tetanus

Tetanus in Cats


Tetanus is caused by the action of the Clostridium tetani neurotoxin causing generalized muscle stiffness. This clever neurotoxin gains access to the CNS via retrograde transport up a peripheral nerve to the spinal cord, or brainstem (if it goes up a cranial nerve). Once in the spinal cord, it will irreversibly inhibit the inhibitory interneurons in the spinal cord thus resulting in generalized or partial muscle stiffness and spasm. Cats are more resistant to tetanus neurotoxin compared to humans or dogs, but they can still get the signs. Let’s talk about how to recognize this rare disease, in cats!

A recent retrospective study out of Europe (11 referral centers) was published in 2024 outlining signalment, clinical and neurologic findings, treatment and outcome. In this report, they cite that cats are thought to be 12 to 2400x more resistant to the toxin than humans or dogs. WOW!
This study described tetanus in 27 cats. Not surprisingly, this was mostly reported in the warmer months of spring, summer and fall with few cases in winter. It is interesting to note that this is not the case with dogs. More tetanus is reported in dogs in winter in Europe. The source of the infection was thought to be a wound in most cases; however, 5 cats had a recent history of sterilization.

The initial clinical signs were lameness or stiffness in a limb in 17/26 cats. This was noted as a difficulty manually flexing the joints in one or more limb on evaluation. Progression was noted in most of the cases, peaking at about 4 days from onset of signs. Two cats demonstrated tonic clonic seizures with loss of consciousness. Marked hyperthermia was noted in 10 cats. Unlike humans or dogs, generalized tetanus was less common in cats. Autonomic signs were rarely reported in cats but are more common in humans or dogs and may result in an increased mortality. Signs might include hypertension, hyperthermia, tachycardia, arrhythmias, profuse sweating and bradycardia. Three cases had wound cultures performed and all 3 were positive for Clostridium tetani.

Treatment

Hospitalization occurred in 21/27 cases with a mean hospitalization time of 7 days. Wound debridement was mentioned in 9/27 cats, along with antibiotics (26/27). Metronidazole was the most common antibiotic recommended, followed by Clavamox. The duration of antibiotic treatment was difficult to determine for many of the cats, but the authors report median treatment duration of 15 days (range 7-28). Muscle relaxation was facilitated with oral diazepam (21/27 cats) monotherapy or combined with methocarbamol, alfuzosin or magnesium sulfate (1 cat). Equine tetanus antitoxin was administered in 6/27 cats and no side effects were reported. The most common adverse effects reported included hyperthermia, urinary retention, dysphagia and osteoarticular disease (fractures due to muscle contractures or osteomyelitis). The more severe cases were noted to have adverse effects more commonly.

Outcome

Outcome was available for 25/27 cats. Of these, 23/25 (92%) regained independent motor within a median period of 25 days (range 11-42). The two cats that did not regain appropriate motor ultimately had limb amputation due to osteomyelitis.
 
What’s Take Away?
Even though more resistant, cats can get tetanus just like dogs. If you are presented with a cat with inappropriate focal stiffness and a wound, consider tetanus. Culturing the wound may aid in making a diagnosis. Metronidazole appears to successfully eliminate the infection, however due to the irreversible binding of the toxin the clinical signs may take longer to abate. When in doubt – refer for a consult!

 Thanks for reading! I hope you have a wonderful week and enjoy this summer-like fall weather that we're having. 
 
Reference: https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2024.1425917/full

Tetanus and Dogs

What is tetanus?

Tetanus is caused by the Clostridium tetani bacteria which produces a neurotoxin that causes muscle contractions. This bacterium is found commonly in soil and is ubiquitous throughout the world. After the bacterium is injected into an anaerobic environment it produces the toxin. The toxin targets inter neurons in the spinal cord, inhibiting their function.

Diagnosis?

A diagnosis is made by observation of classic clinical signs such as limb rigidity, muscle retraction on the face or periocular. Detection of the C. tetani bacterium in the wounds through culture can provide a definitive diagnosis, if obtained.

Treatment?

Wound debridement followed by appropriate antibiotics (penicillin or metronidazole) will result in recovery for the majority of dogs and cats. For severe cases, respiratory assistance with a ventilator, sedation to avoid painful sustained muscle contractions and 24-hour nursing care may be needed.

Seasonality?

An interesting article came across my view recently that identified a spike in tetanus cases in the winter months (December-February) in England. This was surprising because more cases are reported in warm, humid climate than cold ones. The authors didn't provided substantial reasoning for the odd seasonality but suggested it may be related to the exposure by walking in wet muddy environments. Here is the link to the article if you'd like to read more: https://doi.org/10.1111/vec.13068

I hope you have a wonderful, productive, safe week and I look forward to working with you soon. Thanks for reading!

Tetanus and Animals

Tetanus and Animals

I saw a case of suspected tetanus this week in a cat so I thought we could take this opportunity to review this rare, but important, neurologic disease.

Tetanus is cased by the release of tetanus toxin by the Clostridium tetani bacterium. Once the toxin is produced in the wound, it travels via retrograde transportation from the peripheral nerve to the central nervous system where it attacks the real target: the inhibitory interneurons that regulate motor activity. So (you might ask), what is the lesion localization for tetanus? It is a CNS disease at the level of the spinal cord and brain NOT (as one might assume) a peripheral neuromuscular lesion localization!


Signs

The interneurons are focused on regulating muscle tone therefore a disruption of their function results spasticity. Remember, spasticity can occur in all skeletal muscles therefore diaphragm and intercostal muscles can be affected, resulting in respiratory paralysis. The spasticity can be stimulated by noise, touch and light. The incubation period for cats is 5-10 days with a longer suspected incubation period in dogs. According to a recent report about tetanus toxin, strychine intoxication is the only condition that exactly mimics the disease, however other myopathic diseases such as hypocalcemia can be included in the differential diagnoses in the early stages.


Treatment

Debridement of the wound(s) and antibiotics such as penicillin G and metronidazole are recommended to treat the infection but have no effect on the already-formed toxin circulating the body. Therefore, supportive nursing care is critical until a plateau in signs becomes evident. After this point, if the dog or cat can eat, drink, and void voluntarily, supportive care can be continued at home. Tetanus antitoxin is available for cases in which an early diagnosis is obtained however this has limited use in dogs and cats.


Prognosis

Recovery is expected for animals with appropriate supportive care. If respiratory paralysis occurs, ventilatory support may be needed, resulting in added expense and risk of secondary infections. However, a full recovery can be expected for dogs and cats affected by tetanus toxin with appropriate treatment and time.

A special shout out to the vets successfully managing this recent case. Keep it up and way to go!


Happy Thanksgiving! Stay safe, and keep those consults rolling.


Recent open access reference if you are interested: Popoff MR. Tetanus in animals. J Vet Diagn Invest. 2020 Mar;32(2):184-191. doi: 10.1177/1040638720906814. Epub 2020 Feb 18.