Spontaneous extramural coronary arteritis in dogs

Area of Science:

• Veterinary Pathology
• Cardiovascular Pathology
• Toxicological Pathology

Background:

• Microscopic inflammatory lesions in canine coronary arteries are not well-characterized.
• Previous studies have not extensively detailed lesions specific to extramural coronary arteries.

Purpose of the Study:

• To determine the incidence and histological characteristics of a specific microscopic inflammatory lesion in extramural coronary arteries of dogs.
• To differentiate this lesion from other reported canine vasculopathies.

Main Methods:

• Histological evaluation of 119 control and treated beagle and random-source dog hearts from toxicological experiments.
• Detailed examination of extramural coronary arteries, including gross and microscopic assessment.
• Comparison of lesion incidence across different groups (control vs. treated, sex, source).

Main Results:

• A focal extramural coronary arteritis lesion was identified in 23% of experiments.
• Incidence was 2.3% in beagles and 4.7% in random-source dogs; expanded sampling showed 5-9% incidence.
• Histologically, lesions featured adventitial mononuclear cell infiltrates, necrosis, and intimal-medial separation, confined to extramural vessels.

Conclusions:

• A distinct, idiopathic focal extramural coronary arteritis occurs in dogs.
• This lesion is not grossly visible and differs from intramural vessels and other organs.
• The findings suggest this arteritis is not a manifestation of recently described polyarteritis syndromes in dogs.