Transcutaneous Electrical Nerve Stimulation as an adjuvant treatment for thoracolumbar acute hyperesthesia in chondrodystrophic dogs: a prospective blinded controlled clinical study

Débora Gouveia ^1,2 Ana Cardoso ² Carla Carvalho ² Marina Moisés ² André Filipe Monteiro Coelho ^3,4,5 Maria Balça ^3,4,5 Rui Alvites ^3,4,5,6 Ana Colette Maurício ^3,4,7* Antonio Almeida Ferreira ^3,8,9 Ângela Paula Martins ^10,2

• ¹ Faculty of Veterinary Medicine, Lusofona University, Lisboa, Lisbon, Portugal
• ² Arrábida Veterinary Hospital, Arrábida Animal Rehabilitation Center, Azeitão, Portugal
• ³ AL4Animals, Lisbon, Portugal
• ⁴ Centre for the Studies of Animal Science, Institute of Agrarian and Agri-Food Sciences and Technologies, University of Oporto, Porto, Portugal
• ⁵ ICBAS, School of Medicine and Biomedical Sciences, Institute of Biomedical Sciences Abel Salazar, University of Porto, Porto, Porto, Portugal
• ⁶ Cooperativa de Ensino Superior Politécnico e Universitário, Gandra, Porto, Portugal
• ⁷ Institute of Biomedical Sciences Abel Salazar, University of Porto, Porto, Portugal
• ⁸ Faculty of Veterinary Medicine, University of Lisbon, Lisbon, Portugal
• ⁹ Centre for Interdisciplinary Research in Animal Health, Faculty of Veterinary Medicine, University of Lisbon, Lisboa, Lisboa, Portugal
• ¹⁰ Lusofona University, Lisbon, Portugal

Acute paraspinal hyperesthesia could result in a mixture of nociceptive and neuropathic pain that requires drug treatment but it is suggested that could also benefit from a non-pharmacologic approach such as 2-channel transcutaneous electrical nerve stimulation (TENS). From a health perspective that can be transferred from human to veterinary medicine, conventional TENS is suggested to reduce pain score and a possible reduction of pain medication. This prospective, blinded, controlled cohort study was conducted in a clinical setting. The dogs were randomized into the study group (SG) (standard pharmacological protocol (PSP) + TENS) and the control group (CG) (PSP only), with observers unaware of the treatment administered. The aim was to observe the efficacy of TENS in relieving thoracolumbar paraspinal hyperesthesia in dogs. 818 dogs with paraspinal hyperesthesia, classified as grade 4 or 5 in the modified Frankel Scale (MFS) and with a Dynamic Interactive Visual Analog Scale (DIVAS) score ≥14, were enrolled in the study. Two blinded observers were responsible for scoring the video recording results for all checklist parameters. All results were assessed every 24 hours from T0 (admission) to T8, always five minutes before TENS for SG. 74% of dogs (605/818) with PSP with TENS and 26% (213/818) with PSP only. In the first 48 hours, SG showed a faster improvement in the reduction of muscle tone. All were hyperesthetic and became non-painful, but in SG there was a faster recovery from T2 (48h) to T4. There was a statistical difference between groups in terms of DIVAS score (p<0.001) and in terms of treatment duration, SG took on average 2.14 days to discharge, whereas CG took twice as long (p<0.001). TENS may help to improve paraspinal hyperesthesia and promote early recovery by reducing pain, the need for medication and also recovery time. However, these results should be interpreted cautiously as there are no objective measures in a clinical trial, which may lead to potential bias. This modality could be considered in clinical practice as an adjunctive treatment for acute thoracolumbar hyperesthesia in dogs, although further studies are needed.