Rib fractures in adult horses as a cause of poor performance
Hall et al (2022) investigated the presenting signs, diagnosis, treatment and outcomes of horses with rib fractures using nuclear scintigraphy, radiographic and /or ultrasonographic examination. Only seven horses (10%) had a history of trauma to the site; 29% presented with lameness and 56% were presented for investigation of poor performance. Once examined, 18% were forelimb lame and 24% were hindlimb lame, and 12% were lame in both. Following diagnostic analgesia, the lameness was found to be independent of the fracture in all but three horses, where forelimb lameness was attributed to fracture of T1 (first rib). Palpation was recorded as being painful over the affected rib in only 38% cases.
Radiography was performed in 24 horses and was considered diagnostic for rib fracture in 10 horses (42%). Changes included increased opacity, callus formation, a radiolucent line or change in rib contour. Ultrasound was performed in 59 horses and identified the fracture in 98% of cases. Findings included discontinuity of the bone surface echo, cortical deficiencies and displacement. Nuclear scintigraphy was performed in 59 horses and, as expected, identified the presence of the fracture in all horses. The 18th rib was the most commonly fractured rib (42% cases).
Initially, all horses were managed conservatively with rest for up to 12 months, but six horses underwent surgery as a result of failed conservative management. Overall, 28 (51%) horses returned to their previous level of exercise and only three horses did not return to previous use. The authors concluded that rib fracture should be a differential for cases of poor performance and ridden behavioural problems, and that palpation alone may not identify a painful focus over the fracture. Rib fractures are career-ending in only a small proportion of horses and while nuclear scintigraphy is excellent at detecting them, ultrasonography is more available, cheaper, safer and more sensitive than radiography in these cases.
Histological tissue healing with high-power laser treatment
A study by Pluim et al (2022) looked at the histological healing following high-power laser treatment therapy on suspensory desmitis healing, using a model of suspensory ligament branch injury. A core lesion was created in all four lateral branches of the suspensory ligaments in 12 horses. High power (class 4) laser was administered in two of the four affected branches daily for 4 consecutive weeks. Following creation of the surgical lesions, horses entered a controlled exercise programme, with physical parameters such as soundness at walk and local signs of heat, pain and swelling, collected daily. Lameness was assessed weekly using gait analysis for the first four weeks and monthly thereafter. Horses were randomly selected to be euthanised after 4 weeks (short term evaluation) or 12 weeks (long term evaluation). Following euthanasia, all lateral suspensory ligament branches were harvested for histopathological examination and evaluated and scored by two independent blinded observers.
Significantly better post-treatment scores were seen in the short-term study for variation in density and shape of nuclei and fibre/fibre alignment. In both studies, combined improved scores in the treatment group were seen in the size of the lesion and shape of nuclei. In the long-term study, significantly better scores were found in the laser-treated group for the lesion size and density of the nuclei compared with controls.
Naturally occurring desmitis has a strong inflammatory component, whereas the lesions in this study resembled a traumatic insult, which usually has a better prognosis, so the exercise regimen included trotting during the first week post-lesion creation to introduce an inflammatory response.
The authors concluded that significant benefits of class 4 laser were found, and they expect these positive effects to be seen when the therapy is applied to naturally occurring lesions.
Arthroscopic findings and outcomes of meniscal injuries
This study by Davis and Garcia-Lopez (2022) described the findings and long-term outcomes of 76 horses with 93 meniscal injuries in 85 stifles. Radiographic abnormalities were identified pre-operatively in 77% stifles, with osteoarthritis as the most common (59%) abnormality. Ultrasound identified pathology in 89% stifles, with meniscal injuries evident in 65%.
During surgery, the medial meniscus was found to be affected in 83% cases and the lateral in only 16%. Injury severity was grade 1 (injury in the cranial ligament extending into the meniscus, without significant separation of the tissues) in the majority of cases (76%). Additional pathology was identified in 77% stifles and articular cartilage damage was the most common finding. Of the stifles, 69% were treated with an orthobiologic in the postoperative period, the most common of which was autologous conditioned serum; no significant effect was seen with this.
At long-term follow up, 85% of horses returned to some form of athletic performance and 40% returned to at least their previous level of use. Of these, 40% required annual intra-articular corticosteroids to maintain acceptable athletic performance. The presence of pre-operative radiographic abnormalities was not associated with outcome. Of the eight horses with grade 3 tears, none returned to their previous level of use, compared to 49% of horses with grade 1 tears. This study reaffirms the value of arthroscopy in providing more definitive prognostic information.