Wooden tongue is a bacterial infection in cattle that causes the tongue to swell, harden, and lose mobility. It’s caused by Actinobacillus lignieresii, a bacterium that normally lives harmlessly in the mouth and upper digestive tract of cattle but becomes a problem when it enters damaged tissue. The condition gets its name from the distinctive wooden-like rigidity of the infected tongue.
How Cattle Get Wooden Tongue
A. lignieresii is part of the normal bacterial flora in a cow’s mouth. It only causes disease when the lining of the mouth or tongue gets cut, scratched, or abraded. Coarse hay, plant awns, thistles, foxtail, and other rough feedstuffs are the most common culprits. Any wound or abrasion in the oral cavity gives the bacteria an entry point into deeper tissue.
Once inside, the bacteria attach to cells beneath the surface and begin colonizing. They produce substances that damage tissue and trigger a strong immune response. White blood cells flood the area, and the result is the formation of abscesses and granulomatous lesions: dense knots of immune cells walling off clusters of bacteria. These granulomas are what give the tongue its characteristic hardness and bulk. The infection primarily targets soft tissue, including the tongue itself, the gums, the throat, and the lymph nodes of the head and neck.
Recognizing the Signs
The earliest and most obvious sign is a swollen, stiff tongue. As the infection progresses, the tongue may protrude from the mouth because the animal can no longer retract or move it properly. You’ll often see cattle dropping food while trying to eat, since they can’t manipulate feed normally. Drooling is common.
Other signs to watch for:
- Inflamed, reddened gums
- Swollen lymph nodes in the jaw, throat, and neck area, sometimes ranging from golf-ball to football-sized lumps under the skin
- Weight loss and dehydration from reduced feed intake
- Skin lesions around the jaw and throat (sometimes called cutaneous actinobacillosis)
Affected cattle typically eat less and less as the tongue becomes more rigid, so condition loss can happen quickly if the infection isn’t caught early.
How It Differs From Lumpy Jaw
Wooden tongue is often confused with lumpy jaw (actinomycosis), but the two diseases are quite different. Wooden tongue affects soft tissue: the tongue, lymph nodes, and skin of the head. Lumpy jaw attacks bone. It produces hard, immovable swellings on the upper or lower jawbone, typically at the level of the molar teeth. The bacteria in lumpy jaw actually erode bone tissue, creating permanent structural damage.
A key distinction is lymph node involvement. In wooden tongue, the lymph nodes around the head and neck frequently swell. In lumpy jaw, the lymph nodes generally stay uninvolved. If you’re feeling a lump on a cow’s jaw, the question is whether it’s attached to bone (lumpy jaw) or sitting in the soft tissue beneath the skin (more likely wooden tongue or a related abscess). This difference matters because treatment approaches and prognosis differ between the two conditions.
Diagnosis
A veterinarian can often diagnose wooden tongue based on the physical signs alone, particularly the hard, swollen tongue combined with enlarged lymph nodes. For confirmation, tissue biopsy or pus samples are more reliable than swabs. Under a microscope, infected tissue shows characteristic granulomas: clusters of bacteria surrounded by layers of immune cells. Yellowish “sulfur granules,” tiny clumps of bacteria trapped in biofilm, appear in about 75% of tissue samples and are a strong indicator of infection.
Bacterial culture is less reliable than it might seem. Cultures come back negative in over half of cases, so microscopic examination of tissue is generally the more dependable diagnostic tool.
Treatment Options
Wooden tongue responds well to treatment when caught early. The two main approaches are sodium iodide therapy and antibiotics, sometimes used together.
Sodium iodide given intravenously is the traditional first-line treatment. The standard dose is 30 mg per pound of body weight, administered slowly into the vein and repeated at weekly intervals if needed. This treatment helps break down the granulomatous tissue and resolve the swelling. Care must be taken to inject cleanly into the vein, since the solution can damage surrounding tissue if it leaks.
Antibiotics are recommended for severe cases or when sodium iodide alone doesn’t produce results. A course of 5 to 7 consecutive days of antibiotic therapy typically achieves a good response. Tetracyclines, penicillin-streptomycin combinations, and several other antibiotic classes are effective against A. lignieresii. Your veterinarian will choose the appropriate drug based on the severity of infection and withdrawal period considerations if the animal is destined for slaughter.
Affected cattle should be isolated during treatment. Separating them also makes it easier to monitor feed intake and ensure they’re recovering properly.
Recovery and Outlook
With prompt treatment, the prognosis for wooden tongue is generally good. The tongue gradually softens and returns closer to normal function as the granulomatous tissue breaks down. Cattle that were losing weight from inability to eat typically begin feeding normally again within days of starting treatment. Cases caught late, where extensive tissue damage has already occurred, may not recover full tongue mobility, and chronic infections can be harder to clear completely.
Relapse is possible, which is why follow-up observation matters. If swelling returns after an initial round of sodium iodide, the treatment can be repeated. Persistent cases may need a longer course of antibiotics.
Prevention Through Feed Management
Since the bacteria only cause disease when they enter through damaged oral tissue, prevention comes down to minimizing mouth injuries. The most effective step is avoiding coarse, abrasive feeds. Green foxtail, thistles, and feeds with sharp plant awns are particularly risky. Inspecting hay quality and managing pastures to reduce problem plants lowers the chance of oral abrasions that give bacteria their opening. Cattle grazing rough, weedy pastures or eating stemmy, mature hay are at higher risk than those on well-managed forage.