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Feline Panleukopenia: 🐱 A Serious Contagious Disease 🦠 Learn How to Protect Your Cat!

Feline panleukopaenia

 

Feline panleukopenia is a highly contagious viral disease that affects cats, particularly in communities. Prevalence data is limited, but there may have been an increase in cases in certain areas. It is caused by feline parvovirus (FPV), a contagious DNA virus that affects all members of the Felidae family. Control of the disease is complicated due to environmental resistance, high viral shedding, and interspecies transmission.

 

The severity of clinical signs varies based on the cat's immune status and concurrent diseases. Symptoms range from mild or no apparent signs to a hyperacute syndrome that can result in sudden death. Common clinical signs include fever, lethargy, anorexia, vomiting, and watery or bloody diarrhea. Secondary bacterial infections can lead to complications such as sepsis, dehydration, and disseminated intravascular coagulation.

 

Some parvoviruses, like canine parvovirus type 1 (CPV-1) and FPV, have undergone minimal evolution over time. However, canine parvovirus type 2 (CPV-2) has shown significant adaptability and mutation, leading to the development of three pathogenic strains: CPV-2a, CPV-2b, and CPV-2c.

 

The United States has seen a significant increase in FPV cases, possibly due to changes in vaccination protocols. The use of intranasal vaccines has risen to mitigate the risk of vaccine-associated sarcomas. However, these vaccines may be less effective, especially in high-risk animals, compared to injectable vaccines. New vaccination guidelines recommend completing primary vaccination at 14 to 16 weeks of age based on studies showing extended persistence of maternal antibodies. It is possible that these new protocols are not yet widely adopted by most veterinary surgeons.

 

There is a lack of published data on the prevalence increase of feline panleukopenia in Spain. However, based on experience, there has been an increase in diagnosed cases in recent years, with 195 cases reported in a span of six years.




 

Aetiology

 

Feline panleukopenia virus (FPV) is a small non-enveloped DNA virus, measuring 20 nm in size. It is primarily transmitted through the faecal-oral route, and infected cats intermittently shed the virus in their feces for days or weeks.

 

The virus is highly contagious and can be easily transmitted through various means, including clothing, shoes, utensils, and even flies.

 

Disinfecting contaminated areas is challenging due to the virus's resistance to chemical disinfectants and physical agents. Effective disinfectants against FPV include sodium hypochlorite, formaldehyde, and glutaraldehyde.

 

The replication of the virus begins in the oropharyngeal tissue. As a single-stranded DNA virus, FPV requires actively dividing cells in the S phase. Additionally, the virus relies on DNA polymerase enzyme to synthesize the complementary DNA strand, making it dependent on tissues with high mitotic activity. After replication, the virus enters the bloodstream, leading to viremia and dissemination to target organs such as tonsils, mesenteric lymph nodes, lymphatic intestinal tissue, and bone marrow. The pathogenic consequences and clinical manifestations of FPV vary depending on the specific tissue infected (see Table 1 below).

Table 1. Pathogenic consequences and clinical manifestations of FPV depending on the tissue infected.

 

Infected tissue

Consequences

Clinical

manifestations

Intestinal crypt epithelium

Collapse of villi

Enteritis

Lymph  nodes and  thymus

Lymphocyte apoptosis, thymic atrophy

Lymphopaenia

Bone marrow

Decrease in stem cell number

Pancytopaenia

Foetus

Foetal death

Abortion

Developing cerebellum

Cerebellar hypoplasia

Ataxia

 

 

 

 

 

Pathogenesis and Clinical Signs

 

The incubation period of feline panleukopenia, from virus exposure to the onset of clinical signs, ranges from 5 to 9 days. Four types of clinical manifestations are observed.

 

1. Subclinical infection: This is the most common outcome, where infected cats show no apparent clinical signs of the disease. The development of clinical disease depends on various factors, including the rate of intestinal crypt cell mitosis. Low rates of mitosis result in minimal intestinal damage, while high rates, triggered by stress or concurrent diseases, provide an optimal environment for the virus to replicate and cause more severe effects. Even dietary changes can increase the rate of mitosis, facilitating viral replication. For example, adopted kittens may develop severe enteritis and die, while littermates remaining with the mother or in a shelter may show milder or no clinical signs.

 

2. Sudden death: Sudden death is relatively common, especially in young kittens, unvaccinated cats, and animals in shelters or pet shops.

 

3. Classic feline enteritis: This clinical presentation typically occurs suddenly. Owners may mistake the signs for poisoning. Clinical signs include fever, anorexia, dehydration, vomiting, and, in some cases, bloody diarrhea. Pancytopenia (reduced blood cell counts) is often observed in complete blood counts. Severe dehydration and loss of the intestinal barrier, leading to bacterial overgrowth, can result in death.

 

4. Neurological signs: The virus's preference for dividing cells makes the fetus highly vulnerable. Infection during the first trimester of gestation can cause abortion, fetal resorption, and death. Infections at later stages can lead to cerebellar hypoplasia, hydrocephalus with ataxia, intention tremors, and limb abnormalities.

 

Laboratory Diagnosis

 

Laboratory diagnosis of feline panleukopenia involves several methods:

 

1. Virus isolation: The virus can be isolated from stool samples, although this can be challenging.

 

2. Antigen detection: Rapid immunochromatographic tests used for detecting canine parvovirus (CPV) antigen can also be used for FPV detection. However, the results should be interpreted carefully, as the test may cross-react with vaccinated animals and yield false positives.

 

3. PCR: Polymerase chain reaction (PCR) can detect viral genetic material (DNA) in blood or stool samples. Blood samples are preferred when the animal has diarrhea.

 

4. Antibody detection: ELISA and indirect immunofluorescence (IF) are commonly used methods to detect serum antibodies. Differentiating between vaccine-induced antibodies and infection-induced antibodies can be challenging, particularly in vaccinated animals.

 

Treatment

 

If a cat is hospitalized with a confirmed or suspected diagnosis of feline panleukopenia, strict isolation measures should be implemented to prevent virus spread.

 

Supportive care for clinical signs includes:

 

1. Fluid therapy: Intravenous fluid therapy and electrolyte control are crucial. Central venous catheterization is preferred for prolonged hospitalization to manage hypoalbuminemia and peripheral edema.

 

2. Antibiotic therapy: Broad-spectrum antibiotics are administered to prevent bacterial infections due to the compromised intestinal barrier. A combination of amoxicillin and clavulanate with a third-generation cephalosporin is an option.

 

3. Parenteral nutrition: In some cases, supplemental nutrition may be necessary.

 

4. Antiemetics: Medications to control vomiting and alleviate nausea and discomfort.

 

5. Transfusions: Whole blood or plasma transfusions may be required.

 

6. Analgesics: Acute pain management is essential, and opioids such as buprenorphine or fentanyl can be used.

 

Specific Antiviral Therapy

 

1. Antiviral chemotherapy: Feline interferon ω can be administered intravenously at a dose of 2.5 MIU/kg every 24 hours for three consecutive days. Limited studies exist, with a higher level of scientific evidence needed.

 

2. Passive immunotherapy: Subcutaneous administration of serum or homologous plasma from recovered or vaccinated animals with high antibody titers can be considered. Blood group compatibility should be determined beforehand. High-quality studies supporting this approach are lacking.

 

Prevention

 

Vaccination:

 

Vaccination is the most effective method of preventing feline panleukopenia. Live attenuated vaccines are used, starting at 8 to 9 weeks of age, with doses administered every 3 weeks until the final vaccine is given after 16 weeks of age. Revaccination should be done after 1 year. It is important to vaccinate all cats, even those that do not go outdoors.

 

Maternal antibodies are transferred to kittens through colostrum. Kittens should nurse within the first 8 hours of life to acquire these antibodies. Maternal antibody levels decline from the 10th week of life. Vaccinating too early can interfere with active immunity due to passive immunity from maternal antibodies. Recommendations for different scenarios include vaccinating at 8 to 9 weeks of age for kittens that nursed well, vaccinating early (7-12 days of age) with an inactivated vaccine for kittens that did not nurse within the first hours of life, and vaccinating gestating cats with inactivated vaccines. Retrovirus-positive animals should receive inactivated vaccines if their health permits.

 

Live attenuated vaccines provide immunity within three days of vaccination. A general vaccination schedule includes vaccines at 8-9 weeks, 12 weeks, and after 16 weeks of age, with revaccination after 1 year.

 

Sanitary Period:

 

Implementing an adequate sanitary period is crucial for eradicating the virus, especially in feline communities. The virus can persist in the environment for up to a year. Disinfection using sodium hypochlorite (diluted bleach) can reduce viral load. Establishing contamination-free areas in high-risk places such as shelters, catteries, foster homes, and veterinary clinics is recommended.

 

Hyperimmune Sera:

 

Hyperimmune sera can be administered before a high-risk situation, but there is a lack of scientific evidence demonstrating its effectiveness.

 

Feline Interferon ω:

 

A study conducted in naturally infected cats found no significant differences in survival rate or clinical signs between cats pretreated with interferon and untreated cats.

 

Prognosis:

 

In cats infected with feline panleukopenia, leukopenia, lymphopenia, monocytopenia, and eosinopenia indicate a poor prognosis. Decreased cortisol, thyroxine, and serum cholesterol concentrations further complicate the prognosis. Systemic inflammatory response syndrome (SIRS) is more common in dogs that do not survive and have concurrent viral, bacterial, or parasitic diseases. Although data for feline panleukopenia is limited, further studies are necessary to improve treatment, anticipate complications, and enhance survival rates.

 

Results of a Retrospective Study:

 

Findings of a retrospective include:

 

- The survival rate was 52%, with most infections occurring during the first year of life, particularly between 3 and 4 months of age. However, FPV was also diagnosed in adult cats and those without outdoor access.

- Cats infected with FPV had received one or two vaccinations, but none had completed the full vaccination schedule or received vaccines after 16 weeks of age.

- Common clinical signs at diagnosis included anorexia, lack of energy, vomiting, and diarrhea.

- Cats with concomitant respiratory infections had a higher mortality rate.

- Significant laboratory findings included leukopenia and hypoalbuminemia.

 

Frequent Questions

 

1. Can a dog infect a cat?

 

Cats can be infected by both feline parvovirus (FPV) and canine parvovirus (CPV-2a, CPV-2b, and CPV-2c). Both viruses can cause panleukopenia-like signs. Test kits designed for detecting canine parvovirus antigens can also detect both wild and vaccine strains of FPV.

 

2. Can a cat infect a dog?

 

The ability of a cat to infect a dog depends on the strain involved. Cats shedding CPV-2a or CPV-2b antigen can infect dogs, but cats shedding FPV cannot infect dogs.

 

3. If the result of the antigen test is negative, can I rule out FPV infection?

 

Even if the result of the fecal antigen test is negative, FPV infection cannot be ruled out. Viral shedding can occur intermittently or over a short period, and the test may yield false negatives if performed 5 to 7 days after the onset of disease. Viremia occurs before fecal shedding, so a negative result can be obtained if the test is performed too soon. In the early stages of the disease, PCR analysis of blood or bone marrow can provide an earlier positive result for FPV compared to the fecal antigen test.

 

4. Can an indoor cat become infected?

 

Yes, an indoor cat can be indirectly exposed to the virus through contaminated shoes, bags, or objects that serve as vehicles for disease transmission, carrying either canine or feline parvovirus.

 

5. Can a vaccinated cat become infected with FPV?

 

Yes, if the complete vaccination schedule has not been followed. The most common cause of disease in vaccinated cats is interference from maternal antibodies. Vaccination should begin at 9 weeks and 12 weeks, with the final dose always administered after 16 weeks. These new vaccination recommendations are supported by experts in feline infectious diseases.

 

6. Why are neurological signs observed in kittens infected with FPV?

 

Kittens infected with FPV can develop cerebellar disease, which is characterized by symmetrical ataxia, hypermetric movements of the limbs and head, and intention tremors. This is a result of cerebellar hypoplasia caused by intrauterine FPV infection. Affected kittens usually come from litters where multiple kittens are affected, leading to confusion with congenital heart disease. However, affected kittens present with non-progressive cerebellar ataxia once they start walking.

 

7. How is cerebellar hypoplasia diagnosed? Is it contagious to other cats?

 

Diagnosis of cerebellar hypoplasia can be made through magnetic resonance imaging (MRI) or post-mortem analysis, but there is no specific test for detecting parvovirus due to the absence of an active infection. Cerebellar hypoplasia is not contagious to other cats. Affected cats gradually adapt to neurological deficits and can lead normal lives.

 

8. What vaccination schedule is recommended for an adult cat with unknown vaccination status?

 

It is highly recommended to vaccinate the cat with two vaccinations separated by 3 weeks.

 

9. What is the most appropriate treatment? Is antibiotic use appropriate?

 

Cats with feline panleukopenia should be isolated and provided with intensive treatment. Intravenous fluid therapy is crucial, correcting metabolic acidosis and hypokalemia. Restricting food and water intake should only be done if there is vomiting, and it should be restored as soon as possible. Symptomatic medications can be administered for vomiting or nausea. Transfusion of whole blood or plasma may be necessary in cases involving hypoproteinemia. Antibiotics specific to gram-negative and anaerobic bacteria should be given intravenously to prevent bacterial contamination due to intestinal barrier compromise. Treatment should be tailored to individual cases.

 

10. What should be done in case of an outbreak of FPV at a clinic?

 

In case of an outbreak, it is important to implement cleaning and disinfection measures as part of the infectious disease control protocol. Disinfectants should be used after washing biological material with soap. Unvaccinated animals should be handled with gloves and placed on clean surfaces. Surfaces and objects that are not routinely cleaned, such as doorknobs, keyboards, light switches, and countertops, should be periodically cleaned. Personnel handling sick animals should use gloves, gowns, and foot coverings, and a color code can be used to mark contaminated material. Knowledge of the vaccination status of other animals attending the clinic is crucial.

 

Key Points:

 

- Kittens are highly susceptible to FPV infection before acquiring vaccine antibodies, following a decline in maternal antibody levels.

- Vaccination against FPV is recommended, tailored to each animal's circumstances, with vaccination after 16 weeks of age.

- Adult and indoor cats are also susceptible to FPV infection.

- Clinical presentation can vary, with anorexia and depression being common signs without vomiting or diarrhea.

- Rapid tests provide a reliable diagnosis, but false negatives are possible. Results should be interpreted considering the clinical presentation and the animal's risk of exposure. PCR analysis can be used to verify diagnosis.

- Hospitalization and supportive treatment are essential. The duration of hospitalization ranges from 5 to 9 days.

- Concomitant diseases worsen the prognosis, regardless of the animal's age.

- Enteral nutrition is beneficial for vomiting cases, while parenteral or microenteral nutrition can be alternatives. Hypoalbuminemia and leukopenia may be negative prognostic factors.

- Nursing care, keeping cats warm, dry, and clean, is crucial.

- There is a high risk of hospital contamination.

 

Case Study 1: Ketty

 

Summary: Ketty is a 5-month-old non-neutered male cat. He was adopted from a shelter 7 days prior to the consultation. The reason for the consultation is weakness and anorexia.

 

Medical History:

 

Ketty was vaccinated with an inactivated vaccine against feline panleukopenia virus (FPV), feline herpesvirus (FHV), and feline calicivirus (FCV) at 8 weeks of age. Since arriving at his new home, Ketty has been hiding and it is unclear if he has been eating properly. The owners assumed his behavior was normal for a cat in a new environment. However, Ketty was active and friendly during his time at the shelter.

 

Physical Examination:

 

Ketty's physical examination reveals a body condition of 2/5, weighing 1.7 kg. He shows weakness, lethargy, dehydration (approximately 7%), excessive salivation, abdominal pain on palpation, rectal temperature of 40.9 °C, bradycardia (60 beats per minute), and a capillary refill time >2 seconds. A complete blood count is performed.

 

Diagnoses:

 

The most likely diagnosis for Ketty is feline panleukopenia virus (FPV) due to his clinical signs, exposure to a risky environment, inadequate vaccination history (not vaccinated after 16 weeks), and severe leukopenia observed in the complete blood count.

 

Treatment:

 

Ketty requires complete isolation and hospitalization with intensive care. Fluid replacement therapy and antimicrobial treatment are administered. Placement of a central venous catheter is advised if possible. Enteral nutrition is initiated after supportive treatment. Ketty shows significant improvement and is discharged.

 

Case Study 2: Kitty and his two littermates

 

Review: Kitty and his two littermates are domestic shorthair cats, 2 months old, neither vaccinated nor dewormed. The reason for consultation is a lack of energy.

 

Medical History:

 

Kitty and his littermates were found on the street and appear to be from the same litter. They have been in their new home for 10 days and initially showed normal eating and playing behavior. However, Kitty stopped playing and eating three or four days before the consultation.

 

Physical Examination:

 

Kitty's physical examination reveals a body condition of 3/5, weighing 200 g (lower than his littermates). He displays weakness, lethargy, poor coat, dehydration (approximately 8%), excessive salivation, abdominal pain on palpation, rectal temperature of 41.2 °C, bradycardia (80 beats per minute), and a capillary refill time >2 seconds. A complete blood count is performed, and a fecal ELISA for canine parvovirus antigen produces a positive result.

 

Treatment:

 

Kitty needs to be hospitalized in isolation due to the hyperacute clinical signs and positive diagnosis of FPV. His littermates should be monitored and potentially undergo additional tests. In addition to fluid therapy and antibiotic treatment, a blood transfusion and parenteral nutrition are proposed.

 

Evolution:

 

After receiving a blood transfusion and parenteral nutrition, Kitty starts receiving enteral nutrition. He experiences complications with an upper airway respiratory process, requiring extended hospitalization. After 7 days of hospitalization with fluid and supportive therapy, Kitty's body weight increases to 270 g, and he makes a full recovery. One of his littermates dies suddenly, and necropsy reveals intestinal lesions consistent with FPV. The third littermate shows no signs of disease or hematological disorders.