Organophosphate and Carbamate Toxicity in Cats - Causes, Treatment and Associated Conditions

Key takeaways

Organophosphates (OPs) and carbamates (CMs) are compounds commonly found in agricultural pesticides, herbicides, as well as flea and tick collars. Toxicity occurs following ingestion or skin exposure.

Organophosphate or carbamate poisoning is a life threatening emergency requiring immediate veterinary care
Symptoms include excessive urination, vomiting, difficulty breathing, ataxia, convulsions, and paralysis, and can affect all organ systems
Diagnosis is based on history of exposure and specific blood tests
Early decontamination immediately after contact increases the chances of a good outcome
Immediate life-saving treatment once symptoms develop includes anti-seizure medication and oxygen support
Medications are given to reverse the effects of OP/CMs along with intensive supportive care including IV fluids, nutritional support, and temperature regulation

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A closer look: 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.

Risk factors

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.

Possible causes

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.

Main symptoms

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

Testing and diagnosis

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

Steps to Recovery

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.

Prevention

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

Is Organophosphate and Carbamate Toxicity in Cats common?

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.