Organophosphate and Carbamate Toxicity in Cats

Organophosphates and carbamates can be found in:

• Insecticides
• Herbicides
• Agricultural pesticides
• Tick and flea sprays
• Tick and flea collars
• Some types of industrial chemicals

Symptoms of organophosphate/carbamate poisoning can be divided into three different stages.

Muscarinic stage: Muscarinic symptoms are generally the first to appear.

Nicotinic stage: During the second stage muscle symptoms appear.

Central stage: symptoms progress into more severe neurological dysfunction.

Organophosphate/carbamate poisoning is an emergency because small doses have the potential to be fatal. Starting treatment immediately after contact results in the best prognosis.

The onset of symptoms can vary from a few minutes to days. Even if there are no symptoms of toxicosis, medical attention is warranted if exposure is known or suspected, as early decontamination is the best way of assuring a good prognosis.

Once symptoms arise the prognosis is poor and depends largely on the dose.

Acute poisoning with large quantities of highly toxic OPs can cause organophosphate-induced intermediate syndrome (IMS). Symptoms of IMS mostly affect proximal limbs and neck muscles.

Symptoms can occur 24 to 96 hours after ingestion and include:

• Paralysis
• Weakness
• Abnormal posture and behavior

There is no specific treatment for IMS.

OP/CM exposure is often due to contact with pesticides, including flea and tick control products. It is important to consult a veterinarian when choosing flea and tick control to avoid the risk of OP/CM poisoning.

Organophosphate/carbamate poisoning is most commonly caused by ingestion or skin exposure to a toxic dose of pesticides containing these chemicals, but other routes of exposure are possible.

Symptoms usually arise quickly and differ depending on which type of pesticide was ingested.

If ingestion is witnessed, diagnosis is self-evident and the goal of early intervention is decontamination. A cat presenting with symptoms of OP poisoning typically undergoes the following diagnostics:

• Routine screening blood tests
• Advanced blood testing: blood gasses; acetylcholinesterase response test
• Urinalysis

Early treatment of organophosphate poisoning is focused on:

Stabilization and emergency life- savinging efforts: anticonvulsant drugs to reduce seizures; fluid therapy; supplemental oxygen; ventilatory support

Decontamination: Vomiting is one of the earliest symptoms of OP/CM toxicosis, so inducing vomiting is NOT performed once symptoms have begun, but in the event of skin exposure, the product is washed off.

There is no safe method to induce vomiting in cats at home. This should only be performed by a veterinarian.

Once the animal is stabilized treatment options include:

• Muscarinic receptor-blocking drugs
• Cholinesterase reactivators
• Emetics and absorbents :
• Supplemental oxygen
• IV fluids

If rapidly and properly treated soon after ingestion or contact, prognosis of organophosphate/carbamate poisoning is favorable - especially if the dose was small.

Once symptoms develop, the prognosis is guarded and depends on the type and quantity of OP/CMs ingested.

Organophosphate/carbamate poisoning is prevented completely by removing the possibility of exposure to OP/CM-containing chemicals. Strategies include:

• Avoiding using pesticides and herbicides containing OP/CMs
• Diligent storage of pesticides
• Proper disposal of pesticides
• When possible choose safer OP/CMs products, such malathion containing products
• Not letting the animal outdoors if pesticides have been used
• Consulting a veterinarian when choosing flea and tick prevention for all animals in the same household; ensuring medical personnel are aware of all animals and children in the home

Outdoor cats are more at risk of organophosphate poisoning. Younger cats may be at higher risk of exposure and are more at risk of toxicosis due to lower body weight.

• Muscarinic receptor-blocking drugs
• Cholinesterase reactivators
• Emetics and absorbents
• IV fluid therapy
• Decontamination