Pyrantel pamoate has been used as a method of eliminating adult tapeworms for years, but it’s been an off-label use. Only the dewormer drug praziquantel was approved by the FDA to be labeled for use against equine tapes. This is no longer the case.
The FDA has approved Farnam’s pyrantel pamoate-based dewormer, TapeCare Plus ($10). This product uses a 13.2 mg/kg dose and directions call for a single dose. However, the packaging also wisely advises consulting your veterinarian for a program to meet your specific needs. Treatment failures with pyrantel pamoate have been reported, and some horses may need a repeat treatment in three to four weeks.
Several recent studies have taken a more detailed look at the use of pyrantel pamoate against tapes. A study performed by IVX Animal Health looked at safety of a 13.2 mg/kg dose of pyrantel pamoate. No adverse clinical effects, changes in blood work or changes on postmortem examination were found in horses treated at doses as high as 10X that for six consecutive days.
A study performed at East Tennessee Clinical Research reported on field trials of efficacy in horses naturally infected with tapeworms, at sites in Illinois and in Kentucky.
Horses were divided into two groups, control/untreated and treated with 13.2 mg/kg of pyrantel pamoate. The horses’ intestinal tracts were examined 10 to 12 days after treatment. One of 10 treated vs. seven of 10 control horses had tapeworms found on postmortem exam at one site, and five of 11 treated vs. 10 of 11 control were positive at the other.
Calculated effectiveness, based on the actual number of tapeworms recovered, were 98.4% and 95.8%. A similar, but much larger, study was conducted by IVX Animal Health in five locations, involving a total of 178 treated and 63 control horses.
The horses in that study were followed for 16 days after treatment. Effectiveness ranged from 92 to 96%. The study, reported at the 1998 AAEP meeting, where a 19.8 mg/kg dose was used, found negative fecals in all treated horses at the two-week posttreatment mark, which rose to as high as 18.2% positives in treated horses by four weeks. Following a second treatment, there were 9.1% positive at two weeks, but after that point all horses remained negative for the next two weeks.