Clinical Application of Current Research Findings Toward the Prevention and Treatment of Acute Laminitis in Horses With Systemic Inflammatory Diseases: An Internist’s Perspective

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.

Transmural Ultrasonography in the Evaluation of Horse Hoof Internal Structures: Comparative Qualitative Findings-Part 1

Ultrasonography is commonly used to evaluate equine lameness-related structures, but traditional hoof approaches cannot adequately visualize internal structures such as the lamellar layer. To address this limitation, we used 62 healthy hooves without digital radiographic abnormalities, made up of thirty anatomical pieces (phase 1) and thirty-two hooves from living horses (phase 2). In both phases, half of the digits were submerged in water (group 1) and the other half in water and ice (group 2) for 24 h. Ultrasonographic views and temperature and humidity measurements were taken every two hours, and sagittal sections were obtained in phase 1. Good quality images were obtained in both phases. The transmural technique allowed the evaluation of several structures of the DEJ (tubular and lamellar strata of the hoof wall, sublamellar dermis, and solar and coronary papillae) and of the distal phalanx (extensor process, parietal surface, and apex). Our findings suggest that the transmural technique following hoof submersion can be useful for internal evaluation of hoof conditions, such as laminitis. However, further validation of the technique in natural or experimental cases is required.

Impacts of Adiposity on Exercise Performance in Horses

There is ample research describing the increased risk of health concerns associated with equine obesity, including insulin dysregulation and laminitis. For athletes, the negative effect of weight carriage is well documented in racing thoroughbreds (i.e., handicapping with weight) and rider weight has been shown to impact the workload of ridden horses and to some degree their gait and movement. In many groups of competitive and athletic horses and ponies, obesity is still relatively common. Therefore, these animals not only are at risk of metabolic disease, but also must perform at a higher workload due to the weight of their adipose tissue. Excess body weight has been documented to affect gait quality, cause heat stress and is expected to hasten the incidence of arthritis development. Meanwhile, many equine event judges appear to favor the look of adiposity in competitive animals. This potentially rewards horses and ponies that are at higher risk of disease and reinforces the owner's decisions to keep their animals fat. This is a welfare concern for these animals and is of grave concern for the equine industry.

The protective effect of licochalcone A against inflammation injury of primary dairy cow claw dermal cells induced by lipopolysaccharide

Laminitis is one of the most important and intractable diseases in dairy cows, which can lead to enormous economic losses. Although many scholars have conducted a large number of studies on laminitis, the therapeutic test of medicinal plants in vitro is really rare. Licochalcone A is proved to possess anti-inflammatory and anti-oxidant properties. But the effect of licochalcone A on LPS-induced inflammatory claw dermal cells has not been discovered yet. In this study, the primary dairy cow claw dermal cells were treated with gradient concentrations of licochalcone A (1, 5, 10 µg/mL) in the presence of 10 µg/mL lipopolysaccharides (LPS). The results indicated that licochalcone A reduced the concentrations of inflammation mediators (TNF-α, IL-1β and IL-6), increased the activity of SOD, reduced the levels of MDA and ROS, downregulated the mRNA expressions of TLR4 and MyD88, suppressed the protein levels of p-IκBα and p-p65, and upregulated the protein expression of PPARγ. In summary, licochalcone A protected dairy cow claw dermal cells against LPS-induced inflammatory response and oxidative stress through the regulation of TLR4/MyD88/NF-κB and PPARγ signaling pathways.

Distal limb pathologic conditions in horses treated with sleeve-style digital cryotherapy (285 cases)

Digital cryotherapy (DC) is frequently used as laminitis prophylaxis for horses. While DC with ice-water slurries is reported to be safe for up to 48 h, the safety of sleeve-style digital cryotherapy (SSDC) with ice in direct contact with the distal limb has not been evaluated. Our objective was to determine the incidence of distal limb pathologic conditions (DLPC) among horses treated with SSDC. A retrospective study of cases from 2011 to 2015 identified 285 horses treated with SSDC for a minimum of 12 h. Data collected from medical records included demographic, treatment, diagnostic, and SSDC treatment parameters. Bivariate statistics and a generalized linear regression model were created to evaluate risk factors associated with increased incidence of DLPC. Among horses treated with SSDC, 7% had tissue injury of the distal limb. Increasing duration of SSDC was associated with increased incidence of DLPC. Lesions observed included dermatitis, cellulitis, alopecia, coronitis, tissue necrosis, and distal limb edema. These lesions were similar to frostbite, non-freezing cold injury, and prolonged water immersion injuries seen in other species. While the incidence of DLPC was low, the authors recommend that horses undergoing SSDC with ice in direct contact with the skin should be monitored closely for injury when prolonged cryotherapy is clinically indicated. Further studies to improve safety, efficacy, and convenience of alternative methods of DC for horses are warranted.

Diagnosis and Treatment of Undifferentiated and Infectious Acute Diarrhea in the Adult Horse

Acute, infectious, diarrhea in adult horses is a major cause of morbidity and is associated with numerous complications. Common causes include salmonellosis, clostridiosis, Coronavirus, and infection with Neorickettsia risticii (Potomac horse fever). Treatment is empirical and supportive until results of specific diagnostic tests are available. Supportive care is aimed at restoring hydration, correcting electrolyte imbalances, and limiting the systemic inflammatory response. The mainstays of therapy are intravenous fluid therapy, electrolyte supplementation where necessary, nonsteroidal anti-inflammatory agents, and nutritional support. Specific therapies include colloid oncotic support, antibiotics, hyperimmune plasma, polymyxin B, pentoxifylline, probiotics, binding agents, gastroprotectants, laminitis prevention, and coagulation prophylaxis.

Novel dry cryotherapy system for cooling the equine digit

Objectives

Digital cryotherapy is commonly used for laminitis prophylaxis and treatment. Currently validated methods for distal limb cryotherapy involve wet application or compression technology. There is a need for a practical, affordable, dry cryotherapy method that effectively cools the digit. The objective of this study was to evaluate the hoof wall surface temperatures (HWSTs) achieved with a novel dry cryotherapy technology.

Design

Repeated-measures in vivo experimental study.

Setting

Experimental intervention at a single site.

Participants

6 systemically healthy horses (3 mares, 3 geldings).

Interventions

Cryotherapy was applied to six horses for eight hours with a commercially available rubber and rubber and welded fabricice boot, which extended proximally to include the foot and pastern. Reusable malleable cold therapy packs were secured against the foot and pastern with the three built-in hook-and-loop fastener panels.

Primary and secondary outcome measures

HWST and pastern surface temperature of the cryotherapy-treated limb, HWST of the control limb and ambient temperature were recorded every five minutes throughout the study period.

Results

Results were analysed with mixed-effects multivariable regression analysis. The HWST (median 11.1°C, interquartile range 8.6°C–14.7°C) in the cryotherapy-treated limb was significantly decreased compared with the control limb (median 29.7°C, interquartile range 28.9°C–30.4°C) (P≤0.001). Cryotherapy limb HWST reached a minimum of 6.75°C (median) with an interquartile range of 4.1°C–9.3°C. Minimum HWST was achieved 68 minutes after cryotherapy pack application.

Conclusions

Dry application of cryotherapy significantly reduced HWST and reached minimums below the therapeutic target of 10°C. This cryotherapy method might offer an effective alternative for digital cooling.