Introduction

• Of all the petroleum products, pets are most likely to come in contact with refined petroleum products. These can be either aliphatic hydrocarbons or aromatic hydrocarbons. They can also come in contact with mineral oil, mineral spirits and motor oil.
• Aliphatic hydrocarbons include methane, propane, butane, and gasoline. Petroleum distillates found in some insecticides are also included.
• Aromatic hydrocarbons include benzene, toluene and xylene. These are most commonly found in lacquers, glue, paint thinner, some plastics and quick-drying paint. Kerosene contains both aliphatic and aromatic hydrocarbons.
• There are too many different petroleum products to list individually but there are some generalizations that can be useful. Petroleum products with high boiling points, such as mineral oil, are considered relatively non-toxic. Gasoline, benzene, etc. have low boiling points, are more readily aspirated and are therefore more likely to cause toxicity. In addition, products with a high aromatic content, such as benzene and xylene, readily cause systemic affects
• The most common method of toxicity is ingestion and subsequent aspiration. The most common effect of exposure to petroleum hydrocarbons is chemical pneumonitis.
• Toxicity varies from product to product. For some, as little as 1 milliliter can cause aspiration pneumonia Lung: aspiration pneumonia (gasoline, kerosene). Methane and propane have lower toxicities. Prolonged exposure to more than 60 ppm in the air of aromatic hydrocarbons can lead to bone marrow suppression.

Pathogenesis

Etiology

• Animals may accidentally ingest refined petroleum products or they may be given intentionally as folk medicine. Some toxicities are associated with grooming after having the product on their skin. Topical exposure can also result in dermal toxicity.

Predisposing factors

• There are no specific predisposing factors. Any dog can become intoxicated by ingesting petroleum products or through topical exposure.
• Dogs with long hair coats, especially if matted, have an increased risk of systemic absorption since the mats will trap the petroleum against the skin for long periods of time.

Pathophysiology

• The pathophysiology of petroleum product exposure depends on the type of product and the route of exposure. The most serious effect of petroleum product exposure is aspiration/chemical pneumonitis.
• Petroleum products are highly lipophilic and are readily absorbed through the skin or gastrointestinal tract. They are also very volatile and readily absorbed through the lungs.
• Following exposure, hydrocarbons are systemically absorbed and distributed to all major organs. The high viscosity products, such as motor oil, are not absorbed well. The low viscosity products, such as gasoline, are more readily absorbed and when aspirated, are able to penetrate deeper into the lungs, resulting in more serious lung damage. When comparing aromatic hydrocarbons to aliphatic hydrocarbons, the aromatic products are more likely to result in toxicity.
• The high lipophilic nature of petroleum products dissolves the lipid component of cell membranes resulting in swelling and cell necrosis. In the lung, this is followed by inflammation, edema, bronchospasm and alveolar necrosis. These lesions may then become colonized by bacteria. If no bacterial colonization occurs, lung lesions typically resolve within 14 days.
• Due to the high lipophilic nature of hydrocarbons, pulmonary surfactant is altered, causing an increase in alveolar surface tension. This destabilizes the alveoli and results in airway collapse, contributing to the lung damage.
• The aromatic hydrocarbons are metabolized to phenols or carboxylic acids. They are then conjugated and excreted through the urine or bile. A significant amount of excretion also occurs through the lungs.
• The aliphatic hydrocarbons are metabolized through oxidation in the liver and excreted through the lungs.
• Topical exposure may lead to dermatitis and epithelial necrosis.

Timecourse

• Signs typically develop within 1 hour but may take up to 3-4 hours. Signs are often progressive over 24-48 hours and slowly resolve over the next 3-10 days. Severely intoxicated animals may succumb within 2 hours of exposure to respiratory failure.
• Dogs that do not show signs within 12-24 hours will typically not develop signs.

Diagnosis

Treatment

Prevention

Outcomes