There is a potential for maternally derived antibodies (MDA) to interfere with a puppy’s response to core vaccination.

By:  Elizabeth Hart

According to an article by Mark  Kelman,  (a representative of Virbac Animal  Health and a member of the Australian Small Animal Veterinary Association’s (ASAVA) Executive Committee), (published in  the industry  magazine The  Veterinarian in  August   last year   ),  an  alarming amount of alleged parvovirus cases being  reported to the Virbac Disease WatchDog, an industry-funded companion animal disease surveillance database endorsed by the Australian Veterinary Association (AVA), have been  ‘vaccinated’ animals.

The   raw  data   indicates  that   “animals that   have received at least one vaccination  represent 28 per cent of puppies infected, and 11 per cent of adults infected!’  These  alarming  percentages indicate  approximately 197  vaccinated puppies and  11 vaccinated adult dogs were  reported to be infected with  parvovirus (subject to verification) in the period between January 2010 and the time of writing the article, which  was published in August  2010.

Dr  Kelman   notes  that   this  information had  been collected  from   only   an   estimated  20   per   cent   of veterinary clinics  across Australia.   So,  considering that, according to Dr Kelman’s calculation at that time, 80  per  cent  of veterinary clinics  had  not  reported to the  Virbac Disease WatchDog, numbers of vaccinated puppies and  adult dogs  being  diagnosed with parvovirus, or  other  possible adverse experience in relation to vaccination, could  be considerably higher across Australia, possibly many hundreds of vaccinated puppies/dogs.

In  late  January 2011,  I raised concerns about this matter with both  Dr Kelman and  Dr Allen Bryce, Veterinary Medicines Program Manager of the Australian Pesticides and Veterinary Medicines Authority (APVMA),  but  their response was  most unsatisfactory.

I also  tried  to  ascertain  whether  these   cases   of apparent vaccine failure were reported to the APVMA’s Adverse  Experience  Reporting  Program,  but   both Dr Kelman  and  the  APVMA  refused to provide a transparent answer to this question.

If these cases  of  parvovirus in  vaccinated animals are  confirmed, this  indicates a failure of the  vaccine. The World  Small  Animal  Veterinary Association’s (WSAVA) Guidelines for the Vaccination of Dogs and Cats   note  that  vaccines may fail for various reasons, e.g. the  vaccine  may  be  poorly  immunogenic, which may reflect a range of factors from  the stage of vaccine manufacture to administration to the animal. Another reason for failure  may be that  the animal is a poor responder, i.e. its immune system intrinsically fails to recognize the vaccinal antigens.

However,   the   WSAVA   2010   guidelines  suggest th<‘ most common reason for vaccination failure  is maternally  derived  antibodies  (\IDA)   nl utrallZlnr the vaccme vtrus, and  note  that “when the last vaccine dose is given at 14-16 weeks of age, MDA should have decreased to a low level, and active immunization will succeed in most puppies (>98%)

However, many core vaccine product labels generally recommend an early  finish  at  10 or 12 weeks,  advice which  conflicts with  the  more  recent advice  of the WSAVA 2010  guidelines.  The  advice  on  the  vaccine product labels  is particularly contentious given  that trials for  core  vaccines are  conducted with   puppies which   are  seronegative,  i.e.  do  not   have  \IDA ,  so how  can  the  response of these  seronegative puppies to vaccination be comparable with  that  of puppies in the general community, whose  dams  are likely to have been  vaccinated {or exposed  to parvovirus naturally), and  therefore have  MDA which  could  interfere with vaccination?

Due  to the  interference of MDA, it is possible  that puppies    being   vaccinated  in   accordance  with   the earlier finish  of  the  manufacturers’ vaccine product label  recommendations may  be  unprotected and  pet owners are not being  warned about this.

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The possibility of MDA interference has been known for years.  For example, this matter was raised in letters to the British Veterinary Association’s journal The Veterinary Record  in  2006,  with  one  correspondent, Hal  Thompson, noting:  “Maternal antibody   to parvovirus is known to last beyond 12 weeks of age in puppies and kittens. Low titres  of maternal  antibody 3(2) can be breached by modified  live virus vaccines,

but such levels  can also prevent  the  development of active immunity. I have  yet to see any  field  studies by the members  of NOAH (National Office of Animal Health, UK) that  justify the claims in the data  sheets that  their CPV  vaccines induce  active  immunity in an  acceptable  proportion  of 10 week old  vaccinated puppies. The Veterinary Products Committee also stays silent on what standards it expects.   The profession is therefore blackmailed  into blindly following a poor vaccination regimen for fear of disregarding data sheet instructions.”

An article in the  Brisbane Courier Mail on 20 March this year, which included comments by a representative of  the  AVA, referred to  an  apparent victim of parvovirus, a  ‘vaccinated’ five  month old  Rottweiler puppy, but  the  opportunity was  not  taken to  discuss possible non-responders  to  vaccination, nor  to  warn pet  owners about the  confusion regarding the  timing of appropriate puppy  vaccination and the potential for interference by MDA.

In  their  paper  “Vaccination guidelines: a  bridge between official   requirements and   the   daily   use  of vaccines’veterinary experts Etienne Thiry and Marian Horzinek state  that: “It  is  of  primary   importance that    the   vaccination  schedules    followed         by   the veterinary  practitioners are the most  efficacious  ones even if this  means  that  they do not strictly follow the recommendations of the package inserts:’

Why    aren’t   veterinarians   heeding  this    advice, and  ensuring their clients are  warned about the contradictions between non-evidence based  vaccine product labels  and more recent advice  in international vaccination guidelines?

Given  the  warnings in  the WSAVA 2010  guidelines that some puppies may not respond to vaccination until 14-16 weeks,  why aren’t the  AVA and  APVMA  being more proactive in warning the public about the conflict between the early finish  of 10 or 12 weeks generally recommended on  MLV core  vaccine product labels, and   the   WSAVA  2010   guidelines  recommendation for  a later finish, as there is a risk  that  some  puppies that  have  had  the  earlier finish  recommended by the manufacturer might be unprotected?

Why isn’t the  AVA proactively promoting the option of  titre testing to  the  public   as  an  evidence-based means to ascertain if a puppy has  responded to core vaccination?  The WSAVA 2010 guidelines advise  that titre  testing “is  presently  the  only  practical  way  to ensure  that  a  puppy’s immune system  has  recognised the vaccinal antigen’:

Titre tests have been available in Australia for years, yet very  few pet  owners I know  have been  offered  the opportunity of a titre test for their pets.

Contrary to misleading advice by some veterinarians, titre tests are not expensive.  I have been  quoted around $90-100 for a lab-based IFA (immunofluorescent antibody) test  (via a Sydney vet),  and  around $67  for  an  in-surgery titre test  (i.e. Biogal VacciCheck via an Adelaide vet).  The  cautious pet  owner may  not  think this  a high price  to  pay as it  provides a useful  option to  verify  a vaccination response for their pet.

When a vaccination response has  been  verified, I can see  no benefit in either repeated core  vaccination nor titre testing, as the WSAVA 2010 guidelines advise that  ”duration of immunity (DOl) is many  years and may be u.p to the lifetime of the pet’!Vaccination practice in countries such  as Australia, the UK and the US remains a dire shambles, with many pet  owners still  being  misled  into inappropriate, and potentially harmful, vaccination practice for their pets.

As  many  veterinarians are  still  not  properly informing their clients about critical issues regarding vaccination best  practice, (a serious professional lapse which  should be subject to formal investigation), I suggest pet  owners consider the  following key points in the best interests of their pet:

  • the  WSAVA 2010  guidelines advise  duration  of immunity with  core  vaccines is “many years  and  may be up to the lifetime of the pet”;
  • manufacturers’  ‘annual’  and    ‘triennial’ revaccination recommendations  on  core  vaccine product labels are not evidence-based;
  • there is  a  conflict between the   early  finish   of puppy vaccination generally recommended on vaccine product labels  (i.e. 10 or 12 weeks), and the later finish recommended in the WSAVA 2010 guidelines (i.e. 14-16 weeks) which  means some  pets  undergoing an early finish may be unprotected due  to neutralization of the vaccine virus  by maternally derived antibodies (MDA);
  • the   WSAVA  2010   guidelines advise   that   titre testing “is  presently the  only  practical way to  ensure that a  puppy’s immune system  has  recognised the vaccinal antigen’! Lab-based and in-surgery titre tests to test  the  response to core vaccines are available, and have been  for years.
  • the  WSAVA 2010  guidelines advise  to  “reduce the  ‘vaccine load’ on  individual animals in  order to minimize the potential for adverse reactions to vaccine products”;
  • the WSAVA 2010 guidelines advise  to “vaccinate each individual less frequently by only giving non-core vaccines that are necessary for that animal”;
  • request advice  on  how  to  properly isolate vulnerable puppies, and on how to transport vulnerable puppies to the veterinary surgery (a possible source of infection) for vaccination, (and  titre testing, if desired by the pet owner);
  • consider the   potential  risks   of  simultaneous vaccination and application of other medical products (e.g. the  heartworm injection) for individual animals; and
  • demand that   veterinarians provide up-to-date advice on  vaccination practice based  on  current scientific knowledge and thinking.

Given   the   ongoing  confusion  regarding  an appropriate  puppy vaccination protocol, it  is  to  be hoped that the WSAVA Vaccination Guidelines Group will provide clear  and  objective advice  on  the optimal puppy  vaccination and optional titre test confirmation protocol in the very near  future.

*This  article was  based on  information contained in a recent open letter of formal complaint about unnecessary vaccination of pets, forwarded to  the Australian Veterinary Association, Australasian Veterinary Boards Council, and  the  Australian Pesticides and  Veterinary Medicines Authority on  26 March 2011.    The  open letter is freely accessible via this internet link:  http://bit.ly/gBuQZY

Thanks to Bea   Mies for   her   valuable comments on  this article.

 

References:

Kelman, Mark. Australia’s national companion animal disease surveillance system -saving lives. The Veterinarian. August 2010.

Vets fight  puppy parvo outbreak across Australia. Australian

Veterinary Association Media Release, 7 July 2010.

Day, M.J., Horzinek, M.C., Schultz, R.D. World  Small  Animal Veterinary Association’s (WSAVA) Guidelines for the  Vaccination of Dogs and  Cats. Journal of Small  Animal Practice. Vol. 51. June 2010.

See   for   example: Gore, T.  et  al.  Three year   duration  of immunity in dogs following vaccination against canine adenovirus type-1, canine parvovirus, and  canine distemper virus. Veterinary Therapeutics. Spring 2005, Vol. 6, No. 1

Thompson, H.Efficacy of vaccination against canine parvovirus. The Veterinary Record. 159:570-571 2006.

Huge surge in cases of deadly parvo virus  in dogs follow  recent

Queensland floods. Brisbane Courier Mail, 20 March 2011.

Thiry,   E.,  Horzinek, M.C.  2007.  Vaccination guidelines: a bridge between official  requirements and the daily use of vaccines. Veterinary Sciences Tomorrow- 29 June  2007.

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