Proximal Digital Annular Ligament Desmotomy in Horses: A Cadaveric Study

Proximal digital annular ligament (PDAL) desmitis occurs in horses for which PDAL desmotomy is the only reported treatment. The presented work aims to develop a technique for safely performing PDAL desmotomy in horses. Twenty hind limbs and 13 forelimbs, harvested from horses dead or euthanized for reasons unrelated to any structure in the pastern region, were used. All horses were free of disease at the level of their PDAL. Proximal digital annular ligament desmotomy was performed using a minimally invasive approach to the digital flexor tendon sheath between the palmar (plantar) annular ligament and the PDAL, using a medial or a lateral access. Limbs were immediately dissected after the procedure to assess the completeness of the PDAL desmotomy and any possible damage to surrounding structures. The PDAL was successfully transected in all limbs except one. Damage to the surrounding tissue included transection of the palmar digital nerve (n = 1), longitudinal tear of the superficial digital flexor tendon (n = 3), and transection of the ligament of the ergot (n = 21). A medial approach was found to be safer than a lateral approach. In conclusion, PDAL desmotomy can be performed in a safe, repeatable, and technically easy way. This is, to our knowledge, the first report of a standardized technique for performing a PDAL desmotomy in the horse.     

Long-term Outcome of Standing Medial Patellar Ligament Splitting to Manage Horses Exhibiting Delayed Patellar Release: 64 Horses

A standing surgical technique for splitting the medial patellar ligament is described, and the long-term (average 4.5-years) efficacy of the procedure in horses exhibiting delayed patellar release is reported. Medical records of 64 horses that underwent a standing medial patellar ligament splitting surgery performed to treat delayed patellar release were analyzed retrospectively. Horses were sedated in standing stocks. A number 15 scalpel blade was used to percutaneously split the medial patellar ligament from just proximal to its insertion on the tibial tuberosity to its attachment on the parapatellar fibrocartilage, with the goal of inducing a localized desmitis and subsequent thickening of the ligament. Aftercare consisted of oral antibiotics, 14 days stall rest with hand walking, light exercise for 14 days, and full work at 4 weeks. Follow-up information was obtained through telephone calls to owners and/or clinical evaluation by a veterinarian. Results showed that 89% of horses benefitted from the procedure, with complete resolution in 58% of horses and improvement in 31% of horses. A total of 73% of horses were able to perform at the desired level following the procedure; 63% of horses showed signs of improvement or resolution within 30 to 60 days. Two horses had complications following the procedure: 1 horse had an incisional infection, and 1 had a medial patellar ligament rupture. This study shows that standing medial patellar ligament splitting is a successful, long-term surgical option for treatment of delayed patellar release. The procedure has few complications and allows rapid return to desired performance.     

Assessing the Association Between Hoof Thermography and Hoof Doppler Ultrasonography for the Diagnosis of Lameness in Horses

The objectives of this study were to assess the correlation between hoof surface temperature and ultrasonographic measurements of digital blood vessels in horses and to evaluate the measurements' potential as predictors for clinical lameness. Twelve 3-year-old American Quarter Horses, 6 geldings and 6 mares, with average initial body weight of 459 ± 31 kg were used. On days 0, 30, 60, and 90 of the study, horses were weighed and subjected to clinical lameness examinations. Doppler ultrasonography was used to measure diameter of the medial palmar artery in the distal left forelimb and velocity of blood flow through that artery, starting at 60 minutes after morning feeding and repeated at 30-minute intervals. Temperature measurements on the hoof were collected at 15-minute intervals beginning 75 minutes after feeding, using a digital thermographic camera. A series of bivariate linear mixed models were fitted to estimate the correlation between Doppler and temperature measurements. The within-horse and between-horse correlations between hoof surface temperature and velocity of blood flow in the distal limb through the medial palmar artery was estimated at 0.40 (P > .50) and 0.99 (P < .001), respectively. These results indicate that at the horse level, the correlation between hoof temperature and velocity of blood flow in the distal limb was very high but that the within-horse correlation was not significantly different from 0. Velocity of blood flow at 60 minutes after feeding improved model fit to the lameness data, so it was included as a model predictor for lameness.     

Platelet-rich Plasma Combined With a Sterile 3D Polylactic Acid Scaffold for Postoperative Management of Complete Hoof Wall Resection for Keratoma in Four Horses

Keratoma is a nonmalignant horse tumor that grows in the space between the horn of the hoof and the distal phalanx. Keratoma causes lameness in the horse, and surgical excision is the treatment of choice. Four horses underwent removal of a keratoma by complete hoof wall resection. The remaining wound was treated with platelet-rich plasma (PRP) combined with a sterile three-dimensional polylactic acid scaffold. The PRP was applied at 3, 6, 9, 12, 15, and 18 days postoperatively. The surgical site was cleaned with gauzes and swabs soaked in Ringer’s lactate solution before applying PRP and the foot bandage. Healthy granulation tissue developed at 6–21 days postoperatively. The hoof wall defect was completely filled with new hoof wall within 6–8 months after surgery. All horses returned to their previous exercise level, and no recurrence of lameness was reported by the owner.     

Long-Term Follow-up of Superficial Digital Flexor Tendonitis Treated by a Single Intralesional Injection of a ReGeneraTing Agent in 51 Horses

ReGeneraTing Agents (RGTA) are nanopolysaccharides engineered to mimic heparan sulfates and have been shown to stimulate tissue repair and healing (skin, cornea, gingival, and muscle) in several animal models of injury and in human medicine. A preliminary study, monocentric and uncontrolled, was conducted to evaluate the efficacy of a dedicated RGTA (named Equitend) in improving the healing quality of the injured tendon after a single and ultrasound-guided intralesional injection. Improvement of ultrasonographic appearance of tendinous or ligamentous lesion was documented at least over 4 months in Equitend-treated horses and was further supported by another study on superficial digital flexor tendonitis, in 51 horses (16 French Standardbred trotters (ST), 13 Thoroughbreds (TB), and 22 eventers). Long-term follow-up of these horses showed high rates of return to racing, with 95% of eventers, 87.5% of French ST, and 77% of TB. The mean duration before the first race or competition was 6.6 and 7.4 months for ST and eventers, respectively. The group of 16 treated ST was then compared with a matched control group, showing that the Equitend-treated group was able to return to a higher level of earning after lesion (74% vs. 15% in the control group). Furthermore, the Equitend-treated group was back in racing 2.4 months earlier than the control group.     

Clinicopathological Features of Hemangioma in Two Young Horses

The clinicopathological and immunohistochemical features of two vascular tumors in two young horses are described in the present work. These animals were referred to the Veterinary Teaching Hospital of the University of Córdoba because of the presence of hyperpigmented plaques located in the medial aspect of the left leg and also around the hock (case 1) and in the right front leg (case 2). Some of the lesions showed deep ulceration and severe protrusion with abundant bleeding. The histopathological study revealed that lesions were composed of nonencapsulated, proliferated, closely packed small blood vessels, some of which showed irregular shape, whereas others were similar to capillaries, arterioles, and venules. Neoplastic cells expressed vimentin and factor VIIIar, suggesting their endothelial nature, whereas in the wall of some proliferated vessels, some cells expressed vimentin, α-smooth muscle actin and desmin, an immunophenotype consistent with pericytes, and small muscle cells. These features agree with those reported in human juvenile hemangioma rather than with hemangioma in adult horses.     

Incomplete Tears of the Medial Calcaneal Insertion of the Superficial Digital Flexor Tendon of a Hind Limb in Three Horses

Twelve tarsi from six horses humanely destroyed for reasons unrelated to the study were dissected and measurements of the calcaneal insertions of the superficial digital flexor tendon (SDFT) were acquired. The medial calcaneal insertions of the SDFT ranged in length and thickness from 4.0 to 5.4 cm and 0.3 to 0.5 cm, respectively, and the lateral calcaneal insertions ranged in length and width from 4.0 to 6.3 cm and 0.3 to 0.5 cm, respectively. The calcaneal insertions of the SDFT of both hind limbs of six horses with no history or clinical signs of hind limb lameness and no palpable abnormality of the tarsi were examined ultrasonographically. The medial calcaneal insertion of the SDFT was of uniform echogenicity, thickest at the attachment to the SDFT, and smoothly tapering to its insertion on the plantaromedial aspects of the calcaneus. The lateral calcaneal insertion was less echogenic adjacent to the SDFT than the tendon itself but was of similar echogenicity toward the insertion on the plantarolateral aspect of the calcaneus. Three horses with full-thickness incomplete tears of the medial calcaneal insertion of the SDFT had variable enlargement of the calcaneal bursa, an unstable (n = 2) or stable (n = 1) SDFT and lameness. The presence of an extensive but incomplete full-thickness tear of the medial calcaneal insertion of the SDFT was determined ultrasonographically in all horses.     

Desmotomy of the Accessory Ligament of the Deep Digital Flexor Tendon in Horses: An Update

Desmotomy of the accessory ligament of the deep digital flexor tendon is advocated to allow for lengthening of the deep digital flexor musculotendinous unit and axial realignment of the bones of the digit. This procedure has several indications. It can be performed using either the open or the minimally invasive surgical approach. This article describes both surgical approaches. Corrective shoeing before surgery contributes to success in both surgical approaches. The cosmetic results obtained after the minimally invasive procedure are much better as compared with those after the open surgical procedure. The minimally invasive approach compares favorably with results reported after using an open surgical approach and offers the advantages of minimally invasive surgery including reduced incision length, reduced morbidity, and improved cosmetic outcome. The minimally invasive approach may be also performed on the standing sedated horse.     

Ultrasonography of the Collateral Ligaments of the Distal Interphalangeal Joint in Horses: Technique and Reference Images

This study describes ultrasound (US) technique and reference images of the equine distal interphalangeal joint collateral ligaments (CLs), and evaluates the portion of the CLs assessable by US in a series of normal forelimbs. Transverse and longitudinal US images were obtained on five healthy horses and on 25 equine cadaver forelimbs. On six limbs, a needle was placed under US-guidance at the distal limit of visualization of each CL, and the portion of CL visible at US was evaluated on computed tomographic (CT) images. The normal CLs appear as oval structures located abaxial to the fossae of the middle phalanx in the transverse sections, obtained at the level of the coronary band. A centrodorsal hypoechoic image appears with increasing proximodistal probe inclination, demonstrating different fiber orientations within the ligament. Two main fascicles, a deep and a superficial, distally divergent, are visible on longitudinal images obtained in the central part of the ligament. The proportion of CL visible at US examination was more than 50% of the total ligament length in nine of the 12 CLs assessed by CT. Awareness of the estimated portion of distal interphalangeal joint CLs visible at US and detailed knowledge of the US technique and CLs morphology are essential to efficiently use US examination on clinical cases.     

B-Mode Ultrasonographic Abnormalities and Power Doppler Signal in Suspensory Ligament Branches of Nonlame Working Quarter Horses

Information concerning B-mode ultrasonographic abnormalities and power Doppler (PD) signal in suspensory ligament branches of nonlame working Quarter Horses are not reported. The aims of this study were to investigate the prevalence of B-mode ultrasonographic abnormalities and PD signal in suspensory ligament branches in a group of nonlame working Quarter Horses and to compare B-mode findings with PD findings of horses in two different training (barrel racing and team roping). Twenty-one Quarter Horses in training, 14 barrel racing (Group B) and seven team roping horses (Group R), were assessed by ultrasound for screening purpose. A total of 168 suspensory ligament branches were examined (B-mode and PD examinations). B-mode lesions were seen more frequently in forelimbs (25 branches) than in hindlimbs (10 branches). Power Doppler signal was not detected in suspensory ligament branches that were normal at B-mode, whereas it was visible in 22 of the 35 branches abnormal at B-mode. Horses of Group R showed more B-mode abnormalities and more PD signal in branches abnormal in B-mode.     

Replacement of the Medial Collateral Ligament with Polypropylene Mesh or a Polyester Suture in Dogs

The medial collateral ligament of one stifle in 20 adult dogs was excised and replaced with polypropylene mesh or a polyester suture. After 26 weeks, the fibrous tissue-prosthesis composites were evaluated clinically, morphologically, and biomechanically. Clinical lameness was not significantly different after 10 days. The polypropylene mesh reconstructions consistently had more fibrous tissue and greater collagenous ingrowth than the polyester suture reconstructions. There were four complications related to fixation of the polypropylene mesh prosthesis and one to the polyester suture. The polypropylene mesh reconstructions had greater stability and were biomechanically more similar to the natural ligaments than the polyester suture reconstructions. Although the results with polypropylene mesh were favorable, more challenging biomechanical testing and alternative anchoring techniques are required before polypropylene mesh can be recommended as a collateral ligament replacement in dogs.     

Preliminary Examination of Farriery and Hoof Care Practices and Owner-Reported Injuries in Sport Horses in New Zealand

Retrospective management and owner-reported injury data, and measurement of forelimb hoof conformation, were collected via a cross-sectional survey from a convenience sample of 96 registered show jumping (n = 67) and dressage (n = 29) horses. Most of the horses were medium- to upper-level performers, aged 9 (interquartile range [IQR] 7–12) years, and in the current rider's ownership for 28 (IQR 12–60) months. The horses were trained 45 (IQR 35–60) minutes, 6 days per week, on a sand or sand mix arena. Failure to train for ≥7 days was reported in 26 of 96 horses, generally associated with lameness diagnosed by a veterinarian (16/29), with a median time-off of 26 (IQR 14–93) days. During the preceding 12 months, 33% of the riders had been working with the farrier on hoof-related issues, 30% of which had involved ≤2 issues. This remedial work often involved a veterinarian (14/30) or allied health practitioner (6/30). Most horses were hot shod (67/89) with conventional fullered shoes. Uneven feet were identified in 16 of 89 horses but were not positively associated with inability to train, possibly reflecting the minor variation between feet. Uneven feet were associated with variation in heel length and angle measurements and a greater sole length and reduced sole width, rather than smaller and boxy. Multiple correspondence plots identified an association of uneven feet with the dressage horses rather than show jumping horses.     

Management of Subchondral Lucencies of the Medial Aspect of the Equine Antebrachiocarpal Joint

The objective of this study is to describe the management and outcomes of eight horses with subchondral lucencies (SCLs) of the medial aspect of the antebrachiocarpal (ABC) joint. The medical records and radiographs of the carpi of 8 horses with SCLs of the medial aspect of the ABC joint were reviewed. Follow-up clinical information was obtained for 6–60 months (the median duration of 14 months). Treatment was successful if radiographic healing was apparent or lameness was reduced or eliminated. Four horses had SCLs in the distomedial radius (DMR) and four in the proximal aspect of the radiocarpal bone (RCB). Lameness was present in all horses with DMR SCLs and in one horse with an RCB SCL. Treatments included restriction of exercise (n = 3), intra-articular administration of corticosteroids (n = 2), or placement of a screw across the SCL (n = 3). Exercise restriction alone was successful in three nonlame horses younger than one year with proximal RCB SCL and intra-articular corticosteroid administration in the ABC joint in two horses aged 2 years or younger with DMR SCLs. A yearling with a large proximal RCB SCL and two horses aged 5 years or older with DMR SCLs were successfully treated with screw placement across the SCL. Exercise restrictions and intra-articular administration of corticosteroids were successful in management of DMR SCLs in five horses. Placing a screw across the SCL of three horses resulted in resolution of lameness and substantial improvement of the radiographic appearance of the lesion in the RCB or DMR.     

Nutrition and Exercise in the Management of Horses and Ponies at High Risk for Laminitis

Obesity, insulin resistance (IR) and hyperinsulinemia are risk factors for laminitis in horses and ponies. Alterations in management, especially diet and physical activity, can be helpful in the management of these risk factors. Caloric restriction, ideally combined with increased physical activity, to promote weight loss and improve insulin sensitivity is indicated for the management of obese animals. Strict control of dietary NSC through the elimination of grains and sweet feeds and by restricted access to NSC-rich pastures is recommended for insulin-resistant animals, regardless of whether they are obese or not. Medical treatment with levothyroxine or metformin may be indicated in obese or insulin-resistant animals that do not respond to conservative management.     

Laminitis in Horses: Through the Lens of Systems Theory

Systems theory is a way of describing complex and dynamic relationships. We applied systems theory to the structure and function of the equine foot in an effort to better understand laminitis and, in so doing, reconcile the various theories of its etiopathogenesis and find more universally effective preventive and therapeutic strategies. The foot is described as an open system, and its inherent vulnerabilities are explored. Cascade failure is discussed as a potentially unifying theory of laminitis. The fundamental failure in laminitis is failure of the lamellar dermal−epidermal bond, but that endpoint can be reached via vascular, enzymatic, inflammatory, or mechanical mechanisms, or any combination thereof. Inflammation is discussed as a common denominator, making anti-inflammatory therapy of greater importance than just pain management. Multimodal anti-inflammatory therapy is discussed, including selective COX-2 inhibitors, heparin, nutraceuticals, and inhibitors of matrix metalloproteinases (MMPs). Multimodal analgesic therapy also is important and may include nonsteroidal anti-inflammatory drugs (NSAIDs), opiates, epidural analgesics, physical therapy, relief of weight bearing, diligent nursing care, deep digital flexor tenotomy, and case-appropriate trimming and shoeing. Preventing laminitis still comes down to risk management: knowing the risk factors applicable to an individual horse and adjusting the management accordingly. Examples include weight management and control of carbohydrate intake in overweight horses and ponies, the use of pergolide in patients with pituitary pars intermedia dysfunction (PPID), and distal limb cryotherapy in high-risk patients. It is anticipated that application of molecular biologic techniques will further advance treatment and prevention of laminitis.