Performance of serologic tests used to detect heartworm infection in cats.
OBJECTIVE
To compare heartworm serum antibody (Ab) and antigen (Ag) test results, using commercial laboratories and in-house heartworm test kits, with necropsy findings in a population of shelter cats.


METHODS
Prospective study.


METHODS
330 cats at an animal shelter.


METHODS
Between March and June 1998, 30 ml of blood was collected from the cranial and caudal venae cavae of 330 cats that were euthanatized at a local animal shelter. Results of heartworm Ab and Ag serologic tests for heartworm infection were compared with necropsy findings in this population of cats, using commercial laboratories and in-house test kits to measure serum Ab and Ag concentrations.


RESULTS
On necropsy, adult Dirofilaria immitis were found in 19 of 330 (5.8%) cats. Combining results from serum Ab and Ag tests achieved higher sensitivities than using serum Ab and Ag test results alone (i.e., maximum sensitivities of 100% vs 89.5%, respectively, whereas use of serum Ag and Ab test results alone achieved higher specificities compared with the use of a combination of serum Ab and Ag results (i.e., maximum specificities of 99.4% vs 92.9%, respectively).


CONCLUSIONS
On the basis of our findings, if a cat has clinical signs that suggest heartworm disease despite a negative heartworm serum Ab test result, an alternative heartworm Ab test, a heartworm Ag test, thoracic radiography, or two-dimensional echocardiography should be performed.
Snyder
P S
PS
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville 32610-0126, USA.
Levy
J K
JK
Salute
M E
ME
Gorman
S P
SP
Kubilis
P S
PS
Smail
P W
PW
George
L L
LL
D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood*; D000947:Antigens, Helminth / Q000097:blood*; D002371:Cat Diseases / Q000175:diagnosis*; D002415:Cats; D004183:Dirofilaria immitis / Q000276:immunology*; D004184:Dirofilariasis / Q000175:diagnosis*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D006461:Hemolysis; D008055:Lipids / Q000097:blood; D008297:Male; D011446:Prospective Studies; D011933:Reagent Kits, Diagnostic / Q000662:veterinary; D012680:Sensitivity and Specificity
D000909:Antibodies, Helminth; D000947:Antigens, Helminth; D008055:Lipids; D011933:Reagent Kits, Diagnostic