A healthcare plan was created , which included regular medication reviews , a biannual health examination , weekly gait analysis , photobiomodulation therapy ( PBMT ), exercise management and enclosure modifications . Health checks at 6-month intervals showed mild progression and subtle areas of lysis at P2 in the thoracic limbs , as well as an increase in joint space bilaterally in the stifles , indicating a loss of cartilage . Intermittent lameness was present with abduction of the right pelvic limb on the swing phase and a shortened stride length . Amantadine ( Amantadine Hydrochloride , Morningside Healthcare ) was added to the multimodal pain management plan , at a dose of 5 mg / kg orally once daily , to target the central sensitisation component of chronic pain ( Grubb , 2018 ).
Photobiomodulation therapy
PBMT uses wavelengths of light , which have biostimulatory effects on target tissues . The therapeutic benefits of PBMT include anti-inflammatory and analgesic effects , so its use is recommended in chronic pain management ( Dadone & Harrison , 2017 ; Paterniani & Grolli , 2017 ). A Class 3b XP mobile unit ( Omega Laser Systems ) was used in the treatment of this case . Appropriate positioning and acceptance of the treatment was achieved through positive reinforcement and operant conditioning ( learning that occurs when behaviour is affected by consequences ) ( Crowell-Davis , 2008 ). The serval was conditioned to lie in sternal recumbency on an elevated board . Shaping by successive approximations modified the position until the thoracic limbs could be extended rostrally and the time the position could be held allowed for treatment ( Figure 2 ).
Treatment time varied depending on the animal ' s participation but averaged 4 min per session . A 5 × 820 nm probe was used with 16 J / cm 2 and a 1K frequency . The 5 × 820 nm probe enabled treatment of larger areas in the same amount of time . The treatment was initially repeated for 3 consecutive days , then reduced to every 4 days and , at 8 weeks , reduced to once a week . Once maintenance treatment was established , the energy density and frequency were alternated to include 24 J / cm 2 and 5K . Treatment of the stifles was also attempted but was not well tolerated .
In April 2020 , all PBMT ceased , in line with a reduced contact policy with felids because of the Covid-19 risk . The animal was closely monitored and treatment was restarted a month later due to deterioration in gait coinciding with the serval sustaining an injury .
Gait analysis
The assessment of gait , particularly identifying lameness in felids , is difficult and can be time-consuming ( Schnabl-Feichter et al ., 2020 ). However , pain associated with joint disease results in altered or impaired
Figure 2 . Photobiomodulation treatment of digits in a 10-year-old female African serval with osteoarthritis secondary to onychectomy .
mobility , so it is an important part of assessment . A systematic and sequential approach to gait analysis was implemented and repeated for comparison . Videos were reviewed by the same veterinary nurse , for consistency , and seven gait criteria were assessed ( Table 1 ).
The monitoring interval reduced over time , from monthly to weekly videos , as the disease progressed . These were obtained by the animal keepers and included an identical path of movement across an elevated walkway each morning . A turn both ways was included to assess feet placement , flexibility and balance . While videos from other aspects ( front and rear views ) would have given more information , only sideaspect videos were possible to obtain .
A simple scoring system was used to detect abnormalities : a score of one indicated the criteria assessed was normal , while a score of zero indicated an abnormality . This system did not allow for subjective grading of movement on a scale . Instead , it produced an overall numerical score , which was compared over time . High scores indicated a normal gait and good disease management .
Enclosure modifications
Access to height is generally considered important for felids . A more complex environment including multiple levels encourages more movement , which is important for maintaining muscle mass and tone ( Robertson & Lascelles , 2010 ).
50 Veterinary Nursing Journal