Progression of venographic changes after experimentally induced laminitis

Traumatic exungulation in cattle: ten cases (1993-2018)

OBJECTIVE

To describe clinical findings, treatments, and outcomes for cattle with complete traumatic exungulation.

ANIMALS

10 bovines.

PROCEDURES

Record databases of 2 teaching hospitals were searched to identify cattle treated for traumatic exungulation between January 1993 and December 2018. Information about signalment, clinical signs and findings, treatment, and outcome was extracted from the records or obtained by telephone communication with the owner.

RESULTS

Records for 5 bulls, 4 heifers, and 1 cow with a median age of 2 years (range, 1 day to 10 years) and weight of 379.1 kg (range, 30 to 909.1 kg) were reviewed. Duration of clinical signs ranged from ≤ 24 hours to 3.5 days. Five of 7 animals had a lameness score > 3/5. Complete exungulation occurred in 6 medial digits (3 hind limbs and 3 forelimbs) and 5 lateral digits (1 hind limb and 4 forelimbs); 1 calf had complete exungulation of both digits of a forelimb. Treatments included bandaging (n = 9), antimicrobials (9), anti-inflammatories (8), hoof block application to the adjacent digit (7), regional anesthesia (6), cast application (4), curettage of the third phalanx (3), regional antimicrobial perfusion (1), and local application of antimicrobial-impregnated beads (1). All 7 cattle with long-term (≥ 9 months) information available returned to their intended function; 6 had no residual lameness, and 3 required regular corrective trimming of the affected digit.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested the prognosis for long-term survival and return to intended function is fair to good for cattle with complete exungulation.

Synchrotron CT of an equine digit at the Australian Synchrotron Imaging and Medical Beamline

Laminitis is an extremely painful and debilitating condition of horses that can affect their athletic ability and even quality of life. The current gold standard for assessment of laminar tissue is histology, which is the only modality that enables detailed visualization of the lamina. Histology requires dissection of the hoof and therefore can only represent one specific time point. The superior spatial and contrast resolution of synchrotron computed tomography (sCT), when compared with readily available imaging modalities, such as radiographs and conventional CT, provides an opportunity for detailed studies of the lamina without the need for hoof dissection and histological assessment. If the resolution of histology can be matched or even approached, dynamic events, such as laminar blood flow, could also be studied on the microscopic tissue level. To investigate this possible application of sCT further, two objectives are presented: (i) to develop a protocol for sCT of an equine digit using cadaver limbs and (ii) to apply the imaging protocol established during (i) for sCT imaging of the vasculature within the foot using an ex vivo perfusion system to deliver the vascular contrast. The hypotheses were that sCT would allow sufficient resolution for detailed visualization to the level of the secondary lamellae and associated capillaries within the equine digit. Synchrotron CT enabled good visualization of the primary lamellae (average length 3.6 mm) and the ex vivo perfusion system was able to deliver vascular contrast agent to the vessels of the lamina. The individual secondary lamellae (average length 0.142 mm) could not be seen in detail, although differentiation between primary and secondary lamellae was achieved. This approaches, but does not yet reach, the current gold standard, histology, for assessment of the lamellae; however, with further refinement of this imaging technique, improved resolution may be accomplished in future studies.

From Table to Stable: A Comparative Review of Selected Aspects of Human and Equine Metabolic Syndrome

Obesity data in people and companion animals are depicting a future of increasing morbidity, cost for society, and significant health and welfare concerns. Between 25 and 50% of cats, dogs, and horses in developed countries are overweight or obese, which mirrors the situation in humans. Equine metabolic syndrome (EMS) was named after human metabolic syndrome (MetS), which has about 30 years of lead in research efforts. Even though the complications of the two syndromes seem to grossly differ (cardiac vs. laminitis risk), a number of similar disease mechanisms are worthy of investigation. Since the first EMS consensus statement by the American College of Veterinary Internal Medicine in 2010, numerous studies have confirmed the link between insulin dysregulation and laminitis, even though the mechanisms are not fully understood. After the discovery of the role of adipokines in MetS, evidence about inflammatory mechanisms related to adiposity in rodent models, companion animals, horses, and humans is constantly increasing. Oxidative and dicarbonyl stress have been correlated with insulin dysregulation, obesity, and recently with laminitis. Vascular actions of insulin through nitric oxide, endothelin-1, and other mechanisms are being studied in horses and can provide a better understanding of laminitis pathophysiology. More research is needed on neuropathic mechanisms in insulin-dysregulated horses, which could be important in the pathogenesis of laminitis and laminitic pain. Human literature can provide viable material for novel studies in areas that have received limited attention, in addition to being valuable information for clients about the consequences of unhealthy management of their horses.

Estudo da técnica de venografia dos dígitos de vacas

RESUMO O objetivo deste estudo foi descrever a técnica de venografia retrógrada podal em vacas, comparando os acessos da veia digital dorsal comum III com a digital comum II ou IV, nos membros torácicos e pélvicos, mediante a administração de dois diferentes volumes de contraste. Foram utilizados 53 membros torácicos e pélvicos de 14 vacas, com o torniquete de borracha posicionado a 5cm proximal aosparadígitos. Administraram-se 10mL do diatrizoato de meglumina em 24 membros (grupo 1), sendo 13 na veia digital dorsal comum III pelo acesso 1 (A1) e 11 na digital II ou IV no acesso 2 (A2). No grupo 2, administraram-se 20mL em 29 membros, sendo 15 pelo A1 e 19 pelo A2. Após a administração do contraste, as radiografias foram repetidas a cada 20 segundos até 120 segundos. O grau de preenchimento vascular foi maior no grupo 2, não diferindo entre membros e acessos venosos. Conclui-se que a administração de 20mL de contraste apresentou melhor preenchimento vascular e radiopacidade, não havendo diferença entre 20 e 120 segundos após a administração do contraste na qualidade radiográfica, independentemente do acesso venoso.

Angiografia dos dígitos de bovinos jovens antes e após indução de acidose ruminal

RESUMO O presente estudo objetivou descrever a rede vascular dos dígitos dos membros pélvicos de bovinos antes e após aplicação intrarruminal de oligofrutose, empregando a venografia. Utilizaram-se seis bovinos alocados em dois grupos (GI e GII), que receberam 13 e 17g/kg de oligofrutose, respectivamente. A venografia dos dígitos foi feita em quatro momentos: 15 dias antes (M0) e 36 horas (M1), sete dias (M2) e 30 dias (M3) após aplicação de oligofrutose. Mensurou-se a largura das veias visualizadas e avaliou-se possível supressão do fluxo sanguíneo dos vasos. A largura foi avaliada pela análise de variância (ANOVA) e pelo teste t (5%). Em M0, nas radiografias, foram identificadas 25 estruturas, incluindo veias, artérias e rede vascular. As veias mensuradas foram: digital dorsal comum III e dorsal da falange distal e os ramos plantares para o coxim digital do dígito lateral e medial. Apenas a v. digital dorsal comum III apresentou maior largura após 36 horas e constrição com 30 dias (P≤0,05) da aplicação de oligofrutose. Comparando-se os momentos, encontrou-se vasodilatação no M1 e vasoconstrição nos demais. A mensuração da largura dos vasos não sofreu (P≥0,05) interferência quando se compararam os grupos. Concluiu-se que a venografia dos dígitos de bovinos permite estudar e identificar alterações da vascularização.

The Contribution of Adipose Tissue-Derived Mesenchymal Stem Cells and Platelet-Rich Plasma to the Treatment of Chronic Equine Laminitis: A Proof of Concept

Laminitis, a highly debilitating disease of the foot in ungulates, is characterized by pathological changes of the complex lamellar structures that maintain the appendicular skeleton within the hoof. Laminitis is a multifactorial disease that involves perturbation of the vascular, hematological, and inflammatory homeostasis of the foot. Interestingly, the pathogenesis of the disease resembles what is observed in metabolic syndromes and sepsis-induced organ failure in humans and animals. We hypothesized that local administration of mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP) might contribute to establishing an anti-inflammatory and pro-angiogenic environment, and could stimulate the injured tissue in order to restore its functional integrity. According to this assumption, an experimental protocol based on the local intravenous administration of adipose tissue-derived MSCs (aMSCs) in combination with PRP was developed for the treatment of horses affected by chronic laminitis. Nine horses with severely compromised venograms (showing grade III and IV laminitis) that had been unsuccessfully treated with conventional therapies were enrolled. aMSCs and PRP (15 × 10⁶ cells resuspended in 15 mL of PRP) were injected into the lateral or medial digital vein three times, at one-month intervals. The first administration was performed with allogeneic aMSCs, while for the following administrations, autologous aMSCs were used. There was no adverse short-term reaction to the intravenous injection of aMSCs. In the long term, venograms outlined, in all subjects, a progressive amelioration of the vascularization of the foot. An improvement in the structure and function of the hoof was also observed. No adverse events were reported during the follow-up, and the horses returned to a comfortable quality of life. Although the number of animals enrolled in the study is limited, both clinical observations and venography demonstrated an enhancement in the condition of all horses, suggesting that the regenerative therapies in chronic laminitis could be useful, and are worthy of further investigation.

Vascular Dysfunction in Horses with Endocrinopathic Laminitis

Endocrinopathic laminitis (EL) is a vascular condition of the equine hoof resulting in severe lameness with both welfare and economic implications. EL occurs in association with equine metabolic syndrome and equine Cushing’s disease. Vascular dysfunction, most commonly due to endothelial dysfunction, is associated with cardiovascular risk in people with metabolic syndrome and Cushing’s syndrome. We tested the hypothesis that horses with EL have vascular, specifically endothelial, dysfunction. Healthy horses (n = 6) and horses with EL (n = 6) destined for euthanasia were recruited. We studied vessels from the hooves (laminar artery, laminar vein) and the facial skin (facial skin arteries) by small vessel wire myography. The response to vasoconstrictors phenylephrine (10⁻⁹–10^-5M) and 5-hydroxytryptamine (5HT; 10⁻⁹–10^-5M) and the vasodilator acetylcholine (10⁻⁹–10^-5M) was determined. In comparison with healthy controls, acetylcholine-induced relaxation was dramatically reduced in all intact vessels from horses with EL (% relaxation of healthy laminar arteries 323.5 ± 94.1% v EL 90.8 ± 4.4%, P = 0.01, laminar veins 129.4 ± 14.8% v EL 71.2 ± 4.1%, P = 0.005 and facial skin arteries 182.0 ± 40.7% v EL 91.4 ± 4.5%, P = 0.01). In addition, contractile responses to phenylephrine and 5HT were increased in intact laminar veins from horses with EL compared with healthy horses; these differences were endothelium-independent. Sensitivity to phenylephrine was reduced in intact laminar arteries (P = 0.006) and veins (P = 0.009) from horses with EL. Horses with EL exhibit significant vascular dysfunction in laminar vessels and in facial skin arteries. The systemic nature of the abnormalities suggest this dysfunction is associated with the underlying endocrinopathy and not local changes to the hoof.

Técnica venográfica contrastada in vivo dos dígitos de ovinos e caprinos

Foram utilizados 10 membros torácicos e pélvicos de ovinos e caprinos hígidos, de raça e sexo variados, com idade entre dois e quatro anos e peso corpóreo médio de 53kg. A porção distal dos membros torácicos e pélvicos foi submetida à técnica venográfica contrastada e à contagem vascular venosa da mesma região, em ambas as espécies. Não foram observadas diferenças numéricas em relação às veias entre machos e fêmeas, nem entre os membros direito e esquerdo da mesma espécie. Os ovinos possuem maior número de veias em relação aos caprinos. A técnica venográfica distal anterógrada de ambos os membros em ovinos e caprinos se mostrou aplicável revelando a vasculatura distal e podal, a comunicação entre os vasos venosos e a quantidade dos vasos presentes na região.

Morphoquantitative description of bovine digital cushion

Abstract The digital cushion is characterized as a modified subcutaneous tissue that absorbs the shock during gait, assists venous return of the hoof and supports a considerable part of body weight. Digital cushions have particular importance in the pathogenesis of the hoof, since they need to properly work in order to prevent compression and traumas in soft tissues. This study aimed to measure and determine how is the arrangement of these structures, and for this it was established the proportions of connective, adipose, vascular tissues and collagen fibers and collagen types found in palmar and plantar digital cushion of bovine using fore and hindlimbs of twelve adult zebu cattle of both sexes, 11 male and one female, with 269kg average carcass weight and without limb disorders. Fragments of cushions were subjected to conventional histology, cut to a thickness of 4µm and stained with Red Picrosirius. With digital optical microscope, the quantification of the connective tissue and differentiation of types of collagen used the Image Pro Plus® software, and of adipose and vascular tissue, the test point system. The mean and standard error were estimated with the GraphPad Prism 5.0 software, and then data were subjected to Kolmogorov-Smirnov normality test and Student's t-test with significance level set at 5% for determining the amount of different tissues between fore and hindlimbs of studied animals. In forelimbs the mean and standard error of the connective tissue proportion was 50.10%+1.54, of the adipose tissue was 21.34%+1.44, and of vascular tissue was 3.43%+0.28. Hindlimbs presented a proportion of connective tissue of 61.61%+1.47, 20.66%+1.53 of adipose tissue, and 3.06%+0.20 of vascular tissue. A significant difference (p<0.001) was detected in the connective tissue proportion between fore and hindlimbs. Types I and II collagen fibers have presented, respectively, a proportion of 31.89% and 3.9% in forelimbs and 34.05% and 1.78% in hindlimbs. According to the used methodology, digital cushions had a clear differentiation relative to adipose tissue between fore and hindlimbs.

Expression of purinergic P2X receptor subtypes 1, 2, 3 and 7 in equine laminitis

Tissue sensitisation and chronic pain have been described in chronic-active laminitis in the horse, making treatment of such cases difficult. Purinergic P2X receptors are linked to chronic pain and inflammation. The aim of this study was to examine the expression of purinergic P2X receptor subtypes 1, 2, 3 and 7 in the hoof, palmar digital vessels and nerve, dorsal root ganglia and spinal cord in horses with chronic-active laminitis (n=5) compared to non-laminitic horses (n=5). Immunohistochemical analysis was performed on tissue sections using antibodies against P2X receptor subtypes 1-3 and 7. In horses with laminitis, there was a reduction in the thickness of the tunica media layer of the palmar digital vein as a proportion of the whole vessel diameter (0.48±0.05) compared to the non-laminitic group (0.57±0.04; P=0.02). P2X receptor subtype 3 was expressed in the smooth muscle layer (tunica media) of the palmar digital artery of horses with laminitis, but was absent in horses without laminitis. There was strong expression of P2X receptor subtype 7 in the proliferating, partially keratinised, epidermal cells of the secondary epidermal lamellae in the hooves of horses with laminitis, but no immunopositivity in horses without laminitis.