Distribution, Complications, and Outcome of Footpad Injuries in Pet and Military Working Dogs*
This study reports the findings of 120 traumatic pad injuries in pet and military dogs. Most dogs (68%) presented with a laceration to a thoracic limb footpad, and one-third of dogs were middle-aged castrated males. Metacarpal pads were most commonly injured. Short-term complications were noted in 27% of dogs. No long-term complications were identified. No disability from pad injury was present at the completion of healing. Concurrent injuries to adjacent structures were uncommon and did not affect outcome. Dogs with full-thickness pad lacerations were at greater risk for major short-term complications compared to dogs with partial-thickness pad lacerations (odds ratio, 7.27; P = .001). Military working dogs with full-thickness pad lacerations were at greater risk for major short-term complications than pet dogs with a similar injury. When major complications developed in dogs with full-thickness pad injuries, time to final healing was significantly longer (by a median of 12 days). The partial-thickness pad lesions healed uneventfully regardless of whether they were bandaged, surgically repaired, or left to heal by second intention. Suture repair and bandaging of full-thickness lesions could not be shown to either decrease the risk for complications or improve healing. Future work should focus on establishing standards for footpad treatment to reduce complications.
Introduction
Traumatic canine distal limb wounds are a frequent cause for presentation at the Colorado State University Veterinary Teaching Hospital and are consistently reported in working dog populations after large-scale disaster rescue operations.1–4 Limb wounds can involve any number of the distal limb structures that are important for normal limb function. Footpads are the contact surface for weight bearing and are at risk for injury during limb loading. Either partial or complete loss of this durable pad tissue can result in total loss of limb function.3,5 Preserving or repairing injured footpad tissue is an important goal in medical and surgical treatment of pad injuries because preservation/repair greatly influences function, comfort, and cosmesis in dogs.6
Pad injuries are caused by a wide range of insults, including burns, abrasions, lacerations, avulsion, and amputation. Injuries can be either limited to the pad or involve other regional structures including skin, tendon, bones, joints, or neurovascular structures. Pad healing can be complicated by the extent of injuries, the mechanism causing the injury, and/or presence and extent of contamination.6–9 Contact with environmental surfaces predisposes pad wounds to a greater likelihood of contamination, which may increase the potential for complications compared to skin wounds in other areas of the body. Additionally, pads are subject to stresses (including tension, shear, and compression) during weight bearing, which can lead to delayed healing or repair failure.3,9
Healthy footpads are able to resist the forces of weight bearing due to the specialized nature of the skin structure.10 Compared to the adjacent skin, pads contain an increased amount of keratinized epidermis (stratum corneum) suitable to resist those forces.8 A fibrous dermal layer contributes strength to resist the tension and shear forces generated during weight bearing and motion. The deeper fibroadipose layer acts as a dermal cushion (Figure 1) to distribute the compressive force. Full-thickness skin around the pad may, in some cases, be able to adapt to function similar to pad tissue, but it is generally accepted that adjacent skin, particularly epithelialized tissue, is not consistently a suitable replacement for lost pad tissue, especially in active larger dogs.5 Whenever possible, pads should be properly preserved, protected, and/or repaired.
Citation: Journal of the American Animal Hospital Association 51, 4; 10.5326/JAAHA-MS-6193
Neither injury-descriptive nomenclature nor treatment principles for pad injuries have been clearly standardized or defined in the literature. Many veterinary surgical texts contain some information for the diagnosis and treatment of pad injuries, but the information is sparse and often contradictory.7,9,11–13 Despite the importance of pad tissue to the overall function of the limb, very little has been published about causes, treatment, complications, and outcome of canine pad injuries that were not deliberately applied for a controlled study of healing. Multiple sources report information about successful tissue transfer for either substantial or complete pad loss as a result of trauma or tumor resection.1–3,14–22 To date, few clinical studies provide information about the cause, distribution, and/or outcome after treatment of traumatic pad injuries. There is lack of reported clinical evidence regarding cause, depth, and distribution of pad injuries in dogs, as well as how those factors influence wound healing, complication rate, and outcome. Evidence-based clinical reports as well as proven treatment recommendations are lacking from which to make solid clinical treatment recommendations. The focus of this study was to investigate traumatic pad injuries in dogs treated in a clinical setting.
The purpose of this study was to describe causes, distribution, depth, extent of injury, case management, concurrent injuries, complications, and outcomes of traumatic pad injuries. The goal of this study was to obtain a better understanding of factors that influence the healing of pad injuries in a series of pet and military working dogs presenting for treatment of traumatic pad injuries. The primary hypotheses were that all pad injuries would have a similar outcome, risks for short- and long-term complications, and healing time regardless of cause, location, or treatment. The secondary hypothesis was that pad injuries would be equally distributed regardless of limb, pad, or injury cause.
Materials and Methods
A database search of the medical records stored at the Colorado State University Veterinary Teaching Hospital was performed to identify any potential cases of traumatic pad injuries from June 1998 to August 2010. A similar search was performed of the medical records repository stored at the LTC Daniel E. Holland Military Working Dog Hospital to identify any military working dogs (i.e., retired, adopted, deceased) with traumatic pad injuries during that time frame. The injured pets were treated through the emergency and specialty services at the Colorado State University Veterinary Teaching Hospital. The military working dogs were evaluated and treated by a US Army Veterinary Corps Officer (at the nearest veterinary treatment facility to the military working dog's location at the time of injury). A pad injury was defined as any insult to one or more pads that resulted in damage to, or a loss of, any of the pad tissue. If the record described injury to structures around, but not including, the pad tissue, that record was excluded.
The medical record of each patient was reviewed to gather signalment, determine cause and location of injury, extent of injury, concurrent injuries, complications, case management, and outcome. Details regarding clinical signs (i.e., lameness, pain, wound description), diagnostic testing (blood work, culture results), treatment details (wound lavage, debridement, surgical repair, bandage/splint placement, type and amount of administered/prescribed medications), and follow-up examinations were recorded whenever available in the medical record. Healing of the injury was based on information describing a wound that had progressed through the three wound healing phases, visually had dermal continuity as well as the appearance of a return of strength. At times the records did not contain an assessment of “healed wound” but described or documented a healing process that appeared to have reached an end point that we called “Healing”. Injury descriptions (Figure 2) were categorized as either partial (i.e., injury through cornified epithelium and into, but not through, the dermis) or full thickness (i.e., injury extending through dermis exposing the fibroadipose tissue). The injuries were further categorized by injury type (i.e., burn, abrasion, laceration, avulsion, other), and any concurrent injuries were noted. Wounds were categorized as those that were or were not bandaged during the healing phase. Wound closure was categorized into one of two groups based on whether the injuries were allowed to heal by second intention (no closure) or the injuries were repaired (closure). Specific details regarding suture technique were sparsely recorded in the medical records. Repair with a single-layer closure involved placement of appositional to slight everting sutures (i.e., interrupted, cruciate, or mattress through the dermis) or sealing of the wound with tissue adhesive. Double-layer closures involved placement of a deep suture (i.e., interrupted, cruciate, or mattress suture) layer in the fibroadipose tissues and a superficial suture layer through the dermis as described for single-layer closures. Size of the tissue bites taken while suturing pad lacerations was generally not recorded.
Citation: Journal of the American Animal Hospital Association 51, 4; 10.5326/JAAHA-MS-6193
The case outcome was documented with the date that resolution occurred. When records or follow-up notes were incomplete, the referring veterinarian and/or owner were contacted by phone to discuss treatment, complications, and outcome of the case (patients of the Colorado State University Veterinary Teaching Hospital). Any subsequent examination information available in the patient's medical record was utilized to record outcome when a follow-up examination was not available. The date of resolution was documented as the date when the injury on the master problem list was closed, the problem was not listed at the next physical examination/assessment, or was based on owner recollection. A final healing time (recorded in days) was determined from the difference between the dates of injury and resolution. The influence of short- (i.e., <45 days) and long-term complications on outcome was evaluated. A major complication was defined as an event that required presentation for treatment and that affected healing (e.g., premature removal of sutures/bandages, self-trauma, complete epidermal pad sloughing, infection, second intention healing, persistent lameness with a protracted length of activity restriction). A minor complication was defined as an event that might require presentation for treatment but that did not directly affect healing (e.g., a wet bandage, patient removed bandage, a dog licking at the wound without creating additional injury, limited epidermal layer pad sloughing, refocused emphasis on activity restriction/Elizabethan collar use).
Statistical Analysis
A commercially available statistical software package was used for the statistical analysisa. A descriptive analysis was conducted on signalment data from the studied dogs. Continuous data were presented and summarized using either means and standard deviation or median and interquartile range according the data distribution. Categorical data were presented and summarized as proportions. Associations between type and depth of injury (i.e., partial- versus full-thickness lesions) and factors influencing healing (i.e., signalment, treatments performed, complications observed) were evaluated using standard cross tabulation (2 × 2 tables). The risk of experiencing a complication was compared among groups (i.e., partial- versus full-thickness lesions), odds ratios were calculated, and the appropriate test was used (either chi-square or Fisher exact test) to evaluate associations between healing and lesion depth. Multivariate logistic regression analysis was performed to evaluate the influence of multiple factors on the short- and long-term outcome. Statistical significance was set at P < .05 for all comparisons.
Results
Database interrogation identified 120 pad injuries [68 injuries in 63 pet dogs (Colorado State University Veterinary Teaching Hospital) and 52 injuries in 40 military working dogs (LTC Daniel E. Holland Military Working Dog Hospital)]. Overall, 26, 555 animals were presented for evaluation through the Colorado State University Veterinary Teaching Hospital emergency service and 9,894 animals were presented for a scheduled evaluation during the searched period. There were 964 records from retired/adopted/deceased military working dogs that were available for review and had medical record entries during the search period. The two populations were combined for analysis. Included dogs had a mean age of 4.15 ± 2.85 yr (median, 3.18 yr; range, 0.19–15.96 yr) and a mean body weight of 31.5 ± 8.40 kg (median, 32 kg; range, 7–56 kg) at the time of presentation for evaluation of the pad injury. Breeds represented included the German shepherd dog (n = 26; 22%); Labrador retriever (n = 25; 21%); Belgian Malinois (n = 23; 19%); mixed-breed (n = 15; 13%); Australian shepherd and Dutch shepherd (n = 4 of each; 3%); Akita, Staffordshire bull terrier, and Saint Bernard (n = 3 of each; 3%); Great Dane, Doberman pinscher, golden retriever, and husky (n = 2 of each; 2%); and Bernese mountain dog, boxer, Newfoundland, pug, Shetland sheepdog, and vizsla (n = 1 of each, 1%). There were injuries identified in 56 castrated males (47%), 30 males (25%), 24 spayed females (20%), and 10 females (8%) identified. Of the military working dogs, there were injuries identified in 28 castrated males (23%), 15 males (13%), and 9 spayed females (8%). Of the pet dogs, there were injuries identified in 28 castrated males (23%), 15 males (13%), 15 spayed females (13%), and 10 females (8%). Males represented 72% of the cases, and 47% of the overall injuries occurred in castrated males. Spayed/castrated dogs represented 67% of the injury population. Age, body weight, breed, and sexual status were not statistically associated with the depth, cause, or location of injury, complications, or final outcome.
The mechanism of pad injury included lacerations (n = 101; 84%), abrasions (n = 12; 10%), burns [n = 2 thermal (2%) and n = 1 chemical (1%)], crack (n = 1), puncture (n = 1), avulsion (n = 1), and unknown (n = 1). Pad injuries were most commonly due to lacerations of a thoracic limb metacarpal or digital footpad. In term of limb, the injured pad(s) were on 46 right thoracic limbs (38%), 36 left thoracic limbs (30%), 13 left pelvic limbs (11%), and 7 right pelvic limbs (6%). There were 15 injuries in which multiple limbs were involved (13%), and the affected limb was not recorded in 3 cases (3%). The location of the injured pad varied, occurring on 44 metacarpal pads (36%), 37 digital pads [31%, including 13 fifth digital pads (11%), 10 fourth digital pads (8%), 8 second digital pads (7%), 5 third digital pads (4%), and 1 first digital pad (1%)], 14 carpal pads (12%), and 9 metatarsal pads (8%). Multiple pads were involved in 9 injuries (8%), and the specific pad affected was not recorded in 7 dogs (6%). There were 67 full-thickness injuries (56%) and 49 partial-thickness injuries (41%). Depth was not recorded in 4 dogs (3%).
Dogs were 4.1× more likely to have an injured thoracic limb and were 1.5× more likely of experiencing a full-thickness injury (P < .024) when a thoracic-limb injury occurred. Dogs were 5.1× more likely to sustain a laceration injury to a footpad (compared to all other causes) and 7.3× more likely of sustaining a full-thickness injury than a partial-thickness laceration (P < .0006).
The true cause of the injury was often unknown but frequently suspected to be due to trauma from a sharp object (e.g., lawn edging, glass fragments, barbed wire). Partial-thickness injures attributed to contact with hot surfaces (e.g., asphalt) were observed in the military working dog population but not similarly described in the pet population. No information was available in the medical records describing the use (or lack of use) of paw protection.
Treatment was at the discretion of the attending clinician and involved a variety of singular or multiple interventions, including hair coat clipping/wound cleaning/debridement (n = 75; 63%); bandaging [n = 80 (67%), including n = 12 with splints (10%)]; suturing [n = 49 (41%), including n = 35 with a single layer (29%), n = 12 with a double layer (10%), and n = 2 that were poorly described (2%)]; topical applications (n = 22; 18%) with nystatin/neomycin/ thiostrepton/triamcinolone ointmentb,c, medical hydrolysate of type I collagen in gel formd, compound tincture of benzoine, triple antibiotic ointment, silver sulfadiazine creamf (or an equivalent product), or a combination of topical therapies; and/or repair with tissue adhesiveg (n = 8; 7%). Hair coat clipping and wound cleaning were performed in a standard fashion (e.g., wound flushing performed with either fluidh and with or without 1% povidone-iodine solutioni or chlorhexidermj in water. Seventy-five dogs (63%) had the wound clipped, cleaned, and/or debrided prior to repair (n = 49; 41%) and bandaging (n = 80; 67%). Extent of wound debridement was poorly documented in the records. Dogs that sustained a full-thickness wound had a 3.55× greater odds of having a bandage placed (P = .009) and a 12× greater odds of having a suture closure than a partial-thickness wound (P < .0001). Suture material used for closure varied and included polyglyconatek (principally in the deep layer of two-layer closures), glycomer 631l (used rarely in deep layer), tissue adhesive (either alone or to seal sutured closure), and nylonm, which was the predominate choice for the superficial layer. Suture size used varied from 4-0 to 2-0 in both types of closures.
Five dogs (4%) had the site of injury cultured, and organisms were isolated from four of the five wounds. Isolated organisms included methicillin-resistant Staphylococcus aureus, methicillin-resistant Staphylococcus pseudintermedius, Pasteurella multocida, Enterobacter spp., Serratia spp., and Pseudomonas spp. Oral antibiotic therapy (either empirical or, infrequently, culture based) was instituted for 72 dogs (60%). Drugs dispensed included cephalexin, amoxicillin ± clavulanate potassiumn, or marbofloxacino, and administration ranged from 5 to 15 days of therapy. Nonsteroidal anti-inflammatory treatmentp,q was administered in 22 dogs (18%), and other pain medications (including oral butorphanolr, tramadol, and/or hydromorphone) was administered to 17 dogs (14%).The duration and frequency of therapy were rarely documented. No statistical difference was found when comparing treatment method, location/type of injury, or presence of short-term complication.
Short-term complications were recorded in 32 dogs (27%). There were no identified long-term complications. Seventeen dogs (14%) developed major complications, and 15 dogs (12.5%) had minor complications. Full-thickness lacerations occurred in 64 dogs (53%). Of those, 15 dogs (12.5%) experienced major and 7 dogs (6%) experienced minor short-term complications. Partial-thickness lacerations occurred in 33 dogs (27.5%), and 0 dogs experienced a major and 4 dogs (3%) experienced minor short-term complications. Short-term complications (major and minor) for all wounds included bandage related problems (11%), self-trauma/dehiscence (10%), suspected infection (6%), second intention healing (6%), slow to resolve lameness (5%), interdigital dermatitis (3%), delayed healing (3%), and sloughed pad tissue (2%). One major complication occurred in a dog with a laceration, but the medical record was unclear about how the wound was treated or the depth of the injury. One dog with a partial-thickness abrasion injury experienced a major complication that resulted in the delay of cornified epithelialization on multiple pads. The major complications occurred in the thoracic limbs in 16 out of 17 dogs (94%). The risk of development of major complications for full-thickness laceration injuries (n = 15; 23%) was statistically different than partial-thickness laceration injuries (n = 0; 0%). The risk of development of minor complications for partial (n = 4; 3%) and full-thickness (n = 7; 6%) laceration injuries was not statistically different (odds ratio, 0.819; P = .765). Complications were not statistically influenced by suture closure of wounds or bandaging of the affected limb. The study authors found that military working dogs have 3.42× greater odds of complications from full-thickness lacerations compared to pet dogs. Seven out of 17 military working dogs (41%) compared to 8 out of 47 pet dogs (17%) had major complications with full-thickness injuries.
All dogs with a final outcome determination were sound on the injured limb(s), and all wounds had healed (even those that experienced either a major or minor short-term complication). Follow up was lost for 13 dogs (11%) due to incorrect/incomplete owner or referring veterinary information.
A concurrent injury extending beyond the pad was sustained in 17 dogs (14%). Of those, 13 injuries were adjacent skin lacerations, 2 were adjacent skin abrasions, 1 involved a deep puncture/laceration distal to the pad, and 1 involved a digital tendon laceration. The concurrent injuries did not have an association with outcome or complications (i.e., the low number of concurrent injuries hindered statistical analysis). Two dogs (2%) with concurrent injuries had major complications, and 3 dogs (2.5%) had minor complications during healing. No statistical association was found between concurrent injury and risk of development of either minor or major complications.
The date of resolution was recorded in 52 dogs (43%). Incomplete medical records (due to lack/loss of follow up, absence of problem list utilization, and/or failure to inactivate entered problems) prevented exact determination of the date of resolution in the remainder of the cases. Days to final healing were determined from the group of dogs with resolution information (Table 1). Analysis revealed that values for days to final healing were not normally distributed. The data was heavily influenced by a segment of the study population that had an examination (for a separate problem) at some time point after the injury but no re-examination as directed (at either the initial or subsequent visits) within the expected timeframe for resolution. This separate problem examination date was entered as the date of resolution. The study population had an approximately normal distribution if a cut-off value of 45 days was used to exclude outliers. One-way analysis of variance (of the adjusted group of dogs) comparing days to final healing and complications revealed a significant difference among groups (P < .0047) with the Kruskal-Wallis equality of populations rank test. Regression analysis showed a statistically significant difference in median days to final healing (P < .0001) comparing the laceration-caused injuries that experienced no or minor complications to the group that developed major complications. The median days to final healing of the combined no/minor complications was 17.3 ± 7.83 days and for the major complications it was 29 ± 7.98 days. Unbandaged partial-thickness wounds that were sutured had an average 14.6 days to resolution, which was similar to those that were left unsutured (14.5 days). Sutured and bandaged full-thickness lacerations that had no short-term complications had an average of 17 days to resolution, which was similar to those that were left unsutured (18.3 days). In contrast, sutured and bandaged full-thickness lacerations that had major short-term complications had an average of 30.3 days to resolution, which was not statistically different from those that were left unsutured (38.5 days).
Discussion
In this retrospective study, the focus was on traumatic pad injuries in clinical patients because no clinical studies investigating pad injuries in pet dogs appears to be published. The study authors found that the majority of the injuries reported in this study occurred in middle-aged castrated male dogs from an injury causing a laceration (largely suspected to have occurred from stepping on a sharp object such as glass fragments and/or for pet dogs on metal lawn edging). Injuries were more likely to occur in the thoracic limbs and to affect the metacarpal footpads more frequently than the digital footpads. Injury distribution may be related to the fact that the thoracic limbs explore the environment earlier than the pelvic limbs and is at least partially explained by a reported study that showed greater load bearing in the thoracic limbs (particularly by the metacarpal pads compared to other pads in the forelimb and pads in the pelvic limb).23
The study authors reject the primary (similar outcomes) and secondary (similar distribution) hypotheses. The results reveal that all pad injuries eventually healed and had a similar successful outcome without long-term disability independent of cause, location, and treatment. Short-term findings reveal that full-thickness injuries had significantly higher odds (14.67; P = .013) for major complications prior to complete healing compared to partial-thickness injuries. An emphasis on education of owners about the risks and prognosis for short-term complications is recommended to ensure quality monitoring and prevent excessive costs for care. Injuries were not equally distributed across all pads but were more likely to occur in the thoracic limbs and to be laceration injuries.
Working dogs are at risk of experiencing pad injuries in the performance of their duties, and that risk may be influenced by applied paw protection. In a study of working dogs that were utilized in the Oklahoma City federal building bombing, 28% of dogs incurred injuries. Of those, 90% of the injuries were associated with the footpad, and only 16 out of 69 working dogs had paw protection).1 The mechanism of injury in this report was suspected to be due to sharp objects (e.g., glass or metal fragments), but the depth of the injuries was not reported. Information on a subgroup of search dogs reported that lacerations occurred on the thoracic limbs in six out of eight dogs. Half of the lacerations were repaired with cyanoacrylate to seal the pads. No data were available that documented complication rate, healing time, or eventual outcome in that report. More recent studies looking at working dogs employed after the September 11, 2001 terrorist attack reported that injuries to the feet, pads, or limbs accounted for 70–80% of wounds and that 35–40% of the dogs experienced a cut or abrasion to a pad.2,4 Very little detailed information was included about cause, depth, distribution of the injuries. Those study authors, however, did report that two injuries were sutured (one was a laceration above a footpad and the second was a metacarpal pad) and that two dogs had abrasions in combination with heat or chemical burns to pads. One population reportedly experienced a higher incidence of injuries in unprotected paws compared to injured dogs that had paw protection. The decision not to utilize paw protection was related to handler concerns about a perceived negative impact on performance. The authors of this study failed to find any record of paw protection in the dogs reported in the current study and suspect that it was not commonly utilized.
Full-thickness injuries (principally lacerations) were more likely to occur than partial-thickness injuries. Full-thickness injuries were more likely to be sutured than partial-thickness injuries. No reasoning for this difference was reported in the records but the authors suspect that the lack of significant gaping at the injury prompted some of the treating clinicians to leave the partial thickness pad unsutured. When looking at all dogs and all injury causes, the rate of combined short-term complications was not significantly different between dogs that did or did not have a sutured repair. Similarly, pad healing did not appear to be altered significantly whether the bandaged pad lacerations were sutured or unsutured in an experimental study by Newman et al. (1986)6. That study reported healing rates after full-thickness transverse incisions were created in 36 metatarsal footpads. In that injury model, 21 incisions were sutured with a two-layer closure and the remaining incisions were left unsutured. All of the studied limbs were bandaged with a soft, padded bandage that incorporated a metal splint. That study reported little difference in healing (at 16 days) when comparing sutured and unsutured full-thickness lacerations despite including representative images of the healing, which showed marked epidermal gaping in the unsutured group.6 Tensile testing at 16 days postincision determined that both groups had similar wound strength; however, wound strength was significantly lower than the intact control pads. The only differences reported between the incision groups were the presence of wound gaping and that the final cosmesis of the sutured group was superior to the bandage-only group. Those study authors recommend either suturing of lacerations or extensive bandaging. The most commonly affected pad (metacarpal pad) in the current clinical study was different than the experimentally wounded pad (metatarsal pad) in this model; nevertheless, the current study results show no clear advantage (either days to resolution or influence on short-term complications) when pads were sutured versus left to heal by second intention regardless of their depth. In contrast to previous findings of similar healing and complications, the current study author found evidence to reject their primary hypotheses in that injuries that extended through the dermis were at greater risk for complications and resulted in a significantly longer time to complete healing (when complications occurred).
The authors of this study also found that case management of pad injuries was widely variable and was likely dependent on the managing clinician's preference and previous experience. Specific treatment factors could not be found that influenced wound healing and complication rates. That said, treatment may have an influence on the variability in treatments performed or insufficient case numbers may have prevented identification of differences. Prophylactic antibiotic therapy did not influence healing and should be limited to either a single dose or therapy of <24 hr duration.24 The variability in suturing techniques employed may have prevented identification of a benefit in dogs with sutured pad closure versus second intention closure. Nevertheless, the data presented herein do not appear to show a clear benefit to suturing either partial- or full-thickness injuries despite the guideline to repair wounds to speed healing.24 Suture repair and bandage placement were associated with the depth of injury and may be confounding factors in the short-term complications seen. Although the authors of this study found that >30% of the full- and partial-thickness injuries were sutured and bandaged, there was a higher utilization of those treatment modalities with deeper injuries. The placement of sutures or bandaging could have resulted in pain or discomfort to the patient, which manifested as premature bandage removal and self-trauma. Likewise, unlike the wounds that underwent second intention healing, primary repair of contaminated wounds may not have permitted drainage and that may have led to wound dehiscence or infection. Therefore, there may have been management factors that led to complications not entirely due to the manner of closure or the depth of the injury. Concurrent injuries did not appear to influence the healing nor were they prevalent in this patient population.
The pet and military working dog populations were similar in terms of number of cases, distribution, complications, and outcomes. Despite that finding, military working dogs are at an increased risk for major complications from full-thickness laceration injuries compared to the studied pet population. The direct cause of that greater risk is unknown but may be associated with the housing, temperament, or management associated with their working status.
Limitations of this study include its retrospective nature, which could have introduced bias due to an inability to identify eligible cases or the presence of incomplete medical records. The descriptions, treatments, and documentation were not standardized in the medical records and could have introduced errors in categorization of cases. Incomplete, poorly documented, or absent follow up may have prevented correct determination of case outcomes.
Conclusion
This study found that traumatic pad injuries are most likely to be full-thickness lacerations that affect a forelimb footpad, particularly the metacarpal pad. Whether pad wounds were sutured or left to heal by second intention did not appear to influence the short-term complication rate or outcome. However, the greater depth of injury was associated with greater complication risk and longer healing times. These results will help stimulate interest in studying pad injuries with regards to identifying well-substantiated treatment recommendations. The study authors recommend thorough descriptions of injuries and categorization based on location, cause, severity, and depth of injury to guide the treatment process and help determine prognosis. Prospective studies with standardized treatments are needed to prove if a specific suture repair and/or bandaging method improve healing times and reduce complication risk in partial- and full-thickness pad injuries.
A: Photograph of a full-thickness laceration of a digital pad showing the pale dermal layer (arrow) and the fibroadipose layer deep to this tissue (i.e., the reddish pink tissue below the reticular layer in partial shadow). B: Image of the microscopic appearance of the footpad.
A: Photograph of a partial-thickness abrasion injury to a digital pad. B: Photograph of a full-thickness laceration of a metacarpal pad just prior to surgical repair.
Contributor Notes
*The views expressed in this article are those of the authors, and do not reflect the official policy or position of the Department of the Army, Department of Defense, or the US Government.
Kurt M. Hazenfield's updated credentials since article acceptance are MS, DVM, DACVS-SA.
