Metaldehyde Toxicity in Cats

Metaldehyde poisoning results from the ingestion of products containing the active ingredient metaldehyde, a common ingredient used in molluscicides, which are products used to kill snails and slugs. Slug and snail baits generally contain three percent metaldehyde and products are formulated as blue or green colored pellets, powder, liquid or granules. Metaldehyde poisoning is seen more commonly on the West Coast of the United States.

The use of molluscicides increases the risk of exposure for pets, and a metaldehyde dosage of 190 to 240 milligrams per kilogram of body weight is lethal for 50 percent of cats. In practice, the toxic dosage can range from 100 to 1000 milligrams per kilogram of body weight.

Metaldehyde toxicity causes rapid onset of neurological symptoms that can be fatal if untreated. Signs of poisoning begin within 1 to 4 hours of exposure. Repeated seizures due to metaldehyde poisoning can cause very high body temperature, which can lead to complications similar to those observed in pets suffering from heatstroke. Affected pets usually require hospitalization for 24 to 72 hours after metaldehyde ingestion.

What to Watch For

• Panting
• Anxiety
• Excitement
• Disorientation
• Incoordination
• Increased respiratory rate
• Increased heart rate
• Drooling
• Vomiting
• Diarrhea
• Extreme sensitivity to sound and touch
• Generalized muscle tremors which can progress to loss of consciousness, seizures and difficulty breathing

If you suspect your pet has ingested snail or slug bait containing metaldehyde, make certain to include this information in the medical history because metaldehyde poisoning mimics symptoms of other diseases and poisonings. Knowledge of the type of poisoning reduces the need for extensive diagnostic tests and allows more specific treatment of your pet's problem. After performing a thorough physical examination, your veterinarian will likely recommend several diagnostic tests and treatments.

Diagnosis

Witnessed ingestion of a metaldehyde-containing product or history of possible exposure to such a product is the best method of diagnosis. Other tests that may be recommended to aid in diagnosis may include:

• Visualization of stomach contents after induced vomiting or gastric lavage (pumping of the stomach).
• A complete blood count (CBC) to assess the general health of your pet and evaluate for infection or inflammation, anemia, or low platelet count.
• A biochemistry profile to evaluate internal organs (liver, kidneys) for other potential causes of seizures and to evaluate for complications arising from repeated seizures, muscle tremors and high body temperature.
• Arterial blood gas analysis to evaluate changes in the acid-base status of the blood. The blood usually is acidic after repeated seizures, muscle tremors or prolonged high body temperature (hyperthermia).

Treatment

Treatment for metaldehyde toxicity may include one or more of the following:

• Administration of medication to induce vomiting to prevent further absorption of the metaldehyde from the stomach and intestinal tract.
• Gastric lavage and enemas to remove metaldehyde from the gastrointestinal tract.
• A cool water bath to lower body temperature if hyperthermia is present due to muscle tremors or repeated seizures.
• Medication such as diazepam (Valium®) or fentanyl (a narcotic pain reliever) to control anxiety, seizures and excessive muscle tremors.
• Muscle relaxants such as methocarbamol, guaifenesin or xylazine to control muscle tremors.
• Placement of an endotracheal tube (a plastic tube in the airway) to provide artificial respiration if respiratory failure occurs.
• Placement of an intravenous (IV) catheter to provide intravenous fluids to correct dehydration and acidosis (low blood pH), which often occur with extensive muscle activity and repeated seizures.

Home Care and Prevention

If you suspect metaldehyde poisoning has occurred, seek veterinary care as soon as possible. Bring remnants of packages or containers for identification of product ingredients when you take your pet to your veterinarian for treatment.

Administer as directed any medications prescribed by your veterinarian.

To prevent exposure, do not allow pets access to areas where snail and slug bait has been placed.