Pete was a 4-yr old SF DSH who presented to our Neurology service for 2 generalized seizures over 2 months.

Following her first seizure, Pete had routine bloodwork with her primary veterinarian and was found to have a moderate lymphocytosis (13432/uL), monocytosis (2335/uL), and hyperglobulinemia (6.5 g/dL). One month later, a CBC and chemistry were rechecked and revealed a persistent lymphocytosis (12672/uL) and hyperglobulinemia (6.3 g/dL). FeLV/FIV testing was negative at this time.

On examination by Dr. Landry, she had a thin body condition (3-4/9 BCS) but had an otherwise normal physical and neurological examination. With her persistent bloodwork findings, additional preliminary testing was recommended including a CBC with flow cytometry, abdominal ultrasound, thoracic radiographs, and infectious CNS disease testing. Thoracic radiographs and abdominal ultrasound were unremarkable. Infectious testing results are provided below:

The results of her flow cytometry revealed an expansion of CD8 T cells. The results did not meet the criteria for a definitive diagnosis of emerging T cell neoplasm. The PARR assay was suggestive of a clonal T cell population but was also not a definitive positive for early lymphoma/leukemia.

With Pete’s extremely high ehrlichia titer and feline coronavirus titer, an infectious/reactive cause for her lymphocytosis was suspected. Pete was started on phenobarbital for her seizures and compounded liquid doxycycline for her tickborne disease. The chronicity of her seizures and unremarkable neurological/physical examination made feline infectious peritonitis (FIP) unlikely, however if there was no response to antibiotic therapy or any changes to her neurological status at home further testing including brain MRI and additional FIP testing were discussed. Her owner reported that after starting doxycycline, Pete began to be more interactive and affectionate at home.

A recheck CBC was performed almost 2 months following the start of doxycycline, revealing a decrease in the lymphocytosis by 50%. Pete continued to be seizure free and was doing well at home.

At her recheck examination 4 months later, Pete continued to remain seizure free. Her neurological and physical examination remained unremarkable. A recheck CBC, chemistry, and tick panel were performed to reveal a drastically improved ehrlichia titer and resolved hyperglobulinemia and lymphocytosis.

Pete had a recheck one year following her first appointment with Dr. Landry. She has remained seizure free and is acting her normal self at home. Since her first appointment, she has gone from 2.96 kg (BCS 3/9) to 4.30 kg (BCS 5/9). Her phenobarbital is being tapered to discontinue and she has been seizure free as of the date of this publication.

Discussion:

• Tickborne disease is not well understood in cats and very little data is available regarding neurological manifestations of these types of infections in felines. While a brain MRI was not performed in this case, the resolution of lab work anomalies, unremarkable neurological examination, and cessation of generalized seizures is supportive of effectively treated infectious CNS disease. A positive ehrlichia PCR on cerebrospinal fluid would be the gold standard for diagnosing neurological manifestations of tickborne disease.
• While a mature lymphocytosis in cats can be a stress/excitement response, these findings are usually transient. A persistent lymphocytosis in cats should be further investigated as it may suggest chronic antigenic stimulation including immune-mediated disease and/or infectious disease. Progressive/worsening lymphocytosis is concerning for lymphoproliferative disease (the leukemic phase of small cell lymphoma or chronic lymphocytic leukemia). FeLV/FIV testing should be performed in these cases.
• Pete’s positive anaplasma titer was discovered due to concern for a lymphocytosis secondary to chronic infection. Currently this author (AL) routinely recommends tick testing in felines with clinical cases or neurological examinations consistent with infectious CNS disease. This recommendation is based on multiple feline cases seen here in Maine like Pete and most commonly includes serology testing (antibody by IFA for lyme, anaplasma, ehrlichia, and Rocky Mountain Spotted Fever).

Authored by: Amanda Landry, DVM, DACVIM (Neurology)