Research Progress on Diagnosis and Treatment of Bovine Mastitis

Jia YAO, Dacai PENG, Zhengmei CHENG

1. Ya’an Animal Husbandry Development Center, Ya’an 625000, China; 2. Agricultural and Rural Bureau of Yingjing County, Yingjing 625200, China

Abstract Bovine mastitis is a common disease of dairy cows, andit is the main reason for the economic loss of dairy industry. This paper reviews the types, etiology, diagnosis, prevention and treatment of bovine mastitis, in order to provide some reference basis for the prevention and treatment of bovine mastitis.

Key words Bovine mastitis, Etiology, Diagnosis, Prevention and treatment

1 Introduction

Bovine mastitis, also known as cow mastitis, is an inflammatory disease caused by pathogenic bacteria and chemical and physical factors in breast tissue. After the occurrence of mastitis, the resistance of cattle decreases. After mixed infection withBrucella,Mycobacteriumtuberculosis and other bacteria, it will directly or indirectly cause zoonosis, thus endangering human health. The pain caused by mastitis can be followed by bovine forestomach atony, causing cattle to lose weight slowly, and even leading to septicemia and death. With the development of dairy industry, the incidence bovine mastitis in dairy herds has a rising trend, and it has become the main reason for the economic loss of dairy industry[1-2]. This paper reviews the types, etiology, diagnosis, prevention and treatment of bovine mastitis, in order to provide some reference basis for the prevention and treatment of bovine mastitis.

2 Classification of bovine mastitis

According to the different clinical manifestations of mastitis, it can be divided into clinical mastitis and subclinical mastitis. Clinical mastitis is the inflammation of breast stroma, parenchyma or interstitial parenchyma. It is characterized by breast degeneration, breast tissue swelling, warmth and pain. According to the duration and severity of the disease, it can be divided into the most acute, acute, subacute and chronic mastitis. The most acute: sudden onset, rapid development, mostly in one breast area; the affected breast area is obviously swollen and as hard as stone; the skin is purple, cracked, and the pain is obvious; the milk production in the healthy milk area decreases sharply, and the affected milk area can only be squeezed out 1 to 2 handfuls of yellow fluid or light blood; the systemic symptoms are obvious, the appetite is lost, and the body temperature increases to 41.5-42.0 ℃, showing a sign of continued fever; the number of heartbeats is 110-130 min, respiration is accelerated, the spirit is depressed, and the stool is black and dry; weak muscles, unwilling to move, like lying, rapid weight loss. Subclinical mastitis, also known as recessive mastitis, is a kind of mastitis without clinical symptoms. Its characteristic is that no abnormality can be seen in the breast and milk, but the physical and chemical properties and bacteriology of the milk have changed. Specifically, the pH value is higher than 7.0. it is slightly alkaline; there are milk clots, flocs and fibers in the milk, and the content of sodium chloride is more than 0.14%; the number of somatic cells was more than 500 000 mL, and the number of bacteria and electrical conductivity increase.

3 Etiology of mastitis in dairy cows

3.1 Environmental management factorsEnvironmental conditions such as barn, free stall and ground are muddy, there is too much dirt around the cow and breasts, and the sanitary condition is too poor. The temperature is too high (above 36 ℃) or too low (below 5 ℃). The milking conditions do not meet the physiological requirements of lactation, the cows do not adapt to the milking equipment, and the milking machine is used improperly. Some technical indicators of the milking machine not up to standard or other reasons will lead to mastitis[6-9].

3.2 Pathogen infectionSo far, 150 kinds of pathogenic microorganisms have been isolated from the mammary gland tissue of dairy cows. There 23 most common species, including 14 kinds of bacteria, 2 kinds of mycoplasma, 7 kinds of fungi and viruses[2,3,10]. Among them, the bacteria with the highest incidence areStaphylococcusaureus,EscherichiacoliandStreptococcus. In recent years, the incidence of mastitis caused by mycoplasma and fungi has increased year by year. Most of these pathogens lead to infection by contact with towels for cleaning nipples, milkers’ hands and dirty milking cups.

3.3 Cow factorsDairy cows in peak lactation or too high milk yield have a negative balance of body energy, and the aged cows and polytocous cows are more likely to be infected with disease.

3.4 Secondary factorsIn recent years, piroplasmosis of dairy cows has been found in clinical treatment, which will also become a pathogenic factor of bovine mastitis, and it is also very difficult to treat. Postpartum infection can also lead to mastitis. For this reason, the primary disease should be treated first after the diagnosis of secondary mastitis.

4 Diagnosis of bovine mastitis

4.1 Diagnosis based on clinical manifestationsThe symptoms of clinical mastitis are obvious. According to the symptoms of redness, swelling, heat and pain in the affected area, cows refuse to be milked manually. Milk secretion is not smooth and significantly reduced, breast swelling and pain is obvious. When blood and flocculent clots appear in the milk, the disease can be diagnosed. However, recessive mastitis has no obvious clinical symptoms and can only be detected by other experimental methods.

4.2 Test method for pH value of milkWhen mastitis occurs in dairy cows, the value of pH in milk will rise, and the pH of normal fresh milk is 6.2-6.6. The pH value of milk of cows with mastitis increases, showing alkalinity. The higher the pH value of milk, the stronger the alkalinity, the more serious the inflammation of mastitis; on the contrary, the lighter the symptoms. Therefore, the purpose of judging mastitis can be achieved by measuring pH value. At present, there are bromthymol blue (BTB) method and test paper method.

4.3 Somatic examination of milkSomatic cell count (SCC) is an important index widely used to evaluate the health status of dairy cows in different milk areas. At present, the commonly used clinical methods of breast somatic cell examination include California mastitis test (CMT), Japanese PL method, Lanzhou mastitis test (LMT), Hangzhou mastitis test (HMT) and Beijing mastitis test (BMT) and so on. The principle is that under the action of CMT test solution, the lipids in milk cells are emulsified, milk cells are destroyed, and the released DNA precipitates or clots, and the number of cells in milk is indirectly determined according to the amount of DNA.

4.4 Test method for electrical conductivity of milkWhen cow mammary gland is inflamed, the significant increase of Na+and Cl-in milk leads to the change of electrical conductivity of milk. Japan first developed a portable pocket electronic diagnostic instrument based on the electrical conductivity of milk. In China, Professor Hao Qingming of Shanxi Agricultural University developed a similar product—SX-l bovine mastitis diagnostic instrument. This instrument can not only distinguish five types of milk (healthy milk, suspected milk, lightly infected milk, moderately infected milk and severely infected milk), but also preliminarily test the nutritional composition of milk. Subsequently, he developed an international leading ZRD (formerly known as CN) bovine mastitis electronic detector. Northwest University of Agriculture and Forestry Science and Technology also developed a portable milk tester—XND-A milk tester with conductive electrode sensor. It is small in size and can quickly and comprehensively detect adulterated milk, sour milk and mastitis milk.

5 Treatment of bovine mastitis

5.1 Intramammary perfusionIntramammary perfusion is a common, simple and effective method for the treatment of mastitis. Drugs include antibiotics, sulfonamide, 1% boric acid, aminobenzenesulfonamide, potassium permanganate and so on. In order to ensure the drug effect, the following should be paid attention to during breast perfusion: milk ducts, nipples and operators’ hands should be strictly disinfected; the milk and residue in the breast should be squeezed out; if there is pus and it is not easy to squeeze out, we can first use 2%-3% soda to make it "hydrated" before milking; for the use of antibiotics, it is appropriate to choose effective drugs after drug sensitivity test; in the cattle farm where the drug sensitivity test can not be done, the efficacy and resistance of the drug should be paid attention to at any time, and those with poor effect should be replaced properly; the medicine is injected immediately after milking, and the nipple can be gently pinched after the injection to prevent the medicine from leaking out.

5.2 Intramuscular or intravenous injection of antibioticsIt is mainly used in diseased cattle with obvious systemic symptoms. Penicillin (3 500 000 IU) and streptomycin (4 g) are commonly used in clinic, and are injected intramuscularly, twice a day. Tetracycline is injected intravenously twice according to 5-10 mg per kg of body weight per day, and in severe cases, the dosage can be increased by 2 to 3 times, and the effect is better.

5.3 Breast base closureWhen the anterior lobe is inflamed, 8-10 mL of liquid medicine is injected into the contralateral knee joint between the anterior abdominal wall of the breast and the base of the breast. When the posterior lobe is inflamed, the operator behind the cow injects 150-200 mL of procaine solution into the ipsilateral wrist joint with a needle at the posterior edge of the breast base 2 cm from the median line of the left and right breasts.

5.4 Traditional Chinese medicine therapyChinese veterinarians believe that mastitis is mammary welling-abscess, which is caused by phlegm, dampness, qi and blood stagnation. Therefore, the prescription of Chinese herbal medicine should be based on the principles of heat-clearing and detoxification, antibiosis and antiphlogosis, clearing and activating the channels and collaterals, reducing swelling and relieving pain, activating collaterals and promoting lactation. Heat-clearing and detoxifying drugs, blood-activating and cancer-dispelling drugs, the herb for relieving external syndrome and damp excreting drugs are commonly used. At the same time, some tonifying drugs are used to replenish qi, increase yang, strengthen the body and dispel pathogens, so as to treat the purpose of treating mastitis in dairy cows. Commonly used prescriptions are Tiemu Powder mixture, Jinpu decoction and so on.

5.5 Control of recessive mastitisAt present, recessive mastitis is not treated with antibiotics at home and abroad, but comprehensive prevention is advocated to reduce its positive rate.

6 Prevention of mastitis in dairy cows

The prevention of bovine mastitis is the key point, and prevention is more important than treatment. To do a good job in the prevention of mastitis, it is necessary to do the following.

6.1 Paying attention to environmental safety and hygiene during milkingThe barn should meet veterinary hygiene standards, have good ventilation facilities and be disinfected regularly. The barn should be cleaned frequently to prevent the accumulation of feces and urine and reduce the stench such as ammonia. Cattle body should be regularly brushed and cleaned to minimize pathogenic microorganisms in the environment so as to reduce the risk of mastitis infection.

Before milking, 0.1% potassium permanganate solution is used to clean nipples and breasts, and breast massage should be adhered to as much as possible. The phenomenon of one towel for wiping all cow nipples should be reduced. The milkman should raise the hygiene standard and persist in carrying out the work after disinfection. In addition, milking machines are regularly thoroughly disinfected to ensure normal operation.

6.2 Strengthening the feeding and management of dairy cowsThe breast health status of dairy cows should be monitored regularly, the breast health status of cattle herds should be known in time, and corresponding prevention and control measures should be taken for dairy cows with high pH value, excessive chloride content and high somatic cell count. The feed should not be too simple, the mixture should be reasonable, and the drinking water must be clean. Where there are conditions, cows should exercise no less than 4 hours a day to enhance their physique.

6.3 Rationally using vaccines to prevent diseasesThe investigation results of scholars at home and abroad show that there are more than 20 kinds of main pathogens causing bovine mastitis, among whichStreptococcus,StaphylococcusandEscherichiacoliare the most common. These pathogens account for more than 95% of the total mastitis pathogens. Therefore, the cow mastitis vaccine against these pathogens can theoretically prevent most mastitis. The research and development of bovine mastitis vaccine has a broad application prospect for the prevention and treatment of bovine mastitis. On the premise of safe use, it is necessary to improve the immunogenicity of the antigen and the reaction intensity of the mammary gland as much as possible, use molecular biology technology to extract effective antigen components, and further improve the vaccine design procedure to design well-matched vaccines. The dominant serotype strains with strong cross between virulence and serotype should be selected. It is necessary to screen immune adjuvants with obvious enhancement effect and develop a mixed vaccine against more serotype pathogens.