Hydrophilic polymer blends used for dry cow therapy

Details Hydrophilic polymer blends used for dry cow therapy Hydrophilic polymer blends used for dry cow therapy

2000-11-06

2002-08-27

Levy, Neil S. (Department: 1616)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Biocides; animal or insect repellents or attractants

C424S078030, C424S078050, C424S078070, C424S078240, C424S406000, C424S438000, C424S484000, C424S486000, C424S667000, C424S672000, C523S122000, 57

Reexamination Certificate

active

06440442

ABSTRACT:

BACKGROUND OF THE INVENTION
The effective management and maintenance of large dairy herds and the production of dairy products has been a major agricultural accomplishment. One of the problems in maintaining large herds is the health of the individual animals. One health problem that causes significant economic problems relates to mastitis.
The dairy farmer is faced with two different types of mastitis infections, contagious and environmental. Contagious mastitis is spread during the milking process through contact between the animal and dairy equipment that may carry a source of a mastitis pathogen. Environmental mastitis is caused by contamination of the animal skin by materials from the barnyard environment, fields, barn interior, etc, as the animal moves through its environment. Mastitis-causing pathogens include
E. coli, Streptococcus uberis, klebsiella
and others.
Contagious mastitis is most easily controlled by using germicidal post milking teat dip compositions. Such germicidal dips kill bacteria that are introduced onto the surface of the animal from the milking machines. Environmental mastitis is best treated with a barrier film that protects sensitive tissues from contamination.
More particularly, one class of compositions used in the treatment and prevention of mastitis is formed from aqueous coating systems. These coatings reduce the incidence of infection of the animal through the presence of an active biocide. However, these teat dips are easy to remove. For example, polyvinyl alcohol based teat dips, do not provide adequate water resistance. That is, due to exposure to water, these films wear off in about 3 to 4 hours. Without an adequate barrier film the dairy animal is vulnerable to environmental pathogens which will promote mastitis in the herd.
Another class of coating materials is characterized by the formation of film barriers on the skin surface to prevent contact between vulnerable tissues and the environment. Many antimicrobial materials are incompatible with a variety of these film-forming or polymeric materials. For example, antimicrobials cannot be used efficiently with latex since the antimicrobial eventually precipitates out of the latex. Moreover, latex does not provide a long-lasting coverings to the mammalian skin. Recent product developments provide coatings for teat skin which form film barriers, as well as, contain antimicrobial agents. Such coatings include solubilized liquids, polyvinylpyrrolidone and other vinyl polymers, protein hydrozylate, natural and synthetic gums, water, ethanol, methanol, isopropanol, soluble polymers, unsaturated fatty oils, cellulose derivatives, acrylic polymer lattices, etc.
An essential part of a mastitis control program is dry cow therapy. Dry cow therapy is treatment of a cow during the approximately four to ten-week period immediately preceding the delivery of a calf. This period is also known as the dry period or non-lactating period. Although during the dry period the mammal is not exposed to potential contamination form milking machines, forty to fifty percent of teat infections occur during a mammal's dry period. This high rate of infection occurs since a mammal's immune response is diminished during the dry period. Additionally, the teat is distended during the dry period allowing microbials to penetrate the mammary gland more easily; and without the flushing lactation provides, the likelihood of infection increases. Thus, treating a dairy animal during its dry period would minimize the rate of infection.
Furthermore, there are other advantages of treating cows during their dry period vis-à-vis their lactating period. For example, the udder tissue can be exposed to medication for an extended period of time since the medication does not have to be removed prior to milking time. Additionally, if the health of a cow is restored during its dry period, the cow may not have to be treated during its lactating period, thereby reducing the potential of contamination of the milk supply by medicinal agents.
Dry cow therapies that are standard in the industry include teat dip compositions that contain strong solvents, such as tetrahydrofuran. Such solvents are cytotoxic and cause irritation to skin, eyes and the respiratory tract. The irritation to skin includes symptoms such as redness, itching, rash, cracking and pain. Additionally, tetrahydrofuran is harmful if swallowed or inhaled. Repeated or high exposure to tetrahydrofuran may cause kidney or liver damage and may affect the lungs and central nervous system. Additionally, tetrahydrofuran is an extremely flammable liquid and may form explosive peroxides.
Accordingly, it is one of the purposes of this invention, among others, to provide an antimicrobial and long-lasting barrier film teat dip which uses solvents which are dermatologically-acceptable. In particular, these solvents are non-cytotoxic and nonirritating to mammalian skin.
SUMMARY OF THE INVENTION
The present invention provides mammalian teat dip compositions capable of being used during a mammal's dry period. Upon application to mammalian skin, this composition leaves a long-lasting, water-resistant, residual, elastic film. The composition exhibits barrier and antimicrobial properties against mastitis-causing pathogens, thereby protecting the mammal from environmental pathogens. The composition is capable of being removed by peeling.
The composition includes a solution of a film-forming polymer blend and at least one antimicrobial agent.
The polymer blend consists essentially of two polymer components. One polymer component is an organic, solvent-soluble, preformed, thermoplastic polyurethane which has no reactive isocyanate groups. This polymer, along with the solvent used, makes up from about 10 to about 80 weight percent of the composition. The other polymer component is a hydrophilic poly(N-vinyl lactam). This polymer makes up from about 1 to about 15 weight percent of the composition. This polymer blend is capable of withstanding exposure to water without a significant loss of the hydrophilic poly(N-vinyl lactam).
The polyurethane of the polymer blend can be derived from an aromatic polyisocyanate and a polyether polyol; or from an aliphatic polyisocyanate and a polyether polyol; or from an aromatic polyisocyanate and a polyester polyol; or from an aliphatic polyisocyanate and a polyester polyol.
The poly(N-vinyl lactam) of the polymer blend is a water-soluble polyvinylpyrrolidone homopolymer or a poly(N-vinyl caprolactam) homopolymer.
Examples of antimicrobial agents include iodine, chlorhexidine, bronopol and triclosan. In one formulation the iodine antimicrobial agent can be an aqueous solution of polyvinylpyrrolidone-iodine (PVP-I
2
). In another formulation the iodine antimicrobial agent can be an aqueous solution of elemental iodine and iodide salts. In yet another formulation the iodine antimicrobial agent can be an aqueous solution of elemental iodine, hydriodic acid, and a surfactant. The surfactant can range widely in its degree of ionization, including no ionization.
The chlorhexidine antimicrobial agent can be an aqueous solution of chlorhexidine salts.
The polymer blend can contain at least one additional compatible polymer component. The additional polymer component can be a homopolymer or copolymer of at least one monomer selected from the group consisting of alpha-olefin, vinyl chloride, vinylidene chloride, hydroxyethylmethacrylate, acrylic acid, methacrylic acid, vinyl acetate, vinyl alcohol, and vinyl ether.
The composition can also contain water-soluble or water-dispersible skin conditioning agents, such as glycerin; glycols; polyols, such as polyethylene glycol; lanolin; aloe vera and vitamins. The composition can also contain colorants, fragrances and insect repellants. The composition can also contain a thickener such as silica or xanthan gum.
The present invention also provides a method of protecting a mammalian teat from infection, in particular of protecting a mammalian teat during the mammal's dry period. This method includes applying the compos

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