Rodenticide poisoning

Rat poisons

Rodenticides are the name given to any of the group of toxic substances that are used to kill rodents. They are among the most commonly used pesticides … All rodenticides are a group of compounds that exhibit markedly different toxicities to humans and rodents.
Below are listed the three most common rodenticides used in …homes today and their veterinary treatment regimes and relative toxicity as related to primary and secondary poisoning in dogs and cats:
The varieties of rodenticides used over the years are legion, leading to the popular expression, “to build a better mousetrap”. Fortunately, the rodenticides used in modern pest control are not as toxic as their predecessors. In the past highly toxic substances were commonly used in manageing rodents, such as arsenic, strychnine, cyanide, and compound 1080 (a substance developed in World War II-era germany for use in chemical warfare).Below are listed the three most common rodenticides used in Alaska homes today and their veterinary treatment regimes and relative toxicity as related to primary and secondary poisoning in dogs and cats:

Anticoagulant Rodenticides: They block the production of vitamin K-dependent coagulation factors (more commonly found than other rodenticide applications)

First-generation coumarins include D-Con, WARF 42, Rax, Dethmore, Rodex, Tox-Hid, Prolin, Ratron, and others.

Second-generation coumarins include Havoc, Talon, Contrac, Maki, Ratimus, D-Con Mouse Pruf II, brodifacoum, bromadiolone, and others.

Indandiones include diphacinone, chlorophacinone, valone, and pindone, Promar,Diphacin, Ramik, Afnor, Caid, Drat, Quick, Raticide-Caid, Ramucide, Ratomet, Raviac,Pival, PMP, and others.

General Information
These products inhibit the enzymes responsible for recycling of vitamin K, which ultimately reduces production of certain blood clotting factors. There is no effect on circulating clotting factors, so a lag time between poisoning and bleeding problems is seen. The lack of coagulation factors causes the animal to bleed to death because the blood does not clot. First-generation coumarins may be deadly with a larger single dose or smaller doses over multiple days. Clinical signs are usually seen 3-5 days after exposure. Second-generation coumarins and indandiones are toxic with a single dose. Second-generation coumarins are a greater hazard than first-generation coumarins if the dog or cat eats a poisoned rat or mouse.
Treatment, once symptoms appear is more difficult, expensive, and has a much poorer prognosis than treatment that starts immediately after ingestion.

If a female that is nursing puppies or kittens is poisoned, check the clotting ability of the young as the poison may pass in the milk.

Toxic Dose
First generation: Dogs; 2.25-135 mg per pound once, or 0.5-2.25 mg per pound per day for 5-15 days.
Cats; 2.25-13 mg per pound once, or 0.5 mg per pound per day for 5 days.

Second generation: Dogs; 0.11-1.5 mg per pound of Brodifacoums, or 5-6.5 mg per pound of Bromadiolones. Cats; 11 mg per pound of either toxin.

Indandiones: The toxic dose of these varies depending on the specific agent involved.

History of exposure or possible exposure to anticoagulant rodenticides. Difficulty breathing; lethargy; lack of appetite; blood in the stool, vomit, or urine; nose bleed; bleeding gums; hematomas; bruising of skin, ears, or eyes; pallor; or weakness. The most common cause of death is bleeding into the chest cavity.

Immediate Action
If the pet is seen consuming the product, vomiting should be induced. Take the product package and the pet to the veterinarian immediately to begin further treatment. Treatment with vitamin K1 should be started within 24 hours.

Veterinary Care
General treatment: The induction of vomiting may be continued, gastric lavage is performed, and activated charcoal is administered.

Supportive treatment: IV fluids are given. The blood clotting ability is monitored through laboratory tests before, during, and after treatment. Blood transfusions are given if necessary. The animal is kept quiet and confined to reduce the likelihood of causing bleeding to occur through injury such as bumping into objects and bruising.

Specific treatment: Vitamin K1 is given. The oral form is reported to work better than the injectable form. The treatment is continued for 1-4 weeks depending on the toxin ingested. Vitamin K3 is not an effective treatment.

Cholecalciferol-containing rodenticides produce hypercalcemia.

Quintox, True Grit Rampage, Ortho Rat-B-Gone, and cholecalciferol as a livestock feed additive. Vitamins contain Vitamin D, such as Viactiv. Cestrum diurnum (Day Jessamine) and Solanum malacoxylon plants also are a source of cholecalciferol.

General Information
Cholecalciferol poisoning can occur by ingestion of a pesticide, or in farm animals, by the ingestion of an overdose of a feed additive containing cholecalciferol. It causes a drastic increase in the calcium level, which causes heart problems and bleeding secondary to mineralization of the vessels, kidneys, stomach wall, and lungs. This mineralization can also cause kidney failure. This toxin is very lethal.

One IU of vitamin D3 is equivalent to 0.025 mcg of cholecalciferol.

Toxic Dose
Dogs: Symptoms may occur with as little as 1 mg per pound of body weight; deaths have occurred with 4 mg per pound of body weight.

Toxicity rarely occurs in cats.

The Vitamin D in vitamin supplements is not considered a risk for companion animals, even with massive ingestion.

Depression, lack of appetite, increase in drinking and urinating, heart rhythm abnormalities, increased blood pressure, weakness, vomiting and diarrhea which may have blood in it, seizures, and death.

Immediate Action
Induce vomiting and seek veterinary attention immediately.

Veterinary Care
General treatment: The induction of vomiting may be continued, gastric lavage is performed, and activated charcoal is administered.

Supportive treatment: The goal is to decrease serum calcium levels by increasing urine production through administering IV fluids. Prednisone and furosemide may also be used for their diuretic effects. Seizures are controlled and electrolyte and hydration imbalances are corrected. Decreasing the exposure to sunlight decreases conversion of cholecalciferol to active vitamin D by the skin.

Specific treatment: Calcitonin or biphosphonate pamidronate disodium are used to decrease the serum calcium level.

Treatment may be required for two or more weeks as the experimental elimination half-life is 19 days. A low calcium diet is given for a month and vitamin/mineral supplements are also discontinued during this time.


Rodenticide baits such as Assault, Vengeance, and Trounce.

General Information
Bromethalin works by affecting the permeability of the cell membranes resulting in the cell swelling and losing function. Signs are related to central nervous system (CNS) dysfunction. Signs may appear within 10 hours to several days after exposure and may last up to 12 days. Bromethalin poisoning should be considered whenever acute signs of cerebral edema or paresis or paralysis of the hind limbs are seen. Death is usually caused by respiratory paralysis. Death may occur with high or low doses.

Toxic Dose
Dogs: 2 mg per pound of body weight.

Cats: Less than 1 mg per pound of body weight.

Acute high dose exposure results in symptoms within several hours. These include hyperexcitability, tremors, hyperreflexia (exaggerated reflexes) of the hindlimbs, focal or generalized seizures, and death.

Lower doses produce effects in several days. These include depression, lack of appetite, vomiting, tremors, paresis of one or more limbs, paralysis, lateral recumbancy, and death.

Other symptoms include extensor rigidity, Schiff-Sherrington posture, pinpoint pupils, and anisocoria.

Cats may also show signs including depression, ataxia, progressive motor dysfunction to paralysis, abdominal swelling, convulsions, and death.

Immediate Action
Induce vomiting if ingestion was within the last 60 minutes and the patient is not showing any symptoms. Seek veterinary attention.

Veterinary Care
General treatment: The induction of vomiting may be continued, gastric lavage is performed, and activated charcoal is administered.

Supportive treatment: The animal is monitored and treated for cerebral edema. IV fluids are administered with careful monitoring so as not to worsen cerebral edema. Seizures, if present, are treated with anticonvulsants.

Human Toxicity: According to the Toxic Exposure Surveillance System (TESS) of the American Association of Poison Control Centers (AAPCC), 20,300 human exposures to rodenticides were reported. This represents 1.4% of APCC-reported exposures to all nonpharmaceutical substances. According to the 1998 TESS data, anticoagulant rodenticides are associated with 17,724 of rodenticide exposures. Additionally, 15,854 exposures, the vast majority, occurred in children younger than 6 years. Five deaths from rodenticide ingestions were reported in 1998.

Source: Journal of Vertrinary Medicine, archives, vol. 27, May, 1998.

IPM Of Alaska
Solving Pest Problems Sensibly
Rocco Moschetti
PO Box 875006
Wasilla, Alaska 99687-5006
(907)745-SAFE (745-7233)<

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