Generic fenbendazole oral suspension for dairy cattle and goats is approved by the FDA

Veterinarians now have access to a new generic deworming option for food animals, following the FDA approval of Defendazole (fenbendazole) oral suspension for use in beef and dairy cattle, as well as goats. The product is indicated for treatment and control of various species of lungworms, stomach worms, and intestinal worms in beef and dairy cattle, as well as for the treatment and control 2 species of stomach worms in goats.

Defendazole is the first FDA-approved generic equivalent to Safe-Guard, a brand-name anthelmintic first approved for cattle and goats in 1994.1 According to the FDA, the generic formulation was determined to be bioequivalent to Safe-Guard.

“The FDA determined that Defendazole oral suspension is bioequivalent to the brand name product,” the agency said in an announcement.1

When used according to label directions in cattle, Defendazole requires an 8-day withdrawal period and a 48-hour milk discard time. For goats, the withdrawal period is 6 days.

The oral suspension, sponsored by Norbrook Laboratories, is available over the counter in 1-L and 5-L bottles. For beef and dairy cattle, dosage is 2.3 mg/lb (5mg/kg) body weight and 2.3 mg/lb (5 mg/kg) body weight for goats.

Gastrointestinal parasite infections in ruminants

In goats, the most common internal parasites are lung worms (Dictyocaulus spp. or Muellerius capillaris), stomach worms (Haemonchus contortus), and liver flukes (Fasciola hepatica).2

Most gastrointestinal parasite infections in ruminants are mixed, with animals usually harboring multiple parasites, according to Merck Veterinary Manual.3 However, only a few animals show clinical signs. When symptoms do appear, they are usually nonspecific, often showing as chronic, gradually progressive illness.

Animals who are heavily infected may exhibit gradual weight loss, reduced growth or milk production, poor hair coat, and decreased condition. More severely affected ruminants may also become lethargic, weak, or isolated. Decreased appetite leading to emaciation might also be seen.

Some animals may also exhibit diarrhea, and abdominal discomfort or mild colic can be another sign. Additionally, heavy gastrointestinal parasitism can lead to protein loss, with clinical signs including submandibular edema or ventral edema. “In addition to inadequate protein absorption, heavily parasitized ruminants are likely to show poor absorption of critical vitamins and minerals from their diet,” according to Merck.3

References

1. FDA Approves First Generic Fenbendazole Oral Suspension Dewormer for Beef and Dairy Cattle, Goats. News release. US Food and Drug Administration. January 22, 2026. Accessed January 23, 2026. https://www.fda.gov/animal-veterinary/cvm-updates/fda-approves-first-generic-fenbendazole-oral-suspension-dewormer-beef-and-dairy-cattle-goats
2. Internal parasites in sheep and goats. Oregon State University. February 2013. Accessed January 23, 2026. https://smallfarms.oregonstate.edu/sites/agscid7/files/em9055.pdf
3. VanHoy G. Overview of Gastrointestinal Parasites of Ruminants. Merck Veterinary Manual. August 2025 Accessed January 23, 2026. https://www.merckvetmanual.com/digestive-system/gastrointestinal-parasites-of-ruminants/overview-of-gastrointestinal-parasites-of-ruminants