Extensive Epidural Steatitis and Epaxial Myositis Associated with Intramuscular Injection of Melarsomine Dihydrochloride in Two Dogs

Abstract

This is a retrospective case series in which clinicopathological and imaging findings associated with neurological complications secondary to melarsomine dihydrochloride administration are reported in two dogs with Dirofilaria immitis infection. Following intramuscular injection of melarsomine dihydrochloride based on manufacturers' guidelines, two dogs developed acute, progressive, nonambulatory paraparesis or paraplegia. Magnetic resonance imaging was suggestive of epidural steatitis, resulting in compression of the spinal cord and spinal cord oedema. In one dog, emphysematous myositis throughout the lumbar paravertebral muscles was present. Hemilaminectomy with the intent of achieving spinal cord decompression and obtaining specimens for microbiological and histopathological evaluation was performed in both dogs. One dog partially regained function postoperatively whereas the other was euthanatized intraoperatively. Histologically, epidural steatitis was observed in the surviving dog and epidural steatitis, myonecrosis and grey and white matter changes in the spinal cord were observed in the euthanatized dog. Microbiological testing failed to identify bacteria from the affected tissues. Both cases highlight the potential for the development of extensive epidural steatitis and consequent spinal cord compression following intramuscular administration of melarsomine dihydrochloride. Further investigation into the optimal therapeutic intervention in dogs experiencing neurological complications following melarsomine administration is warranted.

Keywords

melarsomine dihydrochloride - epidural steatitis - myelopathy - MRI - dog

Authors' Contributions

S.A.A contributed to conception of study, study design and acquisition of data and data analysis and interpretation. M.K. contributed to study design and acquisition of data and data analysis and interpretation. J.L.R. contributed to image analysis and interpretation. L.L.C. contributed to analysis and interpretation of microbiological and gross and microscopic analysis and interpretation of specimens. R.M.B. contributed to study design, data analysis and interpretation. S.R.P. contributed to study design, data analysis and interpretation. All authors drafted, revised and approved the submitted manuscript.

• References

• 1 Nelson CT, McCall JW, Carithers D. Current canine guidelines forthe prevention, diagnosis, and management of heartworm (Dirofilaria immitis) infection in dogs. Am Heartworm Soc Available at: https://www.heartwormsociety.org/images/pdf/2014-AHS-Canine-Guidelines.pdf . Accessed April 8, 2020
• 2 Maxwell E, Ryan K, Reynolds C, Pariaut R. Outcome of a heartworm treatment protocol in dogs presenting to Louisiana State University from 2008 to 2011: 50 cases. Vet Parasitol 2014; 206 (1-2): 71-77
• 3 Hoch H, Strickland K. Canine and feline dirofilariasis: prophylaxis, treatment, and complications of treatment. Compend Contin Educ Vet 2008; 30 (03) 146-151 , quiz 151–152
• 4 Hettlich BF, Ryan K, Bergman RL. , et al. Neurologic complications after melarsomine dihydrochloride treatment for Dirofilaria immitis in three dogs. J Am Vet Med Assoc 2003; 223 (10) 1456-1461 , 1434
• 5 Moore SA, Mariani CL, Van Wettere A, Borst LB. Chronic compressive myelopathy and progressive neurologic signs associated with melarsomine dihydrochloride administration in a dog. J Am Anim Hosp Assoc 2013; 49 (06) 389-393
• 6 Bonawandt KA, Berg JM, Joseph RJ, Stefanacci JD. Intradural dirofilariasis in a dog with chronic cervical pain. J Am Anim Hosp Assoc 2017; 53 (01) 59-63
• 7 Deshpande DM, Krishnan C, Kerr DA. Transverse myelitis after lumbar steroid injection in a patient with Behcet's disease. Spinal Cord 2005; 43 (12) 735-737
• 8 Peek SF, Semrad SD, Perkins GA. Clostridial myonecrosis in horses (37 cases 1985-2000). Equine Vet J 2003; 35 (01) 86-92
• 9 Songer JG. Chapter 10 - Clostridial Diseases of Animals. In: Rood JI, McClane BA, Songer JG, Titball RW. , eds. The Clostridia. San Diego: Academic Press; 1997: 153-182
• 10 Ray D, Cohle SD, Lamb P. Spontaneous clostridial myonecrosis. J Forensic Sci 1992; 37 (05) 1428-1432