Hairs Causing Pulmonary Emboli A Rare Complication in Long-Term Intravenous Studies in Dogs

Absrracf. Hair particles as arterial lung emboli were an unexpected side effect in a long-term intravenous toxicity study in Beagle dogs. These emboli led to arterial throm-bosis and perivascular granulomas or focal interstitial pneumonitis. The embolic lesions were not severe enough to cause infarction of the lung. This high incidence of hair embolism was related to a moderate solvent-specific chronic dermatitis at injection sites. Skin and hair particles may become punched out and enter the animal’s blood system when injected intravenously. This risk is minor if the injection is carried out with care. Proof of such undesirable side effects is impossible in the living animal and difficult even in histological lung sections unless they are scrutinized. There have been only isolated reports of mature hairs as lung emboli [2,3,5]. Lanugo hairs, however, have been found in the lungs of people with amniotic fluid embolism [l]. We report mature hairs frequently seen as arterial emboli in lungs of Beagle dogs used in a 4-week intravenous toxicity study. Materials and Methods Thirty 8- to 12-month-old Beagle dogs from our own stock were used in a 4-week toxicity test. The toxicity of a galenical preparation of an antitussive agent was tested by injecting the substance daily for 4 weeks into the vena cephalica nnrebrachii after removing hairs with electric clippers. The chemical nature of the compound is irrelevant because there were lesions in treated and control animals. Controls were given a solvent widely used for intravenous preparations. It was a citrate-phosphate buffer of 1.0 mg citric acid, 5.0 mg Na,HP0,,12 H,O, 5.5 mg NaCl in distilled water to 1 ml. The animals were assigned to four groups (table 1)