Fore- or hindlimb lameness and/or pain associated with the sacroiliac joints could mimic primary thoracolumbar pain. A combination of radiology and scintigraphy gives the most accurate prediction of thoracolumbar pain, but diagnostic analgesia is crucial for accurate diagnosis.

Degenerative joint disease (DJD) is a major cause of reduced athletic function and retirement in equine performers. For this reason, regenerative therapies for DJD have gained increasing interest. Platelet-rich plasma (PRP) and mesenchymal stem cells (MSCs) were isolated from a 6-year-old donor horse. MSCs were either used in their native state or after chondrogenic induction. In an initial study, 20 horses with naturally occurring DJD in the fetlock joint were divided in 4 groups and injected with the following: 1) PRP; 2) MSCs; 3) MSCs and PRP; or 4) chondrogenic induced MSCs and PRP. The horses were then evaluated by means of a clinical scoring system after 6 weeks (T1), 12 weeks (T2), 6 months (T3) and 12 months (T4) post injection. In a second study, 30 horses with the same medical background were randomly assigned to one of the two combination therapies and evaluated at T1. The protein expression profile of native MSCs was found to be negative for major histocompatibility (MHC) II and p63, low in MHC I and positive for Ki67, collagen type II (Col II) and Vimentin. Chondrogenic induction resulted in increased mRNA expression of aggrecan, Col II and cartilage oligomeric matrix protein (COMP) as well as in increased protein expression of p63 and glycosaminoglycan, but in decreased protein expression of Ki67. The combined use of PRP and MSCs significantly improved the functionality and sustainability of damaged joints from 6 weeks until 12 months after treatment, compared to PRP treatment alone. The highest short-term clinical evolution scores were obtained with chondrogenic induced MSCs and PRP. This study reports successful in vitro chondrogenic induction of equine MSCs. In vivo application of (induced) MSCs together with PRP in horses suffering from DJD in the fetlock joint resulted in a significant clinical improvement until 12 months after treatment.

Back pain is common in horses, but there has been no large-scale in-depth study describing radiographic changes of the spinous processes, the relationship between radiographic and scintigraphic findings, and the effect of size, age, breed, or discipline. The objectives were to investigate the frequency of occurrence in horses with perceived back pain of: (1) radiographic alteration of the spinous process structure; (2) increased radiopharmaceutical uptake (IRU) in the spinous processes; and (3) to compare radiographic and scintigraphic findings; and to determine if there was breed, gender, age, bodyweight, height, or work discipline predisposition for close, impinging, or overriding spinous processes. Radiographic and scintigraphic images of the thoracolumbar spine of 604 horses were graded. A radiographic grade for each spinous process (T8-L6) was assigned (0-7). The maximum radiographic grade for each horse was defined as the highest grade assigned to any spinous process; the total radiographic grade was the sum of all grades for each horse. A scintigraphic grade for each spinous process was determined (0-3). The maximum scintigraphic grade for each horse was defined as the highest grade assigned to any spinous process; the total scintigraphic grade was the sum of all grades for each horse. Associations between radiology and scintigraphy and age, gender, breed, height, weight, and discipline were analyzed statistically. The severity of radiographic lesions of the spinous processes was associated with the severity of scintigraphic abnormalities. The caudal thoracic spine (T14-T17) was most frequently affected. There was a significant breed and age effect, with Thoroughbreds and older horses having higher total and maximum radiographic grades. The severity of the lesions of the spinous processes was significantly associated with the presence of osteoarthritis of the articular process joints. It was concluded that there is a wide range of radiographic abnormalities of the spinous processes seen in horses with or without back pain. There is an association between radiographic and scintigraphic grades of the spinous processes.

OBJECTIVE To describe articular process joints (APJs) of the cervical spine in horses on the basis of CT and to determine whether abnormalities were associated with clinical signs. ANIMALS 86 client-owned warmblood horses. PROCEDURES Horses that underwent CT of the cervical spine between January 2015 and January 2017 were eligible for study inclusion. Medical records were reviewed for age, body weight, breed, sex, history, clinical signs, and CT findings. Horses were divided into 3 case groups and 1 control group on the basis of clinical signs. RESULTS 70 warmblood horses were cases, and 16 were controls. Abnormalities were more frequent from C5 through T1 and were severe in only horses from the case group. Narrowing of the intervertebral foramen was common in horses in the case group (85.7%), often owing to enlarged, misshaped articular processes, followed by degenerative changes, periarticular osteolysis, cyst-like lesions, and fragmentation. High articular process-to-vertebral body (C6) ratio (APBR) and high-grade narrowing of the intervertebral foramen and periarticular osteolysis were noted for horses with forelimb lameness or signs of cervical pain or stiffness. No association was identified between APBR and age or sex. An APBR > 1.5 was found in only horses in the case group, and 32.3% of APJs with APBRs > 1.5 did not have any degenerative changes and periarticular osteolysis. CONCLUSIONS AND CLINICAL RELEVANCE CT was useful to identify abnormalities of the APJs of the cervical spine. An association existed between CT findings and clinical signs. The APJs can be enlarged without concurrent degenerative changes.

It has been reported that mesenchymal stem cells (MSCs) have homing capacities and immunomodulating effects after an intravenous injection. However, transplanting MSCs in murine tail veins can result in pulmonary reactions and even death of the animals. Unfortunately, only a few intravenous MSC transplantations have been reported in large animal species and these were performed in a limited number of individuals. To assess the safety of MSC transplantations, a large study on 291 recipient horses is reported here. MSCs were isolated from the peripheral blood (PB) of a 4-year-old and 6-year-old donor horse after having tested their PB for a wide range of transmittable diseases. The MSC samples from both donor horses were characterized and resuspended in 1 ml of Dulbecco's Modified Eagle Medium (DMEM) supplemented with 10% Dimethyl Sulfoxide (DMSO). After hand-thawing in the field, 291 horses with ages ranging from 3-months to 33-years were directly injected into their jugular vein. 281 horses (97%) received a single injection of a physiological dose of 0.2 x10(6) MSCs, 5 horses (1.7%) were re-injected after approximately 6 weeks (using the same dose and donor cells) and a single superphysiological dose of 10(6) MSCs was administered to 5 horses as well. In total, 176 recipients were injected with MSCs from the 4-year-old donor and 115 recipients received MSCs from the 6-year-old donor. From all the injected horses (n=291) no acute clinical adverse effects were noticed. Apart from one horse that died of colic 7 months after the treatment, no deaths were registered and all the horses were monitored for 1 year after the injection. In conclusion, no adverse effects were noticed in 291 recipients after an intravenous injection of allogenic PBderived MSCs. Nevertheless, further research is warranted in order to verify the immunogenic properties of these cells after allogenic transplantation into various (patho)physiological sites.