科研之友
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摘要
Background
The US Food and Drug Administration reports an increase in the frequency of reports of lack of effectiveness claims for heartworm (HW) prevention products.
Hypothesis
At their labeled doses, single doses of commercially available HW prevention products are not completely effective against all field isolates of HW.
Animals
Forty-two HW-free dogs experimentally inoculated with a recent HW field isolate.
Methods
Placebo-controlled, blinded laboratory clinical trial. Dogs randomly allocated to 1 of 3 treatment groups with 14 dogs per group. Groups were untreated control or PO dosed with milbemycin oxime (MBO) or ivermectin (IVM). Dogs were inoculated with 50 HW third stage larvae 30 days before dosing and necropsy was performed on Day 123 after treatment to enumerate adult HW.
Results
Thirteen of 14 control dogs had adult HW detected at necropsy with a geometric mean worm count of 22.3. One HW was found in 1 dog in each of the MBO and IVM treatment groups.
Conclusions and Clinical Importance
Two currently approved macrocyclic lactone HW preventives used at their labeled dose rates were < 100% effective against a recent HW field isolate, supporting the hypothesis that the effectiveness of a single dose of these preventives can vary. This is important in guiding clients on expectations of product effectiveness.
- 出版日期2011-2
