Clostridium tetani: The Veterinary Technicians Role Tiffany Bartlett, LVT

Clostridium Species Large Spore forming Gram-positive Rods Obligate anaerobic Catalase negative Oxidase negative Over 200 species- less than 20 are pathogenic Pathogenic species produce potent exotoxins 4 groups Neurotoxic, histotoxic, enteropathogenic & enterotoxaemia producing, and atypical Image from: http://textbookofbacteriology.net/clostridia.html

Clostridium tetani Neurotoxic clostridia T. botulinum Endospores live in soil and feces Affects Humans, domestic, and wild animals Dogs & cats have high resistance *not immunity Less prevalent in developed countries due to vaccines for humans and farm animals Picture from: http://paraibaparadise.com/index.php/come-to-joao-pessoa/living-in-joao-pessoa/health/diseases/tetanus/

Pathogenesis Wounds Proliferation only occurs when tissue necrosis is present Not all patients wounds with c. tetani contamination develop tetanus C. tetani autolyse in the anaerobic necrotic tissue Bacterial cell walls autolysis- neurotoxin is released Neurotoxin is zinc-binding protease Cleaves synaptobrevin (purple circle) Toxin absorbed locally by motor nerves Ascends to spinal cord- ascending tetanus synaptobrevin, a vesicle-associated membrane protein Picture from: http://www.ipsifar.rm.cnr.it/inglese/Luvisetto_1UK.html

Incubation typically 10-14 days Dogs & cats tend to have a longer incubation due to high resistance Site of infection affected 1st Localized stiffness- most common Masseter muscles Neck Pelvic limbs Generalized stiffness- less common Picture from: https://biogeekery.wordpress.com/2013/04/08/tetanospasmin-and-tetanus-the-second-deadliest-toxin/

Tetanospasmin Neurotoxin The 2nd deadliest substance Flaccid paralysis *identical to botulism Localized → General stiffness Prehension and mastication difficulty *AKA Lockjaw “Smiling”- ears pulled back, lips drawn back Increased reflexes Tonic spasms Worsened when excited/startled

Sawhorse stance Hyperesthesia Muscle spasms of the neck, back, and limbs Opisthotonos- muscle spasms causing backward arching of head, neck and spine (see picture) Hyperesthesia Picture from: http://fineartamerica.com/featured/opisthotonos-science-source.html

Diagnosis History Clinical signs Gram stained slides from lesions Recent trauma/ wounds Clinical signs Gram stained slides from lesions Anaerobic culture of wound Tetanus toxin detection in serum analysis Injecting mice with animal serum to see if tetanus occurs Picture from: https://vetgirl.wordpress.com/2008/09/02/tetanus/

Treatment in Dogs Sedatives Anticonvulsants Benzodiazepines, barbiturates, etc. Anticonvulsants Phenobarbital, Keppra, etc. Tetanus antitoxin 1,500-3,000 IU IV q12h May induce anaphylaxis Debride and treat wounds- Oxygen kills C. tetani bacteria Penicillin 20,000-30,000u/kg IV q6-q8h X10d Metronidazole 15mg/kg PO q12h X10d Picture from: https://www.valleyvet.com/ct_detail.html?pgguid=2e87bedd-7b6a-11d5-a192-00b0d0204ae5

Nursing care is critical to good patient outcome Patient rotation q4 to prevent decubital ulcers Clean, padded, safe kennel IVF to prevent dehydration Hand feeding PT- PROM on all joints, on all limbs QID Reduce noise, light, and other sensory inputs that could startle the patient Walk, with support, if able 24hr nursing care

Case Study

Punkin 6 y/o FS Pit Bull Mix HX: Dropping food, weak, lethargy, ataxia, stiffness, no known trauma or wounds Diagnostics MRI- WNL CSF- WNL BW- WNL Tick panel- WNL Neospora- negative Toxoplasma- negative

CT- WNL, no wounds or other abnormalities found On Clindamycin, Prednisone, Gabapentin, Tramadol, and Clonazepam DX over 2 weeks- continual decline Falling, difficulty walking, progressive prehensile difficulty, progressive stiffness Additional DX: CT- WNL, no wounds or other abnormalities found After ruling all other causes out, diagnosis was Tetanus even though no wound could be found On day of hospitalization, patient presented Tonic spasms, worsened when excited Lock jaw Saw horse stance “Smiling”

Punkin’s Treatment Covered cage Antitoxin 3,000 UI IV q12 PT PROM, all joints all limbs QID Recumbency care q4 Acepromazine 0.01mg/kg IV q6 PRN Hand fed meatballs q6 Hand offered water q6 Antitoxin 3,000 UI IV q12 IVF @ 60mL/kg/hr Ear plugs Penicillin 20,000-30,000u/kg IV q6- q8h X10d Metronidazole 15mg/kg PO q12h X10d Diazepam 0.25mg/kg IV PRN for seizures *had 1 seizure on day 3 of treatment

Conclusion After initially deteriorating for the first 72 hours in spite of treatment, Punkin started to improve on day 4 By day 5 she was walking well with a sling Day 8- after a fall, she was able to get back up unassisted Day 10- Punkin was discharged from the hospital

References