Lockjaw in Dogs | petMD

Tetanus Bacillus Infection in Dogs

Tetanus is an occasional disease in dogs, the result of infection with a bacterium called Clostridium tetani. This bacterium is normally present in soil and other low oxygen environments, but also in the intestines of mammals and in the dead tissue of the wounds that are created due to injury, surgery, burns, frostbite, and fractures.

One typical feature of this bacterium is that it can live without oxygen (anaerobic) and can remain in the environment for long periods by forming spores. Once favorable conditions are present, such as an injured animal coming into contact with the spores, they are able to release the potent toxin into the body. These potent toxins bind to nerve cells in the body and generate symptoms that are characteristic of this disease, such as muscle spasms and stiffening of the limbs.

The severity of the symptoms will often depend on the number of organisms that are able to enter the body and the quantity of toxins produced in the body, but this is generally considered a serious condition warranting immediate treatment.

Symptoms and Types

Symptoms can appear after spores have entered the wound and germinated. The muscles around the infected wound may become rigid first. The dog may appear stiff and lame. Weakness and an uncoordinated gait can usually be observed in these dogs. The symptoms may then disappear spontaneously if the infection remains local to the area in which it entered the body, while in other cases the symptoms can escalate to a generalized disease if the toxins are able to gain access to the nervous system.

The symptoms related to generalized disease are:

• Fever
• Constipation
• Pain during urination
• Excessive drooling
• Wrinkled forehead
• Grinning appearance
• Stiff and hard tail
• Continuously erect and stiff ears
• Progressive stiffness of the body muscles, giving the animal a sawhorse appearance
• Difficulty eating
• Breathing difficulty (due to stiffness of the chest muscles)
• Difficulty opening the mouth (due to stiffness of the jaw muscles)
• Whole body muscle spasms with sudden external movement, sound, or touch
• Paralysis
• Death due to inability to breathe

Causes

Because unattended wounds leading to bacterial contamination is the leading cause of lockjaw, outdoor dogs are at higher risk.

Diagnosis

You will need to give a thorough history of your dog’s health, including a background history of symptoms. Your veterinarian will also ask about any previous injuries or traumas that might have led to the infection. After taking a detailed history, your veterinarian will then conduct a complete physical examination on your dog.

Routine laboratory tests will include a complete blood count (CBC), biochemistry profile, and urinalysis. The complete blood count may show an abnormally low or high number of white blood cells (WBCs), both indicating infection. Biochemistry testing may reveal high concentrations of an enzyme called creatine phosphokinase (CPK). This enzyme is mainly found in the heart, brain, and skeletal muscles, but the level of this enzyme increases in the blood in response to the stiffness and damage the muscles are experiencing, which are in turn responding to the bacterial infection.

The results of the urinalysis are often normal except for an increase of myoglobin in the urine. Myoglobin is a protein that is normally found in the muscles, and with constant contractions and stiffness of muscles, it starts appearing in the urine due to its release from the damaged muscles. Your veterinarian will also send samples of tissue and fluid that has been taken from the wound to the laboratory for culture. Culture testing will allow for the controlled growing of the causative organism, thereby confirming its presence in the wound.