Catheter for artificial insemination

The invention generally refers to a catheter for artificial insemination and, in particular, a catheter for artificial insemination of swine. Artificial insemination of swine has been practiced for many decades.

The reproductive system of female swine comprises a cervix that consists of multiple ridges. The boar's penis, which is cork-screw shaped, fits into the folds of the cervix in a natural mating. In artificial insemination the boar's penis is replaced by a catheter with a tampon-like or spiral-shaped form body at its tip. The shape of the tip should be suitable to fix the catheter in the cervix, to prevent backflow of semen and to initiate uterine contractions which are essential for sperm transport through the uterus to the oviduct, the site of fertilization.

In order to perform this function, the catheter tip is introduced into the vagina which tapers into the cervix and is then securely locked in the ridges of the cervix. A secure locking of the catheter tip into the cervix can be verified by gently pulling back on the catheter.

In order to obtain good locking and sealing capabilities of the catheter a sufficiently hard material has to be chosen for the form body. Furthermore, it was observed that harder form body materials such as harder thermoplastic elastomers have a better bonding capability with the catheter tube and hence are preferred for the production of catheters.

However, a harder material of the form body tip has diminished insertion qualities compared to a softer form body tip that can be easier directed through the multiple ridges of the cervix and causes less discomfort for the swine during insertion. However, a gentle and injury-free insertion of the catheter into the cervix is crucial, since it reduces the stress for the animal during insemination and increases fertility.

A catheter of prior art is described, for example, in European patent application No. EP 1 169 978 Al having a filing date of September 29, 2001. The catheter comprises a catheter tube being surrounded at its distal end by a form body that is made of a soft compressible material.

The form body tip is formed by directly moulding a thermoplastic material, such as a thermoplastic elastomer or an expandable foam material, on the catheter tube.

Another common method of making form bodies includes milling of a solid material such as an expandable foam material into a tampon-like shape and bonding the tampon to the catheter tip.

European patent application No. EP0605406 relates to an insemination probe which can be fitted to a flexible thermoplastic dosage bag for artificial animal insemination. The probe consists of a tube which is semi-rigid and, carried by its opposite end, a plug which is moulded over from flexible foam and has an axisymmetric shape and is provided with a duct in which this opposite end of the tube is accommodated and includes a constricted region in its part which lies beyond the tube.

It is the object of the present invention to provide a catheter for artificial insemination permitting a gentle and injury-free insertion of the catheter as well as a secure locking of the catheter in the cervix. This object is achieved by a catheter for artificial insemination of animals according to claim 1 and a method of manufacture of a catheter for artificial insemination of animals according to claim 11.

According to the present invention, a catheter for artificial insemination of animals and in particular of swine is provided that comprises a catheter tube with a longitudinal lumen extending through it and a form body at its distal end comprising a relatively soft, compressible material which surrounds the end of the tube, wherein the form body comprises a channel that extends the lumen of the tube towards an opening of the form body, and wherein the form body comprises two portions of different compressibility.

Due to the form body having two portions of different compressibility, the catheter provides at least two favourable characteristics including a gentle insertion quality of the catheter into a cervix of a sow without hard pushing or injuring the walls of the vagina and the cervix and a good locking quality in the cervix. A secure locking of the form body tip in the cervix is necessary in order to prevent backflow of semen and support uterine contractions which are essential for sperm transport through the uterus to the site of fertilization.

According to a preferred embodiment, the form body comprises a first portion at its distal end with a compressibility that is greater than the compressibility of a second portion of the form body at its proximal end. The first portion at the distal end of the form body having a high compressibility or low hardness permits to easily direct the catheter through the ridges of the cervix, as it easily deforms in the ridges of the cervix and makes the insertion less awkward for the swine. A harder second portion of the form body at its proximal end improves the locking of the catheter in the cervix.

According to another preferred embodiment, the form body comprises a gradient of decreasing compressibility from its distal end to its proximal end providing a gradual transition of compressibility. The gradient can be a linear function, a step function, a polynominal function, or any other function.

According to another embodiment, the form body is arranged on the catheter tube, so that the catheter tube extends into the form body to about half of the longitudinal extension of the form body. Providing the form body on the catheter tube, so that the catheter tube is surrounded over half of the length of the catheter tube, results in a form body having a distal portion having a reduced compressibility and a proximal portion that surrounds the catheter tube and has an higher compressibility. At the same time the catheter tip is sufficiently offset from the opening of the form body, so that the catheter tube cannot touch or injure the vagina or cervix of the sow during the insertion of the catheter. Preferably, the form body is made of a single material.

According to yet another embodiment, the form body comprises at least two materials of different density. This may result in a form body comprising two or more portions of different compressibility. The possibilities to form a form body comprising two materials of different densities are versatile. For example, a form body can be formed by using two different materials. Furthermore, a form body may comprise a single material comprising portions of two or more different densities. This may be achieved by inserting a fluid such as a gas or a liquid into the material during moulding that changes the density of the material.

Furthermore, a mechanical removal of portions of a material such as punching or perforating the material in one or several portions of the form body may be conceived to adjust portions of the form body with different compressibilities. It may also be conceived to provide cavities

in a material such as fins during the moulding by using a correspondingly formed mould. In addition, cavities obtained during a moulding or by mechanically processing can be filled with a second material or the same material, however, comprising a different density or with a fluid.

According to yet another preferred embodiment, the form body comprises in at least one portion thereof a first material at the outside of the form body and at least a second material in the interior of the form body and covered by the first material. According to this embodiment, it becomes possible to provide a form body comprising in its interior a material that better bonds to the catheter tube or alternatively is cheaper or has both characteristics, although it does not comprise the highest quality for a material forming the outside surface of the form body such as high compressibility and good gliding qualities. On such a core of the form body comprising the first material, a second material can be applied having the preferred qualities for the outside surface of the form body.

According to yet another embodiment, the form body comprises a thermoplastic elastomer material such as polyurethane (PUR) comprising one or several components. Thermoplastic elastomer material can be moulded on a catheter tube using a mould that defines the outside structure of the form body. The thermoplastic elastomer also permits to carry out several moulding steps that permit to manufacture form bodies with different portions of compressibility. A thermoplastic elastomer material comprises good adhesion characteristics on a polypropylene catheter tube and permits to achieve a good bonding without any additional treatment of the catheter tube.

According to another embodiment, the form body comprises at least one expandable material. The expandable material can be, for example, a foam material such as polyurethane (PUR). However, also different components of expandable materials can be used in multi-component foaming techniques. Preferably the catheter tube is treated by a corona process before bonding the form body to the tube in order to improve the adhering.

According to yet another embodiment, the catheter tube comprises a portion at its distal end having a larger outer diameter compared to the diameter of the tube in a middle portion or at its proximal end. The tube can for example be flared at its distal end. The flaring may comprise a conical shape. Furthermore, the tube may comprise an enlargement or swelling at or

near its end. Preferably, the form body is arranged on the portion of the tube having the larger outer diameter. A catheter tube having an enlarged diameter in the inside of the form body reduces the amount of material of the form body, since the catheter tube consumes a larger volume in the inside of the form body. Furthermore, a catheter tube having an enlarged outer diameter within the form body influences the compressibility of the form body material in different portions. A flared end of the catheter tube in the form body can be used as an anchoring means and improves the bonding between the catheter tube and the form body.

According to a further embodiment of the invention the catheter tube comprises several pieces that are configured for their mutual attachment. For example, the catheter tube is assembled of two or more pieces that are mounted before using the catheter. Such a catheter has advantages for shipment and storage, since it is shorter when it is disassembled than a catheter comprising a one-piece catheter tube.

According to one embodiment one of the catheter tube pieces comprises an indentation such as a circular groove and another catheter tube piece comprises a mating protrusion such as a circular rib that engages the notch when one catheter tube piece is inserted into the other.

According to another embodiment of the invention an expandable catheter tube is provided comprising two or more shaft pieces having different diameters that fit into each other and can be expanded in a telescope-like manner.

According to yet another embodiment of the invention, the tube pieces comprise cone shaped end portions. In particular, one of the tube pieces can have a tapered end section that may be inserted into another tube piece having a correspondingly flared end section to receive the tapered end section. Both tube pieces can be locked in a frictional engagement and optionally in addition by means of an indentation provided on one tube piece and a corresponding protrusion provided on the other tube piece. It may be conceived to alternatively or additionally provide threads at the ends of the tube pieces for their attachment.

According to another embodiment, the catheter tube may be formed so that is has a more flexible portion at its proximal end. The more flexible portion allows an easier bending of the catheter tube. This permits to bend the end of the catheter tube during the insemination into a basically vertical orientation that is more suitable for an infusion of the semen. The more

flexible end of the tube may comprise between 5% and 50 % of the total length of the catheter tube.

A catheter tube having portions of varying hardness or flexibility along its length may be formed by extrusion moulding using materials with different degrees of hardness in subsequent extrusion stages of the same extrusion process.

According to the present invention, a method of manufacture of a catheter for artificial insemination of animals is provided. It comprises providing a catheter tube with a longitudinal lumen extending through it and arranging a form body at the distal end of the catheter tube wherein the form body is formed, so that it comprises a channel that extends the lumen of the catheter tube towards an opening of the form body and wherein the form body comprises two portions of different compressibility.

According to one embodiment, the method further comprises thermally moulding the form body using one or several moulding steps, one or several moulds, and one or several moulding materials. In particular, the form body may be directly moulded on a catheter tube or shaft. Form bodies moulded of thermoplastic elastomers adhere very well on polypropylene catheter tubes without any treatment of the tubes.

According to another embodiment, the method further comprises the forming of the form body using one or several foaming steps, one or several moulds, and one or several foam materials.

According to yet another embodiment, arranging the form body at the distal end of the catheter tube comprises bonding the form body to the catheter tube. It may be provided to subject the surface of the catheter tube to a corona treatment in order to improve the adhesion of the form body on the catheter tube. A corona treatment may be provided in cases when a form body of a foam material such as polyurethane is formed or fixed on a polypropylene catheter tube in order to improve its adhesion.

According to yet another embodiment, the form body is arranged on the catheter tube, so that the catheter tube extends to about half of the longitudinal length of the form body in the completed catheter.

The invention also includes a use of a catheter for artificial insemination of animals and, in particular, of swine.

Further aspects and objects of the present invention will result from the following description of a preferred embodiment of the invention in conjunction with accompanying drawings, in which:

Fig. 1 shows the inventive catheter for artificial insemination of animals in a longitudinal cross section according to one embodiment;

Fig. 2 shows the proximal end of a catheter tube of the catheter of fig. 1 in a longitudinal cross section;

Fig. 3 shows the catheter tip of the catheter of fig. 1 in a cross section perpendicular to the longitudinal extension of the catheter taken along points A-A in fig. 1.

In the following the present invention will be described by means of an exemplifying embodiment shown in figs. 1 to 3.

The catheter includes a catheter tube 1 having a longitudinal lumen extending through it. The catheter tube 1 is surrounded at its distal end by a form body 3 forming a catheter tip. The form body has a circular symmetry with respect to its longitudinal axis which in the completed catheter coincides with the longitudinal axis of the catheter tube 1. As is visible in fig. 3, the form body 3 has a circular cross section. Furthermore, the form body 3 is tapered towards its proximal and distal ends. At about half of its length the form body 3 comprises a circular notch 4 that extends perpendicular with respect to the longitudinal axis of the form body 3. The circular notch 4 comprises a semi-circular profile. The circular notch 4 separates the form body 3 into a distal portion 5 and a proximal portion 6 of the form body. Both portions 5, 6 have similar shapes.

The catheter tube 1 extends into the form body 3 to about half of its length, and ends at about the centre of the circular notch 4. The inner lumen 2 of the catheter tube 1 is prolonged by a channel 7 formed in the form body 3 that extends to a distal opening of the form body 3. The channel 7 extends along the centre axis of the form body 3. The channel 7 has a slightly

channel 7 extends along the centre axis of the form body 3. The channel 7 has a slightly smaller diameter than the inner diameter of the catheter tube 1 but a slightly larger diameter than the outer diameter of the catheter tube 1.

The catheter tube 1 may optionally comprise a thread in a portion surrounded by the form body 3 to enhance the bonding strength between the catheter tube 1 and the form body 3.

The distal portion 5 of the form body 3 comprises a higher compressibility than the proximal portion 6 of the form body 3. In the embodiment shown in fig. 1 this is achieved by the reduced extension of the catheter tube 1 in the form body 3 which extends to about the middle of the length of the form body 3. Because of the support and rigidity provided by the catheter tube 1 the proximal portion 6 of the form body 3 comprises a lower compressibility and hence an increased hardness compared to the distal portion 5 of the form body 3 which does not surround the catheter tube 1.

Because of a softer distal portion of the form body 3, the catheter tip offers the advantage of an improved insertion quality. Simultaneously, due to a harder proximal portion 4 of the form body, the catheter provides an improved locking function in the cervix of the sow. Both advantages result in improved insemination results, since a higher comfort for the sow during insertion of the catheter and a prevention of a backflow of semen and enhanced initiation of uterine contractions can be achieved at the same time.

Figure 2 shows the proximal end of the catheter tube 1 which comprises a thread 9 for connecting the proximal end of the catheter tube 1 with a container or bag (not shown) for storage of the semen.

In the present example the form body is formed of a single elastomer material having a hardness of 60 ± 5 Shore and the catheter tube is formed of polypropylene. However, other materials for making form bodies may also be suitable. For example, the form body can be made of different thermoplastic elastomer materials having different densities for the distal portion 5 and the proximal portion 6 of the form body 3. For example, a material having a hardness of 65 - 90 Shore may be used for the proximal portion and a material having a hardness of 15 - 65 Shore may be used for the distal portion of the form body 3. The form body 3 can also be made of one or several expandable materials or foam materials like PUR. In the case of a

foam material, the form body can be foamed on the catheter tube using one or several foaming steps. Before the foaming the catheter tube may be subjected to a corona process.

Other modifications can be provided. For example, the catheter tube 1 can be advanced further into form body 3. The catheter tube 1 may be positioned in the form body so that it is surrounded by the form body over a length of for example two third (2/3), three quarters (3/4), 4/5 or 4/6 of the length of the form body 3. In order not to injure the vagina or the cervix of the sow during insertion of the catheter it is necessary that the catheter tube 1 does not extend up to the distal end of the form body but is offset from the end, since otherwise the pushing of the catheter during insertion will expose the sharp edge of the catheter tube and possibly bring it into contact with and injure the vagina or the cervix. Also the catheter tube may be positioned at less than the middle of the longitudinal extension of the form body.

Portions of different compressibility of the form body 3 can also be achieved by other designs of the form body 3. For example, different materials having different densities may be provided in different portions of the form body. For example, a material having a higher density and hardness may be provided in a proximal portion 6 of the form body 3, and a material having a lower density and thus a higher compressibility may be provided in a distal portion 5 of the form body 3.

Furthermore, portions of different compressibilities can be achieved in a form body by using a single material having different densities. For example, a portion with a lower density can be achieved by introducing a fluid such as gas into the material during a moulding process of the form body. Similarly, the form body can be formed of one or several expandable materials.

Also different materials or materials comprising different compressibilities can be used in different portions of the form body such as in an inner portion and an outer portion of the form body 3. For example, a material having a lower compressibility, i.e. a higher density, can be provided in the inside of the form body 3. In particular, the material having a lower compressibility can be provided in a portion of the form body that should have a lower compressibility or a larger hardness in the completed catheter. Preferably, this will be the proximal portion 6 of the form body. The material in the inside can be a cheaper material than the material at the outside so that the overall cost of the catheter is reduced. Furthermore, the inner material can be a material having better bonding capabilities with the catheter tube 1.

In addition, a second material having a higher compressibility and forming the outside of the form body is provided on the first material having a higher compressibility and also in the distal portion 5 of the form body that does not comprise the first material. If the first material having the reduced compressibility is provided only in the proximal portion 6 of the form body 3, the resulting form body 3 will have a higher compressibility in its distal portion 5 and a lower compressibility 6 in its proximal portion.

Form bodies comprising portions of different densities may also be formed by fins of material that for example extend perpendicular to the longitudinal axis of the form body. The cavities between the fins can be filled with a different material than the material of the fins.

Furthermore, a catheter tube 1 comprising a varying outer diameter in the form body can be provided. The shape of the form body can be different than in the embodiment shown in the figures. For example, the circular notch 4 can be omitted. Further, the shape of the distal portion of the form body can be different at the proximal portion. For example, the form body can comprise a bullet like shape including a distal portion having a tapered tip and a proximal portion having a non tapered end with the same diameter than the main form body.

Also modifications to the catheter tube can be provided. For example, the catheter tube may be formed of a soft material. In order to insert the catheter a mandrel may be used that is removed before the infusion of the semen.

The different features of the invention as described above may be of importance for the invention in any combination.