Bovine necrobacteriosis: causative agent and diagnostics. Description of the disease, symptoms, treatment

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Bovine necrobacteriosis is an infectious animal disease caused by the anaerobic bacterium Fusobacterium necrophorum of the genus Fusarium. Its main unpleasant consequences are a significant reduction in milk yield and breeding losses. Although the loss of livestock from this disease is rare, it can cause enormous damage to farms. And therefore, it is important for farmers and homeowners to know how to properly prevent and treat it.

A bit of history

The causative agent of necrobacteriosis in cattle is thus the bacterium Fusobacterium necrophorum. It was described already quite a long time ago - in 1882 by Leffler with diphtheria in calves. This bacillus was isolated from the cornea of a ram affected by smallpox in 1881 by R. Koch. Subsequently, this virus was also identified by scientists Schutz and Tartakovsky. A pure culture of Fusobacterium necrophorum was first obtained by Bang in 1890. Independently of him, a microbiologist did the same in 1891Shmorl.

Bovine necrobacillosis: pathogen

The microbe Fusobacterium necrophorum is polymorphic and has the form of sticks or thin long threads. The latter can form spherical or flask-shaped swellings. The bacterium Fusobacterium necrophorum is non-motile, has no flagella, and does not form spores or capsules. At the same time, it ferments glucose, levulose, galactose, sucrose, salicin and m altose. This microbe does not produce ammonia. It does not restore nitrates to nitrates either.

The causative agent Fusobacterium necrophorum is relatively unstable. But, unfortunately, it can persist for a long time in a variety of environmental objects. So, in the faeces of animals, he lives up to 50 days, in urine and water - up to 15, and in milk - up to 35 days. The sun's rays on this microbe are detrimental. Being not in the shade, the bacterium dies in half a day.

The sensitivity of Fusobacterium necrophorum to various kinds of disinfectants is high. Therefore, keeping barns clean can significantly reduce the risk of developing this disease in animals. Fusobacterium necrophorum bacteria are killed by antiseptics such as:

• caustic soda and potassium (0.5%);
• Lysol (5%);
• creolin;
• phenol (2%);
• potassium permanganate (1:1000).

Also, this microbe is extremely sensitive to tetracycline drugs.

Symptoms of disease

Bovine necrobacteriosis manifests itself mainly as purulentdefeats. They appear most often in cattle:

• on the udder;
• lower limbs;
• The mucous membrane of the vagina and uterus.

Nekrobacteriosis of cattle is also characterized by diphtheritic inflammation of the mucous membranes of the larynx, oral cavity and internal organs. These symptoms are usually seen in young animals.

How infection occurs

Necrobacteriosis develops in cattle most often when injured with damage to the skin. In wounds, as a result of a violation of the integrity of the capillaries, an oxygen-free environment favorable for the life of this anaerobic bacillus is formed. In particular, this virus multiplies well in the blood of hematomas. As a result of the vital activity of Fusobacterium necrophorum, a huge amount of toxic substances is formed. The latter block intracellular enzyme systems, which causes tissue necrosis. At the same time, there is also such an unfavorable process as blockage of capillaries by microbial cells.

Infection can occur not only through wounds, but also through the mucous membranes of the gastrointestinal tract, during pathological childbirth or during mating.

This virus spreads throughout the body by the hematogenous route, that is, with the bloodstream. As a result, secondary lesions appear in the tissues. In addition, due to the penetration of the virus into the blood, septicemia develops and metastases of necrotic foci form in the heart, liver and lungs. If the disease progresses to this stage, treatment is usuallyto no avail. With the formation of metastases, necrobacteriosis of cattle becomes malignant and the animal dies in most cases. Unfortunately, immunity in cows that have had this disease is practically not developed.

In what cases can an animal be infected

Infection with necrobacteriosis of cattle often occurs:

• due to unsanitary conditions in the barn;
• due to non-compliance with the prescribed frequency of preventive hoof trimming;
• due to shortcomings in barn equipment (in very shortened stalls, in the absence of bedding for animals);
• as a result of chronic rumen acidosis.

Sources of infection

The causative agent of necrobacteriosis is released into the environment with feces, saliva and urine of infected animals. Also, this virus is found in purulent secretions.

The causative agent of necrobacteriosis most often enters the farm with acquired sick replacement young animals or producers. Some time after infection of the first animal, the infection in the barn becomes stationary. If measures for the treatment of cattle are not taken in time, the pathological processes become aggravated due to the repeated transfer of bacteria from one individual to another.

The disease necrobacillosis of cattle proceeds unevenly in the barn, manifesting itself as small epizootic outbreaks (consecutive infection of animals).

Clinical picture

The incubation period of necrobacteriosis lasts for several days. The symptoms of this contagious disease depend on manyfactors. For example, such as the age of the animal, the form of manifestation of necrobacteriosis and the features of its course. This disease can be both acute and chronic, as well as benign or malignant.

There are three main forms of necrobacteriosis:

• limbs (ungulate);
• mucous and skin;
• internal organs.

The most common is ungulate necrobacteriosis in cattle. A photo of the characteristic lesions that appear with this disease is presented below on the page. Most often in cattle with this form of the disease, the hind limbs (or one of them) suffer. Such necrobacteriosis usually begins with reddening of the interhoof gap. At the next stage of the disease, bleeding purulent wounds, fistulas and abscesses appear. The animal experiences extremely unpleasant sensations and holds the affected limb in weight. During the examination, swelling of the joint of the hoofed phalanx is detected. With the further development of the disease, damage to the ligaments, bones and tendons is observed. If the process takes on a malignant character, the overlying joints begin to hurt in the animal - up to the hip joint.

The body temperature of an infected individual can rise up to 42 gr. Sometimes it also remains within the normal range. Only adult cows and bulls suffer from necrobacteriosis of the extremities. This form is extremely rare in calves.

When necrobacillosis of mucous membranes and skin lesions are observed most often in the area of the trunk, usually in the back of itparts. Young animals may also experience purulent necrosis of the mucous membranes of the mouth, gums, trachea, tongue, nose, larynx, gastrointestinal tract, etc.

Necrobacteriosis of internal organs in cattle manifests itself most often as a liver abscess. In this case, characteristic clinical signs are usually not observed. But the animals themselves, infected with this form of necrobacteriosis, feel extremely unwell - they eat poorly, lose weight quickly, significantly reduce productivity, and groan when trying to get up. With necrobacillosis of the internal organs, among other things, cows can have a very high body temperature.

Diagnosis

In addition to symptomatic signs, bovine necrobacillosis (a photo of the pathogen is presented just below) can be determined by the results of laboratory tests. This verification must be mandatory. The fact is that the clinical picture of this disease can be similar to other common cattle infections. This may be, for example, foot and mouth disease, vesicular stomatitis, viral diarrhea, plague or dermatophilia. Also, when diagnosing necrobacteriosis, arthritis of various etiologies, erosion, hoof ulcers, and dermatitis should be excluded.

How exactly is a disease such as necrobacteriosis of cattle defined? Its diagnosis is usually performed on a selected piece of tissue affected by necrosis, taken at the border with a he althy area. In the laboratory, this material is placed in a special medium (most often Kitt-Tarozzi with 10% blood serum) and incubated for two days attemperature 37 C. To determine the associated microflora, additional studies are carried out on the BCH and MPA. The final diagnosis of animals is made if the pathogen is detected in the smears.

Bovine necrobacillosis: antibiotic treatment

Take action when you find signs of this disease should be immediately. Otherwise, pathological changes may become irreversible. Necrobacteriosis is treated in a complex. At the same time, group methods are used in large farms, and individual methods in small ones. When treating dairy cows, only drugs that do not pass into milk are used.

When a diagnosis of necrobacillosis is established in cattle, the following he alth measures are performed:

• They do a thorough chemical treatment of the affected areas with the removal of tissue.
• Wounds are washed with hydrogen peroxide, furacilin solution, etc.
• Use liquid and powder antiseptic preparations.

Anaerobic bacteria, including Fusobacterium necrophorum, always form a barrier between the vascular bed and the affected tissues. And this, in turn, greatly complicates the penetration of drugs. Therefore, antibiotics in the treatment of necrobacillosis are used in high doses. In addition to tetracyclines, the most effective types of drugs used for this disease include:

• levomycetin;
• ampicillin;
• erythromycin;
• penicillin;
• telazin.

Also for the treatment of diseases such asbovine necrobacillosis in cows, modern broad-spectrum antibacterial drugs can be used. Aerosol antibiotics based on the above preparations are also well suited for topical use. They are mainly used to treat hooves after dry cleaning.

Restrictions on farms during an outbreak of necrobacteriosis

When this disease is detected in animals, the following measures are taken on the farm:

• infected animals are isolated from the herd;
• hooves of he althy bulls and cows are treated in foot disinfectant baths;
• treat diseased animals according to the method described above.

If treatment, due to the neglect of necrobacteriosis, is inappropriate, cows and bulls are handed over to a sanitary slaughterhouse.

What you need to know

Unfortunately, bovine necrobacteriosis is a contagious disease, including for humans. Cases of infection of farm personnel with this infection are rare, but the existing danger should not be ignored. In order to exclude the possibility of infection of people working on the farm, during an outbreak of necrobacteriosis of livestock, you should:

• be sure to follow the rules of personal hygiene when working with sick animals (wear overalls and gloves, take a shower after work);
• all existing wounds on the skin should be treated with effective antiseptics in time.

In the farm staff roomthere must be a first aid kit, equipped with all the necessary medicines according to the standards.

Prevention of necrobacteriosis

A number of measures taken in advance helps to prevent the outbreak of such a dangerous disease as necrobacteriosis in cattle. A vaccine for the prevention of this disease can be used polyvalent, emulsified VIEV or Nekovac. On farms located near farms that are unfavorable for necrobacteriosis, among other things, the following measures should be taken:

• Farm staff should carry out activities aimed at the overall strengthening of the animal body. To do this, first of all, balancing the feeding of animals is performed. Various vitamin and mineral supplements are mandatory introduced into the diet of cows, bulls and calves. In addition, they carefully monitor the quality of feed.
• Perform activities aimed at improving the conditions of animals on the farm. Manure in stalls must be cleaned carefully and on time. Also, if a possible infection with necrobacteriosis is suspected, all premises should be inspected for the presence of traumatic objects.
• Clean and drain pastures and walking areas.

Among other things, should be periodically carried out on the farm in case of an outbreak of a disease such as necrobacteriosis in cattle, disinfection. In order to minimize the possible risks of loss of livestock, it is also necessary to carry outtimely prevention and treatment of endometritis and mastitis. The fact is that these diseases can greatly complicate the course of necrobacteriosis.

How they treat meat and milk

Nekrobacteriosis of cattle causes significant harm to farms, primarily due to a decrease in the productivity of diseased animals. With a local pathological process, only the affected areas of the carcass of a cow or bull are sent for disposal. If the disease proceeded septically, all slaughter products are burned. If several internal organs are affected in an animal, but its carcass has a sufficient degree of fatness, the decision on the possibility of using the meat for food or for sale is made after a thorough microbiological examination in the laboratory.

The skins of animals suffering from necrobacteriosis are dried in isolated rooms, disinfected according to the instructions and sold. The milk of sick cows can be eaten only after pasteurization, carried out in accordance with all the rules. From he althy animals, even from a dysfunctional farm, it is allowed to be sold freely.