Characteristics and Prevention and Treatment Methods of Deer Necrobacillosis

Deer necrobacillosis is a chronic infectious disease caused by Fusobacterium necrophorum, generally mostly caused by infection of skin and mucosal wounds. Clinically, necrotic lesions are common, and sometimes it can spread to organs such as the liver and lungs to form lesions, causing necrotizing pneumonia and purulent hepatitis. If not treated in time, it often causes mass death, and it is one of the most serious infectious diseases harming the @#@253@#@ industry.

1 Pathogen characteristics

The pathogen is Fusobacterium necrophorum, mainly divided into type A and type AB, Gram stain negative, mostly filamentous, without flagella, non-motile, and does not form spores. It is known that Fusobacterium necrophorum can produce at least two toxins, which can cause tissue edema and necrosis, and also have hemolytic effects. Fusobacterium necrophorum is strictly anaerobic and widely exists in nature and in the intestinal tract of animals, especially common on farms. Fusobacterium necrophorum has weak resistance. Heating to 100°C for about 1 minute can kill it, and 2.5% formalin or 6% Lysol for 10-15 minutes can also kill it.

2 Epidemiological characteristics

Deer necrobacillosis can occur throughout the year, but clinically it is more common in summer and autumn. Deer of all ages can be infected. Skin injury is the main route of infection, and it can also be infected through digestive tract wounds, injuries from sawing antlers, birth canal and umbilical wounds. In addition, wet ground, stuffy and hot climate, and poor feeding management can all promote the occurrence of necrobacillosis.

3 Clinical characteristics

Affected deer are listless, have decreased appetite, become emaciated, and lie down. Clinically common lesions mainly occur in the limbs, especially the hooves, manifesting as suppuration, ulcers, and necrosis. Locally, an abscess first forms, then necrosis occurs. The center of the necrotic focus is sunken, and after rupture, pus and blood flow out. In severe cases, millet-rice-soup-like foul-smelling pus flows from the swollen coronary band, and the necrotic tissue is mostly gray-black or green, mixed with gray-white pus, with a special foul odor. After the hooves become erosive and gangrenous, the lesions can spread upward to the subcutaneous tissue of the limbs, causing swelling and necrosis of the metacarpal region and even the joints, and in severe cases fistulas form. In severe cases, the hoof cartilage, joints, and ligaments become necrotic, the hoof capsule falls off, and the hooves become severely deformed, becoming "big-footed deer." If the lesions spread to internal organs, it often leads to death.

Fawns born during continuous rainy seasons are mostly infected through the umbilicus and develop necrobacillosis. After onset, the fawns show arched back when urinating, lethargy, and rough hair coat. Careful examination of the umbilicus may reveal a cord-like induration, in severe cases as large as a fist, with gray-white foul-smelling rice-soup-like pus flowing from the umbilical cord.

4 Necropsy characteristics

The carcasses of deer that died of necrobacillosis are emaciated, with obvious necrotic lesions on the limbs and varying degrees of necrotic lesions in other parts, and the veins around the affected areas are purple-black. There is pleural effusion with a fishy foul odor, containing gray-yellow fibrinous exudate. There is pericardial effusion, turbid, with fibrinous exudate on the pericardium and myocardium. The lungs show pathological changes of necrotizing pneumonia. The liver is enlarged, with necrotic lesions of varying sizes. The forestomach mucosa has necrotic lesions of varying sizes, and the peritoneum shows widespread inflammation.

5 Treatment

For deer necrobacillosis, clinically it is necessary to adopt measures combining local treatment with systemic treatment to achieve ideal therapeutic effects.

5.1 Local therapy

External wounds can be flushed with 3% hydrogen peroxide, and pus should be completely drained; if necessary, incision and drainage treatment should be performed. After cleaning the wound, sprinkle iodoform sulfonamide powder (iodoform 1 part, sulfonamide powder 9 parts) on the wound surface, then apply iodoform ichthammol ointment (iodoform 10 parts, ichthammol 15 parts, petrolatum 75 parts) or apply iodoform cod liver oil ointment (iodoform powder mixed with cod liver oil into a paste). Bandage the wound and change the dressing every 1-2 days. In severe cases, 0.25% procaine 20 mL, sulfadiazine injection 20 mL, and streptomycin 1,000,000 international units can be used for limb and hoof block.

5.2 Systemic therapy

Antibiotics and sulfonamide drugs can be selected. Tetracycline and chlortetracycline at a dosage of 5-10 mg per kg body weight, intramuscular injection or intravenous injection, twice daily. Erythromycin at a dosage of 2-4 mg per kg body weight, dissolved in 5% glucose injection, intravenous injection, twice daily. Compound clarithromycin injection, dosage 0.1 mL per kg body weight, intramuscular or intravenous injection, once every 12 hours. 10% sulfadiazine sodium 100-150 mg, intravenous injection, twice daily. Streptomycin 3,000,000 international units and penicillin 4,000,000 international units can also be injected intramuscularly, twice daily. Medication must be continued for 1 week to achieve ideal therapeutic effects.

For affected deer with poor appetite, administering stomachics such as gentian powder, rhubarb powder, and ginger tincture can promote appetite, improve disease resistance, and promote early recovery of the body.

6 Prevention principles

6.1 Do a good job in disinfection

Attention should be paid to regular and irregular disinfection work and maintaining clean and hygienic pens. Disinfectants can include 3% bleaching powder solution, 3% Lysol, and 10%-20% fresh lime milk, etc. The umbilical cord of newborn fawns should be disinfected with 5% iodine tincture. Attention should also be paid to disinfection when sawing antlers. If skin injuries on the limbs are found, disinfection treatment must be carried out in time. Letting the deer herd bask in the sun more can also play a sterilizing and disinfecting role.

6.2 Keep dry

Strengthen management during normal times, clean up manure in time, spread dry bedding soil and bedding materials, and keep the deer shed dry and clean. During rainy seasons, check the roof and drain accumulated water in time to prevent rainwater from accumulating in the pens.

6.3 Provide sufficient nutrition

Practice has proven that deficiency of calcium, phosphorus, and vitamins can induce necrobacillosis in deer. Therefore, the deer herd must be allowed to consume sufficient minerals such as calcium and phosphorus and multiple vitamins. After 10-15 days of age, the rumen of fawns begins to function, and they can consume a small amount of feed. Attention should be paid to supplementary feeding of green feed, especially high-quality green and succulent feed rich in calcium and phosphorus.

6.4 Reasonable weaning

Fawns during the weaning period are most susceptible to necrobacillosis. Therefore, nutritional regulation must be strengthened, appropriately increasing substances with antioxidant and anti-stress effects such as Vc and VE, feeding a full-price diet, and achieving feed diversity, good palatability, and easy digestion. Attention should be paid to the transition of feed and environment, and fawns should not be driven or whipped, reducing or avoiding various adverse stimuli as much as possible.

6.5 Prevent injuries

Keep the ground of pens and exercise yards level, and do not feed feed with sharp awns or thorns. Operate carefully when grouping or regrouping to prevent trampling and collision injuries. Strengthen the management of the deer herd during the breeding season to prevent injuries caused by fighting among deer. Do not graze in places overgrown with thorns or uneven terrain. Check whether feed troughs, wooden posts, etc. have protruding wood splinters or iron nails, and check whether the edges of drinking waterers have sharp foreign objects. Outsiders are strictly prohibited from entering the pens to visit, to prevent disturbing the deer herd and causing panic.

6.6 Pay attention to isolation

Affected deer are the main source of infection of this disease. Therefore, if deer are found to be sick, they should be isolated and treated in time, and disinfection work should be done at the same time. Newly transferred deer must be quarantined before entering the farm. If sick deer are found, they should be immediately isolated and raised, and the equipment in the isolation pen must not be shared with healthy pens.

6.7 Do a good job in foot bathing

Setting up foot bath troughs can not only prevent disease onset, but also have a relatively good auxiliary therapeutic effect on deer that already have hoof lesions. The method is: set the drinking water area as a dead end, and build a disinfection pool at the entrance and exit with a length of 2 m and the same width as the dead end. Put 1% Lysol water in the pool, or use 10% copper sulfate solution or 3% potassium permanganate solution. Keep the medicinal liquid at a depth of about 30 cm. Require that when deer drink water, all four limbs must stand in the disinfection pool, so that when the deer drink water, the hooves can be soaked and disinfected for a relatively long time. It should be noted that the medicinal liquid must be added in time, and there must be enough clean water in the drinking container.