Plus-Hex CLINICAL
A test for feline leukaemia virus and feline immunodeficiency virus was negative, and tests for Toxoplasma immunoglobulin( Ig) M(< 20) and IgG(< 50) confirmed no active Toxoplasma infection.
Based on the patient ' s history, the progression of clinical signs and the blood test results, Sybil was prescribed midazolam 0.2 mg / kg, IV every 8 hours( Dormazolam, Dechra, 5 mg / ml) to control muscle spasms. Additional treatment included methadone 0.1 mg / kg IV every 4 – 6 hours( Comfortan, Dechra, 10 mg / ml), metronidazole 10 mg / kg IV every 12 hours( B Braun Medical, 500 mg / 100 ml) and clindamycin 17.6 mg / kg orally every 24 hours( Antirobe, MSD Animal Health, 75 mg) for myositis secondary to suspected Clostridium infection, consistent with tetanus.
Despite no observation of an entry point for infection during her initial examination, it was assumed that Sybil had acquired a wound that had gone undetected and healed by the time she was showing clinical signs, as the incubation period can be up to 3 weeks [ 2 ]. Sybil ' s appetite continued to be normal throughout and her faecal and urine output were unchanged. Her body temperature was slightly elevated at times, but this was most likely attributable to stress.
On day 15, a constant-rate infusion( CRI) of fentanyl 3 µ g / kg / hour( Fentadon, Dechra, 50 µ g / ml) was prescribed for additional analgesia, as she was still showing signs of considerable pain when assessed for mobility. Although tetanus antitoxin was considered, it was not administered owing to the potential risk of phenol toxicity. Its benefit is limited when treatment is not initiated early, as it is unlikely to alter the disease progression once the toxin has irreversibly bound to neural tissue [ 3 ]. In cases where generalised tetanus is more likely, such as in dogs, administering antitoxin may be beneficial in an attempt to reduce the severity of clinical signs, but each case must be considered based on the risk-benefit for that individual [ 3, 7 ].
At this stage, physiotherapy was not well tolerated, so the decision was made to withhold it until clinical improvement was evident. Muscle spasms of the hindlimbs were becoming more frequent, and the patient ' s medication was changed to a CRI of midazolam 0.3 mg / kg / hour( Dormazolam, Dechra, 5 mg / ml) instead of IV injections every 8 hours. Methocarbamol 43.6 mg / kg orally( Robaxin, Zoetis, 750 mg) was also trialled to help reduce the muscle spasms, but this was not well tolerated by the patient and was therefore discontinued. Some mild tone had also been reported in her forelimbs, but this was nothing of significance and was not progressive.
By day 24, Sybil was showing some improvement in the left hindlimb and attempting to place it, although no changes had been seen with the right hindlimb. Given the mild improvement in clinical signs and with pain now being well managed( pain score 4 / 20) [ 8 ], the decision was made to transfer her back to the general practice where her owner( the author) works, for ongoing hospitalisation with continued close monitoring. Sybil was medicated with buprenorphine 0.02 mg / kg( Bupredine Multidose, Dechra, 0.3 mg / ml) IV every 6 – 8 hours and gabapentin 6 mg / kg orally every 8 hours( Gabapentin, Summit Pharmaceuticals, 25 mg), for continued pain management. An 8-week course of metronidazole 12.5 mg / kg( Metronidazole, Summit Pharmaceuticals, 50 mg) orally every 12 hours was also prescribed following her discharge to the general practice, due to the deep-seated infection within the muscle. Metronidazole was the antibiotic of choice due to a reported mortality reduction when prescribed for the treatment of tetanus [ 9, 10 ].
Over the following week of hospitalisation in the general practice, Sybil started to use her left hindlimb to a point where she was able to mobilise with minimal aid for short periods of time( Figure 2). At this stage, she was still unable to bear any weight on her right hindlimb, and supported herself on three legs. Physiotherapy was now tolerated, consisting of light massage and mild extension and flexion of the stifle and hock.
Figure 2. The patient during a short walk to encourage mobilisation.
Outcome and follow-up
On day 29, Sybil was discharged back to her owner ' s care to continue treatment( Table 3).
Table 3. Medication prescribed at discharge on day 29.
Drug Gabapentin Meloxicam Metronidazole
Dosage 6 mg / kg orally every 8 hours 0.05 mg / kg orally every 24 hours 12.5 mg / kg orally every 12 hours
Additionally, dantrolene sodium 25 mg orally every 12 hours( Dantrium, Norgine, 25 mg) was prescribed to treat muscle spasms. Sybil ' s owner confined her to a large crate when unsupervised, as her mobility
Volume 41( 4) • August 2026
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