FrançaisWhich cats get it
- Kittens first. Cats of all ages may be affected, but kittens are most susceptible, and mortality is over 90% in kittens [1].
- Unvaccinated and young cats. In German shelters, unvaccinated cats and cats aged 4 weeks to 2 years were significantly more likely to have panleukopenia [4].
- Indoor cats too. The virus is carried on objects such as shoes and clothing, so a cat that never goes outside can still be infected [1].
- Vaccine timing matters. In a Munich study, none of the vaccinated cats that fell ill had received a vaccine after 12 weeks of age [3]. Because antibodies from the mother can block the vaccine, the European ABCD guideline recommends a kitten dose at 15 to 16 weeks [2].
- Dog parvovirus. The dog strains CPV-2a, 2b and 2c can also cause panleukopenia in cats [2]. See parvo in dogs.
The signs
The European guideline lists diarrhea, then vomiting and dehydration, which are prominent. The blood count shows low lymphocytes and neutrophils, followed by low platelets and anemia. The virus also weakens the immune system, can cause a wobbly gait from cerebellar damage in kittens only, and can cause abortion in pregnant queens [1]. The white cells fall because the virus damages the bone marrow [9].
What the blood work shows
| Test | Frequent result | What it means |
|---|---|---|
| White blood cells (WBC) | Markedly low, as low as 0.05–3 ×10⁹/L | The virus destroys white cell production in the bone marrow; this is the “leukopenia” in the name [2, 9]. |
| Neutrophils and lymphocytes | Profound neutropenia and lymphopenia | Both main white cell types fall [2]. |
| Platelets | Sometimes low (thrombocytopenia) | Non-survivors had lower platelet counts at presentation in one study [2, 3]. |
| Red cells | Anemia can follow | It usually comes after the drop in white cells [1]. |
| Albumin | Can be low | Albumin below 30 g/L (3.0 g/dL) was linked with a higher risk of death [2, 3]. |
| Sodium, chloride, potassium | Can be low | Losses from vomiting and diarrhea; potassium below 4 mmol/L was linked with a higher risk of death [2, 3]. |
Other studies found the same pattern of low white cells, low lymphocytes, low monocytes, low granulocytes and low platelets [10]. A low total T4 (thyroid hormone) at admission, at or below 0.82 µg/dL, also predicted death in an Italian study [6]. Read more about low platelets in cats, anemia in cats, albumin and potassium, or the whole cat blood work.
How to read the white cell line
Here is an example line from a young unvaccinated cat with vomiting and diarrhea.
- Abbreviation WBC, white blood cells or leukocytes. Neutrophils (NEU) and lymphocytes (LYM) are listed underneath.
- Result 0.8 ×10³/µL in this illustrative line, which is 800 cells per µL. In panleukopenia, counts as low as 0.05–3 ×10⁹/L are reported [2].
- Unit ×10³/µL is the same number as ×10⁹/L, the unit used in Europe. 1,000/µL equals 1 ×10³/µL.
- Laboratory interval Each laboratory prints its own interval for cats. Compare with the range on your report.
- Flag L: below the interval. In 244 cats, fewer than 1,000 white cells per µL at presentation was linked with a higher risk of death than higher counts [3]. One count is not a verdict: other studies found that counts on days 3 to 7 mattered more, or that no admission value predicted survival [5, 11].
How panleukopenia is confirmed
- Fecal antigen test. In-clinic tests sold for dog parvovirus also detect the cat virus. A positive result confirms the diagnosis; a negative result does not rule it out [2]. Canine and feline kits from the same maker agreed almost perfectly in one study [12].
- Sensitivity is limited. Compared with electron microscopy, five in-clinic tests found 50% to 80% of infected cats (SNAP Parvo 60%), while specificity was 94.2–100% [7].
- PCR is more sensitive and is done when the antigen test is negative but the disease is suspected [2]. It can be run on feces or on whole blood, which is preferred when the cat has no diarrhea or no stool sample is available [1].
- After a vaccine. A recent modified-live vaccine can make tests positive: up to 2 weeks after vaccination with antigen tests [7], and vaccine virus can give positive antigen and PCR results for at least 4 weeks [2]. In 64 vaccinated kittens, 1, 4 or 13 tested positive depending on the dog test used [8].
- Antibody tests (serology) are not recommended for diagnosis, because they cannot tell infection from vaccination [1].
Cats can also be tested for FeLV and FIV, which weaken the immune system in other ways.
Outlook
| Study | Cats | Outcome |
|---|---|---|
| ABCD guideline (Europe) | Kittens | Mortality over 90% in kittens [1]. |
| Munich, Germany | 244 cats | 51.1% survived [3]. |
| Padua, Italy | 70 cats | 23 (33%) died; non-survivors lived a median of 3.5 days [6]. |
| Clinic study | 30 cats | 36.7% died [10]. |
| Italian shelter | 177 cats | 20.3% survived to discharge [5]. |
| Zaragoza, Spain | 58 cats | 10.3% died [11]. |
Related articles
En français : typhus du chat.
Questions to ask your veterinarian
- How low are the white cells, neutrophils and lymphocytes?
- Are the platelets, albumin and potassium normal?
- Was the fecal antigen test positive, and should PCR be done if it was negative?
- Could a recent vaccine have made the test positive?
- When should the blood count be repeated?
Get your cat’s blood work explained together.
AI DiagAnimals reads the white cell count, neutrophils, lymphocytes, platelets, albumin and potassium together with your laboratory’s intervals, and prepares the questions for your vet. The service opens soon: leave your email to be told first.
Frequently asked questions
What are the major clinical signs of feline panleukopenia?
Diarrhea, vomiting and dehydration, with very low white blood cells on the blood count. Kittens can also show a wobbly gait, and pregnant queens can abort [1].
What is the mortality rate for cats with feline panleukopenia?
It varies by study: over 90% in kittens according to the European guideline, 33% died in an Italian hospital study, and about half survived in a German study [1, 3, 6].
How can an indoor cat get panleukopenia?
The virus is carried on objects such as shoes and clothing, so indoor cats are at risk too [1].
How long can a kitten live with panleukopenia?
The disease moves fast: in an Italian study, cats that died lived a median of 3.5 days after admission [6].
Can dog parvovirus infect cats?
Yes. The dog strains CPV-2a, 2b and 2c can also cause panleukopenia in cats [2].
Sources
- Truyen U et al. Feline panleukopenia. ABCD guidelines on prevention and management. J Feline Med Surg. 2009;11(7):538-546. doi.org/10.1016/j.jfms.2009.05.002
- ABCD Europe (European Advisory Board on Cat Diseases). Guideline for Feline Panleukopenia. Last updated 10/02/2022. abcdcatsvets.org/guideline-for-feline-panleukopenia
- Kruse BD et al. Prognostic factors in cats with feline panleukopenia. J Vet Intern Med. 2010;24(6):1271-1276. doi.org/10.1111/j.1939-1676.2010.0604.x
- Rehme T et al. Feline panleukopenia outbreaks and risk factors in cats in animal shelters. Viruses. 2022;14(6):1248. doi.org/10.3390/v14061248
- Porporato F et al. Survival estimates and outcome predictors for shelter cats with feline panleukopenia virus infection. J Am Vet Med Assoc. 2018;253(2):188-195. doi.org/10.2460/javma.253.2.188
- Petini M et al. Prognostic value of systemic inflammatory response syndrome and serum concentrations of acute phase proteins, cholesterol, and total thyroxine in cats with panleukopenia. J Vet Intern Med. 2020;34(2):719-724. doi.org/10.1111/jvim.15704
- Neuerer FF et al. Comparison of different in-house test systems to detect parvovirus in faeces of cats. J Feline Med Surg. 2008;10(3):247-251. doi.org/10.1016/j.jfms.2007.12.001
- Patterson EV et al. Effect of vaccination on parvovirus antigen testing in kittens. J Am Vet Med Assoc. 2007;230(3):359-363. doi.org/10.2460/javma.230.3.359
- eClinPath, Cornell University College of Veterinary Medicine. Individual WBC. eclinpath.com/hematology/leukogram-changes/leukocytes
- Naseri A et al. Feline panleukopenia-associated clinicopathological abnormalities: endothelial glycocalyx degradation biomarkers. Vet Q. 2025;45(1):2573815. doi.org/10.1080/01652176.2025.2573815
- Esteban Jiménez JJ et al. Feline panleukopenia: analysis of possible survival biomarkers. Vet J. 2026;317:106619. doi.org/10.1016/j.tvjl.2026.106619
- Safwat MS et al. Perfect diagnostic agreement between canine- and feline-specific parvovirus PoC antigen kits in feline panleukopenia. Vet Q. 2026;46(1):2604234. doi.org/10.1080/01652176.2025.2604234
Laboratory methods and reference intervals vary. This article explains; it does not diagnose. For a decision about your pet, use the original report and talk to your veterinarian. Our editorial policy.