In California, snail bait constitutes the most common poisoning agent in the dog. Most cases are inadvertent as many gardens have snail problems. Snail bait is commonly formulated in pellets and flavored with molasses or bran to attract snails. Animals can be affected by ingesting the bait directly, or eating snails, slugs, or rats that have eaten the bait. Snail baits are also available as liquids and powders which can get onto paws and be licked off during normal grooming. Very little snail bait is required to cause poisoning (less than a teaspoon per 10 lbs of body weight).
Signs of Poisioning
Signs of poisoning begin fairly quickly after the poison is consumed. The dog will begin twitching at first only slightly and then uncontrollably. This progresses to seizures and potentially to death. The muscle contractions of the twitches raise body temperature so high that brain damage can result. Patients can also exhibit racing heart rates, vomiting, diarrhea, rigidity, and respiratory failure.
Metaldehyde, is toxic to the central nervous system. Clinical signs from metaldehyde can occur within one to four hours after exposure and include the following:
- Restlessness and anxiety
- Over-reaction to stimuli (sounds)
- Difficulty walking
- Rapid heart rate and respiration
- Hyperthermia (elevated body temperature)
- Vomiting and diarrhea
- Muscle tremors progressing to seizures
- Loss of consciousness
- Respiratory failure
There is the possibility of liver failure that can occur in some patients approximately 2-3 days after poisoning, so it is important for liver enzymes to be monitored using blood tests through out the recovery period.
Making the Diagnosis:
The appearance of the “twitching patient” is very characteristic even if there is no known history of snail bait exposure. Testing of stomach contents or urine for the presence of metaldehyde can be done but is generally not necessary.
There is no direct antidote for metaldehyde toxicity. Treatment is geared toward controlling the clinical signs. If less than one hour has passed since exposure, it may be possible to induce vomiting. If the patient is already twitching badly the stimulation involved in inducing vomiting may not be in the patient’s best interest. In this case, the patient can be anesthetized and stomach pumped. Activated charcoal can be given to prevent absorption of metaldehyde into the body from the intestine. Cathartics (used to induce diarrhea) can also be used with the activated charcoal to assist in removing the metaldehyde from the intestinal tract promptly.
Twitching can be controlled with methocarbamol (a muscle relaxant) or injectable valium (diazepam). Fluid therapy and body temperature monitoring will be needed through the recovery period.
Chance of recovery depends on how much poison was ingested, how quickly therapy was initiated, and the general health of the patient. While this is a very serious type of poisoning most patients have a good chance at recovery if treated properly.
At home the yard should be hosed down with water to dissolve remaining metaldehyde and the dog should be restricted from the treated area for a two week period.
Many people who have used slug and snail baits for years and never had a problem think that their pets will never decide to “try” it. Don’t assume this will always be the case. We frequently treat animals with distraught owners who claim that their animal has never been interested in the snail bait in the past. Snail bait is very enticing because it smells and tastes good. Please consult your local gardening store for alternative methods of pest control. Alternatively, you can obtain decollate snails at a nursery. The dried snails are activated by soaking them in water and then scattered in the garden. They eat the snail larvae to naturally control the snail population.
Pet owners should exercise extreme caution when using metaldehyde-containing baits, taking steps to ensure that the product is applied only to areas completely inaccessible to pets. Any unused bait should be stored in a secure container and cabinet out of the reach of pets. Alternatively, other less toxic formulations of snail and slug bait could be considered, such as those containing ferric phosphate.
Treating an animal for metaldehyde toxicity can be a very costly and frustrating experience for pet owners, and yet the condition is, in most cases, totally preventable. If you suspect that your pet may have ingested a product containing metaldehyde, contact your local veterinarian or the ASPCA Animal Poison Control Center (1-888-426-4435) for immediate assistance. To learn how to “Make Your Pet’s Home Poison Safe visit www.aspca.org/apcc