Method for systemic control of parasitic insects

A method for systemic control of insects on animals which includes the step of continuously contacting the skin of the animal with chlorpyrifos to establish and maintain an insecticidally effective concentration of chlorpyrifos in the animal's blood stream.

This invention relates to a method for systemic control of parasitic 
insects on animals. 
In still another aspect, the invention pertains to restraining apparatus 
which can conveniently and continuously be employed for killing and 
controlling parasitic insects on animals for an extended period of time. 
Harnesses for restraining animals, in particular collars which can be 
placed around an animal's neck, are well known in the art. Such collars 
are often comprised of a simple strap or band of material with a buckle on 
one end of the strap to secure the other end of the strap when the collar 
is placed around the neck of the animal. However, collars of greater 
complexity, where the strap consists of a number of interconnecting or 
layered segments of material, are also known in the art. 
A wide variety of materials, including metals, leather, polyvinylchloride 
and cloth, have been employed in the construction of collar bands. 
Combinations of different materials are common. For example, plastic or 
metal is often layered on leather. 
The collar strap is typically provided with a buckle or other fastening 
device which permits the fit of the collar to be adjusted. Perhaps the 
most prevalent means of attaching the two ends of the collar band consists 
of punching holes in one end of the band and then attaching to the other 
end of the band a belt-type buckle with a tongue that fits through the 
holes. A somewhat similar arrangement eliminates both the punching of 
holes in one end of the collar strap and the tongue in the buckle by 
attaching a tongue-less buckle to one end of the strap. The tongue-less 
buckle receives and frictionally secures the other end of the strap. 
Other methods of fastening the ends of the collar band include either 
attaching a friction contact material like Velcro to each end of the band 
or providing the ends of the collar strap with attachments that will snap 
or screw together. 
Also known in the art is the adapting of such collars for the purpose of 
repelling or killing parasitic insects which might otherwise inhabit the 
animal's body. Such so called "flea and tick collars" are commonly 
employed on domestic cats and dogs. The collars generally are comprised of 
a thermo-plastic material which is permeated with contact insecticide and 
then extruded to form a collar. When the collar is fastened around the 
animal's neck, the insecticide in the collar bleeds to the surface of the 
collar and is abraded from the collar surface onto the animal's fur. 
Parasitic insects are killed on contacting insecticide adhering to the 
collar or to the animal's fur. 
While the prior art flea and tick collars are generally effective, they 
have a limited useful life of only 5 to 9 months. Also, the overall 
effectiveness of the prior art flea and tick collars is limited in that 
insects, in order to be killed, must actually come in contact with the 
insecticide on the collar or on the animal's surrounding fur. 
Accordingly, it would be highly desirable to provide a collar for 
restraining animals which would kill parasitic insects that would 
otherwise infest the animal. 
It would also be highly desirable to provide such a collar which would kill 
parasitic insects more effectively than prior art collars. 
Further, it would be highly desirable to provide a collar which would 
provide continuous protection over an extended period of time greater than 
the period of protection of prior art flea and tick collars. 
It is therefore a principal object of the present invention to provide a 
collar for restraining an animal which provides a means for killing 
parasitic insects that would otherwise inhabit the animal. 
Another object of the invention is to provide such a collar which would 
kill parasitic insects more effectively than prior art flea and tick 
collars. 
A further object of the invention is to provide such a collar which would 
provide continuous protection against parasitic insects over an extended 
period of time that is greater than the period of protection of prior art 
flea and tick collars.

Briefly, in accordance with my invention, I provide a method for 
systemically controlling parasitic insects on animals. The method 
comprises the step of continuously contacting the skin of the animal with 
chlorpyrifos to establish and maintain an insecticidally effective 
concentration of chlorpyrifos in the animal's blood stream. According to 
the presently preferred embodiment of the invention, the chlorpyrifos is 
maintained in contact with the animal's skin by incorporating the 
chlorpyrifos in a polyvinylchloride collar. The collar means is at least 
partially constructed of a polyvinylchloride substrate containing 7.5-15% 
by weight of chlorpyrifos and a lubricating plasticizer. The chlorpyrifos 
continuously bleeds to the surface of the polyvinylchloride substrate with 
said plasticizer over an extended period of time to contact the skin of 
the animal. 
In the presently preferred embodiment of the invention, the collar band 
consists entirely of a polyvinylchloride (PVC) substrate with 7.5-15% by 
weight of chlorpyrifos. The collar strap is provided with a buckle or 
other suitable fastener. 
PVC is one of a class of generally synthetic thermoplastic polymer resins 
which can be "filled" with solid materials and then extruded in numerous 
forms. PVC, as do all vinyl plastics, contains a "plasticizer" which 
provides internal lubrication for and imparts flexibility to the plastic. 
As this gradual depletion of plasticizer takes place, the plastic becomes 
more brittle. Once an appropriate period of time has elapsed, and a 
substantial portion of the plasticizer has diffused from the plastic, the 
plastic may be fractured with minimal tensile force. 
Chlorpyrifos is an organophosphate insecticide known to be readily absorbed 
through animal and human skin and is not harmful to animals in small but 
insecticidally-effective concentrations in the animal's blood. 
Chlorpyrifos (0,0-diethyl-0-3,5,6-trichloro-2-pyridylphosphorothioate) is 
marketed by Dow Chemical Company under the trade name "DURSBAN A". 
The chlorpyrifos is mixed with PVC powder and the resultant mixture is then 
melted and extruded into flat strips which are cut to the desired length 
and provided with a buckle or other suitable fastener to form the collar. 
When the collar is placed on the animal's neck, the insecticidally active 
chlorpyrifos, along with the plasticizer, bleeds at a controlled rate to 
the surface of the collar and is transferred from the collar surface to 
the fur and ultimately to the skin of the animal. The insecticide is 
absorbed through the skin of the animal and enters the animal's 
bloodstream. By simply leaving the collar around the animal's neck 
indefinitely, controlled quantities of the insecticide are maintained in 
contact with and absorbed through the animal's skin to maintain an 
insecticidally effective concentration of the insecticide in the animal's 
bloodstream. When a parasitic insect such as a flea, a tick or a mite 
punctures the animal's skin, it is contacted with the insecticide-blood 
composition and is killed either by contact with or by ingestion of the 
composition. 
Present experience indicates that a collar fabricated in accordance with 
the presently preferred embodiment of the invention will maintain its 
efficiency for at least twelve months, as compared to only about 5 months 
for the flea and tick collars in the prior art and about 9 months for a 
collar effective against fleas only. 
Turning now to the drawings, which depict the presently preferred 
embodiment of the invention for the purpose of illustrating the practice 
thereof and not by way of limitation of the scope of the invention, FIGS. 
1-5 illustrate the presently preferred embodiment of the invention, a 
collar 10 with a strap 10a composed entirely of a polyvinylchloride 
containing 7.5-15% by weight chlorpyrifos. 
FIG. 1 depicts the collar 10 fastened around the neck of a dog. The dog is 
represented by the dotted lines 11. 
In FIG. 2, the chlorpyrifos, represented by the dots 15, permeates the 
polyvinylchloride strap 10a. As shown by the dotted lines 16, over an 
extended period of time the chlorpyrifos 15 gradually bleeds to the 
surface of the polyvinylchloride strap 10a, is abraded onto the fur of the 
dog 11 and then is absorbed through the skin 17 into the body 18 of the 
dog 11. 
As illustrated in FIG. 3, the strap 10a of the collar 10 may be provided 
with a belt-type buckle 12 having a tongue 13. Apertures 13a in the strap 
10a receive the tongue 13 when the collar 10 is attached about the neck of 
the dog 11. 
In FIG. 4, the strap 10a of the collar 10 is provided with a buckle 12a 
which receives and frictionally secures the free end 14 of the collar 
strap 10a. 
Another method of connecting the ends of the collar strap 10 is disclosed 
in FIG. 5, which depicts the strap 10a provided with negative Velcro 12c 
and positive Velcro 12b so that the ends of the strap 10a may simply be 
pressed together to fasten the collar 10 around the neck of the dog 11.