Casts are a common form of external coaptation used to immobilize limbs of horses that have sustained injuries resulting in skeletal instability; casts are also used to provide stability after internal fixation or for improved healing of soft tissue wounds of horses.1,2 Types of casts for horses are typically described by the proximal extent of the cast on a limb. Distal limb casts encompass the foot and interphalangeal joints, and the proximal extent of such casts is just distal to the metacarpophalangeal or metatarsophalangeal (ie, fetlock) joint.3,4 Such casts are commonly used to immobilize injuries of the distal aspects of limbs, such as lacerations of the soft tissues at the palmar or plantar aspects of limbs just proximal to the coronary band (ie, heel bulb lacerations). The most commonly applied type of cast is a half-limb cast, which extends from the foot to the proximal aspect of the metacarpal or metatarsal region.5 Full-limb casts extend from the foot to the level of the proximal aspect of the radius or tibia. Half-limb and full-limb casts are typically applied for the treatment of fractures, tendon and ligament disruptions, joint luxations, and wounds. Tube casts are most commonly applied for the treatment of young horses with angular limb deformities of the forelimbs.5 Such casts extend from the distal metacarpal region (just proximal to the fetlock joint) to the level of the proximal aspect of the radius or tibia. The foot is not enclosed in such a cast so that soft tissues are loaded during weight bearing; this is intended to avoid development of soft tissue laxity. Tube casts do not bear any of the load on a limb during weight bearing.
Full-limb and half-limb casts typically consist of polyurethane resin–impregnated fiberglass tape strips placed over a thin layer of padding. Excessive padding placed under a cast may deform and slip, resulting in excessive movement of the limb within the cast and an uneven distribution of pressure on the skin of a horse. Placement of too little padding under a cast results in rubbing or increased pressure of rigid cast material on the skin.1 Use of polyurethane resin-impregnated foam as cast padding decreases cast complications.6 In some horses for which less rigid stability is needed (typically those for which the cast is applied to provide soft tissue protection), BCs are used.7 Such casts consist of fiberglass cast tape placed over a compressed bandage. Casts placed over a thin layer of polyurethane padding and those placed over bandages are applied for different purposes; however, potential complications of both types of cast may be similar.
Casts can be applied in various configurations for the treatment of different conditions or to minimize complications in horses. The amount of cast material placed at the toe or heel of a foot (for functional toe extension or heel support, respectively) and choice of limb position (ie, amount of limb flexion or extension) in a cast may depend on the condition being treated (eg, placement of a fetlock joint in flexion for the treatment of flexor tendon lacerations) or surgeon preference. Bandaging of the contralateral limb and elevation of the contralateral foot may balance weight bearing between limbs and prevent development of contralateral limb laminitis or angular limb deformities.8
Casts may be used alone or with other devices to provide limb stability. Complications attributable to casts can develop, such as soft tissue wounds caused by motion or pressure of a cast (ie, cast sores).1,2,7,9 Such cast sores often heal via second-intention healing with few long-term consequences; however, lameness may develop.7 Less common cast complications include breakage of the cast, osteopenia, development of fractures attributable to osteopenia, fracture of bones at the proximal aspect of the cast, and damage to tendons or avulsion of ligaments from bone.10–15 Full-limb casts on hind limbs can cause peroneus tertius rupture and coxofemoral joint luxation.5 Joints immobilized in a cast may have reduced range of motion after removal of the cast because of joint capsule fibrosis; thinning of articular cartilage attributable to extracellular matrix degradation may also develop.11,13,14 The objective of the study reported here was to determine the frequency of complications associated with half-limb and full-limb casts in horses and to identify risk factors for such complications.
Materials and Methods
Selection of cases—Medical records (including radiographic images) of horses that underwent cast application at the University of Missouri, Iowa State University, Purdue University, and the University of Georgia veterinary medical teaching hospitals from January 1997 through December 2006 were reviewed. Horses treated with transfixation pin casts, distal limb casts (such as those for treatment of heel bulb lacerations), tube casts, or plaster of Paris casts and those for which casts were removed immediately after recovery from anesthesia were excluded from the study. All horses included in the study had casts that included the hoof and were either a TC consisting of a stockinette, resin-impregnated foam, and fiberglass casting tape or a BC consisting of fiberglass casting tape placed over a compressed cotton bandage. During the years included in the present study, personnel at all 4 hospitals used a similar standard TC application technique that included placement of a stockinette, orthopedic felt at the proximal aspect of the cast, resin-impregnated foam padding,a and then fiberglass casting tape. Various amounts and types of bandage materials were used for BCs; however, such casts were considered similar enough to be included in 1 group of the present study.
Procedures—Information collected from medical records and radiographic images included the hospital where horses were treated, signalment (ie, age, breed, and sex), injury or medical problem at the time of hospital admission, type of tissue involved in the injury (bone vs soft tissue), limb affected, emergency care prior to referral, time from injury to hospital admission, surgical procedure performed, length of cast (full-limb vs half-limb), type of cast (TC vs BC), limb position in the cast (flexed [ie, flexion of fetlock and proximal and distal interphalangeal joints], extended [ie, extension of fetlock and proximal and distal interphalangeal joints], or neutral [ie, dorsal cortices of phalangeal and third metacarpal or metatarsal bones aligned]; Figure 1), and outcome (cast complication vs no cast complication). Data were recorded in a spreadsheetb for further analysis. For horses with a cast complication, information collected from medical records included the type of complication, time in the cast before clinical signs attributable to the complication were detected, type of clinical signs attributable to the complication, and treatments for the cast complication. The site of cast breakage was recorded for casts that broke. The number and locations of cast sores were recorded. For horses with cast sores that were identified prior to cast removal, the first cast sore identified prior to cast removal was identified as the primary cast sore. For horses with cast sores that were not identified until the first cast change or after cast removal, the largest cast sore was identified as the primary cast sore. Placement of a horse in a cast for a problem was considered 1 casting episode, even if the cast was changed during treatment. The time to development of cast complications was calculated as the time from cast placement to the time that cast complications were detected. All horses were maintained in the same type of cast during each casting episode. Some cast complications (including osteopenia, decreased range of joint motion, and cartilage thinning) were not evaluated in the present study. Horses that were euthanized during the study period because of a poor prognosis, implant failure, laminitis, gastrointestinal tract disease, or financial constraints prior to cast removal were not included in the study.
Statistical analysis—Descriptive statistical data were reported as median (range). A statistical analysis programc was used to determine a generalized linear mixed modeld via a logit link function with a binomial response to data by use of only those variables (hospital, sex, and limb position in the cast) that were significant in the logistic regression model. In this model, the estimated values and P values for those 3 variables (hospital, sex, and limb position in the cast) were comparable with those determined via logistic regression. Cast type was a confounding variable in the model; when horses where classified by cast type (TC vs BC), hospital, sex, and limb position in the cast remained significant for horses with a TC but not for those with a BC. Few horses were included in the BC group; therefore, statistical analyses for this group had low power. Therefore, data for horses with a BC were removed and analyses were repeated for horses with a TC via those same statistical procedures. Interactions between variables could not be determined because of the low number of horses included in some categories. Values of P ≤ 0.05 were considered significant.
Results
Three hundred ninety-eight horses met the criteria for inclusion in the study. One hundred eighty-three horses were treated at Purdue University, 114 horses were treated at the University of Missouri, 81 horses were treated at Iowa State University, and 20 horses were treated at the University of Georgia. The median age of horses was 8 years (range, 1 day to 26 years); the median weight of horses was 431 kg (948 lb; range, 23 to 818 kg [51 to 1,800 lb]). Horses included 70 sexually intact males, 134 castrated males (ie, geldings), and 193 sexually intact females; sex was not recorded for 1 horse. Breeds included Quarter Horse (n = 164), Paint (59), Thoroughbred (38), Arabian (27), Standardbred (16), Tennessee Walking Horse (10), warmblood (8), Appaloosa (7), Miniature (7), pony (7), Saddlebred (7), draft (6), mule (6), Morgan (4), Missouri Fox Trotting Horse (3), and Peruvian Paso (2); breed was not recorded for 27 horses. A cast was applied to a forelimb of 152 horses (71 left and 81 right forelimbs) and a hind limb of 246 horses (120 left and 126 right hind limbs).
The median time from injury to hospital admission was 1 day (range, 30 minutes to 365 days). Prior to referral, treatments included application of a bandage (n = 88 horses), splint (36), temporary cast for transportation (19), or therapeutic shoe (3). Information regarding application of stabilization devices prior to hospital admission was unknown for 127 horses, and no such devices were applied for 125 horses.
A cast was applied for the treatment of injuries involving hard tissues (bones, joints, or physes) for 185 horses. Procedures performed prior to application of casts for these horses included internal fixation (n = 122 horses) and closed fracture reduction (25). A cast was applied for the treatment of soft tissue injuries (involving tendons, ligaments, tendon sheaths, bursas, or other lacerations or wounds) for 213 horses. One hundred fifty-four horses underwent wound debridement, and 47 horses underwent tendon sheath lavage and debridement prior to cast application. Bandage casts were applied for 53 horses, and TCs were applied for 345 horses. The distal aspect of the limb was in a flexed, neutral, and extended position in the cast for 28, 98, and 248 horses, respectively (Table 1). Limb position in the cast was not recorded for 24 horses.
A cast complication was detected for 197 of 398 (49%) horses, and no cast complications were detected for 201 (51%) horses (Table 1). One hundred seventy-nine of the 345 (52%) horses with a TC had a complication, and 18 of the 53 (34%) horses with a BC had a complication. Of the 345 horses with a TC, 278 had a half-limb cast (139 [50%] of which had a complication) and 67 had a full-limb cast (40 [60%] of which had a complication). Of the 53 horses with a BC, 24 had a half-limb cast (7 [29%] of which had a complication) and 29 had a full-limb cast (11 [38%] of which had a complication). Of the 197 horses with a cast complication, 152 (77%) had clinical signs of complications prior to cast removal. The most common clinical sign of cast complications was increased severity of lameness (n = 55 horses); other complications included visible cast sores (44), discharge or staining of the cast with exudate (ie, strikethrough; 16), soft tissue swelling proximal to the cast (12), palpably increased temperature of a portion of the limb under the cast (11), fracture (3), pyrexia (2), and intolerance to casting (1). Of the 3 (0.8%) horses with secondary fractures associated with casting, 1 horse (that had undergone arthrodesis of a proximal interphalangeal joint) with a half-limb TC on a forelimb fractured the proximal aspect of the third metacarpal bone 27 days after cast application, 1 horse (that had undergone surgical repair of a fractured third metatarsal bone) with a half-limb TC on a hind limb fractured the proximal aspect of the third metatarsal bone 7 days after cast application, and 1 horse (that had undergone surgical repair of a fractured calcaneus) with a full-limb BC on a hind limb fractured the proximal aspect of the tibia 14 days after cast application.
Frequency of cast complications in 398 horses undergoing application of TCs (n = 345) or BCs* (53) for treatment of various injuries.
Limb position† | TC | BC | Total | ||||||
---|---|---|---|---|---|---|---|---|---|
Half-limb (n = 278) | Full-limb (n = 67) | Half-limb (n = 24) | Full-limb (n = 29) | ||||||
Forelimb | Hind limb | Forelimb | Hind limb | Forelimb | Hind limb | Forelimb | Hind limb | ||
Flexed | 9/12 (75%) | 10/15 (67%) | 0 | 1/1 (100%) | 0 | 0 | 0 | 0 | 20/28 (71%) |
Neutral | 14/32 (44%) | 22/44 (50%) | 2/6 (33%) | 5/10 (50%) | 2/3 (67%) | 0/1 (0%) | 0 | 2/2 (100%) | 47/98 (48%) |
Extended | 39/68 (57%) | 40/93 (43%) | 4/7 (57%) | 21/34 (62%) | 1/6 (17%) | 4/14 (29%) | 0/7 (0%) | 8/19 (42%) | 117/248 (47%) |
Unknown | 3/9 (33%) | 2/5 (40%) | 1/2 (50%) | 6/7 (86%) | 0 | 0 | 0 | 1/1 (100%) | 13/24 (54%) |
Total | 65/121 (54%) | 74/157 (47%) | 7/15 (47%) | 33/52 (63%) | 3/9 (33%) | 4/15 (27%) | 0/7 (0%) | 11/22 (50%) | 197/398 (49%) |
Data are number of horses with cast complications/total number of horses with a cast for each combination of variables (%).
Traditional casts consisted of a stockinette, resin-impregnated foam, and fiberglass casting tape and BCs consisted of fiberglass casting tape placed over a compressed cotton bandage.
Limb position in the cast (flexed [ie, flexion of metacarpophalangeal or metatarsophalangeal {ie, fetlock} and proximal and distal interphalangeal joints], neutral [ie, alignment of the dorsal cortices of the phalangeal and third metacarpal or metatarsal bones], extended [ie, extension of fetlock and proximal and distal interphalangeal joints], or unknown [limb position in the cast was not reported]).
n = No. of horses.
The most common cast complication was cast sores, which developed in 179 of 398 (45%) horses; 165 of 345 (48%) horses with a TC and 14 of 53 (26%) horses with a BC developed cast sores. Thirty of 52 (58%) horses with a full-limb TC on a hind limb had cast sores, which was the configuration with the highest percentage of cast sores; the cast sore for 17 (57%) of those horses was at the level of the proximal aspect of the tibia. For horses with half-limb TCs, the location with the highest frequency of cast sores was at the most proximal aspect of the cast (62/278 [22%] horses). Overall, the location with the highest frequency of cast sores in horses with any type of TC was the palmar or plantar aspect of the fetlock region (44/345 [13%] horses). Cast sores of a heel bulb were detected in 14 (4%) horses of the present study. Cast sores were detected less frequently at other locations, including the palmar or plantar aspect of the metacarpal or metatarsal region (n = 5 horses), lateral or medial malleolus of the tibia (4), calcaneus (4), middle of the plantar aspect of the metatarsal region (2), coronary band (2), and proximal aspect of the radius, accessory carpal bone, palmar aspect of the region from the coronary band to the proximal aspect of the first phalangeal bone (ie, pastern), and dorsal aspect of the carpal joint region (1 each).
The median time to detection of complications for horses with any type of cast was 12 days (range, 1 to 97 days). The median time to detection of complications for horses with a TC was 12 days (range, 1 to 97 days). For horses with half-limb TCs, median time to detection of complications was 12.5 days (range, 2 to 97 days; 12 days [range, 2 to 44 days] for forelimbs and 13 days [range, 2 to 97 days] for hind limbs]). For horses with full-limb TCs, median time to detection of complications was 10.5 days (range, 1 to 27 days; 13.5 days [range, 8 to 20 days] for forelimbs and 9.5 days [range, 1 to 27 days] for hind limbs). The median time to detection of complications for horses with a BC was 8 days (range, 1 to 28 days). For horses with half-limb BCs, median time to detection of complications was 14 days (range, 4 to 25 days; 14 days [range, 8 to 20 days] for forelimbs and 10.5 days [range, 4 to 25 days] for hind limbs). For horses with full-limb BCs, median time to detection of complications was 8 days (range, 1 to 28 days); all such horses had casts on hind limbs.
Casts of 20 of 398 (5%) horses broke (17/345 [5%] horses with a TC and 3/53 [6%] horses with a BC). Full-limb TCs on hind limbs broke more frequently (8/52 [15%] horses) than did any other cast configuration. Casts broke in the fetlock joint region for 4 of 278 (1%) horses with a half-limb TC. The bottom of the cast (ie, portion of the cast distal to the foot) broke for 3 half-limb TCs on a forelimb, 1 full-limb TC on a hind limb, and 1 half-limb BC on a hind limb. The location of the cast breakage was not recorded for 4 horses of the present study. The median time to breakage for any cast configuration was 4.5 days (range, 0 to 36 days). The median time to breakage for TCs was 4 days (range, 0 to 36 days). For half-limb TCs, median time to breakage was 7 days (range, 3 to 36 days; 12 days [range, 4 to 36 days] for forelimbs and 5.5 days [range, 3 to 11 days] for hind limbs). For full-limb TCs, median time to breakage was 3 days (range, 0 to 28 days; 1 day for the 1 horse with a forelimb cast of this type and 3 days [range, 0 to 28 days] for casts of this type on hind limbs). The median time to breakage of BCs was 5 days (range, 3 to 20 days). A cast broke for only 1 horse with a half-limb BC on a hind limb; time to cast breakage for this horse was 3 days. For full-limb BCs, median time to breakage was 12.5 days (range, 5 to 20 days); all casts of this type were on the hind limbs of horses.
The median number of casts applied to limbs of each horse was 1 (range, 1 to 8 casts); the median number of casts for any cast configuration was 1, except for horses with full-limb TCs (median, 2 casts). Number of casts ranged from 1 to 8 for horses with half-limb TCs on forelimbs, 1 to 7 for horses with half-limb TCs on hind limbs, 1 to 5 for horses with full-limb TCs on forelimbs, 1 to 4 for horses with full-limb TCs on hind limbs, 1 to 2 for horses with half-limb BCs on hind limbs, 1 to 2 for horses with full-limb BCs on forelimbs, and 1 to 3 for horses with full-limb BCs on hind limbs; all horses with a half-limb BC on a forelimb had 1 cast.
Overall, median time to removal or change of the first cast was 15 days (range, 0 to 75 days). Median time to removal or change of the first cast was 15 days (range, 0 to 75 days) for horses with TCs and 11 days (range, 1 to 32 days) for horses with BCs. For horses with half-limb TCs, median time to removal or change of the first cast was 15 days (range, 1 to 75 days; 16 days [range, 1 to 56 days] for forelimbs and 15 days [range, 2 to 75 days] for hind limbs). For horses with full-limb TCs, median time to removal or change of the first cast was 15 days (range, 0 to 50 days; 9 days [range, 1 to 24 days] for forelimbs and 16 days [range, 0 to 50 days] for hind limbs). For horses with half-limb BCs, median time to removal or change of the first cast was 10 days (range, 1 to 26 days; 14 days [range, 3 to 20 days] for forelimbs and 9 days [range, 1 to 26 days] for hind limbs). For horses with full-limb BCs, median time to removal or change of the first cast was 11 days (range, 1 to 32 days; 10 days [range, 1 to 21 days] for forelimbs and 11 days [range, 5 to 32 days] for hind limbs). Multiple casts were applied for 149 horses; 114 horses had 2 casts, 27 horses had 3 casts, 4 horses had 4 casts, 2 horses had 5 casts, 1 horse had 7 casts, and 1 horse had 8 casts.
For TCs, hospital (P = 0.029), limb position in the cast (P = 0.008), and sex (P = 0.002) were identified as significant risk factors for the development of cast complications. Horses treated at Purdue University had significantly (P = 0.026; OR, 1.9) higher odds of developing cast complications versus horses treated at all other hospitals. Horses treated at Iowa State University had significantly (P = 0.034; OR, 2.2) higher odds of developing cast complications versus horses treated at the University of Missouri. Horses treated at Purdue University had significantly (P = 0.008; OR, 2.4) higher odds of developing cast complications versus horses treated at the University of Missouri. No other differences between hospitals were detected regarding odds of cast complications in horses.
Horses that had the casted limb in a flexed position had significantly (P = 0.004; OR, 4.1) higher odds of developing cast complications versus horses with a casted limb in any other position. Horses with the casted limb in a flexed position had significantly higher odds of developing a cast complication than did horses with the casted limb in an extended (P = 0.003; OR, 4.5) or a neutral (P = 0.005; OR, 4.6) position.
Geldings were significantly (P < 0.001; OR, 2.7) more likely to develop cast complications versus sexually intact males and females combined. Geldings were significantly more likely to develop cast complications than were sexually intact females (P = 0.006; OR, 2.1) or males (P = 0.002; OR, 3.1).
Discussion
Forty-nine percent of horses with a cast in the present study developed a complication. Clinical signs attributable to cast complications were detected prior to cast removal for 77% of horses with such complications. Cast sores were the most common complication, developing in 26% of horses with a BC and 57% of horses with a TC. In another study,9 57 of 70 (81%) horses with a half-limb cast developed cast sores, which was higher than the percentage of horses with a TC in the study reported here that developed a cast sore. In that other study,9 investigators prospectively examined horses for cast sores, including superficial sores. Those investigators may have been more likely to detect cast sores than were clinicians who evaluated horses with routine clinical problems in the study reported here. Another difference between this study and the other study9 was that investigators in that other study applied cotton padding on limbs, followed by a layer of plaster of Paris before applying fiberglass cast tape. Casts for horses of the study reported here included resin-impregnated foam padding, which decreases the development of cast sores.6 Use of thermography may aid in the identification of cast sores prior to cast removal, which may decrease complications attributable to casts.9
The most common location of cast sores was the proximal aspects of casts and fetlock joint regions. Motion of tissues at the top of a cast is unavoidable, and sores commonly develop at such sites. Changes in fetlock joint angle during weight bearing can increase pressure on the palmar or plantar aspect of the fetlock joint region and cause sores in horses with a cast. Such fetlock joint motion can be exacerbated in horses with disrupted flexor tendons or ligaments on the palmar or plantar aspect of a limb. Even after surgical repair, tendon or ligament tension can gradually decrease because of tearing of sutures through the tissue, which results in progressive extension of the fetlock joint.16,17 Such fetlock joint extension may be prevented via application of casts to limbs in a flexed position.
Results of the present study indicated that limb position was a significant variable for the development of complications in horses with TCs. Complication rates were substantially higher (71%) for horses with limbs in a flexed position in casts than they were horses with limbs in other positions in casts. Eighteen of the 28 (64%) horses for which limbs were casted in a flexed position had injuries to the palmar or plantar supporting structures (ie, flexor tendons and ligaments on the palmar or plantar aspect of a limb). Such horses may be predisposed to development of complications regardless of limb position in a cast because of limb instability caused by the initial injury. Cast sores also developed at other locations in horses of the present study. Some cast sores may have been attributable to inadvertent focal application of pressure by the clinician during cast application, focal swelling associated with the injury, or insufficient amount or uneven distribution of cast padding material.
Only 3 of 398 (0.8%) horses in the present study developed a secondary fracture attributable to the cast. To our knowledge, no other studies have been conducted in which the incidence of such fractures was determined. In the present study, all casts were applied in accordance with current clinical recommendations; half-limb casts extended from the foot to the proximal aspect of the metacarpal or metatarsal region, and full-limb casts extended from the foot to the level of the proximal aspect of the radius or tibia. Casts that end at the mid-diaphyseal region of a long bone increase the risks for development of secondary fractures and tendon and ligament injuries in horses.5
Casts of 5% of horses in the present study broke. The fetlock joint region and bottom of the cast were the most common sites of cast breakage. Damage to the bottom of a cast can be prevented via application of acrylic to that area. Casts are subjected to bending forces in the fetlock joint region; therefore, breakage of casts at that location may be expected. Cast breakage was most common for full-limb TCs on the hind limbs of horses (8/52 [15%] horses). Bending forces in the region of the tarsal joints may increase the risk of cast breakage at that location.
Cast complications developed in horses during a short period. Median times to detection of complications were 12 days for TCs and 8 days for BCs. The reason for rapid development of BC complications was not known. Bandage casts may have been applied for horses that had wounds with severe soft tissue swelling. An increase in soft tissue swelling could have increased pressure on the skin; a decrease in swelling could have caused loosening of the BC. Bandage material in BCs might have moved or compressed after application, which may have caused a focal increase in pressure on soft tissues, lack of protection of soft tissues, or instability of the portion of the limb in the BC. Overall, horses with BCs had fewer complications than did horses with TCs; however, complications for horses with BCs were detected earlier after cast application than they were for horses with TCs.
Overall, median time to removal or change of the first cast was 15 days (range, 0 to 75 days); median time to removal or change of the first cast was also 15 days for TCs. This period was shorter than expected. The reason for the short times to removal or change of the first cast was not identified. This finding may be attributable to the early detection of complications (median time to detection of complications, 12 days). In the present study, the time to development of cast complications was defined as the time from application of the first cast to detection of complications. Only 9 horses with cast complications developed those complications after the first cast change; complications were detected for these horses during the period they wore the second cast.
Results of the present study indicated that 34% of horses with BCs developed complications, compared with 52% of horses with TCs. This result was expected because BCs are heavily padded; however, our results did not suggest that BCs rather than TCs should be applied to horses. Bandage casts are typically applied for horses in which the amount of limb immobilization required is less than that attained with a TC and greater than that attained with a bandage.5 In the study reported here, BCs were less commonly applied to horses than were TCs and only 13% of horses had BCs. The majority (76%) of horses with BCs had casts for external coaptation of soft tissue injuries; such injuries were predominantly (87%) lacerations.
Results of the present study indicated that the hospital where horses were treated was a significant variable for risk of complications for horses with TCs. Variables regarding selection of cases could not be evaluated retrospectively. Horses with less severe injuries requiring less complicated care may have been treated at some of the hospitals in the present study.
Some complications of horses that may have affected outcome were not evaluated in the present study. Horses were not evaluated for the detection of osteopenia, decreased range of motion of joints, or cartilage thinning; all of these complications can develop after immobilization of limbs with casts.11–14 Contralateral limb support is typically provided for horses to decrease difference in foot height between limbs with casts and those without casts; this is intended to decrease complications.8 Elevation of the contralateral foot was not evaluated as a variable for risk of development of cast complications in the study reported here.
Results of another study9 (conducted prospectively) that included 70 horses with casts indicated that increasing age, weight, limb swelling, time in a cast, and number of casts applied to a horse were significant risk factors for development of cast complications. All of those variables were evaluated in the study reported here, but results indicated that none of them were significant risk factors for the development of cast complications. The present study included horses treated at 4 hospitals by an unknown number of veterinarians; approximately 5.5 times as many horses were included in the study reported here as in the other study.9 Variations among data in the retrospective study reported here may have decreased the ability to detect risk factors for development of cast complications associated with 1 hospital or group of veterinarians.
ABBREVIATIONS
BC | Bandage cast |
TC | Traditional cast |
Custom support foam, 3M Healthcare, Saint Paul, Minn.
Excel, Microsoft Corp, Redmond, Wash.
SAS, version 9.3, SAS Institute Inc, Cary, NC.
PROC GLIMMIX without a RANDOM statement, SAS, version 9.3, SAS Institute Inc, Cary, NC.
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