What Is Tetanus in Dogs? - Symptoms and Treatment

Tetanus is an acute disease caused by neurotoxins of the bacterium Clostridium tetani, which by their action on the nervous system cause spasms or violent muscle contractions, stiffness, and instability of the autonomic system.

This bacterium is commonly found in the environment and gastrointestinal tract of some animals and even humans. However, when the sporulated form of the bacterium enters an anaerobic (low oxygen) environment, such as a necrotic wound, it transforms into its vegetative form, which is capable of releasing neurotoxins responsible for tetanus symptoms.

It is introduced into the body through open wounds due to contact with soil, contaminated manure; through cuts or penetration by rusty objects such as nails, hooks or rusty blades; through dog bites, etcetera.

It affects both humans and animals, but is rare in dogs. Nevertheless, the disease can be fatal if left untreated.

As we have already mentioned, tetanus is caused by the bacterium Clostridium tetani, namely by the two neurotoxic toxins released by this bacterium:

• Tetanospasmin: is a toxin that prevents the release of inhibitory neurotransmitters (glycine and GABA) in the spinal cord and brain. The absence of these neurotransmitters leads to predominant neuronal excitation, which causes the characteristic clinical signs of this disease.
  
  
• Tetanolisin: is a toxin that has a necrotizing effect on tissues. The tissue necrosis favors the creation of an anaerobic environment in the wound, which in turn favors the growth of bacteria. It can therefore be said that this toxin favors the spread of infection.

But how do these bacteria come into contact with the dog's body in the first place? The bacterium usually enters the body through a wound.

As mentioned earlier, Clostridium tetani is widely distributed in the environment. Therefore, the bacterium, which is found in soil, dust, feces, or contaminated objects, can easily enter the body through any type of open wound (large or small, deep or superficial). There they find an anaerobic environment (without oxygen) where they can transform into a vegetative form and produce neurotoxins.

Can tetanus in dogs be transmitted to humans?

It is worth noting that although it is believed that tetanus can be transmitted by dog bites, the tetanus-producing bacteria in dog saliva are rarely isolated. The risk of direct transmission through a bite would only occur if the dog's mouth or saliva were contaminated with soil or dust, which in turn contain spores of Clostridium tetani.

You may be interested in this other article, where we discuss the most common canine diseases that are transmissible to humans.

Typically, dogs show signs of tetanus 5 to 10 days after the contaminated wound appears, although it may take up to three weeks after infection for symptoms to appear.

Tetanus can be localized or generalized in dogs, with the generalized form being more common. Below, we explain in more detail the two forms in which tetanus can occur in dogs and the associated clinical signs:

Localized tetanus

It is usually associated with less exposure to tetanus neurotoxins and is characterized by muscle rigidity that occurs only in the area where the bacteria have invaded, that is, around the contaminated wound. However, it is important to note that localized tetanus can gradually progress to generalized tetanus.

Generalized tetanus

Generalized tetanus is the most common form, with about 8 in 10 reported cases of tetanus. As the disease progresses, symptoms change.

The first clinical signs to appear are usually ocular:

• Enophthalmos: collapse of the eyeball, eyes appear sunken.
  
  
• Cherry eye: prolapsed gland of the nictitating membrane (PGNM).
  
  
• Blepharospamus: abnormal contraction of eyelid muscles.
  
  
• Ventromedial strabismus: abnormal position of the eyes.
  
  
• Miosis: excessive constriction of the pupil of the eye.

As the disease progresses, other symptoms appear, such as:

• Contraction of facial muscles and, in some cases, chattering of teeth.
  
  
• Erect ears and tail, but despite the stiffness there is no sign of pain.
  
  
• Painful muscle spasms.
  
  
• Hypersensitivity to light, noise, and touch.
  
  
• Generally increased muscle tone.
• Excessive extension of the joints of the extremities.
  
  
• Difficulty or inability to urinate and defecate, which may result in dysuria, urinary retention, tenesmus, or flatulence due to persistent contraction of the anal and urethral sphincters.

In severe cases, signs may include:

• Fatigue
• Muscle cramps
• Seizures
• Tachycardia or bradycardia
• Respiratory failure
• Cardiac and respiratory arrest

You may be interested in this other article, where we explain all the possible reasons why your dog trembles in their sleep.

Although it is an infectious disease, the diagnosis is usually not made in the laboratory because the culture of the bacteria is complicated and fails in most cases.

For this reason, tetanus diagnosis is usually made based on the clinical signs associated with the disease. Generally, the appearance of symptoms suggestive of tetanus is associated with the presence of a wound. However, the disease should not be ruled out in patients without visible wounds, as these may have healed by the time clinical signs appear.

In addition, blood tests may be performed. Blood work may show neutrophilia as a result of the injury, while blood chemistry and muscle enzymes are often elevated due to muscle injury.

Is there a vaccine against tetanus in dogs? Unfortunately, there is no vaccine against tetanus.

The treatment of tetanus in dogs is based on three main objectives:

• The destruction of the bacterium responsible for the infection.
• The neutralization of the toxin released.
• The limitation of the effects of the toxin on the central nervous system.

Our next section explains each of these objectives in detail.

Destruction of the bacteria

This prevents the bacteria from continuing to release the neurotoxin that causes the clinical signs in the animal. Destruction of the bacteria first requires debridement and surgical cleaning of the wound that has served as a portal of entry for the bacteria. The use of hydrogen peroxide in this area is recommended because it reduces the anaerobic conditions in the wound, making it more difficult for the bacteria to multiply.

On the other hand, it is important to apply antibiotic treatment, with metronidazole being the most effective antibiotic.

It should be noted that after starting the treatment, clinical deterioration may be observed due to the release of toxins by the killed bacteria.

Neutralization of the released toxin

Administration of equine tetanus antitoxin is indicated for this purpose. However, this therapy should not be administered routinely, but should be reserved for dogs with severe clinical signs.

Limiting the effects of toxins

On the one hand, the animal must be isolated from external stimuli (both visual and auditory) and handling must be kept to a minimum. To do this, the animal should be placed in a dark, low-noise room and its ears covered with absorbent cotton to avoid any auditory or visual stimuli that could trigger muscle spasms or seizures.

On the other hand, pharmacological treatment for muscle spasms and seizures should be initiated. The drugs most commonly used for this purpose are phenothiazines, benzodiazepines, and methocarbamol. The doses used must be adjusted to the needs of the particular animal to achieve acceptable muscle relaxation.

It is worth noting that long-term exaggerated muscle contractions may be observed during sleep, but these should not be confused with seizures, as these muscle contractions do not require specific anticonvulsant treatment.

Finally, it is important to establish supportive therapy to meet the physiological needs of the animal and avoid complications associated with the disease. These additional measures are as follows:

• If the animal cannot urinate, it is necessary to place a urinary catheter to ensure urine output.
  
  
• If the animal is unable to swallow on its own, enteral feeding systems should be placed so that patients can continue to be fed and hydrated.
  
  
• If the animal is in the prone position, bed them with a soft, comfortable, dry material and change positions every 4–6 hours to prevent pressure ulcers.

You may be interested in this other article where we talk about sepsis in dogs, its symptoms and its most effective treatment.

Despite the obvious severity of the disease, the prognosis for tetanus in dogs is favorable if appropriate and early treatment is given. In these cases, the survival rate is high, and the animals recover completely.

However, if tetanus is not diagnosed in time and treated aggressively, complications and progression of the disease to death of the animal often occur. Consequently, if you notice any signs of this disease in your dog, especially if there is a new injury, you should contact your veterinarian as soon as possible.

Early recognition of the clinical picture and timely initiation of appropriate measures are critical to the survival of the animal.

The best prevention of tetanus in dogs is thorough disinfection of wounds as soon as they appear and, of course, going to the veterinarian at any sign of infection. As we have seen, quick action is the key to preventing the outbreak of the disease.

Do not miss this other article where we explain how to treat wounds in dogs at home.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to What Is Tetanus in Dogs? - Symptoms and Treatment, we recommend you visit our Infectious diseases category.