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Dry Form Feline Infectious Peritonitis

Patient Information

11 Years
Male, Neutered


Dry Form Feline Infectious Peritonitis. Another great mystery turned inside out with the ultrasound probe.
Imaging performed by Dr. Lindsey Daniel, NJ Mobile Associates & Mobile Veterinary Ultrasound, Atlanta, GA, Case managed by Dr. Jim Brousse & staff at Cat and Dog Clinic, Athens, Georgia.

History (Kohmescer): Smokey, an 11-year-old, M/N, DSH indoor/outdoor cat. His presenting complaint was weight loss and anemia, and he was negative for FELV (+ for FIV from vaccination). Bloodwork was otherwise uneventful.

Clinical Differential Diagnosis

(Remo Lobetti PhD, DECVIM): Differentials include gastrointestinal tract blood loss (neoplasia, foreign body, ulcer), anemia of chronic infection, neoplasia, bone marrow pathology, lead/zinc toxicity, systemic mastocytosis.

Sonographic Differential Diagnosis

(Lindquist DMV, DABVP): Infiltrated descending colon with associated lymphadenopathy. Loss of intestinal mural detail and structural loss in the adjacent lymph node meets neoplastic criteria such as that of lymphoma, mast cell disease, and less likely intestinal carcinoma. Complicated inflammatory disease (IBD) bacterial, fungal, viral colitis, or dry form FIP also possible with associated lymphadenitis.


FNA of both the lymph nodes and the colonic infiltrate were inconclusive, so exploratory surgery and the referring veterinarian performed biopsies. Primary surgical differential was neoplasia such as lymphoma. However, surgically obtained histopathology was both “characteristic and diagnostic” for FIP. The pathologist described the GI lesions (colon) and the lymph node as “granulomatous, multifocal, moderate; with necrosis”. The laboratory also performed Immunostaining for Feline Coronavirus on the colon, which was positive for FECV.


The patient was put on supportive care post surgery. Patient is doing well 2 months after surgery (Intestinal resection).


Special thanks to Dr. Jim Brousse & staff at Cat and Dog Clinic, Athens, Georgia for the thorough management of this case. Also special thanks to Dr. Lindsey Daniel, NJ Mobile Associates & Mobile Veterinary Ultrasound, Atlanta, GA for submitting this case.


A section of intestine (likely colon given the position) is thickened (0.68 cm serosa to lumen) with uniform loss of mural detail and deviated hyperechoic luminal interface. The wall is coarsely hypoechoic with uniform echogenicity without discernable submucosal, muscularis, or mucosal layering.
A uniformly hypoechoic enlarged (1cm) mesenteric lymph node is enlarged likely draining the infiltrated portion of small intestine. A smaller 0.5 cm similar lymph node is also prominent caudal to the primary lymph node.
An oblique view of the infiltrated portion of intestine reveals another adjacent irregular hypoechoic structure consistent with an enlarged lymph node (right of the intestine) that has lost its structure. The hyperechoic capsule is thickened, ill defined, and is irregularly hyperechoic consistent with capsular inflammation. No effusions were present.