Fenbendazole is a medication used in animals to kill various types of worms. It is safe enough for pregnant pets. It is available as generic fenbendazole or as the brand names Panacur and Safe-Guard. It is not intended for use in humans. Fenbendazole is only approved by the U.S. Food and Drug Administration for use in dogs, but vets often prescribe it off-label for pet rodents, reptiles, birds and cats.
Dosage is based on how much the dog or cat weighs: 25 mg per pound or 50 mg per kilogram. Since other types of pets like mice, gerbils or hamsters often weigh less than one pound, a veterinarian needs to determine dosing for that individual animal.
Pregnant dogs should receive fenbendazole three days in a row after their 40th day of gestation. You can give fenbendazole as late as two weeks after the puppies have been born. You can also give fenbendazole three days in a row to other pregnant mammal species like pet rodents or cats, provided that they are late in their pregnancies. Always contact a vet before giving any medication to a pregnant animal.
Roundworms pass from pregnant cat or dog to her offspring through nursing and while they are developing in her womb. Adult dogs and cats are often immune to roundworms, but puppies and kittens will not have this immunity and are vulnerable to infections before and immediately after they are born. If the pregnant dog or cat has not been regularly wormed, then fenbendazole is a safe means to kill the roundworms.
The most common side effect of fenbendazole is nausea and vomiting. In order to prevent this, give fenbendazole with food. Although available in an oral suspension liquid and paste, a granule form sprinkled over food may be the easiest way to give to pregnant dogs and cats. If the pet still vomits, the dose may be too high, according to “The Pet Book Guide to Medication for Your Dog and Cat.” Contact your vet immediately. Another common side effect is seeing dead worms in the pet’s stool, but there is no need to call a vet for this.
Fenbendazole is classified as a benzimidazole, a type of dewormer that can kill a wide variety of parasites. Another benzimidazole used in veterinary medicine is thiabenzadole. If a pet is allergic to any benzimidazole, it should not take fenbendazole. Allergic reactions are unmistakable and include seizures or breathing difficulties. Contact a vet immediately if any animal on fenbendazole shows these signs.