Company: HARTZ

FORMULATION: «paste» for oral administration in pre-filled syringes

ACTIVE INGREDIENT(S): PIPERAZINE (adipate): 200 mg/g (=20%)


PARASITES CONTROLLED* (spectrum of activity):


Cats and kittens: 200 mg piperazine per 5 lbs bw. (equivalent to 88 mg/kg bw); Each syringe treats up to 20 lbs. ≈ 9 kg bw

* Can be slightly different in some countries: read the product label!


  • LD50 (acute oral) in rats: n.a. for the paste. >7900 mg/kg for piperazine
  • Estimated Hazard Class according to the WHO: not applicable for veterinary medicines

Suspected poisoning? Read the article on piperazine safety in this site.

Never use on cats products approved only for use on dogs, and vice-versa

You may be interested in the following articles in this site dealing with the general safety of veterinary products:


Risk of resistance development? NO

There are no reports on resistance of dog and cat worms to piperazine after more than a century of use.

Learn more about resistance and how it develops.


Are the active ingredients of this product ORIGINAL* or GENERICS**?

  • Piperazine: GENERIC (introduced already in the XIX century)

*Meaning that they are still patent protected and generics are not yet available
**Meaning that they have lost patent protection and may be acquired from manufacturers of generic active ingredients other than the holder of the original patent.

COUNTRIES where this product is marketed: USA.
GENERIC BRANDS available? YES, in many countries.

Click here to learn more about GENERIC vs. ORIGINAL drugs.


ULTRAGUARD PLUS RID WORM is a generic wormer for cats from HARTZ, with piperazine, a veteran anthelmintic effective only against ascarid roundworms (Toxocara cati, Toxascaris leonina), Piperazine has been used against worms since the XIXth century.

Piperazine was already used as a human medicine at the end of the 19th century. Its anthelmintic properties for animals were discovered in the 1950's. It is still used on livestock and pets, although it has been vastly replaced with more effective compounds, especially in ruminants (cattle, sheep and goats). It is also used in anthelmintics for humans, but also in antidepressants, antihistamines, antipsychotics, etc. Piperazine derivatives are also used in plastics, resins, and other industrial materials, as well as an adulterant in the psychedelic drug scene.

Piperazine derivatives have a narrow spectrum of anthelmintic activity. They are especially effective against adult ascarid roundworms (in pets e.g.Toxocara canis and Toxocara cati) but not against hookworms or tapeworms. Worm stages in the tissues (e.g. migrating larvae) are less susceptible than those inside the gastrointestinal tract.

Piperazine as well as pyrantel and the benzimidazoles (e.g. fenbendazole, febantel, albendazole, mebendazole, etc.) has no residual effect, i.e. it acts against the worms during a few hours after administration but is quickly metabolized and excreted. For this reason treatment must often be repeated for certain indications. This is in contrast with wormers containing macrocyclic lactones (e.g. milbemycin oxime, selamectin) that ensure efficacy against numerous roundworms during weeks after a single treatment.

For an overview and a list of the most popular pet wormers click here.


This article IS NOT A PRODUCT LABEL. It offers complementary information that may be useful to veterinary professionals and users that are not familiar with veterinary antiparasitics. 

Information offered in this article has been extracted from publications issued by manufacturers, government agencies (e.g. EMEA, FDA, USDA, etc.) or in the scientific literature. No guarantee is given on its accuracy, integrity, sufficiency, actuality and opportunity, and any liability is denied. Read the site's DISCLAIMER.

In case of doubt contact the manufacturer or a veterinary professional.