ABSTRACT: Tetanus is uncommon in dogs and cats as they are relatively resistant to the disease compared to humans and horses, and vaccination is, therefore, not generally recommended. Although it is a disease with a severe presentation, with careful monitoring and nursing, it has a good prognosis for full recovery.

Mode of infection

Tetanus is caused by the exotoxin, tetanospasmin, which is produced by the Gram-negative, obligate anaerobic bacterium, Clostridium tetani. The organism lives in soil and the intestinal tract of mammals and the spherical spores can remain infectious for more than 40 years in the environment.

Transmission occurs through infection of open wounds leading to rapid multiplication under anaerobic conditions (such as puncture wounds) and toxin release. The toxin is taken up by the motor nerves in the area and passes up the nerve tracts to the spinal cord. The wounded limb is usually the first to be affected. Signs can become generalised and may vary with toxin dose. Resolution occurs in the reverse order of affected areas.

Tetanospasmin prevents release of the inhibitory neurotransmitters, glycine and gamma-aminobutyric acid (GABA), which normally act to dampen down excitation in the lower motor neurons in the brainstem and spinal cord. This dysfunction results in the continued contraction of skeletal muscles, including the diaphragmatic and facial muscles.

The time from initial infection to clinical signs may be five days to three weeks and full resolution of signs can take up to four weeks. Diagnosis is usually made from the distinct clinical signs, as there are no readily available confirmatory tests.

Clinical signs

Localised tetanus only involves a small group of muscles – typically one leg or the facial muscles. Generalised tetanus affects the whole body and causes trismus (lockjaw/difficulty opening the jaw), a ‘sardonic grin’, lip retraction, and retraction of the ears and the eyelids, or even dysphagia and hypersalivation as a consequence of masticatory muscle involvement (Figure 1).

Figure 1: The typical facial signs that present in the tetanus patient

The reduced ‘gag reflex’ means patients are susceptible to aspiration pneumonia, and regurgitation as a result of megaoesophagus or hiatal hernia can also be seen. Respiratory complications and arrest may occur following the effects on the diaphragm, larynx and intercostal muscles. Bone fractures are extremely rare but occasionally autonomic nervous system involvement results in cardiac arrythymias, tachycardia and hypertension.


If a wound is identified, it should be explored surgically, debrided and flushed.

In severe cases of infection – or osteomyelitis of, for example, a digit – amputation may be required. Intravenous metronidazole (metronidazole 5mg/ml Baxter) or penicillin is administered to combat bacteria, although antibiosis will not shorten the course of clinical illness caused by the toxin already released.

Muscle relaxants, including phenothiazines and benzodiazepines, are used to reduce muscle rigidity. Analgesia helps if muscle spasms are painful. A combination of midazolam (Hypnovel – Roche) and acepromazine (ACP – Novartis) is commonly used. A low dose of phenothiazine should not increase the likelihood of seizures and is beneficial as a spasmolytic and sedative.

Here, we use midazolam rather than diazepam as a constant rate infusion. Diazepam in solution contains propylene glycol which can cause thrombophlebitis, whilst the active compound in the emulsified form (Diazemuls – Actavis) binds to plastic. Midazolam is short- acting, more potent than diazepam, and is not associated with thrombophlebitis when administered intravenously.

Midazolam should not be mixed in fluid lines with calcium-containing products (compound sodium lactate, for example) because it can be inactivated. Some of the drugs used in this regimen are not licensed for veterinary use and so are used off licence using the cascade. All the drugs used have well-documented dose ranges in veterinary pharmacology books and can be used safely.

Pure opioid agonists, such as morphine and methadone (Morphine Sulphate – Martindale) can be given every four to six hours, but often troughs are seen as the analgesia subsides. A constant rate infusion of morphine is beneficial in very painful cases.

If analgesia and sedatives are inadequate, a propofol (Vetofol – Norbrook) infusion may be appropriate. The airway must be maintained with intubation and if ventilatory or pulmonary dysfunction occur – evidenced by hypoxia or respiratory acidosis – ventilation is required.

Tetanus antitoxin is most useful in the early stages of the disease. Reportedly, once the toxin is bound to the nerve endings, it cannot be displaced. The antitoxin can, however, be used to neutralise circulating tetanospasmin. It is, therefore, probably most useful in the early stages of the disease.

A test dose, injected subcutaneously, is recommended initially, as anaphylaxis can occur. If no adverse reaction is seen – such as a wheal or reddening – a subcutaneous or intravenous injection may be given. A total dose of 500iu is now recommended rather than per kilo dosing.

Nursing the tetanus patient

At the Royal Veterinary College, the emergency, critical care and neurology specialists work together to manage tetanus cases.

The patients are placed in the high dependency unit in the ICU; the lights are dimmed and traffic into the ward is minimised in order to limit stimulation. Cotton wool is also placed in the patient’s ears. Hypersensitivity to noise and photophobia is a common problem with tetanus patients – they become very distressed, tachypnoeic, tachycardic and their muscular spasms increase in intensity.

Turning patients every four hours helps prevent atelectasis of the dependant lung lobe and decubital ulcers. Gently massaging limbs helps relieve tetanus spasms and pain and encourages venous return and lymphatic drainage to prevent limb oedema. Effleurage, petrissage and friction techniques are used in conjunction with hot compresses to warm the muscles to encourage deep muscle relaxation.

These techniques are most useful in recovery, as initially the tetanic response to touch is too marked to allow them to be effective. Once the patient is able to flex the limbs without pain, passive and active movement physiotherapy is implemented (Figures 2a & 2b).

Figures 2a and 2b: A patient receiving physiotherapy – a hoist and inflatable support are used to support him whilst standing

If a patient develops aspiration pneumonia, he or she may be nebulised using saline to warm and moisten the airway to decrease bronchial secretions/mucus production and coupaged to encourage coughing if it is considered appropriate.

Ocular and oral care are implemented in all tetanus patients as they cannot lubricate their eyes and mouths appropriately. Eye lubricant is used in the eyes every four hours to prevent corneal ulceration and small volumes (to minimise aspiration) of warm water, vegetable oil or an antiseptic mouthwash are used on the tongue and gums to lubricate and freshen the mouth and prevent oral ulcers.

Some patients really res
pond to gentle touch and a soft low level sound. Time spent sitting with individuals frustrated by immobility and calming them is sometimes just as effective as sedatives. A good nursing team interprets whether the patient is distressed from pain or just frustrated.

In recumbent patients, a urinary catheter can be placed to prevent urine scalding and to monitor urine output. Expressing the bladder is necessary in patients that have lost bladder function and they can appear distressed when they need to urinate. Bladder size checks should be done routinely (Figure 3).

Figure 3: An example of some of the management aids used – closed urinary system, oesophagostomy tube, an orthopaedic mattress and pillows to make the patient more comfortable

Hyperthermia can occur as a result of the constant muscle spasm and active cooling may be appropriate. Wet towels should be avoided, as they tend to trap heat.

Blood gas analysis should be performed in severely affected cases as a rise in PaCO2 levels indicate that the respiratory muscles are affected. This is rare, but these patients may succumb to respiratory arrest and require mechanical ventilation until the paralysis subsides. Careful monitoring and 24-hour supervision is required in most tetanus patients; but as time goes on, it becomes easier to interpret the patient’s needs through their behaviour.


Patients are fed via feeding tubes, to minimise the risk of aspiration until they are able to lap and swallow. Muscle spasms can increase a patient’s calorific requirements and weight loss is common if nutritional support is not provided early. A percutaneously placed endoscopic gastrotomy (PEG) tube can be placed in patients that may require long-term supportive therapy. Naso-oesophageal tubes are less invasive and do not require a general anaesthetic; but are easy to dislodge and may not withstand large volumes of food.

Oesophagostomy tubes can also be placed, but in the event of regurgitation as a result of megaoesophagus or hiatal hernias, it is often more appropriate to bypass the oesophagus completely.

If the patient is not stable enough to receive an anaesthetic for placement of feeding tubes, then partial parenteral (PPN) or total parenteral nutrition (TPN) can be given intravenously.

A central venous catheter is required for TPN infusions as the high glucose and lipid content of the solutions can cause thrombophlebitis in smaller veins and sloughing and necrosis of tissues if extravasation occurs.


The tetanus patient requires a high level of critical care nursing. A variety of nursing specialties are called into play to successfully treat and re-habilitate the tetanus patient.

The cases can be very rewarding, whilst testing your nursing skills at the same time. 2


Paula Holmes DipAVN (Surg) RVN

Paula Holmes trained in a small animal first opinion and ophthalmology referral practice in Lincolnshire before transferring to the Royal Veterinary College in 2004, where she studied for the RCVS Diploma in Advanced Veterinary Nursing (Surgical).

After that she chose to work in the intensive care unit at the RVC where she is now senior emergency and critical care nurse. Next year, Paula plans to study for the American Technician Specialist in Emergency and Critical Care.

Useful reading

BATTAGLIA, A. M. (2007) Small Animal Emergency and Critical Care for Veterinary Technicians Second Edition

BSAVA Manual of Canine and feline emergency anc critical care Second Edition 2007 Eds King, L. G. and Boag, A.

HIRSCH, D. C., MACHLACHLAN, N. J. and WALKER, R. L. (2004) Veterinary Microbiology Second edition Merck online Veterinary Manual MACINTIRE, D. K., DROBATZ, K. J., HASKINS, S. C. and SAXON, W. D. (2006) Manual of Small Animal Emergency and Critical Care

Veterinary Nursing Journal • VOL 25 • No10 • October 2010 •