CT study points to earlier airway changes in cats with HARD

A new CT-based study adds objective imaging evidence that cats with clinical signs and serologic findings compatible with heartworm-associated respiratory disease, or HARD, show measurable early bronchial remodeling. In a cohort of 38 cats, researchers compared 30 symptomatic, Dirofilaria immitis-seropositive cats with eight asymptomatic seronegative controls and found significantly higher bronchus-to-artery and bronchus-to-vertebral body ratios across multiple lung lobes in the suspected HARD group, while pulmonary vascular changes were less pronounced. The work, published in Veterinary Sciences, builds on the group’s earlier Animals paper and suggests CT morphometric indices may help quantify airway injury in feline heartworm cases that can be difficult to confirm with routine testing alone. (mdpi.com)

Why it matters: For veterinary professionals, the study reinforces a familiar challenge: feline heartworm disease often presents as respiratory disease first, and standard diagnostics can miss it. The American Heartworm Society says antigen testing alone can’t reliably rule out heartworm disease in cats because immature infections and male-only infections are common, and it recommends routine heat treatment of samples for antigen recovery plus annual testing. The same guidelines also stress year-round prevention for all cats, including indoor cats, because mosquitoes enter homes and a meaningful share of infected cats are reported as indoor-only. In practice, that makes these CT-derived airway measurements less of a screening tool and more of a useful adjunct in referral or specialty settings when a coughing or dyspneic cat has equivocal serology and imaging findings that overlap with asthma or bronchitis. (idexx.com)

What to watch: The next question is whether these CT indices can be validated in larger cohorts, tied to outcomes, and translated into clearer diagnostic pathways for differentiating HARD from feline asthma in everyday practice. (mdpi.com)