Feline Infectious Peritonitis – neurotropic

History: A 7 month old female intact DSH kitten had neurologic signs and seizures in the past few months (Along with several others from a shelter).  This particular kitten presented for circling and ataxia.

Gross Findings:

Gross lesions were limited to multifocal petechiae  in the white matter of the cerebellum.

Histopathology:

Brain:  There are moderate numbers of lymphocytes, plasma cells, and histiocytes tightly surrounding blood vessels in the meninges,  superficial cerebral and brainstem blood vessels and expanding Virchow-Robbins space.  Similar cellular infiltrates surround blood vessels adjacent to the lateral ventricle and central canal.  There are lesser numbers of these cells located below the ependyma of the lateral ventricles and central canal.

A 7 month old female intact DSH kitten was presented for necropsy 12/8/08.  Several kittens at the

humane society have had neurologic signs and seizures in the past few months.  They are from

different litters and have been euthanized.  This particular kitten presented for circling, ataxia, and

possible seizures (none observed).  The primary concern is for a possible cause on a kennel-level,

and JCHS would like to prevent future deaths through the sacrifice of this kitten.

Brain, bordering the lateral ventricle: vasculitis, primarily lymphocytes, macrophages and plasma cells

Brain and meninges: Vasculitis and perivasculitis, lymphoplasmacytic and histiocytic

Brain: Lymphocytes, macrophages, and plasma cells surrounding and infiltrating a blood vessel

Brain: Inflammation often spreads into parenchyma

Morphologic Diagnosis:

Brain:  Multifocal granulomatous meningitis, perivasculitis and periventriculitis

Comment:

Further diagnostics were cost prohibitive in this case.  The character of the lesions were attributed to the dry form of FIP.  More typical lesions of the dry form include multifocal pyogranulomas on serosal surfaces of visceral organs.  In constrast, the wet form presents as profuse body cavity effusions that are protein rich.

The neurologic form of FIP is a recognized subset of the infection with the FIP mutation of feline enteric coronavirus.  A high CSF IgG titer to feline coronavirus is considered diagnostic.

References:

Foley JE, Lapointe JM, Koblik P, Poland A, Pedersen NC. Diagnostic features of clinical neurologic feline infectious peritonitis. J Vet Intern Med. 1998 Nov-Dec;12(6):415-23.

Niels C Pedersen. A synopsis of feline infectious peritonitis virus infection. http://www.vetmed.ucdavis.edu/ccah/documents/FIP_Synopsis_Jan13_09.pdf