal vaccine for control of URI give mixed reviews. Some shelters report a decrease in disease, some an increase, and some report no change. Shelters choosing to try this vaccine should monitor URI levels carefully to make an informed decision.

Which animals should be vaccinated?

All animals should be considered unvaccinated unless a documented medical record exists. Therefore, with a few exceptions described below, all animals over 4 weeks of age regardless of health status should be vaccinated upon shelter entry provided they can be safely handled. Special consideration should be given to animals with medical conditions, pregnant and animals < 4 weeks old.

Animals with medical conditions:
In general, even injured animals and those with medical conditions should be vaccinated. Although they may not mount an optimal response, the risk of exposure to the full strength pathogen is too great in most shelters to warrant delaying vaccination. Vaccination can be repeated after recovery (no less than two weeks later.) There is nothing more frustrating than treating an animal for an injury only to have it succumb to infectious disease. Vaccine response has been shown to be impaired in animals with a temperature of >103.6 whether due to fever or high environmental temperature. [Greene, 1998] If possible, such animals should be cooled down prior to vaccination. Animals with severe immunosuppression (such as cats symptomatic for FIV or animals being treated with some chemotherapeutics) should be carefully isolated and given killed or recombinant vaccines if available. Remember, if an animal is too immune-suppressed to be safely vaccinated, it is unlikely to survive exposure to all the many pathogens present in a typical shelter environment.

Other conditions that must be considered:

1. The age of the animal- Modified live parvo/panleukopenia vaccines should not be given to puppies or kittens less than four weeks old. Intranasal/intraocular vaccines for upper respiratory infection may be used in puppies and kittens as young as 2-4 weeks old. (The 3 way intranasal FVRCP vaccine can not be used, however, as the panleukopenia component is contraindicated as described above.)
   
   
2. Pregnant animals:

   Although very little data exists, it is thought that in a mother who has never been vaccinated or exposed, modified live parvo and panleukopenia vaccines may cause abortion or fetal damage. In mothers who have been previously immunized, on the other hand, there is likely no risk to the litter. In one study, abortions were no more common in queens vaccinated with an MLV FVRCP vaccine during pregnancy, and their kittens were considerably less likely to suffer from upper respiratory infection than kittens born to queens not vaccinated during pregnancy. (We can chalk that benefit up to the increased maternal antibody received by the litter.) The bottom line is, there is likely some risk of causing fetal damage when we vaccinate pregnant animals who have never been vaccinated before. On the other hand, there is some risk in not vaccinating: if the mother contracts a fatal illness, both mother and litter will be lost. It all comes down to weighing the risk of exposure versus the risk to the litter. If you almost never see serious disease in your shelter or you can reliably prevent exposure, then the risk may outweigh the benefit. If risk of exposure is reasonably high, then the benefit of vaccination likely outweighs the risk. If URI is a frequent problem in foster litters, that provides further reason to vaccinate during pregnancy. Keep in mind the special considerations for a legal hold – there are many reasons besides vaccination for abortion, but a vaccine may be blamed if given to an animal at the center of a contentious legal case. In that situation, make every effort to find out the animal’s vaccine status from the owner, and either gain consent from the owner for vaccination or carefully protect her from exposure to illness rather than risking a vaccine without consent. Finally, any time a spay-abortion is planned, immediate vaccination of the pregnant animal is indicated.

   
   
3. Finally, adoptability is sometimes a factor when deciding who should be vaccinated. As discussed above, shelters which euthanize a high proportion of animals may limit vaccines to animals deemed likely to be adopted. Although preferable to not vaccinating at all, this approach has several disadvantages:
   
   1. Numerous non-vaccinates in the population may lead to overwhelming levels of disease in the environment.
   2. Animals deemed unadoptable but redeemed by their owners will be at risk of acquiring infectious disease at the shelter and may carry that disease back into the community
   3. Animals that don’t seem adoptable at first but come around after a few days will be at risk.

When should the vaccine be given?

Immediately upon intake, if not sooner! In almost all cases, shelter animals should be vaccinated immediately upon intake. A delay of even a day or two will significantly compromise the vaccine’s ability to provide protection. In a cost saving effort, some shelters delay vaccination until the animal is made available for adoption, or even until it is adopted. While this does provide a service to adopters, the protective effect of the vaccine within the shelter is greatly reduced or eliminated. (In some cases, the chance of the vaccine preventing disease may be 90% or better if given the day before exposure, but will drop to less than 1% if given the day after exposure.) When possible, vaccination prior to intake is ideal (e.g. for owner surrendered animals or those returning from foster care).

An exception may be made for animals that are not good candidates for vaccination upon shelter entry due to severe disease (as described previously). For shelters which euthanize the great majority of their population, vaccinating all animals upon intake may be impractical. Resources may be better spent on improving adoption opportunities in this case. Good adoption candidates should still be identified and vaccinated upon intake, however, rather than waiting until the end of the holding period to make this decision. This will facilitate work with rescue groups as well as improving the animal’s chance of surviving its shelter stay.

What should the revaccination (booster) schedule be?

In animals with a normal immune response, booster vaccines per se are not required for modified live vaccines. Repeated vaccines are given to animals under about four months of age in order to minimize problems with maternal antibody interference. Revaccination may also be indicated in case of a sub-optimal immune response to the initial vaccination.

Puppies and kittens should be vaccinated every 2-3 weeks until they reach 16- 18 weeks of age. Consider revaccination of adults in 2-3 weeks or after adoption. If killed virus vaccine is used, all animals must receive a booster 2-4 weeks later. As noted, booster vaccines are not normally needed for modified live products. However, animals in shelters may not respond optimally to the initial vaccine, especially if they were in a debilitated condition at the time. Particularly if the animal was mildly ill at the time of initial vaccination, a second vaccine after recovery may be helpful (at least two weeks later). Alternatively, a recommendation could be made to adopters to discuss revaccination along with additional indicated preventive health measures with their new veterinarian. Although this imposes a slight extra cost on adopters and subjects the animal to another vaccination, a parvo case in a “supposedly vaccinated” adopted animal is well worth avoiding.

A few words on Maternal Antibodies:
Maternally derived antibodies are transmitted primarily in colostrum received by nursing puppies and kittens in the first 24-72 hours of life. The level of protection from maternal antibodies depend on the quality of the mother’s colostrum (that is, the amount of antibody it contains) and the amount ingested and absorbed by the neonate. Low levels of antibody may exist if the mother was neither immunized nor naturally exposed, or if the puppies or kittens did not nurse well due to illness, stress or separation from mom.

Maternal antibodies are a mixed blessing in the shelter environment. They provide much needed protection while the newborn animal’s immune system develops, but also can prevent effective vaccination for up to 16 weeks. At the age of 4-6 weeks, maternal antibody levels start to decrease, and they are usually gone by the age of 16 weeks.  The problem is, there is a variable time period over which the level of maternal antibodies wanes, so we never know exactly when the levels will be low enough to no longer protect the animal and to allow effective vaccination.

Figure 1. Window of susceptibility; The time at which antibody level is no longer sufficient to protect from infection, yet high enough to prevent vaccination.

During the "window of susceptibility" antibody levels are sufficient to prevent vaccination but inadequate to prevent infection (figure 1). The time at which this window occurs depends on the disease agent and the amount of antibodies initially present. For most diseases, this window occurs somewhere between 6-16 weeks old. Although greatly reduced by “high antigen mass” vaccines now widely available, this window still exists and is particularly a problem with parvovirus vaccination.

Young animals are given a series of vaccines in order to minimize the window of susceptibility and ensure that a vaccine is received as soon as possible after maternal antibodies have dropped to a level that allows the animal’s immune system to respond. In shelter animals, vaccines 2-3 weeks apart until 16 weeks of age are recommended. Vaccination less than 2 weeks apart runs the risk of interference by the immune response to the previous vaccine and should be avoided.

Proper Vaccine Handling and Administration

In order to be effective, vaccines must be stored and administered correctly. Following manufacturer directions not only preserves efficacy of the vaccine, it makes it easier to obtain manufacturer support in cases of vaccine failure or adverse reactions. As in private practice, date of vaccination, vaccine type, manufacturer and serial number should be entered into a permanent medical record. At minimum, vaccine type and date must be recorded for each animal, and the dates of use for each batch recorded by serial number in some central location in case of adverse reactions.

Handling and storage

Heat, excessive cold, and exposure to light are capable of inactivating vaccines. Modified live vaccines should arrive cold from the manufacturer and be refrigerated immediately. Always refrigerate vaccines away from the freezer compartment (Excessive cold can alter the vaccine, which may cause pain and local reactions to injection.) Modified live vaccines that have not been refrigerated for more than 2 hours may be ineffective and should be discarded.

Vaccine preparation

Always follow manufacturer’s guidelines for preparing the vaccine. Use appropriate size syringe & needle to safely prepare and administer the vaccine. In most cases, a 3cc Lure-lock type syringe with a 22 gauge inch needle is appropriate. Smaller gauge needles may be used, but may result in slower administration. Use only one vaccine per single-use syringe and needle. Use only the diluent provided by the manufacturer. Vaccines that are reconstituted in a diluent must be completely dissolved before drawing into syringe.

Administration

All vaccines should be administered only by the route designated by the manufacturer. Administration by the wrong route may cause serious disease or death. Intranasal canine Bordetella vaccine may cause severe reactions if given subcutaneously. Modified live subcutaneous feline FVRCP vaccine may cause serious upper respiratory infection if administered intranasally, or even if a cat licks up spilled vaccine. If a vaccine is accidentally given by the wrong route, the vaccine manufacturer should be contacted for specific recommendations. If an injectable vaccine is spilled, clean vaccine off animal’s fur with alcohol swabs. Use standard dilute bleach (1:32) for table tops, etc.

Parenteral (subcutaneous) vaccine administration procedure

1. Always have enough people and use proper animal restraint to administer the vaccine safely.
2. Gently grasp and lift a fold of skin to tent the skin over the proper location.
3. Insert the needle into the fold of skin (make sure that the needle is all the way into the subcutaneous space but not poking through to the other side of the fold).
4. Aspirate by drawing back on the syringe plunger. You should encounter some resistance. If you draw back and aspirate anything other than a small bubble of air (often trapped in the needle hub):
a. Remove the needle from the skin.
b. Check needle for proper seal on syringe, replace if defective.
c. Reinsert needle into skin.
5. Depress the plunger slowly to inject the vaccine. If a large amount of resistance is encountered, reposition the needle into the subcutaneous space and attempt to re-inject.
6. When vaccine is completely injected, remove needle from skin.
7. Dispose of syringe and needle appropriately.
8. Check the injection site immediately afterward for any blood or spilled vaccine.
9. Gently massage the vaccine area to disperse the vaccine under the skin.

Proper locations of vaccine injections

DOGS

All subcutaneous vaccines should be given in the subcutaneous space between the shoulder blades.

CATS Follow the guidelines from the American Association of Feline Practitioners, with all vaccines given as far down on the limb as possible:

• FVRCP - Right shoulder
• Rabies - Right rear leg
• FeLV - Left rear leg

Intranasal/intraocular vaccine administration procedure

These vaccines should be administered topically according to the manufacturer’s instructions.
Use a single use syringe for each vaccination. Splitting vaccine for very young kittens may be acceptable, check with your vaccine manufacturer.

Vaccine reactions

Vaccines can have a range of adverse effects, including:

1. Local inflammation, swelling or hair loss (most common).
2. Mild symptoms such as sneezing or lethargy.
3. Systemic reactions
   • fever and limping secondary to MLV feline calicivirus in kittens- Usually responsive to analgesics, resolves in 3-4 days
   • Vaccine associated hypertrophic osteodystrophy and juvenile cellulitis associated with modified live distemper vaccination- Most common in Weimaraners, occasionally seen in other large breeds.
   • Vaccine site sarcomas- AAFP guidelines should be followed. See AAFP Guidelines
   • Anaphylactic shock (type 1 hypersensitivity)

Fortunately the more severe reactions are very uncommon, and the benefits of vaccinating shelter animals greatly outweigh the risks. Reported reactions in one study were estimated at .004%. However, many shelters care for thousands or even tens of thousands of animals a year, leading to a high probability of eventually seeing a serious reaction. All adverse vaccine reactions should be documented on the animal’s permanent record so that adopters can be made aware of this history. Even mild reactions such as vaccine site swelling should be noted and monitored closely. Anaphylactic shock in particular requires immediate recognition and treatment. If vaccines are administered by staff other than the veterinarian, clear written directions should be posted regarding recognition and treatment of anaphylactic shock (“treatment” may include taking the animal immediately to a local emergency clinic if resources are available and treatment in-house exceeds staff training). A crash kit for treatment of anaphylactic shock should be available at all times.

Adverse effects of vaccines given by the incorrect route

Some modified live vaccines can produce significant disease when given by the wrong route.

Bordetella bronchiseptica vaccine

Intranasal Bordetella vaccine inadvertently given subcutaneously can cause a local inflammatory reaction, abscessation and in rare cases severe complications including liver failure and death. [Toshach, 1997] The most important thing is to make sure such mistakes are reported so the animal can be monitored and treated accordingly (not so staff get in trouble – it can happen to anyone!).

Pre-emptive treatment recommendations for the incorrect SQ administration of the intranasal Bordetella vaccine as provided by the ASPCA Animal Poison Control Center include:
1. Local infusion of gentamicin (2-4 mgs/kg) diluted in 10-30 mls sterile saline at the injection site.
2. Oral antibiotics effective against Bordetella (e.g. doxycycline).
3. Monitor and provide additional supportive care and diagnostics if further signs develop (e.g. vomiting, diarrhea, anorexia).

Feline respiratory virus vaccines (FVRC)

Modified live parenteral feline respiratory virus vaccines are temperature sensitive mutants that depend on being given at the higher core body temperature in order to reduce virulence. When these vaccines are accidentally given by the oronasal route, severe upper respiratory infection can develop. This is most likely due to the calicivirus component, and most commonly occurs when vaccine is spilled on the cats fur (e.g. when the needle is poked all the way through and out the skin instead of placed in the subcutaneous space).

In order to avoid this:
1. Draw up vaccine and eliminate air bubbles well away from the cat’s face.
2. Immediately wipe any spilled vaccine with alcohol (on the cat) or bleach (in the environment).

Vaccine failures

Vaccines may fail to protect animals for a variety of reasons, including:

Animal problems:
1. Already infected at time of (or soon after) vaccination. This is the most common reason for failure in shelters.
2. Maternal antibody interference (figure 1).
3. Failure to mount immune response.

Response to vaccination follows a bell curve. There will always be a few outlying animals which do not respond well to a vaccine. Even excellent vaccines given correctly will not protect 100% of animals

Always remember that vaccine can never generate better protection than natural infection. For agents such as feline herpesvirus or feline calicivirus that do not produce sterilizing immunity even with full blown disease, vaccines can not offer complete protection.

Potential sources of vaccine problems:
1. Incorrect storage or administration.
2. Use of chemicals to sterilize re-used syringe.
3. Vaccine antigens not protective against field strain virus.
4. Problem in manufacturing of vaccine

Always remember, a well thought out vaccination strategy can reduce, but will never completely eliminate, vaccine failures.

Other Sources of Information

• Dr. Kate Hurley's Article on Shelter Vaccination Frequently Asked Questions (464KB PDF) originally published in Animal Sheltering Magazine
  
  
• The 2006 American Animal Hospital Association Canine Vaccine Guidelines
  
  
• The 2006 Feline Vaccine Advisory Panel Report- posted November 6, 2006 (This is a 685KB PDF file) For more information visit The American Association of Feline Practitioners website
  
  
• Craig Greene’s C. Infectious diseases of the dog and cat. Especially the chapter on Immunoprophylaxis and immunotherapy. (3rd. ed Philadelphia: W. B. Saunders Company, 1998;717-750.)

 

References used in creating this protocol

 

Larson, L. J. and R. D. Schultz (2006). "Effect of vaccination with recombinant canine distemper virus vaccine immediately before exposure under shelter-like conditions." Vet Ther 7(2): 113-8.

Edinboro CH, Ward MP, Glickman LT. A placebo-controlled trial of two intranasal vaccines to prevent tracheobronchitis (kennel cough) in dogs entering a humane shelter. Preventive Veterinary Medicine 2004;62:89-99.

Greene C. Immunoprophylaxis and immunotherapy. Infectious diseases of the dog and cat. 2 ed. Philadelphia: W. B. Saunders Company, 1998;717-750.

Miyamoto T, Taura Y, Une S, et al. Immunological responses after vaccination pre- and post-surgery in dogs. J Vet Med Sci 1995;57:29-32.

Cocker FM, Newby TJ, Gaskell RM, et al. Responses of cats to nasal vaccination with a live, modified feline herpesvirus type 1. Res Vet Sci 1986;41:323-30.

Ellis JA, Haines DM, West KH, et al. Effect of vaccination on experimental infection with Bordetella bronchiseptica in dogs. J Am Vet Med Assoc 2001;218:367-75.

Pedersen NC, Hawkins KF. Mechanisms for persistence of acute and chronic feline calicivirus infections in the face of vaccination. Vet Microbiol 1995;47:141-56.

Weigler BJ, Guy JS, Nasisse MP, et al. Effect of a live attenuated intranasal vaccine on latency and shedding of feline herpesvirus 1 in domestic cats. Arch Virol 1997;142:2389-400.

Lauritzen A, Jarrett O, Sabara M. Serological analysis of feline calicivirus isolates from the United States and United Kingdom. Veterinary Microbiology 1997;56:55-63.

Dawson S, McArdle F, Bennett D, et al. Investigation of vaccine reactions and breakdowns after feline calicivirus vaccination. Vet Rec 1993;132:346-50.

Edinboro CH, Janowitz LK, Guptill-Yoran L, et al. A clinical trial of intranasal and subcutaneous vaccines to prevent upper respiratory infection in cats at an animal shelter. Feline Practice 1999;27:7-13.

Toshach K, Jackson MW, Dubielzig RR. Hepatocellular necrosis associated with the subcutaneous injection of an intranasal Bordetella bronchiseptica-canine parainfluenza vaccine. J Am Anim Hosp Assoc 1997;33:126-8.

Tizzard IR. Vaccination and vaccines In: I. R. Tizzard, ed. Veterinary Immunology. 6 ed. Philadelphia: W.B. Saunders, 2000;235-252.

---