Evaluation of digital cryotherapy using a commercially available sleeve style ice boot in healthy horses and horses receiving i.v. endotoxin

Ice application without water drainage supports optimal hoof cooling in adult horses

Cryotherapy is often used to reduce inflammation in acute equine laminitis cases. Certain hoof temperatures have been suggested as effective in minimizing the inflammatory process; however, there is limited evidence on which methods are best at achieving these temperatures. Our objective was to determine how different methods of cryotherapy influence the rate and extent of cooling for the equine hoof wall. Four horses received three hoof cooling treatments and a control (CON; no treatment application) in a 4 × 4 Latin square design. Treatments included (1) ice surrounding the hoof in a 5 L fluid bag with water drainage holes (DB), (2) ice surrounding the hoof in an undrained bag (UB), and (3) ice in a commercial wader boot (CW). Hoof wall temperatures were collected via thermal imaging for 12 h. Thermally imaged body temperatures and thermometer-based rectal temperatures, heat index, relative humidity, and ambient temperature were recorded. A treatment × time interaction (P < 0.001) was observed for all hoof temperatures. All treatments differed from CON after 2 h post-application, with the UB treatment resulting in the greatest and most sustained reduction in hoof temperatures over the 12 h period (a change of -23.7 °C ± 1.6). The wader boot showed similar trends to the UB treatment but was poorly tolerated by the horses. Environmental effects differed between hoof and body surface. Our findings indicate that cryotherapy treatments that maintain an ice-water slurry around the hoof result in greater decreases in hoof temperatures 2 h post-treatment compared to drained ice application.

Treatment approaches to horses with acute diarrhea admitted to referral institutions: A multicenter retrospective study

BACKGROUND

This study aimed to describe and compare therapeutic approaches for horses with acute diarrhea in different geographic regions worldwide.

METHODS

Clinical information was retrospectively collected from diarrheic horses presented to participating institutions between 2016 and 2020, including fluid therapy on admission, antimicrobial drugs, probiotics, anti-endotoxic medications, anti-inflammatory drugs, gastroprotectants, digital cryotherapy, and toxin-binding agents. Seasonal and geographic differences were investigated.

RESULTS

1438 horses from 26 participating hospitals from 5 continents were included. On admission, 65% (926/1419) of horses were administered a fluid bolus. Antimicrobial drugs were administered to 55% (792/1419) within the first 24 hours of admission, with penicillin and gentamicin being the most used combination (25%, 198/792). Horses with leukopenia (OR: 2.264, 95%CI: 1.754 to 2.921; P<0.001) or meeting systemic inflammatory response syndrome criteria (OR: 2.542, 95%CI: 1.919 to 3.368; P<0.001) had higher odds of being administered antimicrobial drugs. Other treatments administered included probiotics (15%, 215/1438), polymyxin B (13%; 187/1438), pentoxifylline (8%; 118/1438), gastroprotectants (44%; 626/1419), digital cryotherapy (34%; 489/1435), plasma transfusion (13%; 182/1410) and toxin-binding agents (36%; 515/1438).

LIMITATIONS

Due to the retrospective nature of the study, the rationale for treatment decisions was unavailable, and associations with survival could not be evaluated.

CONCLUSIONS

Treatments varied between hospitals from different geographic regions. Prospective clinical trials are required to evaluate the effects of various treatments on survival.

Continuous digital hypothermia for prevention and treatment of equine acute laminitis: A practical review

Laminitis is a severely debilitating and life-threatening condition that occurs as a consequence of different primary triggering factors. Continuous digital hypothermia (CDH) is recommended in horses at risk of, or diagnosed with, acute laminitis due to its several physiological and biochemical alterations that may be positive for the prevention and early treatment of the condition, representing a low risk of adverse effects. Modulation of the inflammatory response, profound vasoconstriction, and prevention of tissue damage are the most notable protective effects of cryotherapy on the lamellae. This practical review aims to summarize the published literature evaluating CDH efficacy in the prevention and early treatment of acute laminitis in horses, highlighting the most important clinical findings and discussing the best methods to provide cryotherapy. Nineteen publications evaluated different CDH methods, including the use of commercially available ice boots or fluid bags filled with iced water or crushed ice, as well as alternatives to immersion in ice, e.g., frozen gel packs and a perfused cuff prototype. Although some techniques were effective for cooling and maintaining the hooves below the optimal temperature of 10 °C, relevant limitations such as labor intensiveness, reliance on an ice source and price make its use impractical in some clinical situations. Twelve experimental studies assessed the efficacy of CDH on the prevention or early treatment of laminitis, finding multiple positive effects in terms of clinical improvement, immunological and inflammatory modulation, and histological protection. After the analysis of the literature, the clinical importance of CDH in different stages of laminitis remains clear. However, it also highlights the need for a safer, more user-friendly, and more effective method of cryotherapy that can be used both in a hospital and an ambulatory setting.

Efficacy of a commercial dry sleeve cryotherapy system for cooling the equine metacarpus

OBJECTIVE

To determine the ability of a commercial cryotherapy system (Game Ready Equine) to cool the metacarpal subcutaneous tissue and the superficial digital flexor tendon (SDFT) in horses.

STUDY DESIGN

Experimental study.

ANIMALS OR SAMPLE POPULATION

Six healthy adult horses.

METHODS

Thermocouples were implanted into the metacarpal subcutaneous tissues and the SDFT of six horses. Two treatments (cryotherapy or cryotherapy with 5-50 mmHg intermittent compression) were randomly assigned to forelimbs and performed for 20 minutes. Temperatures were compared to the target range of 10-19°C and between groups.

RESULTS

Only one limb in the cryotherapy/compression group reached the target range after cryotherapy. Temperatures did not differ between treatment groups at time 0. Lowest temperatures achieved in the subcutaneous tissue (p = .0043) and SDFT (p = .005) were 4.9 and 7.6°C lower when intermittent compression was applied. Similarly, applying compression induced a maximum change in temperature of approximately 7.0°C in the subcutaneous tissue (p = .014) and 10.2°C in the SDFT (p = .0001).

CONCLUSION

The cryotherapy system did not cool equine subcutaneous tissue or SDFT to the target temperature range, except in one limb. Combining cryotherapy with intermittent compression did result in lower temperatures and a greater change in temperature of the subcutaneous tissue and SDFT.

CLINICAL SIGNIFICANCE

When using this cryotherapy system, the addition of intermittent compression should be considered to achieve lower temperatures and potentially greater reduction in inflammation. Further studies are warranted to determine the effect of longer treatment times, higher compression settings, and the optimal temperature for benefits in normal and diseased equine tissues.

Cryotherapy Techniques: Best Protocols to Support the Foot in Health and Disease

Treatment of equine laminitis continues to be a challenge despite recent advancements in knowledge of the pathophysiology of laminitis. With more evidence supporting its use, distal limb hypothermia or cryotherapy has become a standard of care for both prevention of laminitis and treatment of the early stages of acute laminitis. Recent studies have demonstrated that cryotherapy reduces the severity of sepsis-related laminitis and hyperinsulinemic laminitis in experimental models and reduces the incidence of laminitis in clinical colitis cases. This article reviews the recent literature supporting the use of distal limb cryotherapy in horses.

Risk factors for laminitis and nonsurvival in acute colitis: Retrospective study of 85 hospitalized horses (2011-2019)

Background

Acute colitis is a serious cause of morbidity and death in horses. Recent studies have compared clinical features of coronavirus and salmonellosis, but no study has compared clinical features of enteric salmonellosis, coronavirus, and neorickettsiosis.

Hypothesis/Objectives

To identify risk factors for laminitis and nonsurvival to discharge in horses with enteric salmonellosis, coronavirus, or neorickettsiosis.

Animals

Eighty‐five horses hospitalized for acute colitis from 2011 to 2019.

Methods

Retrospective case series. Medical record review (2011‐2019) of adult (≥2 years) horses with colitis. Primary outcomes were laminitis and survival to discharge. Multivariable logistic regression was performed to assess association between variables and the development of laminitis. Stepwise Cox regression was performed to assess association between variables and survival.

Results

Seventeen of 85 (20%) horses developed laminitis during hospitalization. Neorickettsiosis cases (11/26, 42%) were more likely to develop laminitis than coronavirus (0/16, 0%) cases (odds ratio [OR] 24.48; 95% confidence interval [CI]: 1.33‐451.74, P = .03). There was no significant difference in laminitis between salmonellosis and neorickettsiosis cases (OR 0.27; 95% CI: 0.07‐1.07, P = .06). Admission heart rate (OR 1.08; 95% CI: 1.02‐1.15, P = .01), total solids (OR 0.17; 95% CI: 0.06‐0.54, P = .003), band neutrophils (OR 1248.47; 95% CI: 6.62‐235 540, P = .008), and bicarbonate concentration (OR 0.68; 95% CI: 0.5‐0.92, P = .01) were predictive of development of laminitis during hospitalization. Sixty‐three of 85 (74%) horses survived to discharge: 16/16 (100%) coronavirus cases, 17/26 (65%) neorickettsiosis cases, 14/20 (70%) salmonellosis cases, and 16/23 (70%) unknown cases. Packed cell volume (hazard ratio [HR] 1.17; 95% CI: 1.09‐1.26, P < .001), L‐lactate concentration (HR 1.33; 95% CI: 1.14‐1.55, P < .001), and development of laminitis (HR 7.07; 95% CI: 1.67‐29.95, P = .008) were retained in the final multivariable model for prediction of nonsurvival to discharge.

Conclusion and Clinical Importance

Nonsurvival and laminitis rates were high, likely related to the presence of neorickettsiosis in the region.