Antibacterial veterinary drug for respiratory tract and preparation method thereof

Abstract

The invention relates to the field of veterinary drugs, and provides an antibacterial veterinary drug for respiratory tracts and a preparation method thereof.The veterinary drug is prepared from, by weight, 20-25 parts of sodium salicylate, 13-18 parts of modified mequindox, 1-3 parts of theophylline, 18-23 parts of gentamicin sulfate, 26-31 parts of spectinomycin hydrochloride, 6-11 parts of calcium chloride, 6-8 parts of immunopotentiator and 1-3 parts of compound preservative. The antibacterial veterinary drug for the respiratory tract provided by the invention has the characteristics of good antibacterial property, corrosion resistance and high treatment effect, and has better commercial application value.

Description

Technical Field

[0001] The present invention relates to the field of veterinary drugs, and particularly to an antibacterial veterinary drug for respiratory tract and its preparation method. Background Art

[0002] Respiratory diseases are one of the common diseases of animals, especially poultry and livestock, such as chickens, pigs, etc. These diseases often lead to growth retardation, decreased productivity, and even death of animals, causing significant losses to the breeding industry. Therefore, the development and research of veterinary drugs for the efficient treatment of respiratory tract are of great significance for ensuring animal health and improving breeding efficiency. Moreover, the antibacterial property of veterinary drugs is also crucial for improving the treatment effect and has important significance for enhancing animal productivity.

[0003] Mequindox, also known as Baytril, is a chemical antibacterial drug developed by the Institute of Traditional Chinese Veterinary Medicine, Chinese Academy of Agricultural Sciences. It has a broad antibacterial spectrum and strong antibacterial activity in vivo and in vitro. When treating animal respiratory diseases, the broad-spectrum antibacterial effect of mequindox enables it to resist various bacterial infections, reduce the inflammatory response, and relieve related symptoms. For example, it can effectively kill or inhibit pathogenic Escherichia coli, block its invasion and destruction of host cells, and achieve the purpose of preventing and treating respiratory tract infections. In addition, mequindox can also regulate the intestinal flora of animals, improve the utilization rate of energy substances and proteins, increase the synthesis of proteins in the body, and also has a positive promoting effect on the growth and development of animals. However, mequindox is limited in its application due to its poor water solubility, bitter taste, and fast metabolism. In addition, the current veterinary drugs on the market have insufficient anti-corrosion properties and are often easily contaminated by microorganisms during storage and use, thus having an adverse impact on the safety and effectiveness of the drugs.

[0004] Patent CN 104586874B discloses a drug for preventing and treating avian respiratory tract infections and its preparation method, including the following components: ribavirin, sodium acetylsalicylate, mequindox, sodium carboxymethylcellulose, propylene glycol, and Tween-80. It can effectively reduce the incidence of avian respiratory tract infections and has a good treatment effect. However, it does not solve the problems of poor water solubility, bitter taste, and fast metabolism of mequindox, and there are still certain limitations in its application.

[0005] Therefore, there is an urgent need on the market for an antibacterial veterinary drug for respiratory tract with good antibacterial property, anti-corrosion property, and high treatment effect. Summary of the Invention

[0006] Aiming at the problems existing in the prior art, the present invention uses sodium salicylate, modified mequindox, gentamicin sulfate, etc. as the main components of the veterinary drug, and adds a compound preservative to synthesize an antibacterial veterinary drug for respiratory tract, which has good antibacterial property, anti-corrosion property, and high treatment effect.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] On the one hand, the present invention provides an antibacterial veterinary drug for the respiratory tract. Calculated by weight parts, the veterinary drug comprises the following raw materials: 20-25 parts of sodium salicylate, 13-18 parts of modified mequindox, 1-3 parts of theophylline, 18-23 parts of gentamicin sulfate, 26-31 parts of spectinomycin hydrochloride, 6-11 parts of calcium chloride, 6-8 parts of an immune enhancer, and 1-3 parts of a compound preservative.

[0009] In some embodiments of the present invention, the preparation method of the modified mequindox comprises the following steps:

[0010] (1) Add ethylene carbonate to dimethyl sulfoxide, stir to obtain solution 1 for standby. Add chitosan to a mixed solution of isopropanol and deionized water, stir, add sodium hydroxide, stir, let stand at -20 to -15 °C for 6-10 h, return to room temperature, dropwise add solution 1, heat to 100-120 °C, stir, neutralize, wash, filter, centrifuge, add deionized water, stir, dialyze, and freeze-dry to obtain product 1 for standby;

[0011] (2) Add proline to MES buffer solution, stir, add 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide ester, keep away from light for 30-40 min, add the product 1 of step (1), dropwise add hydrochloric acid aqueous solution to adjust pH = 7-8, stir, dialyze, and freeze-dry to obtain product 2 for standby;

[0012] (3) Add the product 2 of step (2) and mequindox to anhydrous methanol, heat under reflux, concentrate under reduced pressure, wash, centrifuge, and dry to obtain the modified mequindox.

[0013] In some embodiments of the present invention, in step (1), the mass ratio of chitosan to ethylene carbonate is 1:(1.5-2).

[0014] Preferably, in step (1), the mass ratio of chitosan to ethylene carbonate is 1:1.65.

[0015] In some embodiments of the present invention, in step (2), the mass ratio of product 1 to proline is 1:(1-1.5).

[0016] Preferably, in step (2), the mass ratio of product 1 to proline is 1:1.15.

[0017] In some embodiments of the present invention, in step (3), the mass ratio of product 2 to mequindox is 1:(1-2).

[0018] Preferably, in the step (3), the mass ratio of product 2 to mequindox is 1:1.5.

[0019] Mequindox is an antibacterial and growth-promoting drug, which has the advantages of a broad antibacterial spectrum and being not easy to produce drug resistance. However, mequindox has disadvantages such as poor water solubility, bitter taste, and fast metabolism, which severely limit the application of mequindox.

[0020] The applicant selects chitosan as the matrix of the mequindox carrier. As a natural polysaccharide, chitosan has low toxic side effects, good biodegradability and biocompatibility, and has a high surface charge density, which helps the adsorption and release of drug molecules. Moreover, the chitosan structure also contains amino groups, and the amino groups can form Schiff base covalent bonds with the carbonyl groups in the mequindox molecules, so that mequindox can be stably loaded on chitosan to achieve the effect of masking the taste. When the drug reaches the acidic gastric juice, the formed Schiff base will break, and mequindox can be released, achieving the purpose of drug delivery; further, the applicant modifies chitosan with ethylene carbonate as an etherifying reagent to introduce hydrophilic hydroxyethyl groups onto the chitosan molecule to synthesize product 1. Ethylene carbonate is environmentally friendly and has good reaction selectivity and surface activity, thereby improving the water solubility and antibacterial property of chitosan; furthermore, the applicant graft-modifies product 1 with proline to obtain product 2. The hydrophilicity of proline effectively improves the water solubility of chitosan, which is beneficial to the absorption of modified mequindox by animals, and further increases the proportion of amino groups in the modified chitosan, so that mequindox can be better loaded, and thus can effectively improve the therapeutic effect of veterinary drugs.

[0021] In some embodiments of the present invention, the immunopotentiator is saccharicterpenin.

[0022] In some embodiments of the present invention, the preparation method of the compound preservative includes the following steps:

[0023] 1) Wash the banana peel with deionized water, slice it, dry it, pulverize it, and sieve it to obtain powder for later use;

[0024] 2) Take the powder from step 1), add sodium N,N-dicarboxymethylalaninate and an ethanol aqueous solution, and ultrasonicate for 20 - 40 min at 50 - 55 °C and 190 - 210 W, centrifuge, take the supernatant, and rotary evaporate under vacuum at 35 - 45 °C, and then freeze-dry to obtain banana peel polyphenols for later use;

[0025] 3) Mix the banana peel polyphenols and sodium diacetate, and stir to obtain the compound preservative.

[0026] In some embodiments of the present invention, in the step 2), the mass ratio of the powder to sodium N,N-dicarboxymethylalaninate is 1:(0.005 - 0.007).

[0027] Preferably, in the step 2), the mass ratio of the powder to trisodium N,N-dicarboxymethylalanine is 1:0.006.

[0028] In some embodiments of the present invention, in the step 3), the mass ratio of banana peel polyphenols to sodium diacetate is 1:(2 - 4).

[0029] Preferably, in the step 3), the mass ratio of banana peel polyphenols to sodium diacetate is 1:3.

[0030] Preservatives are very important in veterinary drugs, which can effectively prevent veterinary drugs from being contaminated by microorganisms during storage and use, thus ensuring the safety and effectiveness of the drugs. Especially for respiratory veterinary drugs, since they directly act on the respiratory system of animals, higher requirements are placed on the purity and safety of the drugs.

[0031] Banana peels are green, environmentally friendly and widely sourced. Banana peels contain a large amount of pectin, oligosaccharides, cellulose and polyphenolic substances. Among them, polyphenolic substances have strong antioxidant and bactericidal abilities and can resist various bacteria and viruses. The applicant provides an extraction method of banana peel polyphenols with convenient operation, short extraction time and high extraction rate. On the one hand, the applicant adds trisodium N,N-dicarboxymethylalanine as an extraction agent to assist in the extraction of banana peel polyphenols. Trisodium N,N-dicarboxymethylalanine can chelate with polyvalent metal ions in banana peels to form soluble metal complexes, thereby promoting the release of organic macromolecules in banana peels and further promoting the extraction of banana peel polyphenols. Further, the applicant uses ultrasonic-assisted extraction. The thermal effect, mechanical action and cavitation effect generated by ultrasound can quickly break the cell walls of raw materials, promote the extraction agent to enter the cells and fully mix with the target extraction components, and thus facilitate the dissolution of polyphenolic substances. On the other hand, the applicant mixes the extracted banana peel polyphenols with sodium diacetate in a controlled ratio to form a composite preservative. Sodium diacetate inhibits the growth and reproduction of molds and bacteria by releasing acetic acid, and can play a synergistic anti-corrosion role with banana peel polyphenols, thereby improving the curative effect of veterinary drugs.

[0032] On the other hand, the present invention also provides a preparation method of the respiratory antibacterial veterinary drug described in the above technical solution, including the following steps:

[0033] Mix sodium salicylate, modified mequindox, theophylline, gentamicin sulfate, spectinomycin hydrochloride, calcium chloride, immune enhancer and composite preservative, and stir for 1.5 - 2.5 h to obtain the respiratory antibacterial veterinary drug.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) The present invention uses sodium salicylate, modified mequindox, gentamicin sulfate, etc. as the main components of veterinary drugs, and adds a compound preservative to synthesize an antibacterial veterinary drug for the respiratory tract. Through the synergistic effect among the components, the veterinary drug has the advantages of good antibacterial property, preservative property and high therapeutic effect.

[0036] (2) The present invention uses chitosan as the matrix of the mequindox carrier, modifies chitosan with ethylene carbonate and proline, improves the water solubility and antibacterial property of chitosan, and enables mequindox to be well loaded in chitosan, playing the role of taste masking and drug transportation, thereby improving the therapeutic effect of the veterinary drug.

[0037] (3) The present invention provides a novel method for extracting banana peel polyphenols from banana peels, and mixes banana peel polyphenols and sodium diacetate in a controlled ratio to form a compound preservative, which plays a synergistic preservative effect and effectively improves the therapeutic effect of the veterinary drug.

[0038] (4) The veterinary drug prepared by the present invention has excellent antibacterial property, preservative property and therapeutic effect, can be widely applied to the respiratory tract field, and has good commercial application value. Specific Embodiments

[0039] The following will illustrate the present invention in combination with specific implementation embodiments. It should be noted that the following examples are examples of the present invention, only used to illustrate the present invention, rather than used to limit the present invention. Without departing from the gist or scope of the present invention, other combinations and various improvements within the concept of the present invention can be made.

[0040] In the following examples and comparative examples, except for the modified mequindox and the compound preservative, the other compound monomers and related reagents used can be purchased from the market. Among them, chitosan is purchased from Qingdao Bozhihuilai Biotechnology Co., Ltd.

[0041] Preparation Example 1

[0042] The synthesis method of modified mequindox A includes the following steps:

[0043] (1) Add 13.2 g of ethylene carbonate to 40 ml of dimethyl sulfoxide, stir for 20 min to obtain solution 1 for standby. Add 8 g of chitosan to a mixed solution of 90 ml of isopropanol and 10 ml of deionized water, stir for 20 min, add 20 g of sodium hydroxide, stir for 30 min, let stand at -18 °C for 8 h, return to room temperature, dropwise add solution 1, heat to 110 °C, stir for 10 h, dropwise add 10 wt% hydrochloric acid aqueous solution to neutralize to pH = 7, wash 3 times with absolute ethanol, filter, centrifuge, add 100 ml of deionized water, stir for 10 min, dialyze, and freeze-dry at -40 °C for 24 h to obtain product 1 for standby;

[0044] (2) Add 11.5 g of proline to 100 ml of 0.1 mol / L MES buffer solution, stir for 20 min, add 0.8 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 1.2 g of N-hydroxysuccinimide ester, keep in the dark for 35 min, add 10 g of the product 1 in step (1), dropwise add 10 wt% hydrochloric acid aqueous solution to adjust the pH to 7.6, stir for 24 h, dialyze with deionized water, and freeze-dry at -40 °C for 24 h to obtain the product 2 for standby;

[0045] (3) Add 2 g of the product 2 in step (2) and 3 g of mequindox to 30 ml of anhydrous methanol, heat to 40 °C and reflux for 5 h, concentrate under reduced pressure, wash with anhydrous methanol three times, centrifuge, and dry at 60 °C for 12 h to obtain the modified mequindox A.

[0046] Preparation Example 2

[0047] Modified mequindox B, the specific implementation method is the same as that of modified mequindox A, the difference is that in step (1), the mass of ethylene carbonate is replaced by 10 g.

[0048] Preparation Example 3

[0049] Modified mequindox C, the specific implementation method is the same as that of modified mequindox A, the difference is that in step (2), the mass of proline is replaced by 8 g.

[0050] Preparation Example 4

[0051] Modified mequindox D, the specific implementation method is the same as that of modified mequindox A, the difference is that in step (3), the mass of the product 2 is replaced by 1.2 g.

[0052] Preparation Example 5

[0053] The synthesis method of the composite preservative A includes the following steps:

[0054] 1) Wash the banana peel with deionized water, slice it, dry at 50 °C for 12 h, pulverize it, and pass through a 40-mesh sieve to obtain the powder for standby;

[0055] 2) Take 5 g of the powder in step 1), add 0.03 g of N,N-dicarboxymethylalanine trisodium and 50 ml of 50 wt% ethanol aqueous solution, carry out ultrasonic treatment at 53 °C and 200 W for 30 min, cool to 0 °C, centrifuge at 10000 r / min for 15 min, take the supernatant, carry out rotary evaporation at 40 °C under vacuum conditions, and freeze-dry at -40 °C for 24 h to obtain banana peel polyphenols for standby;

[0056] 3) Mix 5 g of banana peel polyphenols and 15 g of sodium diacetate, and stir for 10 min to obtain the composite preservative A.

[0057] Preparation Example 6

[0058] Compound preservative B, the specific implementation method is the same as that of compound preservative A, the difference is that: in step 2), the mass of trisodium N,N-dicarboxymethylalanine is replaced with 0.015 g.

[0059] Preparation Example 7

[0060] Compound preservative C, the specific implementation method is the same as that of compound preservative A, the difference is that: in step 3), the mass of sodium diacetate is replaced with 9 g.

[0061] Preparation Example 8

[0062] Compound preservative D, the specific implementation method is the same as that of compound preservative A, the difference is that: in step 3), the mass of sodium diacetate is replaced with 21 g.

[0063] Example 1

[0064] An antibacterial veterinary drug for the respiratory tract, calculated by weight, the veterinary drug includes the following raw materials: 20-25 parts of sodium salicylate, 15.5 parts of modified mequindox A, 2 parts of theophylline, 20.5 parts of gentamicin sulfate, 28.5 parts of spectinomycin hydrochloride, 8.5 parts of calcium chloride, 7 parts of saponin, and 2 parts of compound preservative A.

[0065] The preparation method of the antibacterial veterinary drug for the respiratory tract in this embodiment includes the following steps:

[0066] Mix sodium salicylate, modified mequindox A, theophylline, gentamicin sulfate, spectinomycin hydrochloride, calcium chloride, saponin and compound preservative A, and stir for 2 h to obtain the antibacterial veterinary drug for the respiratory tract.

[0067] Example 2

[0068] An antibacterial veterinary drug for the respiratory tract, calculated by weight, the veterinary drug includes the following raw materials: 20 parts of sodium salicylate, 15.5 parts of modified mequindox A, 1 part of theophylline, 18 parts of gentamicin sulfate, 26 parts of spectinomycin hydrochloride, 6 parts of calcium chloride, 6 parts of saponin, and 1 part of compound preservative A.

[0069] The preparation method of the antibacterial veterinary drug for the respiratory tract in this embodiment includes the following steps:

[0070] Mix sodium salicylate, modified mequindox A, theophylline, gentamicin sulfate, spectinomycin hydrochloride, calcium chloride, saponin and compound preservative A, and stir for 1.5 h to obtain the antibacterial veterinary drug for the respiratory tract.

[0071] Example 3

[0072] An antibacterial veterinary drug for the respiratory tract. By weight, the veterinary drug comprises the following raw materials: 25 parts of sodium salicylate, 15.5 parts of modified mequindox A, 3 parts of theophylline, 23 parts of gentamicin sulfate, 31 parts of spectinomycin hydrochloride, 11 parts of calcium chloride, 8 parts of sugar terpenoids, and 3 parts of compound preservative A.

[0073] The preparation method of the antibacterial veterinary drug for the respiratory tract in this embodiment comprises the following steps:

[0074] Mix sodium salicylate, modified mequindox A, theophylline, gentamicin sulfate, spectinomycin hydrochloride, calcium chloride, sugar terpenoids and compound preservative A, and stir for 2.5 h to obtain the antibacterial veterinary drug for the respiratory tract.

[0075] Example 4

[0076] An antibacterial veterinary drug for the respiratory tract. By weight, the veterinary drug comprises the following raw materials: 21 parts of sodium salicylate, 13 parts of modified mequindox A, 1.5 parts of theophylline, 19 parts of gentamicin sulfate, 27 parts of spectinomycin hydrochloride, 7 parts of calcium chloride, 6.5 parts of sugar terpenoids, and 2 parts of compound preservative A.

[0077] The preparation method of the antibacterial veterinary drug for the respiratory tract in this embodiment is the same as that in Embodiment 1.

[0078] Example 5

[0079] An antibacterial veterinary drug for the respiratory tract. By weight, the veterinary drug comprises the following raw materials: 24 parts of sodium salicylate, 18 parts of modified mequindox A, 2.5 parts of theophylline, 22 parts of gentamicin sulfate, 30 parts of spectinomycin hydrochloride, 10 parts of calcium chloride, 7.5 parts of sugar terpenoids, and 2 parts of compound preservative A.

[0080] The preparation method of the antibacterial veterinary drug for the respiratory tract in this embodiment is the same as that in Embodiment 1.

[0081] Example 6

[0082] This embodiment provides an antibacterial veterinary drug for the respiratory tract and its preparation method. The specific implementation manner is the same as that in Embodiment 1, except that modified mequindox B is used to replace modified mequindox A in equal amount.

[0083] Example 7

[0084] This embodiment provides an antibacterial veterinary drug for the respiratory tract and its preparation method. The specific implementation manner is the same as that in Embodiment 1, except that modified mequindox C is used to replace modified mequindox A in equal amount.

[0085] Example 8

[0086] This embodiment provides an antibacterial veterinary drug for the respiratory tract and its preparation method. The specific implementation manner is the same as that of Embodiment 1, except that modified mequindox D is used to replace modified mequindox A in equal amount.

[0087] Example 9

[0088] This embodiment provides an antibacterial veterinary drug for the respiratory tract and its preparation method. The specific implementation manner is the same as that of Embodiment 1, except that compound preservative B is used to replace compound preservative A in equal amount.

[0089] Example 10

[0090] This embodiment provides an antibacterial veterinary drug for the respiratory tract and its preparation method. The specific implementation manner is the same as that of Embodiment 1, except that compound preservative C is used to replace compound preservative A in equal amount.

[0091] Example 11

[0092] This embodiment provides an antibacterial veterinary drug for the respiratory tract and its preparation method. The specific implementation manner is the same as that of Embodiment 1, except that compound preservative D is used to replace compound preservative A in equal amount.

[0093] Comparative Example 1

[0094] This comparative example provides an antibacterial veterinary drug for the respiratory tract and its preparation method. The specific implementation manner is the same as that of Embodiment 1, except that mequindox is used to replace modified mequindox A in equal amount.

[0095] Comparative Example 2

[0096] This comparative example provides an antibacterial veterinary drug for the respiratory tract and its preparation method. The specific implementation manner is the same as that of Embodiment 1, except that banana peel polyphenols are used to replace compound preservative A in equal amount.

[0097] The preparation method of banana peel polyphenols is the same as that of Preparation Example 5.

[0098] Comparative Example 3

[0099] This comparative example provides an antibacterial veterinary drug for the respiratory tract and its preparation method. The specific implementation manner is the same as that of Embodiment 1, except that sodium diacetate is used to replace compound preservative A in equal amount.

[0100] Performance test

[0101] Test the therapeutic effects of the antibacterial veterinary drugs for the respiratory tract in the above-mentioned Embodiments 1-11 and Comparative Examples 1-3, and the test results are shown in Table 1.

[0102] Dosage and Administration: The administration method is feeding. The dosage for each administration is 1.5 g of the antibacterial veterinary drug for respiratory tract per 1 kg body weight of poultry, once a day, and a three-day course of treatment.

[0103] Test Examples

[0104] Test Animals: 525 diseased chickens diagnosed as having bronchitis through comprehensive diagnosis based on epidemiology, clinical symptoms, pathological dissection, pathogen isolation and identification were randomly selected and divided into 15 groups, with 35 chickens in each group. In experimental groups 1 - 14, the antibacterial veterinary drugs for respiratory tract prepared in Examples 1 - 11 and Comparative Examples 1 - 3 were used for treatment in sequence. The control group used commercially available Huchuanning (purchased from Shandong Fuliite Pharmaceutical Co., Ltd.). The curative effect was observed, and the number of cured, effective and ineffective cases was counted, and the cure rate was calculated.

[0105] Curative Effect Judgment Criteria:

[0106] Cured: Good mental state, no slow breathing or nose flicking, and no secretions in the bronchus;

[0107] Effective: The symptoms improved significantly;

[0108] Ineffective: Poor mental state, unable to get up from lying down, clustering phenomenon, slow breathing and nose flicking phenomenon.

[0109] Cure Rate (%) = Number of cured chickens in each group ÷ Number of initial diseased chickens in each group × 100%

[0110] Table 1

[0111]

[0112]

[0113] It can be seen from the data in Table 1 that the antibacterial veterinary drugs for respiratory tract in Examples 1 - 5 of the present invention generally have a good cure rate, that is, a high treatment effect. Among them, in Examples 6 - 8, the modification ratios of ethylene carbonate and proline to chitosan and the modification ratio of mequindox during the synthesis of modified mequindox were changed, resulting in the poor improvement of the water solubility and antibacterial property of chitosan and the poor loading of mequindox on chitosan. As a result, the modified mequindox could not be well absorbed by chickens, leading to a decrease in the cure rate of chickens; in Examples 9 - 11, the dosage of sodium N,N - dicarboxymethylalanine during the extraction of banana peel polyphenols and the compounding ratio between banana peel polyphenols and sodium diacetate during the preparation of the compound preservative were changed, resulting in a decrease in the synergistic preservation effect of the compound preservative, and further leading to a decrease in the cure rate of chickens; in Comparative Examples 1 - 3, mequindox was used to equally replace modified mequindox A, and banana peel polyphenols and sodium diacetate were used to equally replace compound preservative A respectively. The test found that the cure rates of chickens all showed poor results.

[0114] The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose is to enable those skilled in the art to understand the content of the present invention and implement it. It should not be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. An antibacterial veterinary drug for the respiratory tract, characterized in that, By weight parts, the veterinary drug comprises the following raw materials: 20-25 parts of sodium salicylate, 13-18 parts of modified mequindox, 1-3 parts of theophylline, 18-23 parts of gentamicin sulfate, 26-31 parts of spectinomycin hydrochloride, 6-11 parts of calcium chloride, 6-8 parts of immune enhancer, and 1-3 parts of compound preservative.

2. The antibacterial veterinary drug for respiratory tract according to claim 1, characterized in that, The preparation method of the modified mequindox comprises the following steps: (1) Add ethylene carbonate into dimethyl sulfoxide, stir to obtain solution 1 for standby. Add chitosan into the mixed solution of isopropanol and deionized water, stir, add sodium hydroxide, stir, let stand at -20~-15°C for 6-10 h, return to room temperature, dropwise add solution 1, heat to 100-120°C, stir, neutralize, wash, filter, centrifuge, add deionized water, stir, dialyze, and freeze-dry to obtain product 1 for standby; (2) Add proline into MES buffer solution, stir, add 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide ester, keep away from light for 30-40 min, add product 1 from step (1), dropwise add hydrochloric acid aqueous solution to adjust pH = 7-8, stir, dialyze, and freeze-dry to obtain product 2 for standby; (3) Add product 2 from step (2) and mequindox into anhydrous methanol, heat under reflux, concentrate under reduced pressure, wash, centrifuge, and dry to obtain the modified mequindox.

3. The antibacterial veterinary drug for respiratory tract according to claim 2, characterized in that, In the step (1), the mass ratio of chitosan to ethylene carbonate is 1:(1.5-2).

4. The antibacterial veterinary drug for respiratory tract according to claim 2, wherein In the step (2), the mass ratio of product 1 to proline is 1:(1-1.5).

5. The antibacterial veterinary drug for respiratory tract according to claim 2, characterized in that, In the step (3), the mass ratio of product 2 to mequindox is 1:(1-2).

6. The antibacterial veterinary drug for respiratory tract according to claim 1, characterized in that, The immune enhancer is glycotetin.

7. The antibacterial veterinary drug for respiratory tract according to claim 1, characterized in that, The preparation method of the compound preservative comprises the following steps: 1) Wash banana peel with deionized water, slice, dry, pulverize, and sieve to obtain powder for standby; 2) Take the powder from step 1), add sodium N,N-dicarboxymethylalaninate and ethanol aqueous solution, ultrasonically treat at 50-55°C and 190-210 W for 20-40 min, centrifuge, take the supernatant, rotary evaporate under vacuum at 35-45°C, and freeze-dry to obtain banana peel polyphenols for standby; 3) Mix the banana peel polyphenols and sodium diacetate, stir to obtain the compound preservative.

8. The antibacterial veterinary drug for respiratory tract according to claim 7, characterized in that, In the step 2), the mass ratio of the powder to sodium N,N-dicarboxymethylalaninate is 1:(0.005-0.007).

9. The antibacterial veterinary drug for respiratory tract according to claim 7, characterized in that, In the step 3), the mass ratio of the banana peel polyphenols to sodium diacetate is 1:(2-4).

10. A method for preparing the antibacterial veterinary drug for respiratory tract according to any one of claims 1-9, characterized in that, Comprises the following steps: Mix sodium salicylate, modified mequindox, theophylline, gentamicin sulfate, spectinomycin hydrochloride, calcium chloride, immune enhancer and compound preservative, and stir for 1.5-2.5 h to obtain the respiratory antibacterial veterinary drug.

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