Carotid pseudoaneurysm in a kitten after accidental puncture with a needle.

Case summary: A 3-month-old intact male domestic shorthair kitten's cervical region was inadvertently punctured during routine subcutaneous fluid administration. A swelling rapidly developed on the left lateral neck and continued to grow, despite compression. An emergency facility evaluated the kitten 48 h later and the swelling was determined to be blood. Fine-needle aspiration of the swelling resulted in further swelling of the mass on the neck. The kitten began showing signs of systemic shock, necessitating a blood transfusion. The kitten was referred to a tertiary facility 24 h later for further diagnostics and treatment. CT of the head and neck revealed a large fluid-filled mass with progressive contrast enhancement noted during the filling phase, consistent with active hemorrhage. A carotid pseudoaneurysm was suspected and surgery was recommended. The left carotid artery was ligated proximal to the pseudoaneurysm; hemorrhage continued and the swelling was further explored. A small connection to the carotid artery within the medial aspect of the swelling was identified and ligated. The kitten required autotransfusion and massive allotransfusion during surgery due to blood loss. Recovery was uneventful. A head tilt and Horner's syndrome were noted postoperatively and improved over the following months. Histopathology was consistent with pseudoaneurysm. Relevance and novel information: This is the first reported case of pseudoaneurysm in a kitten that was treated surgically, with massive blood transfusion and minimal complications. Early surgical intervention can result in excellent prognosis. The need for blood product administration should be anticipated.