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specificity of 99% for FPV [3], but another reports 78% and 89%, respectively [4]. In the same animals (in the first study) the sensitivity for FHV was 91% with 97% specificity and for FCV, the figures were 90% and 91%, respectively. The TitreChek kit was evaluated in a study of shelter dogs in Florida, giving a sensitivity of 98%
for CPV (specificity 98%) and a sensitivity of 88% for CDV (specificity 95%) [5]. A further shelter study used the TitreChek kit to evaluate seroconversion one and two weeks after vaccination in a population of proven seronegative dogs entering the shelter [6].
A new UK study has used VacciCheck to test serologically a population of 486 dogs visiting two large practice groups. These dogs were last vaccinated up to 124 months previously and the rates of protection were 96% for CDV, 97% for CAV and 98.5% for CPV-2 [7].
Although this current generation of test kits is a major advance, the ideal test would be rapid (i.e. 5 minutes within the period of a consultation), individual (rather than needing to be batched), cheap (cheaper than a vaccine) and able to give a simple yes/no (protected/not protected) answer.
Applications of In-house Testing
There are several applications of these test kits within
the veterinary practice. The first of these is to determine whether puppies have appropriately responded to the primary course of core vaccination. According to current guidelines, the third dose of core vaccine should be administered at16 weeks of age or older. Testing pups at 20 weeks of age will indicate those that are seropositive and therefore protected. Such pups may not require
the fourth 26 week (or 52 week) vaccine. Seronegative pups are not protected and may be revaccinated and retested. Those that fail to respond after revaccination may be either ‘low responders’ or genetically-determined ‘non-responders’ that are incapable of making an immune response to that antigenic component of the vaccine. Such animals are estimated to be rare within the population, but there are higher risk breeds including the rottweiler that has a known predisposition to mounting less effective immune responses to CPV and rabies virus.
Another indication for serological testing is to determine the protective status (and therefore core vaccination requirements) of a newly adopted dog of unknown vaccination history or a dog which has not been revaccinated for some time. Seropositive dogs remain protected, while seronegative animals should be vaccinated.
When an animal has a history of an adverse event following vaccination, serological testing can be used to determine whether core revaccination is necessary for that animal. If vaccination is suspected as a trigger factor in an adverse event (e.g. an immune-mediated disease), then vaccination should be minimized in that animal in
An Urban Experience
the future. As long as dogs remain seropositive for CDV, CAV and CPV they do not require revaccination. The use of non-core vaccines in such dogs should be considered carefully.
It is becoming increasingly popular for practices that have embraced the ‘annual health check’ concept to routinely offer serological testing in lieu of triennial core revaccination. Clients are appreciative of this option and it makes greater medical sense to determine whether
a core vaccine is required than to give a vaccine unnecessarily. Triennial ‘titre testing’ is adequate for adult animals, but current advice for geriatric patients (i.e. dogs > 10 years of age and cats >15 years old) would be to perform annual testing.
Finally, in-house serological testing has revolutionized the ability of the veterinarian to manage infectious disease outbreaks in animal shelters – particularly CDV, CPV or FPV outbreaks. Animals within the shelter are tested in order to identify seropositive and protected animals that should be housed together and separated from seronegative (susceptible) animals that will then
be vaccinated. Seronegative and vaccinated animals should not be adopted out of the shelter until beyond the incubation period for the disease (2 weeks for CPV or FPV; 6 weeks for CDV) and they have seroconverted. Animals needing to enter the shelter should also be tested. Seropositive (protected) animals may enter
and be housed with the seropositive residents, while seronegative animals should not enter the shelter and rather be fostered elsewhere.
Further Reading
1. Mitchell SA, Zwijnenberg RJ, Huang J, Hodge A, Day MJ. Duration of serological response to canine parvovirus-type 2, canine distemper virus, canine adenovirus type 1 and canine parainfluenza virus in client-owned dogs in Australia. Aust Vet J. 2012. 90: 468-473.
2. Schultz RD, Thiel B, Mukhtar E, Sharp P, Larson LJ. Age and long-term protective immunity in dogs and cats. J Comp Pathol. 2010. 142: S102-S108.
3. DiGangi BA, Gray LK, Levy JK, Dubovi EJ, Tucker SJ. Detection of protective antibody titers against feline panleukopenia virus, feline herpesvirus-1, and feline calicivirus in shelter cats using a point-of-care ELISA. J Feline Med Surg. 2011. 13: 912-918.
4. Mende K, Stuetzer B, Truyen U, Hartmann K. Evaluation of an in-house
dot enzyme-linked immunosorbent assay to detect antibodies against feline panleukopenia virus. J Feline Med Surg. 2014. DOI: 1177/10986 12X 145208 12.
5. Gray LK, Crawford C, Levy JK, Dubovi EJ. Comparison of two assays for detection of antibodies against canine parvovirus and canine distemper virus in dogs admitted to a Florida animal shelter. J Am Vet Med Assoc. 2012. 240: 1084-1087.
6. Litster A, Nichols J, Volpe A. Prevalence of positive antibody test results for canine parvovirus and canine distemper virus and response to modified live vaccination against CPV and CDV in dogs entering animal shelters. Vet Microbiol. 2012. 157: 86-90.
7. Killey R, Mynors C, Pearce R, Nell A, Prentis A, Day MJ. Long-lived immunity to canine core vaccine antigens in UK dogs as assessed by an in-practice test kit. 2017. Manuscript submitted.
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