The harm of influenza virus during bovine pregnancy must not be ignored

Bovine influenza is an acute febrile infectious disease, characterized by strong transmissibility, rapid spread, fast progression, and a fierce onset. As long as one cow in the herd is infected, most cattle will be infected and fall ill within a short period, especially during the spring and autumn seasons when the climate changes drastically and cold and heat fluctuate greatly, when the incidence rate is higher. Unsanitary, cold and damp cowsheds, poor feeding and management, exposure to wind or the shock of drinking cold water, and a decline in the cattle's resistance all make influenza more likely to be triggered. According to statistics, during the winter and spring influenza epidemics in Muling City, Heilongjiang Province over the past two years, the incidence rate among dairy cows reached 15.32%, while the incidence rate among yellow cattle was only 4.52%. The incidence rate in dairy cows was more than 11% higher than in yellow cattle, and among them, pregnant cows with influenza accounted for about 60%~70%. This is not only harmful to the pregnant cow itself, but also seriously affects the growth, development, and safety of the fetus, causing even greater harm that must not be ignored.

Causes of susceptibility to influenza in pregnant cows

The pathogen of bovine influenza is a filtrable virus, mainly present in the respiratory secretions of sick cows and virus-carrying cows. This virus spreads through air and droplets, and causes disease through respiratory infection, often infecting the entire herd within 2 days to 3 days. The virus invades the bovine body and causes fever. Its fever-inducing effect comes from the heat produced by the bovine body during metabolism, which is released through sweating, breathing, and urination. Because after fever, heat production increases, metabolism accelerates, less heat is released, skin blood vessels constrict, and sweat secretion decreases, the sick cow has a fever, a dry nose, and a dry mouth and tongue, which is exactly the reason. Heat continuously accumulates in the body, and body temperature rises, thus leading to a series of pathological processes of functional and metabolic changes in the bovine body. Although influenza virus can infect cattle of different ages, sexes, and breeds, cows after conception are more susceptible to infection and disease. This is because during pregnancy, the immune function of the pregnant cow declines, and its ability to resist invasion by external viruses decreases, making the cow physically weak. This is why cows during pregnancy are more likely to catch a cold than other cattle.

Harmful effects of influenza on the fetus

After a pregnant cow catches a cold, the harm to the fetus mainly comes from two aspects: one is the direct effect of the virus; the other is the indirect effect of the high fever caused by the cold and the toxins produced by metabolic disorders. In early pregnancy, because the various organs of the fetus are not yet fully developed, once the cow catches a cold, the virus can affect fetal organ development through the placenta. In particular, during the formation of the fetal cardiovascular system, the virus can cause the fetus to develop congenital heart disease, and can even lead to hydrocephalus and brain malformation, seriously affecting the lifelong health of the fetus. Influenza can also cause high fever and viral metabolic product toxins, stimulating the uterus and causing it to contract, resulting in miscarriage or premature birth, etc. After influenza, if it is not controlled, it can also secondarily cause tracheitis, pneumonia, etc., further aggravating the condition and increasing mortality, thereby bringing serious economic losses and requiring great attention.

Early prevention of influenza in pregnant cows

In view of the many effects of influenza virus on the fetus, prevention of influenza in pregnant cows should be emphasized, and nutrition should usually be strengthened to increase the resistance of pregnant cows. During a cold epidemic, disinfection should be intensified, frequently using new-type drugs that can kill bacteria and viruses, such as Jundudi, Nongfu, and Baidusha. The cowshed should be kept warm to prevent the cattle from catching cold, and they should not come into contact with susceptible animals. The cow bed should be frequently spread with straw, and a living environment that is hygienic, dry, not damp, and well ventilated should be maintained. The cattle should be allowed to rest and have enough sleep time to improve their immunity.

Before the cold epidemic season, where conditions permit, if an inactivated oil vaccine can be made from local bovine influenza isolates and inoculated into cattle, immune protection against bovine influenza can be obtained, and this is the most effective method. Even in epidemic areas, for cattle that have not fallen ill, a single Chinese herbal prescription of 400 grams of Guanzhong can be decocted in water and fed, once daily for 3 consecutive days; or 45 grams each of Guanzhong, Jingjie, and Zisu, plus 30 grams of dried grass, can be decocted in water and administered, one dose daily for 3 consecutive days; or 1000 mg of amantadine hydrochloride can be mixed into feed and fed twice daily for 5 consecutive days. All of these have a certain preventive effect against bovine influenza.