Feline Plasma Cell Pododermatitis (PCP)

Summary

Feline pododermatitis (also known as plasma cell pododermatitis, or PCP) is a rare disease that causes inflammation of the paw pads. Cats with PCP typically have swollen paw pads criss-crossed by white lines. The paw pads may have open or healed sores that bleed, become ulcerated, or get infected. The affected toes are usually painful and cause lameness or difficulty walking.    The exact cause of PCP has not been proven, but it is thought to be an overreaction of the immune system. In most cases, a presumptive diagnosis of PCP is made based on improvement in response to therapy, but sometimes a biopsy of the paw pad is necessary. The primary treatment is doxycycline, which has both immunomodulating and antibiotic effects. Feline pododermatitis does not spread to other pets or people in the household.

Risk Factors

PCP is rare in cats. It is painful, but does not present a life-threatening emergency. PCP often occurs concurrently with feline immunodeficiency virus (FIV), so a thorough diagnostic approach is advised for any cat showing symptoms of PCP.

Possible Causes

The exact cause of PCP in cats is unknown, but it appears to be an immune system dysfunction. With PCP, plasma cells (a type of immune cell) accumulate within the pad tissue. This leads to swelling, loss of pigment, and open sores. Secondary bacterial and fungal infections are common complications of PCP. 

Although PCP is related to an overactive immune system, approximately 50% of cats with PCP are diagnosed with feline immunodeficiency virus, which suppresses the immune system. The mechanism behind this paradox is unknown. 

Other associated diseases include: 

• plasma cell stomatitis • nasal plasma cell infiltrates • indolent ulcers• eosinophilic skin granulomas

Main Symptoms

The main symptoms associated with PCP are:

Swollen, puffy paw pads • White lines on the paw pads • Loss of pigment on the paw pads

• Sores on the paw pads

Detailed Characterization

Clinical signs of PCP range from mild, barely noticeable swelling and discoloration, to severe, bloody, ulcerated, and painful sores with secondary infections. Any or all limbs may be affected, but it is rare for only one foot to develop pododermatitis. 

Although many cases of PCP do not have symptoms beyond swelling and sores on the affected paw pads, some cats may experience the following:

• Bleeding • Pain • Lameness • Appetite loss • Lymph node enlargement (lymphadenopathy)

Testing and Diagnosis

Diagnostic tests for PCP include: 

• Physical examination: A thorough physical provides information about the cat’s overall health status as well as potential concurrent conditions like eosinophilic granuloma complex.

• Bloodwork: Routine tests as well as testing for feline leukemia virus and FIV are important for cats with suspected PCP. 

• Cytology: A needle or swab is used to sample small numbers of cells from the paw pad for microscopic examination.

• Biopsy: A tissue section from the paw pad is taken and submitted to a pathologist for evaluation. 

Steps to Recovery

Treatment of PCP is directed at relieving pain and swelling as well as eliminating any secondary infections. Doxycycline has both immunomodulating and antibiotic properties, so it’s a common choice for first-line treatment. 

If the swelling does not respond to doxycycline, other immunosuppressive medications may be used. In cases with secondary infections, more specific antibiotics and antifungal medications may be necessary. Surgery may also be beneficial in severe cases.

The overall prognosis for recovering from symptoms of PCP is good, but relapses are common, especially when treatment is discontinued. Some cases of PCP may go away on their own without treatment.

Prevention

PCP is not contagious to humans or to other animals. Since it may be indicative of FIV or FeLV, taking steps to protect cats from contracting these viruses may help to prevent future development of PCP.

Is PCP Common in Cats?

PCP is a rare feline condition.

Typical Treatment

Typical treatment of PCP may include

• Oral doxycycline • Immunosuppressive medications  • Surgery

As well as treatment for any primary conditions associated with the occurrence of PCP as needed.

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