Retrospective Observational Study & Analysis of Two Different Photobiomodulation Therapy Protocols Combined with Rehabilitation Therapy as Therapeutic Interventions for Canine Degenerative Myelopathy

Published: Photobiomodulation, Photomedicine, and Laser Surgery, Published Online:16 Apr 2020. https://doi.org/10.1089/photob.2019.4723

Keyword: degenerative myelopathy, photobiomodulation, low-level laser therapy, LLLT, ALS, amyotrophic lateral sclerosis, canine, physical rehabilitation

Author(s): Lisa A. Miller, DVM, CCRT, CVA; Debbie (Gross) Torraca, DPT, MSPT, OCS, CCRP; and Luis De Taboada, MSEE.

Study site: Wizard of Paws Physical Rehabilitation for Animals, Colchester, Connecticut.

Authors’ affiliations: Companion Animal Health, LiteCure LLC, New Castle, Delaware (Miller and De Taboada), and Wizard of Paws Physical Rehabilitation for Animals, Colchester, Connecticut (Torraca). 

Abstract

Objective: The objective of this retrospective review was to examine the impact that adding photobiomodulation therapy (PBMt) to rehabilitation therapy had on the pathology of degenerative myelopathy (DM) in canine patients.

Background: Canine DM is a progressive, fatal neurodegenerative disease for which there exists a dearth of effective treatments, limiting clinicians to pursue symptom palliation.

Methods: Clinical records of dogs referred for presumed DM to a specialty rehabilitation facility were screened for patients meeting study criteria. Qualifying patients were divided into two groups: Protocol A (PTCL-A) and Protocol B (PTCL-B) group, based on the PBMt protocol used. Data related to demographics, diagnostics, rehabilitation protocols, and progression of clinical signs were collected. Data were analyzed to determine differences in outcomes between the two treated groups and historical data expectations*, as given by a previously published study.

Results: The times between symptom onset and euthanasia of dogs in the PTCL-B group: 38.2 ± 14.67 months (mean ± SD), were significantly longer than those of dogs in the PTCL-A group: 11.09 ± 2.68 months. Similarly, the times between symptom onset and nonambulatory paresis (NAP) or paralysis of dogs in the PTCL-B group: 31.76 ± 12.53 months, were significantly longer than those of dogs in the PTCL-A group: 8.79 ± 1.60 months. Further, Kaplan–Meier survival analysis showed that the times from symptom onset to NAP of dogs in the PTCL-B group were significantly longer than those of dogs in the PTCL-A group (Mantel-Cox Log Rank statistic = 20.434, p < 0.05) or the historical data group (Mantel-Cox Log Rank statistic = 16.334, p < 0.05).

Conclusions: The data reviewed show significantly slower disease progression—longer survival times—for patients in the PTCL-B group than those in the PTCL-A group or published historical data. Further studies are warranted.

Key Points:

1. Canine degenerative myelopathy (DM) is a progressive adult-onset neurodegenerative disease that ultimately results in paresis and eventually paralysis. Non-ambulation, and/or other factors including urinary and fecal incontinence often lead pet owners to choose euthanasia over a very poor quality of life for their affected dog(s).
 

2. There are no clinically tested, effective treatments for DM, leading clinicians to pursue symptom palliation using conventional or novel therapies.
 

3. In this study, all clinical records of dogs referred to a specialty rehabilitation facility over a 9-year period (872) were screened for patients meeting study criteria. Patients who had clinical signs typical of DM and at least one additional advanced diagnostic test result suggestive of DM-- magnetic resonance imaging (MRI) of the spine to rule out other lesions, DNA testing for SOD1 mutation, and/or postmortem histopathologic examination were included in the study.
 

4. Twenty patients met all inclusion criteria and none of the exclusion criteria. Six (6) patients treated using 904nm, 0.5W/cm2 at the skin surface, 8J/cm2 per point were assigned to the PTCL-A group. The remaining fourteen (14) patients were treated using 980nm, 1.2-2.4 W/cm2 at the skin surface, 14-21 J/cm2 over the entire treatment area and were assigned to the PTCL-B group. Patients in both groups received identical in-clinic rehabilitation therapy and at-home care instructions.
 

5. The study showed that when compared to historical expectations* or dogs in the PTCL-A group, dogs in the PTCL-B** group had significantly delayed progression of symptoms and significantly longer survival times.
 

6. The study also showed that the disease progression rate and survival times for the PTCL-A group were similar to published historical data (expectations).
 

7. The data analysis suggests that the combination of PBMt using 14-21 J/cm2 of 980nm laser light administered to the thoracic and lumbar spine at 6-12W (irradiance 1.2-2.4W/cm2 at the skin surface) and intensive rehabilitation therapy may delay the progression of clinical signs and extend the survival time of dogs with DM and should be considered for treatment in light of the lack of other effective therapies.
 

8. Given that there is a linear correlation between the irradiance (intensity) of the light applied at the skin surface and that of the light measured at the spinal canal, the irradiance at the spinal canal of patients in the PTCL-B group was much greater than that of patients in the PTCL-A group. Since both wavelengths and fluence ranges used in PTCL-A and PTCL-B groups, have been shown to have benefit for various conditions in vitro, the authors surmise that the different irradiances at the spinal cord in vivo were primarily responsible for the difference in response between groups.

*expectations are based on the only published study with a data set available that could be used for formal statistical comparison

**PTCL-B group utilized a Companion Therapy Laser