MATERIALS AND METHODS
A cryotherapy chamber using circulating nitrogen vapor was constructed for the study. Temperature probes were placed above the dog’s back, above the floor of the unit, and in the return duct. The chamber was constructed so that the dog’s head was outside it and at ambient temperature, while the entire body was exposed to the vapor. (Dogs must be completely dry when entering a cryotherapy chamber; accidental injury has been reported in some human cases in which wet apparel was worn into the unit.)
POTENTIAL VETERINARY APPLICATIONS
These include skin disease such as allergic dermatitis or hot spots, musculoskeletal pain/osteoarthritis, exercise recovery, post-fracture repair or weight loss. WBC may provide an additional tool for palliative therapy or treatment of a variety of common canine problems, since skin disease and musculoskeletal pain are among the top reasons for canine veterinary visits.
Dogs were placed in the chamber when it was pre-cooled to a treatment temperature of -100°C. Additional nitrogen vapor was introduced when any of the temperature probes showed a reading of -90°C. Temperatures were maintained between a maximum of -90°C and -110°C during treatment. The dogs were exposed for three minutes to the treatment temperatures before removal from the chamber.
The 12 dogs in the study were randomly assigned into four treatment groups. Each group received three weeks of twiceweekly treatment and one week of no treatments – the latter could have occurred in the first, second, third or fourth week of the trial. The dogs ranged in weight from 14.8 lbs to 105.4 lbs. Blood chemistry and hematology tests were performed prior to the first treatment, and then weekly. The dogs were weighed immediately prior to entering the cold chamber. Photographs were taken of each dog’s tail dock, pinna, and inguinal area prior to each treatment. They were assessed by owners for pain, pruritus, skin irritation, activity level, quality of life, appetite and anxiety, starting on the day of first treatment and continuing for one week after the final treatment. Additionally, the owners of these animals filled out a questionnaire concerning the dogs’ behavior during the periods between WBC treatments.
For a list of the presenting complaints in the study dogs, see sidebar on next page. No dogs suffered any adverse effects during treatment, nor were any abnormalities reported by owners. During treatment, technicians noted shivering in the third minute of treatment, but no dogs attempted to exit the chamber or showed other signs of discomfort. Technicians reported that dogs exiting the chamber were active and excited. Dogs returning after initial or multiple therapies did not show increased resistance to being placed in the chamber or apprehension about the therapy. Cold therapy was absolutely safe and well tolerated.
• No hematology or blood chemistry parameters were outside normal limits during the study, with the exception of one dog with elevated GGT prior to the initial treatment.
• Improvement of at least one point on a subjective scale of 0-5 in itching/skin irritation was seen in 5/6 dogs.
• Hair loss improved dramatically in the one dog with this presenting complaint, with a softer, smoother coat reported by the owner.
• Improvement in pain scores were seen in only 2/6 dogs with that complaint. One dog with no change in pain scores did have increased activity levels as reported by the owner on each treatment day and the day after.
• The four dogs presenting with obesity lost 0.5 lb (1.3%), 0.2 lb (0.6%), 1.0 lb (1.3%) and 1.0 lb (2.5%) by the final treatment. The dog showing the least improvement gained one pound during the untreated second week and lost 1.2 lbs (3.6%) during the subsequent two weeks for a total loss of only 0.2 lbs (0.6%).
• The one dog presenting with reduced activity levels responded with increased activity during all three treatment weeks, and returned to original levels during the untreated week.
The physiologic mechanism supporting the use of WBC is the dramatic drop in skin temperature, resulting in massive vasoconstriction followed by whole body vasodilation. The effect of cold therapy is directly proportional to the magnitude and speed of the temperature drop experienced by thermoreceptors in the skin.2 This stimulates cold “shock” neuroendocrine pathways, release of anti-inflammatory mediators (IL-10, IL- 4) and decreased pro-inflammatory mediators (IL-2, IL-8). The feeling of “well being” described by many WBC participants is likely a result of endorphin release. The vasodilatory phase results in increased perfusion of injured tissue and skin.
Current scientific research concerning WBC therapy has shown that this procedure is safe and well tolerated in humans. It has been employed mainly as an aid to exercise recovery and as therapy for musculoskeletal pain. Additionally, WBC has shown efficacy as therapy for arthritis, dermatologic conditions and bone remodeling. Many of the athletes who use this therapy report anecdotally that recovery from vigorous physical activity is much quicker, with less fatigue and inflammation than without WBC. WBC has been shown to induce an improvement in the maximal aerobic power of athletes.3 A study using professional rugby players showed a significant decrease in indicators of muscle inflammation, CPK and LDH.
1. WBC is used to treat the pain and inflammation of arthritis. It was found to reduce histamine levels in patients with rheumatoid arthritis.4 A researcher determined that using a WBC regimen allowed patients with adhesive capsulitis to regain a significant range of motion and improved movement.5
2. Additionally, research suggests that WBC may be useful in dermal6 and psychological7 applications.
3. It has been shown to positively influence the bone remodeling osteoimmunologic biomarkers RANK, RANKL and OPG.8 Due to these osteogenic and anti-inflammatory properties, WBC may have a role in the clinical setting for recovery of post-fracture patients.
4. Obesity was improved during the study, but did not meet the established ideal of 3% to 5% weight loss per month. It is worth noting, however, that these dogs lost weight without any change to their exercise or diet during the study period. It has been suggested that a human may use up 800 calories during and in recovery from a WBC session. WBC may therefore be a beneficial adjunct therapy to a weight loss regimen. With increased treatment frequency, WBC may be useful as a primary treatment for obesity.
5. Pain was the most unreliably treated complaint in this study. An owner’s assessment of pain, however, is frequently based on gait abnormality. In dogs with chronic arthritis or musculoskeletal conditions, it is possible to alleviate chronic pain without gait improvement. Further assessment of WBC is needed to accurately assess whether this modality is beneficial for chronic pain. The dog with increased activity levels following treatment may be an indication that although the owner did not note any pain improvement, the dog may have experienced a reduction in pain as reflected by those increased activity levels. A better system is needed for objective pain measurement in these animals.
6. The current treatment regimen does not seem useful for anxiety.
7. The dogs with skin irritation/itching responded reliably, with reduced severity or resolution of their complaints during the treatment period. Further study is required for establishing ideal treatment intensity and frequency for pruritic conditions in dogs, but WBC does show promise as a safe, effective therapy.
Overall, WBC is quick, inexpensive and well-tolerated by canine patients.