Pulmonary arterial disease in cats seropositive for Dirofilaria immitis but lacking adult heartworms in the heart and lungs.
OBJECTIVE
To determine the prevalence and severity of pulmonary arterial lesions in cats seropositive for heartworms (Dirofilaria immitis) but lacking adult heartworms in the heart and lungs during necropsy.


METHODS
630 adult cats from an animal control shelter in Florida.


METHODS
Cats were tested for adult heartworms in the heart and pulmonary arteries and antibody against heartworms in the serum. Histologic examination was conducted on the right caudal lung lobe of 24 heartworm- and antibody-positive cats; 24 heartworm-negative and antibody-positive cats; and 24 heartworm-, antibody-, and antigen-negative cats. Wall areas of 10 small to medium-sized pulmonary arteries of each cat were measured and expressed as a proportion of total cross-sectional area.


RESULTS
Heartworm infection or seropositive status was significantly and strongly associated with seventy of medial hypertrophy of pulmonary arterial walls. Heartworm- and antibody-positive cats and heartworm-negative and antibody-positive cats had a significant increase in wall thickness, compared with wall thickness for heartworm- and antibody-negative cats. Heartworm- and antibody-positive cats had the most severe hypertrophy. The proportion with occlusive medial hypertrophy was significantly higher in heartworm- and antibody-positive cats (19/24 [79%]) and heartworm-negative and antibody-positive cats (12/24 [50%]), compared with heartworm- and antibody-negative cats (3/24 [13%]).


CONCLUSIONS
Cats with serologic evidence of exposure to heartworms, including those without adult heartworms in the lungs and heart, have a greater prevalence of pulmonary arterial lesions than heartworm-negative cats without serologic evidence of exposure. Additional studies are needed to define the pathogenesis, specificity, and clinical importance of these lesions.
Browne
Leanne E
LE
Veterinary Medical Program, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610, USA.
Carter
Todd D
TD
Levy
Julie K
JK
Snyder
Patti S
PS
Johnson
Calvin M
CM
D000704:Analysis of Variance; D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood; D001837:Body Weights and Measures; D002371:Cat Diseases / Q000276:immunology / Q000469:parasitology* / Q000473:pathology*; D002415:Cats; D004183:Dirofilaria immitis / Q000276:immunology*; D004184:Dirofilariasis / Q000276:immunology* / Q000473:pathology; D005260:Female; D006321:Heart / Q000469:parasitology; D008168:Lung / Q000469:parasitology; D008297:Male; D011651:Pulmonary Artery / Q000473:pathology*; D014652:Vascular Diseases / Q000473:pathology / Q000662:veterinary*
D000909:Antibodies, Helminth