PARVOVIRUS 2c...NEED FOR A NEW VACCINE?...OR NOT?
Canine parvovirus (CPV) is the best known and most serious form of infectious enteritis in dogs worldwide. But...all CPV is not exactly alike...at least at the level of the virus. A number of variants [NOT STRAINS] have been recognized: CPV-2a was discovered in the late 70’s and emerged as the cause of widespread disease throughout the 80’s...this variant has since been replaced by CPV-2b today as the most common cause of clinical parvovirus infection in the US. Meanwhile, CPV-2c, which has been in the US for at least the past few years, makes its way onto the scene.
What’s the difference?
Not much...variant change (minor variations at a single point in the viral DNA) in canine parvovirus occurs naturally and is attributed to “genetic drift”. The risk for exposure and the clinical signs of infection caused by CPV-2c appear to be the same as that associated with CPV-2b.
What about transmission?
No change...it’s still a very contagious infection transmitted by direct contact with infected dogs, feces, and contaminated environments. Disinfection requirements for contaminated facilities/surfaces are no different.
Does the Parvovirus SNAP test still identify CPV-2c?
Yes...that study has been done. In fact, all commercially available fecal antigen tests will accurately detect CPV-2c.
Treatment?
No change...conventionally administered supportive care as usual.
Vaccination Failures?
None of the current parvovirus vaccines contain CPV-2c. HOWEVER...studies already have been conducted that clearly show excellent cross protection derived from all of the current vaccines on the market...see the AVMA website at:
http://www.avma.org/animal_health/canine_parvovirus_faq.asp
And...duration of immunity is not changed. Veterinarians who elect to re-vaccinate triennially may do so with the confidence that the vaccine currently being used will protect against the CPV-2c variant as well as it will against the CPV-2b variant.
Vaccine Administration:
In accordance with AAHA Canine Vaccine Guidelines...administration of a Modified-Live Virus (MLV) parvovirus vaccine (in combination with recombinant or MLV distemper and MLV adenovirus-2) to dogs should include at least 3 doses between 6 and 16 weeks of age...
VERY IMPORTANT: the last dose in the series should be administered
at 15-16 weeks of age...that’s to assure being there with vaccine when interfering levels of maternal antibody are not. Among the MLV vaccines on the market, one vaccine has not been found to be better than any other vaccine.
References (taken from the AVMA Website on CPV):
Hong C, Decaro N, Desario C et al. Occurrence of canine parvovirus type 2c in the United States. J Vet Diagn Invest 2007; 19: 535-539.
Kapil S, Cooper E, Lamm C et al. Canine parvovirus types 2c and 2b circulating in North American dogs in 2006 and 2007. J Clin Microbiol 2007; 45: 4044-4047.
Larson LJ, Quesada M; Mukhtar E, et al. Evaluation of a CPV-2 fecal parvovirus ELISA (SNAP Fecal Parvo Test © ) from Idexx Laboratories. 88th Conf Res Workers in Anim Dis 2007, p. 112.
CPV Update, Amer Anim Hosp Assoc; May 28, 2007.
Oklahoma State University press release:
http://www.cvhs.okstate.edu/index.php?option=com_content&task=view&id=437
Schultz RD, Larson LJ. Current canine parvovirus type 2 (CPV-2) vaccines provide excellent immunity to all genotypes of CPV-2 (eg CPV-2a, 2b, and 2c). 88th Conf Res Workers in Anim Dis 2007, p. 113.
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VS-FELINE CALICIVIRUS (Virulent Systemic 'Feline' Calicivirus)
Released in February 2007 (Fort Dodge Animal Health), this killed virus vaccine is sold as a killed, adjuvanted vaccine in four separate products, each of which contains their original calicivirus strain. Several questions about disease risk and vaccine use have surfaced subsequent to vaccine marketing.
- FACTS TO CONSIDER…
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- infections are severe (mortality = 30% to 50%), but rare. 8 outbreaks have been documented in the US and UK over the past 10 years. There is no evidence to suggest the incidence has recently increased in the US or the UK.
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- the VS Calicivirus strain in the vaccine is the same virus strain used in the manufacturer’s vaccine challenge studies (homologous challenge). There are no studies showing vaccine efficacy in a (naturally occurring or experimental) heterologous challenge.
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- this vaccine is adjuvanted.
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- at this writing, technical data from the manufacturer on the vaccine has not been released.
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- until independent studies are published regarding vaccine efficacy, veterinarians should use discretion in deciding whether or not to administer this vaccine. Cats considered to be at risk appear to be shelter/rescue cats and domestic pet cats exposed to these high risk groups.
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- the vaccine is NOT generally recommended for routine use in household pet kittens or cats.
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Canine Bordetella bronchiseptica VACCINES
A summary of the most recent facts on the INTRANASAL vs
INJECTABLE vaccines follows:
- There are currently 2 types of vaccines:
- ◊ only one vaccine (Bronchicine, Pfizer) is for parenteral
administration.
- ◊ Various intranasal products are available that
contain:
- · Bordetella bronchiseptica
+ parainfluenza virus + adenovirus-2, or,
- · Bordetella bronchiseptica
+ parainfluenza virus only
(recommended by the AAHA Canine Vaccine Guidelines)
- Like most bacterins, BOTH vaccine types lessen the severity of disease following
exposure; neither vaccine is believed to prevent infection.
- Following challenge, the intranasal vaccine prevented bacterial shedding; the
injectable vaccine did not. Implication in kennels and shelters: dogs vaccinated by the
intranasal route minimize the risk of bacterial transmission to other dogs at risk in
the same facility.
- ALL intranasal vaccines on the market include MLV parainfluenza virus vaccine…a
preferred route of administration.
- Initial Vaccination: ONE dose for intranasal vaccines-onset of immunity is 3 to 5
days post vaccination; TWO doses, 2 to 4 weeks apart, are required-onset of immunity may
be several days following the second dose.
- Booster Vaccination: ONE dose of either vaccine.
There appears to be NO contraindication to switching vaccine types. Onset of immunity in
previously vaccinated dogs is not known. (it’s probably within days for either vaccine
type)
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RECOMBINANT CANINE DISTEMPER
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- Duration of Protective Immunity: challenge studies performed at U of Wisconsin have shown efficacy
of the recombinant canine distemper vaccine (Merial) to be comparable to that of any Modified Live
Virus (MLV) vaccine. The Duration of Protective Immunity, based on challenge studies, exceeds 3
years.
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- Maternal Antibody is the single most significant factor in preventing immunization of puppies
vaccinated with a MLV distemper vaccine. However, the recombinant distemper vaccine (Merial) was
able to induce protective immunity in 8 week old puppies despite the presence of maternal antibody.
Reason: maternal antibody against canine distemper virus does not recognize the virus vector
(canarypox) used in the recombinant vaccine.
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- Some authors have recommended use of the recombinant canine distemper vaccine (RECOMBITEK
Canine Distemper, Merial) in Weimaraners due to the possible risk of vaccine-induced
osteopathy (HOD) in puppies. See comments below: #6 Bone Lesions.
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- The recombinant canine distemper vaccine (RECOMBITEK Canine Distemper, Merial) is recommended to be
administered as early as 3 weeks of age in puppies deemed to be at high risk of exposure to canine
distemper virus. (see the AAHA Canine Vaccine Guidelines)
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Feline VACCINE ASSOCIATED SARCOMA
Adverse reactions subsequent to vaccine administration, although
uncommon, are known to occur in both dogs and cats. Reactions can range from
mild to severe (fatal) and are localized or systemic. The actual prevalence and
types of injury, however, have not been established. Feline vaccine associated
sarcoma is the most serious adverse reaction that has been reported (see updates
below).
- Veterinarians are encouraged to report adverse vaccine events directly to the
manufacturer. However, data generated by these reports are not available to practitioners; there
is no national database of adverse vaccine reactions available to veterinarians.
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- Feline vaccine associated sarcoma is the most widely documented vaccine adverse event, generally
associated with adjuvanted feline leukemia and rabies vaccines. The true prevalence is unknown.
A paper (U of California-Davis) recently presented at the 2007 Veterinary Cancer Society Conference
assessed changes in injection site sarcomas in cats from 1990 through 2006.
Conclusion: Tumors are occurring with increasing frequency in difficult
surgical sites such as the
lateral abdomen. Also, there has been a shift in the sarcoma site from the cranial to the caudal
half of the body...which corresponds with vaccination site recommendations of the AVMA’s
Vaccine-Associated Feline Sarcoma Task Force.
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Canine SKIN REACTIONS ASSOCIATED WITH VACCINATION:
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- Dermatologists throughout the US have attributed single and multifocal skin lesions, characterized
as ischemic vasculitis, to recent (1 to 3 months) vaccine administration. Although no known deaths
have occurred, reactions can be painful and may require expensive treatment.
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Lesions seem to develop from 1 to 3 months post-vaccination. Solitary lesions may occur at the
injection site (hair loss and change in hair color are reported). Multifocal lesions can affect the
skin of the ear tips (with associated necrosis), eyelids, nasal planum, tail, footpads, and
occasionally the trunk. Poodles and other dogs under 25 pounds may be over represented.
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Killed rabies vaccine (particularly RabVac-3, Fort Dodge Animal Health) is most often implicated in
anecdotal reports from veterinarians.
Focal post-vaccination skin lesion in a young Maltese. Lesion is non-painful and characterized by a
change in hair and skin color at the injection site.
Multifocal lesions on the ear-tip of a Chihuahua. Both ear-tips were affected.
- TREATMENT: most clinicians/dermatologists recommend against using corticosteroids (may promote coagulation) in the management of these lesions. The following drugs have been used in combination:
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- Pentoxyphylline (Trental): 15 mg/kg, PO, q12h (duration is 10 days to 3 weeks as needed to manage the cutaneous lesions).
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- Oral Antimicrobials: example: cephalexin, marbofloxacin.
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- Vitamin E: 400 IU, PO, q12h, as needed.
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- Analgesics: buprenorphine, 0.005 to 0.02 mg/kg, SC, q6-12h as needed to control pain.
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BONE LESIONS ATTRIBUTED to POST-VACCINATION
ADVERSE EVENTS
Over the past 2 years, a few papers have implicated Modified-Live Virus Canine Distemper Vaccine in causing bone lesions in puppies. Presumably, this is attributed to replication of the modified-live virus in bone. Hypertrophic Osteodystrophy (HOD), particularly in Weimaraners, and Craniomandibular Osteopathy are cited.
It has been suggested that use of the Recombinant Canine Distemper Vaccine (Recombitek Canine Distemper, Merial) would be indicated in breeds that may be at risk for developing these orthopedic disorders.
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