Symptoms and Control Methods of Six Common Diseases in Forest Frogs

1. Red Leg Disease

This disease is common in tadpoles, young frogs and adult frogs, also known as septicemia. Its pathogens are Gram-negative bacteria such as Aeromonas hydrophila and non-acid-producing strains of Acinetobacter calcoaceticus. The disease can occur in all four seasons, spreads quickly and has a high mortality rate. The main causes of the disease are unclean pond water, excessively high breeding density, and external injuries to the frog's body.

Symptoms: Affected individuals are generally listless, with weakened mobility, often lurking in the water, unwilling to move, not feeding, with abdominal swelling, and blood-tinged mucus at the mouth and anus. In the early stage of the disease, the tips of the toes of the hind limbs are red and swollen with bleeding points, which quickly spread to the entire hind limb. Necropsy shows: a large amount of ascites in the abdominal cavity, enlargement of the liver, spleen and kidneys with bleeding points, and congestion of the gastrointestinal tract with mucus.

Control methods: Change the water regularly, maintain water quality, reasonably control the breeding density, and feed at fixed times and in fixed amounts. When affected individuals are found, isolate and treat them promptly to prevent spread; soak the diseased frogs in 3% salt water for 20 minutes, and use chloramphenicol to disinfect the whole pond with the frogs present, with the water concentration reaching 10X10-6, once a day for three consecutive days. Add sulfadiazine to the bait, 1-2 grams per kilogram of bait, and feed continuously for three days.

2. Saprolegniasis

The pathogen is Saprolegnia, which mainly parasitizes damaged areas of the tadpole's body surface skin. The pathogen invades through skin wounds and gradually penetrates deep into the muscles. At the same time, the mycelium of the pathogen grows outward into cotton-like hyphae visible to the naked eye, and gradually spreads from the wound to the surroundings, causing the tadpole to swim slowly, have difficulty feeding, and ultimately die.

Control method: Apply 10% gentian violet.

3. Gas Bubble Disease

This disease is a common disease of tadpoles. If diagnosed and treated in time, it is easily cured; if not treated in time, it can cause mass mortality. The cause is mainly that phytoplankton in the water, under strong light conditions, produce a large amount of oxygen through photosynthesis, causing the dissolved oxygen in the water to become supersaturated, and tadpoles swallow large amounts of gas bubbles while moving and feeding.

Symptoms: Tadpoles suffering from this disease have gas filling their intestinal tract, their bodies swell, and they float on the water surface in an upward-facing swimming posture. In severe cases, the gas bubbles expanding inside the body hinder normal blood circulation, and the tadpoles die quickly. Necropsy shows congestion of the intestinal wall.

Control methods: Frequently observe the water quality of the tadpole pond, frequently add fresh water, and prevent excessive aquatic plants in the water; immediately isolate affected individuals and place them in clean water for 1-2 days without feeding bait, so that the partial pressure of the gas inside the body gradually balances, thereby making the gas bubbles disappear. Afterwards, feed a small amount of cooked fermented corn (2315, -8.00, -0.34%) powder, and they will recover within a few days. Salt can also be added to the pond for treatment, generally 15 grams of salt per cubic meter of water. 

4. Trichodiniasis

Symptoms: After tadpoles are heavily parasitized by Trichodina, their appetite decreases and breathing becomes difficult. They often swim alone and move slowly. If not treated in time, it will cause mass mortality. It mostly occurs in ponds with high density.

Control methods: Reduce breeding density and expand the tadpoles' activity space to avoid the occurrence of this disease. In the early stage of the disease, a mixture of copper sulfate and ferrous sulfate can be splashed over the whole pond, using 0.5 grams of copper sulfate and 0.2 grams of ferrous sulfate per cubic meter of water.

5. Skin Rot Disease

At the initial onset of the disease, the skin on the frog's head loses its luster and white patterns appear, then the epidermal layer falls off, exposing the back muscles, and later spreads to the entire trunk and back. Granular protrusions appear in the pupil of the eye, initially black, and finally the whole eye becomes white. The frog likes to lurk in dark places and scratches the affected area from time to time, accompanied by bleeding.

Control methods: This disease is mainly caused by long-term intake of a single bait and lack of vitamins. Therefore, the bait fed should be diversified; appropriately add multiple vitamins to the bait to ensure vitamin supply.

6. Enteritis

This disease can occur in tadpoles, young frogs and adult frogs, is highly contagious and has a high mortality rate. Feeding unclean bait easily triggers this disease. Its pathogen is bacteria; improperly disinfected fly maggots fed as bait can easily cause this disease.

Symptoms: Diseased frogs often droop their heads and arch their backs, become emaciated, move abnormally, sharply reduce food intake, and respond slowly. After tadpoles become diseased, they mostly float on the water surface.

Control methods: Change the water regularly to keep the water quality fresh; do not feed moldy or spoiled bait, and appropriately add garlic, ginger, berberine, etc. to the bait; feed the bait at fixed times, in fixed amounts and at fixed locations to prevent this disease caused by overeating.