Anthelmintics provide an excellent tool for controlling parasites. Application of dewormers should not be aimed at treating infected cattle showing signs of parasitism. Instead, apply dewormers in a timely manner to reduce infection before symptoms of disease occur. Treatment should also be aimed at interrupting the life cycle of the parasite in an effort to minimize pasture contamination. Unfortunately, instead of implementing a deworming program, producers typically deworm their cattle when the herd is being worked for another purpose. The 1997 NAHMS cow/calf health survey showed that 50 percent of beef cattle operations in the United States deworm their herd according to tradition. Twenty-one percent base treatment upon animal appearance. In the latter case, the herd has already suffered economic losses. Only 14 percent of beef cattle producers in the U.S. follow the recommendations of a veterinarian.
Many anthelmintic products are on the market. Most of the products are either avermectins/ milbemycins (ivermectin, dormectin, eprinomectin, and moxidectin) or benzimidazoles (oxfendazole, albendazole, fendbendazole). Avermectins/ milbemycins provide an additional benefit of external parasite control plus internal parasite control, as well as persistent protection for days to weeks after treatment. When selecting a dewormer, the following should be kept in mind:
Ø Type of animal being treated (calf vs. cow, beef vs. dairy)
Ø Product efficacy
Ø Ease of application
Ø Broad spectrum of control (immature,mature, inhibited)
Ø Cost effectiveness
Ø Slaughter/milk withdrawal time
Ø Personal safety
Source: Shane Gadberry, Extension Livestock Specialist Jodie Pennington Extension Dairy Specialist Jeremy Powell, DVM Extension Veterinarian