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Diagnostic testing for feline panleukopenia in a shelter setting: a prospective, observational study

Jacobson, L. S., Janke, K. J., Giacinti, J., & Weese, J. S. (2021). Diagnostic testing for feline panleukopenia in a shelter setting: a prospective, observational study. Journal of Feline Medicine and Surgery, 1098612X2110053.

https://doi.org/10.1177/1098612×211005301

https://www.ncbi.nlm.nih.gov/pubmed/33847532

Feline panleukopenia virus (feline parvovirus; FPV; Feline infectious enteritis) is a highly contagious and often fatal disease of cats. While vaccines are widely available and highly effective, young kittens (especially those born to unvaccinated queens and those in shelters) are not protected. The virus is highly stable and persistent in the environment for long periods of time, and so infection may occur without direct exposure to sick cats. As such, outbreaks of panleukopenia are of major concern in shelters.

Clinical signs of panleukopenia virus may be non-specific, especially in the early stages. As such, testing of sick animals may be performed without a high pre-test probability of disease. While feces are the traditional sample for diagnostic testing, virus sis shed in a wide variety of bodily fluids. Point of Care ELISA-based tests for canine parvovirus have been reliably used to detect FPV; however, PCR methods run at labs may be more sensitive and specific.

The objectives of this study were to determine the optimal technique for FPV diagnosis by comparing the results of a point of care ELISA with a lab-based PCR, determining whether vomit and anal/rectal swabs can be used for diagnosis, and determining how to interpret weak positive ELISA results.

This study was designed as a prospective observational study at a private animal shelter in Canada with an ~200 cat capacity. It was carried out from May to November of a single year. At intake, cats over 4 weeks of age were vaccinated with a modified live subcutaneous feline viral rhinotracheitis, feline calicivirus, and FPV vaccine, and then re-vaccinated every 2-3 weeks for kittens or 2-4 weeks for adults. They were also treated with selamectin, pyrantel, and ponazuril in kittens. Pyrantel was repeated at 2 weeks and then every 2 weeks thereafter in kittens. Woods lamp and retrovirus screening was performed.

Cats were recruited if they filled any of the admission criteria: death within 12 h of admission, with few or no clinical signs; dehydration, obtundation to coma, hypothermia or hypoglycemia; adult cats with anorexia/hyporexia and lethargy in association with vomiting and/or diarrhea; kittens with anorexia/hyporexia, lethargy, and weight loss; or diarrhea with or without additional signs; or vomiting with anorexia/hyporexia or fever.

Adult cats with up-to-date FVRCP vaccines at admission and adult cats ⩾10 days following vaccination were excluded. Anal or rectal swabs, feces, and vomit were collected within 24 h of clinical signs being noted.

340 cats presented to the shelter in the study period, of which 198 met inclusion criteria and 53 were excluded. One hundred and forty-five cats were included in the analysis.

102 fecal samples were analyzed, 78 individually and 24 in groups; as well as 7 vomit samples and 55 swabs.
Sensitivity of the fecal ELISA was 55%, swab ELISA 30%. Swab PCR was 77%, and vomit PCR 100% sensitive. Specificity was 100% for all sample types.

The authors concluded that the ELISA has a high specificity and low sensitivity for FPV. Positive ELISA tests, even if weakly positive, were highly likely to be true positives in animals with consistent clinical signs. However, animals with consistent clinical signs should have negative tests confirmed with PCR. Rectal swabs and vomit show potential usefulness in screening for FPV.
Some limitations were present in this study. It was a single-center study with a relatively small population of cats from a single geographic area. Only one ELISA and one PCR were used, and other brands or techniques may show different results.
See Also
Kruse, BD, Unterer, S, Horlacher, K, et al. Prognostic factors in cats with feline panleukopenia. J Vet Intern Med 2010; 24: 1271–1276.

Litster, A, Benjanirut, C. Case series of feline panleukopenia virus in an animal shelter. J Feline Med Surg 2014; 16: 346–353.

Porporato, F, Horzinek, MC, Hofmann-Lehmann, R, et al. Survival estimates and outcome predictors for shelter cats with feline panleukopenia virus infection. J Am Vet Med Assoc 2018; 253: 188–195.

Related Blog Posts
https://everycat.org/cat-health/antibody-response-to-feline-panleukopenia-virus-vaccination/

Related Terms
Parvovirus
Feline infectious enteritis