| Currently, there are approximately 80 million dogs in the United States. The majority of these dogs are pets, while some are used in military and police K9 units. Recently, trained dogs have also been used for the early detection of cancer (breast, cervical, and prostate) and seizures in humans. Dogs are easily infested with fleas, ticks, and other ectoparasites, some of which may serve as vectors for transmitting bacterial, viral, and parasitic diseases. Therefore, the use of ectoparasiticides is inevitable and important. The present investigation was undertaken with two specific objectives: one, to evaluate the safety of fipronil and cyphenothrin in dogs after topical application of ParastarRTM Plus, and two, to determine the transferable residue of these insecticides from dogs to humans. Six healthy, adult dogs (medium length hair, weighing between 45--60 pounds) received topical application of ParastarRTM Plus (2.68 mL; fipronil, 9.8% and cyphenothrin, 5.2%) on the back between the shoulder blades. At pre-determined intervals, dogs were given a full physical exam, and residues of fipronil and cyphenothrin were determined in dog blood and cotton glove extracts using GC/MS. Fipronil and cyphenothrin peaks eluted at 7.453 and 9.913 minutes, correspondingly, and the compounds were confirmed based on their characteristic ions. At no time was fipronil or cyphenothrin residue detected in blood samples. In glove extracts, residues of fipronil and cyphenothrin were maximally present at 24 hr post-treatment (43.84 +/- 5.69 and 59.26 +/- 8.97 ppm, respectively). By 48 hr, the residue levels sharply declined (16.89 +/- 2.82 and 17.98 +/- 2.07 ppm, respectively). The insecticides' residues were detected in insignificant amounts after one week (5.69 +/- 2.16 and 10.00 +/- 1.51 ppm, respectively), and only in trace amounts after two weeks. At no time did any dog show any side effects, except itching at the site of ParastarRTM Plus application. The findings suggest that ParastarRTM Plus is safe for dogs and transferable residues of fipronil and cyphenothrin are minimal, posing very little or no health concern to pet-owners or veterinary personnel. Of course, veterinary personnel, who handle many dogs daily, may require proper protection to avoid cumulative exposure. |
