When the temperature falls and rodents seek a snug environment in which to pass the winter, pest control can become a big problem. People often choose to retaliate with an arsenal of poisons designed to remove these unwanted guests. Dr. Petra Volmer, a veterinary toxicologist at the University of Illinois College of Veterinary Medicine says, "What people do not always realize is that these toxic substances as deadly to family pets as they are to the pests."

There are several classes of rodenticides in use today. The most common are the coagulants, which act by blocking the clotting mechanisms in the blood. After ingestion of the poison, the animal begins to bleed internally. If left untreated the bleeding will continue until the animal dies. One major problem with these rodenticides is that they have a delayed onset and hemorrhage may not begin until 3 to 5 days after ingestion. This means that if you did not see the animal eat the poison, then you might not know that anything is wrong until the animal begins to exhibit symptoms such as weakness, pale mucous membranes, rapid breathing, or frank bleeding (hemorrhage). An even bigger problem with newer anticoagulants is that they have a very long duration of action. Dr. Volmer says, "Some brands can produce effects lasting for up to 3 to 4 weeks, which can make treatment expensive." The treatment for anticoagulent rodenticide poisoning is a prescription of Vitamin K1, which must be administered on a regular basis until the effects of the poison are gone, and then it is important to retest for bleeding problems after the therapy has ended to make sure that the toxin has really been cleared from the system.

A newer type of active ingredient is bromethalin, which is a neurotoxin that may cause an accumulation of fluid in the brain and spinal cord. Some of the signs of bromethalin poisoning are incoordination, hyper excitability, tremors, seizures, depression, hide leg weakness, and death. Its us should be monitored closely.

Cholicalciferol, a form of vitamin D, which causes toxic effects by raising blood calcium to dangerously high levels. This causes an accumulation of calcium in the tissues of the heart, gut, kidneys and blood vessels. Signs of poisoning can include muscle weakness and cardiac problems that can lead to cardiac arrest. Death may occur due to renal failure or rupture of the aorta. Treatment includes blocking the absorption of calcium from the gut and reabsorption from bone, by enhancing excretion of calcium by the kidneys. This type of toxin is very dangerous for pets because it only takes a small amount to cause a toxicosis.

Dr. Volmer says, "By far, the best way to avoid toxicity is to avoid using these products altogether, but if you must use them, make sure that they are stored in a place where your pet cannot get them. Check them often to make sure that they haven't been tampered with by your pet and if you suspect that any of it may have been ingested, call your veterinarian immediately."

If you have any questions regarding rodenticides or if you think that your pet may have been poisoned please contact your local veterinarian or the ASPCA Animal Poison Control Center at 1-888-4ANI-HELP.