Genetic basis of Acute Respiratory Distress Syndrome in Dalmatians - is caused by a recessive nonsense mutation (c.31C>T, p.R11*) in the ANLN gene. The ANLN gene encodes anillin, an actin-binding protein that plays a critical role in cell division and maintaining the integrity of intercellular junctions. Affected dogs are homozygous for the ANLN mutation; carriers are heterozygous and clinically normal. The mutation is inherited in an autosomal recessive manner. Carrier frequency in Dalmatians is low (about 1.7%), and the mutation is not found in genetically similar breeds such as Pointers.
Pathophysiology - The mutated ANLN gene leads to early truncation and absence of functional anillin protein in the bronchiolar epithelium of the lungs. This causes abnormal cellular organization, affecting bronchiolar epithelial regeneration and alveolar epithelial repair. These defects compromise pulmonary gas exchange and lead to fatal respiratory distress. Histopathology in affected dogs shows hyperplasia and squamous metaplasia of bronchiolar epithelium, consistent with a failure in epithelial repair.
Complications - Clinical signs usually begin around 7 months of age, including progressive tachypnea (rapid breathing), dyspnea (difficulty breathing), and respiratory failure. The disease progresses rapidly with an average survival time of about 3 weeks after clinical onset. Some affected puppies may also show additional abnormalities like renal aplasia (missing kidney) and hydrocephalus, though these are less common. The disease is fatal; clinical management options are limited.
Why This Matters to Breeders and Vets - For breeders, genetic testing for the ANLN mutation allows identification of carriers to prevent breeding two carriers, thus avoiding affected puppies. Awareness of the genetic cause helps in breeding decisions aimed at eradicating this fatal respiratory syndrome from the Dalmatian breed. For veterinarians, understanding the genetic and pathophysiologic basis assists in diagnosis and differentiating ARDS from other respiratory conditions. Early diagnosis can guide supportive care decisions and prompt owner counseling.
Summary - Acute Respiratory Distress Syndrome (Dalmatian Type) is a fatal, autosomal recessive lung disease caused by a nonsense mutation in the ANLN gene resulting in defective lung epithelial repair and severe respiratory failure. The condition manifests in young dogs with progressive breathing difficulties and is invariably fatal within weeks. Genetic testing enables breeders to avoid at-risk matings and prevent affected litters, improving breed health. Veterinarians benefit from understanding this disease for diagnosis and supportive care planning.