Veterinary Drug Handbook (VDH) is the reference veterinarians turn to when they want an independent source of information on the drugs that are used in veterinary medicine today.


Chemistry - An organophosphate insecticide, dichlorvos is also known as 2, 2, -dichlorovinyldimethyl phosphate or DDVP.

Storage, Stability, Compatibility

Dichlorvos tablets and capsules should be kept refrigerated(2-8°C). Dichlorvos feed additives should not be stored at temperatures below freezing. Dichlorvosis sensitive to hydrolysis if exposed to moisture and to oxidizing agents.

Pharmacology - DICHLORVOS

Like other organophosphate agents, dichlorvos inhibits acetylcholinesterase interfering with neuromuscular transmission in susceptible parasites.
Uses, Indications - Dichlorvos is indicated for use internally in dogs and cats for the treatment ofroundworms (Toxocara canis, Toxocara cati, Toxacaris leonina) and hookworms (Ancylostomacaninum, Ancylostoma tubaeforme, Uncinaria stenocephala). It is effective in swine against
Ascaris, Trichuris, Ascarops strongylina and Oesophagostomum spp. In horses, dichlorvos is labeled as being effective for the treatment and control of bots, pinworms, large and small blood-worms and large roundworms. It is also used as a premise spray to keep fly populations controlledand as a flea and tick collar for dogs and cats.

Pharmacokinetics - DICHLORVOS

Specific information was not located for this agent.

Contraindications, Precautions, Reproductive Safety

Do not administer to horses sufferingfrom heaves, colic, diarrhea, constipation, or infectious diseases until these conditions have beencorrected. In dogs and cats, dichlorvos is contraindicated in animals exhibiting symptoms of severeconstipation, intestinal impaction, liver dysfunction, circulatory failure, or to animals exposed to, orshowing signs of infection. Dogs infected with D. immitis should not receive dichlorvos.
Dichlorvos should not be used in conjunction with any other anthelmintics, taeniacides, filaricides(DEC exempted) or within a few days of other medications that inhibit cholinesterase (see druginteractions below).
Studies performed in target species have demonstrated no teratogenic effects at usual doses.

Adverse Effects, Warnings

Adverse effects are generally dose-related and may include thoselisted below in the Overdosage, Acute Toxicity section. Cats, young animals, or debilitated animalsmay be more susceptible to toxic effects. Use in young kittens, cats with any other concurrentdiseases or debilitated or animals otherwise stressed, should probably be avoided.
Overdosage, Acute Toxicity - If overdoses occur, vomiting, tremors, bradycardia, respiratorydistress, hyperexcitability, salivation and diarrhea may occur. Atropine (see atropine and pralidoxime monographs for more information) may be antidotal. Use of succinylcholine, theophylline, aminophylline, reserpine, or respiratory depressant drugs (e.g., narcotics, phenothiazines) should beavoided in patients with organophosphate toxicity. If an ingestion occurs by a human, contact apoison control center, physician or hospital emergency room.

Drug Interactions

Acepromazine or other phenothiazines should not be given within onemonth of worming with an organophosphate agent as their effects may be potentiated. Because ofits anticholinesterase activity, avoid the use of organophosphates with DMSO. Cythioate couldtheoretically enhance the toxic effects of levamisole. Pyrantel Pamoate (or tartrate) adverseeffects could be intensified if used concomitantly with an organophosphate. Patients receivingorganophosphate anthelmintics should not receive succinylcholine or other depolarizing musclerelaxants for at least 48 hours. Drugs such as morphine, neostigmine, physostigmine andpyridostigmine should be avoided when using organophosphates as they can inhibitcholinesterase.