The timeline of lamellar basement membrane changes during equine laminitis development

Reasons for performing study: The timing of lamellar basement membrane (BM) changes occurring during laminitis development is incompletely understood. Objectives: To determine the temporal progression of lamellar BM changes and whether laminin‐332 (Ln‐332) γ2 cleavage products are generated during laminitis development. Methods: Eight clinically normal Standardbred horses were allocated into treatment (n = 5) or sham (n = 3) groups. The treatment group received, via nasogastric intubation, an oligofructose (OF) bolus (10 g/kg bwt) while the sham group was given water. Laminitis induction proceeded for 48 h followed by euthanasia. Lamellar biopsies were obtained prior to dosing and at intervals during the treatment period for analysis (at 12, 18, 24, 30 and 36 h and at 48 h following euthanasia). Results: Changes in lamellar collagen type IV and Ln‐332 were first observed at 12 h post dosing. A unique pattern of reactivity for the Ln‐332 γ2 antibody D4B5 occurred, in which reactivity was observed only in lamellar tissue affected by laminitis. No bioactive Ln‐332 γ2 proteolytic fragments were detected in lamellar samples. Conclusions: Basement membrane changes occurred early during the laminitis process. Direct Ln‐332 γ2 cleavage to release biologically active products did not appear to occur. Thus loss of stability or protein interaction of the BM is probably responsible for the γ2 specific reactivity observed. Potential relevance: Basement membrane changes may a first step in lamellar failure occurring prior to detection with conventional methods. Thus, more sensitive detection methods of BM changes are required to study laminitis development.     

The timeline of metalloprotease events during oligofructose induced equine laminitis development

Reason for performing study: The role of matrix metalloproteases (MMPs) and the timeline of proteolysis during laminitis development are incompletely understood. Objectives: To determine the temporal progression of selected MMPs and protease regulators during laminitis development. Methods: Five clinically normal Standardbred horses received, via nasogastric intubation, an oligofructose (OF) bolus (10 g/kg bwt). Laminitis induction proceeded for 48 h followed by euthanasia. Lamellar biopsies were obtained prior to dosing and at intervals during the treatment period for analysis (12, 18, 24, 30 and 36 h and at 48 h following euthanasia). Tissue samples were analysed by real‐time PCR, zymography and western blotting. Results: Activation of proMMP‐2 occurs either simultaneously or at least 12 h following lamellar basement membrane (BM) damage, while no activation of proMMP‐9 is seen during OF laminitis induction. Aggrecanase gene expression increased initially at 12–18 h post OF dosing, similar to BM changes. Gene expression of TIMP‐2, a MMP regulator, decreases during laminitis development. Conclusions: The MMP‐2/MT1‐MMP complex may not play a major role in initiating lamellar BM damage. Aggrecanase and TIMP‐2 gene expression appear related to BM lamellar changes. Potential relevance: MMPs, historically thought to cause laminitis, do not appear to play an initiating role in the lamellar lesion. Other host derived proteases and degradation of alternative lamellar matrix components need to be considered.     

The treatment of laminitis in horses

The structural and vascular anatomy of the healthy equine foot is compared with the pathologic changes in the foot of horses with acute and chronic laminitis. The structural and vascular abnormalities present in the foot of horses with laminitis are demonstrated in order to explain the abnormal manner in which their feet grow. The medical, surgical, dietary, and endocrine management of acute and chronic laminitis is discussed. Various forms of hoof trimming beneficial to the reestablishment of normal digital perfusion, normal hoof growth, and normal spatial orientation among the distal phalanx, hoof wall, and sole are described. Guidelines for the provision of frog support provided by adjustable heart-bar shoes are presented.     

Arteriographical and pathological changes in chronic laminitis in dairy cattle

The arteriographic appearance of 76 bovine hind digits, obtained from a slaughterhouse, was related to the macroscopic signs of chronic laminitis in the digits. There were statistically significant correlations between the macroscopic and the arteriographic appearance of the claws. Subsequent histological examination of the radiographically abnormal arteries revealed features indicative of arteriosclerosis. The results of this study indicate that chronic laminitis develops following a subclinical attack of laminitis due to a continous hypoperfusion of the digit.     

Obesity induced by force-feeding and accompanying changes in body temperature and fertility in the male domestic fowl.

1. Excessive amounts of food (two-fold more than the ad libitum intake) introduced into the gastro-intestinal tract of three adult male fowls, for 5 weeks, caused a marked increase in body weight resulting mainly from fat deposition. 2. The induced obesity was accompanied by an increase of the rectal temperature (0-2 to 0-3 degrees C) and a decrease of the skin and comb temperatures, a cessation in the growth of the comb, a reduction in the blood packed cell volume, an eight-fold reduction in the number of spermatozoa in the vasa deferentia and a concomitant depression in their motility. 3. A decrease of the testosterone and an increase of luteinising hormone concentrations in the blood plasma was obtained in two of the three treated birds.     

奶牛蹄叶炎的诊治

2006年夏季,河北滦县奶牛流行一种牛蹄肿胀的疾病,发病原因尚不明确。本病发病快、恢复慢,用抗风湿类药治疗同时调节酸碱平衡,虽能治愈,但病程较长。由于行动迟缓,有的牛甚     

Arteriographical and pathological changes in chronic laminitis in dairy cattle

Summary

The arteriographic appearance of 76 bovine hind digits, obtained from a slaughterhouse, was related to the macroscopic signs of chronic laminitis in the digits. There were statistically significant correlations between the macroscopic and the arteriographic appearance of the claws. Subsequent histological examination of the radiographically abnormal arteries revealed features indicative of arteriosclerosis. The results of this study indicate that chronic laminitis develops following a subclinical attack of laminitis due to a continous hypoperfusion of the digit.     

Influence of idazoxan on the respiratory blood gas changes induced by alpha 2-adrenoceptor agonist drugs in conscious sheep

Administration of either xylazine (50 micrograms/kg) or detomidine (10 micrograms/kg) caused a significant degree of arterial hypoxaemia in six conscious sheep. This effect was independent of any changes produced by changes in posture as all the sheep remained standing. Administration of the specific alpha 2-antagonist drug idazoxan (0.1 mg/kg bodyweight) five minutes before injection of either of the drugs completely abolished the hypoxaemia. These results lend support to the view that the respiratory effect of these drugs is mediated via alpha 2-adrenoceptor activity.     

The pharmacologic basis for the treatment of developmental and acute laminitis.

Each horse with laminitis is presented to the veterinarian at a different stage in progression of the condition and with varying severity. The pathogenic timing is often unknown and is difficult to determine. Because timing and severity are related to both the lesion's severity and responsiveness to treatment, these factors are critical to treatment selection and success. It is erroneous to assume that each horse with laminitis should receive each treatment. It is therefore important to ascertain as logically and objectively as possible the pathophysiological stage of development of each horse when it is examined. Therapeutic failure may result from inappropriate interpretation of the clinical signs and pathophysiologic condition of the patient in order to coordinate a treatment regimen.     

The effect of a treatment protocol on the prognosis of equine laminitis

All horses and ponies with laminitis treated at the Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, between 1995 and 1998 were analysed retrospectively (n = 152). Based on the results of this study and on the world-wide knowledge on laminitis a standardised treatment protocol was adopted in 1999. Fifty-eight patients have been treated for laminitis between 1999 and 2001 following the treatment protocol. Compared to our hospital-population (orthopaedic patients), mares and ponies are at higher risk developing laminitis, but the prognosis does not differ between sexes as between breeds. Radiological evidence of rotation of the third phalanx seems to be of minor importance for the prognosis. Distal displacement of the third phalanx, however, seems to worsen the prognosis. The outcome of the acute cases is significantly better in the group treated following the protocol, than in the group without protocol. The outcome of the chronic cases is not influenced by the treatment protocol. Although the cases in both groups differ, as they are all clinical cases, our data suggest that the standardised treatment protocol results in a better outcome for cases of acute laminitis.     

Lamellar leukocyte infiltration and involvement of IL-6 during oligofructose-induced equine laminitis development

Laminitis is known to involve deregulation of proteases and destruction of the lamellar basement membrane with the host inflammatory response also playing a role. Leukocyte infiltration has been well characterized in the black walnut model of laminitis induction, but not in carbohydrate induced models. Increased gene expression of multiple cytokines, including IL-6, has also been implicated in laminitis development. Using real time PCR, immunohistochemistry and zymography methods, we characterize leukocyte infiltration and IL-6 gene expression in oligofructose (OF) induced laminitis. As well, we use two in vitro models to investigate a role for IL-6 in protease regulation. Laminitis was induced in normal standardbred horses (n=5) by alimentary OF dosing and lamellar biopsies were obtained throughout the 48 h experimental period. Lamellar explants and keratinocytes were also isolated from clinically normal horses for in vitro experiments. We found infiltration of calprotectin-positive leukocytes (monocytes and neutrophils) at 18-24h post oligofructose dosing, while IL-6 gene expression was increased as early as 12h post dosing. Additionally, while we found that IL-6 did not cause significant BM damage in vitro, it did result in increased secreted proMMP-9 levels from lamellar explants. Thus, we find that leukocyte infiltration does occur during oligofructose-induced laminitis development, however, IL-6 gene expression in the lamellae may precede leukocyte infiltration. Additionally, we show IL-6 plays a role in increasing the level of proMMP-9 in vivo in a manner that does not involve keratinocytes.     

Dynamic changes in circulating leukocytes during the induction of equine laminitis with black walnut extract

Administration of black walnut heartwood extract (BWHE) via nasogastric tube induces acute laminitis in horses. However, the processes responsible for the development of laminitis, including laminitis induced with BWHE, remain unclear. The results of recent studies indicate that administration of BWHE initiates an inflammatory response in the laminar tissues and that this response may be due to extravasation of activated leukocytes from the circulation. This study examines the effects of BWHE administration on the dynamics of circulating neutrophils and monocytes, and the capacity of blood leukocytes to produce radical oxygen species (ROS) over the time period from administration of BWHE to the development of lameness consistent with Obel grade I laminitis.

Individual horses, free of pre-existing musculoskeletal disease, were administered either 6 l of BWHE or an equal volume of water at time 0 (T = 0). Blood samples were collected prior to dosing and at 1, 2, 3, 4, 6, 8, 10 and 12 h after dosing, or until the onset of Obel grade I laminitis. For each sample, total leukocyte counts were determined followed by collection of buffy coats and removal of erythrocytes by hypotonic lysis. Leukocytes were either fixed for flow cytometric assessment of differential counts or maintained in culture to measure endogenous and phorbol ester-induced production of ROS. At each sample time, the number of cells recovered and the flow cytometric differential counts were compared with corresponding total leukocyte counts determined by the Clinical Pathology laboratory.

Horses administered BWHE had a significant reduction in circulating leukocytes at 3–4 h relative to values for horses administered the same volume of water. Horses that developed Obel grade I laminitis had a significant reduction in circulating leukocytes when compared to values for horses administered BWHE that did not become lame. Flow cytometric analysis revealed a consistent decrease in the total number of monocytes obtained from horses that developed laminitis. In these same horses, the endogenous level of ROS production was significantly higher at T = 0 than for horses that did not become lame. Furthermore, production of ROS by leukocytes from horses that developed laminitis increased significantly and coincided with the decrease in circulating leukocytes.

Collectively, these findings support a role for systemic activation of leukocytes and induction of inflammation by BWHE as a factor in the early pathogenesis of acute laminitis. Because laminitis often develops as a sequel to diseases characterized by systemic inflammatory events, activation and emigration of neutrophils and monocytes may be important factors in the early pathogenesis of laminitis in clinical cases.     

中西医结合治疗奶牛蹄叶炎

笔者在兽医门诊工作中经常接诊患有蹄叶炎的奶牛,通常采用中西医结合的方法治疗,效果非常明显.