Serological and molecular detection of Dirofilaria immitis in pet dogs of Lahore, Pakistan.

Heartworms, parasitic nematodes, are responsible to cause a potentially life threatening condition, heartworm disease in mammals particularly dogs and cats. The disease is prevalent in warm, humid areas with mosquitoes as intermediate hosts, increases the chances of transmission. This study aimed to investigate heartworm infection (Dirofilaria immitis) in pet dogs for the first time in Lahore using morphological, serological and molecular techniques including microscopy, PCR and rapid diagnostic kit tests. Blood samples were tested for antigens, with positive cases further analyzed using microscopy, Polymerase Chain Reaction, X-ray imaging, and echocardiography to detect heart-related changes. Modified Knott's Test, remained a valuable tool for detecting and differentiating microfilariae, particularly when used alongside other diagnostic techniques. The microfilariae was confirmed morphologically through wet mount method but had low sensitivity and requires expertise, while microscopy showed high sensitivity but yielded more false positives compared to PCR. Thoracic radiography revealed characteristic signs of D. immitis infection, but may not show early-stage changes. PCR detected D. immitis in 10% of samples, with positive bands (at 203 bp for specific primers and 450 bp for general primers) observed for both species-specific and general primers. Using these diagnostic techniques improves early detection and treatment of heartworm disease in dogs, setting a new standard for veterinary care in Pakistan.