Topic:Aging
The aging process in horses involves a series of physiological and metabolic changes that occur over time. These changes can affect various systems, including the musculoskeletal, cardiovascular, and endocrine systems. As horses age, they may experience alterations in body condition, joint function, and metabolic efficiency. Understanding the aging process is important for managing the health and welfare of senior horses. This page compiles peer-reviewed research studies and scholarly articles that explore the biological mechanisms of aging in horses, the impact on different bodily systems, and strategies for managing age-related conditions in equine populations.
Age-related morphometry of equine calcified cartilage. Although there are many studies in the equine literature focused on articular diseases and the aetiology of osteoarthritis, few have concentrated on normal articular structures and how they change with age. The objective of this investigation was to study the thickness and morphology of the calcified cartilage layer of the distal metacarpus over a range of ages. A parasagittal slab of bone was sectioned from the region of sesamoid contact on the medial condyle of the metacarpi from 34 horses. The slab of bone was preserved, dehydrated and embedded, undecalcified, in methylmethacrylate and then...
The new conundrum: do estrogens have any cardiovascular benefits? Clearly, a new era has begun, with increasing numbers of the scientific/medical community asking whether estrogens have any cardiovascular benefits. Doubts have arisen from two randomized prospective trials. The Heart and Estrogen/progestin Replacement Study (women who were generally beyond 65 years of age with preexisting coronary heart disease) found no benefit in reducing coronary events by a combination of estrogens and a progestin. Later, the Estrogen Replacement Atherosclerosis Trial reported that no benefit could be shown for either conjugated equine estrogens only or the combined thera...
Osteoarthrosis of the antebrachiocarpal joint of 7 riding horses. Osteoarthrosis (OA) of the antebrachiocarpal joint from 7 riding horses is described. The horses were old mares and developed severe OA, with ankylosis in some of the joints. The lesions were bilateral, and the owners noticed the lameness in a late event. The cause of severe OA in these mares is not clear. The fact that OA was bilateral indicates that a single traumatic injury is unlikely as an etiologic factor. Considering the severe joint lesions it took long time before the horse-owners noticed the lameness. It is discussed if the threshold of pain is higher in the antebrachiocarpal joint c...
Effect of continuous and sequential oral estrogen-progestogen replacement regimens on postmenopausal bone loss: a 2-year prospective study. The aim of the present study was to determine whether assignment to continuous estrogen-progestin therapy is more effective in protecting against bone loss than assignment to a sequential regimen. Methods: A total of 104 postmenopausal women were randomly assigned to one of two groups of treatment, Conjugated Equine Estrogens and Medroxyprogestin without interruption (continuous group) and Conjugated Equine Estrogens over 25 days with Medroxyprogestin beyond the 14th day (sequential group). Bone mineral density (BMD) was measured at inclusion, 12 and 24 months later by dual energy X-ray absorp...
Effects of age and recombinant equine somatotropin (eST) administration on immune function in female horses. Aging has been associated with declines in somatotropin and IGF-I levels as well as declines in immune function. To determine the effects of age and whether ST administration could reverse immunosenescence in horses, eight young and eight aged female standardbred horses were given 10 mg/d recombinant equine somatotropin (eST) or vehicle buffer for 49 d. Plasma IGF-I concentrations in both age groups were higher in eST-treated animals (P < 0.001), and higher in young eST-treated mares than in aged eST-treated mares during wk 4 to 7 (P < 0.001). There was a trend toward lower monocyte and ...
[Equine estrogens vs. esterified estrogens in the climacteric and menopause. The controversy arrives in Mexico]. It exists controversies about if the effects and benefits of the esterified estrogens could be similar to those informed for equines, because its chemical composition and bioavailability are different. Esterified estrogens has not delta 8,9 dehydroestrone, and its absorption and level of maximum plasmatic concentrations are reached very fast. In United States of America and another countries, esterified estrogens has been marketed and using for treatment of climacteric syndrome and prevention of postmenopausal osteoporosis, based on the pharmacopoiea of that country, but the Food and Drug admi...
Effect of GnRH and hCG administration on plasma LH and testosterone concentrations in normal stallions, aged stallions and stallions with lack of libido. Gonadotrophin-releasing hormone (GnRH) (a single intravenous injection with 0.042 mg busereline acetate) was administered to control stallions (n=5), aged stallions (n=5) and stallions with lack of libido (n=5). Jugular blood samples were taken at -10, 0, 10, 20, 40 and 80 minutes after treatment and measured for luteinizing hormone (LH) and testosterone concentrations. A single intravenous injection of hCG (3000 IE) was given 1 day later. Venous blood samples were taken at -60, 0, 15, 30, 60, 120, and 240 minutes after treatment and measured for the testosterone concentration. The experiment ...
Effect of contact stress in bones of the distal interphalangeal joint on microscopic changes in articular cartilage and ligaments. To examine articular cartilage of the distal interphalangeal (DIP) joint and distal sesamoidean impar ligament (DSIL) as well as the deep digital flexor tendon (DDFT) for adaptive responses to contact stress. Methods: Specimens from 21 horses. Methods: Pressure-sensitive film was inserted between articular surfaces of the DIP joint. The digit was subjected to a load. Finite element models (FEM) were developed from the data. The navicular bone, distal phalanx, and distal attachments of the DSIL and DDFT were examined histologically. Results: Analysis of pressure-sensitive film revealed signific...
[Basic principles of hormone replacement therapy in the postmenopause]. 17 beta-estradiol, conjugated equine estrogens, esterified estrogens, and estriol constitute postmenopausal replacement therapy, all of which are in clinical use as oral preparations. Non-oral routes--matrix and reservoir patches, gel--were developed for estradiol, as was the intravaginal administration of estriol and estradiol. Daily doses of 1 mg estradiol(valerate) or 25 micrograms estradiol delivered via a patch or 0.5 mg gel or 0.3 mg conjugated equine estrogens are often sufficient to alleviate climacteric symptoms. Bone resorption may be effectively reduced and bone mineral density main...
Morphometric study of the equine navicular bone: age-related changes and influence of exercise. Navicular bones from the four limbs of 95 horses, classified in 9 categories, were studied. The effects of age on navicular bone morphometry and histomorphometry were estimated, after adjustment of the data to even out the effects of front and rear limbs, morphometrical type, sex, weight, and size. All the external measurements of the navicular bone decreased significantly with increasing age. From the histomorphometrical data, cortical bone volume decreased with age in most horses, whereas cancellous bone volume and, in particular, the marrow spaces increased. The increase in the cancellous b...
Spinal cord compression secondary to hemangiosarcoma in a saddlebred stallion. Hemangiosarcoma in the spinal canal was diagnosed in a 25-year-old stallion showing progressive and symmetrical 4-limb ataxia, proprioceptive deficits, and weakness. On necropsy, an extradural mass consisting of spindle-shaped cells and numerous free erythrocytes was found at the level of C7-T1. Immunohistochemical staining confirmed a neoplasm of endothelial origin.
Tumors of the central nervous system. Neoplasia of the central nervous system (CNS) can be divided into two main categories: nonpituitary CNS neoplasia and pituitary adenomas. Nonpituitary CNS neoplasias are generally compressive in nature, although some are also invasive. The majority of reported CNS tumors are secondary with only a few originating from nervous tissue. Pituitary adenomas predominantly occur in the pars intermedia of the older horse. Clinical signs, diagnostic testing, and possible treatments are discussed.
Carboxymethylated phosphatidylethanolamine in mitochondrial membranes of mammals–evidence for intracellular lipid glycoxidation. The non-enzymatic modification of aminophospholipids with lipoperoxidation-derived aldehydes and glycoxidation-derived products have been reported previously. However, it remains unknown whether intracellular membranes are damaged by these glycoxidation-derived products. To investigate this issue, we tested whether aminophospholipids from mitochondrial membranes are damaged by glycoxidative stress the mitochondrion being identified as the major site of reactive-species production in the cell. We have used a selected-ion-monitoring/gas-chromatography/mass-spectrometry assay for carboxymethyleth...
Changes in sulfation patterns of chondroitin sulfate in equine articular cartilage and synovial fluid in response to aging and osteoarthritis. To determine effects of aging on sulfation of chondroitin sulfate (CS) in articular cartilage and synovial fluid from normal equine middle carpal joints, and to determine whether CS compositional analysis can be used to assess alterations in proteoglycan turnover in degenerative cartilage obtained from horses with carpal osteochondral fractures. Methods: Carpal articular cartilage and synovial fluid from 44 cadavers with normal joints and from 16 Thoroughbred racehorses during routine carpal arthroscopic surgery. Methods: After papain/chondroitinase digestion of cartilage, CS disaccharides (un...
Chronic recombinant equine somatotropin (eST) administration does not affect aerobic capacity or exercise performance in geriatric mares. The purpose of this experiment was to test the hypothesis that chronic (89 days) administration of recombinant equine somatotropin (eST) would increase aerobic capacity and improve exercise performance in old mares. Fifteen, healthy, unfit, aged (20-26 year old) mares were randomly assigned to a treatment (eST, 12.5 mg day-1 in 3 ml glycine/manitol buffer, s.c., n = 7) or control (vehicle, 3 ml day-1, s.c., n = 8) group. Aerobic capacity and exercise performance were measured using a standardized exercise test (SET) performed on a high speed treadmill. Tests were conducted before (-21 days), d...
Protonophoric activity of NADH coenzyme Q reductase and ATP synthase in coupled submitochondrial particles from horse platelets. A method to prepare coupled submitochondrial particles from horse platelets is described. The method allowed us to study the protonophoric activities of both complex I and complex V following the fluorescence quenching of the monoamine 9-amino-6-chloro-2 methoxyacridine (ACMA), a probe highly sensitive to the generation of a transmembrane delta pH. We carried out a kinetic analysis of each enzyme complex studying the proton translocation and the electron transfer activities of complex I as well as the proton translocation and the ATP hydrolytic activities of complex V. A micromethod to prepare...
Feed intake, body weight, body condition score, musculation, and immunocompetence in aged mares given equine somatotropin. Sixteen 20- to 26-yr-old mares were given 0, 6.25, or 12.5 mg/d equine somatotropin (eST) to determine whether aged mares respond to ST with changes in feed intake, body weight, body condition score (based mostly on fat cover), or immunocompetence. Neither dry matter intake, body weight, nor body condition scores were altered during the 6 wk of eST injection. However, based on photographs taken to evaluate musculation before and after treatment (scores 0 to 4), mares given eST developed greater (P < .07) muscle definition (1.8 +/- .6 and 2.5 +/- .6 for 6.25 and 12.5 mg eST/d, respectively) ...
Regulation of glycosaminoglycan metabolism by bone morphogenetic protein-2 in equine cartilage explant cultures. To investigate whether recombinant human bone morphogenetic protein-2 (rhBMP-2) regulates glycosaminoglycan (GAG) synthesis and release from equine articular cartilage explant cultures. Methods: Equine articular cartilage explants were maintained in vitro for 7 days in the presence of 0 (control), 1, 10, or 100 ng of rhBMP-2/ml. Synthesis and release of GAG were assessed as measures of production and degradation of the extracellular matrix, respectively. Methods: 6 horses (age range, 2 to 25 years old) without clinically detectable musculoskeletal abnormalities. Methods: Rate of synthesis of G...
Dense microspheres in normal horse brain. Here were report eosinophilic globular bodies referred to as dense microspheres (DMS), in the brains of normal horse in relation to the ageing process. The characteristic structures of DMS found in the horse were in similar to those previously reported in the human. The DMS were found predominantly in the neuropil of the cerebral cortex, and were shown histochemically to have a proteinaceous content. Electron microscopy showed that the DMS consisted of homogeneous electron-dense material bound by a single membrane and that they were found within the neuronal processes. In addition, immature or...
An immunohistochemical study of three equine pulmonary granular cell tumors. Granular cell tumor (GCT) is a morphologic designation for tumors of varied histogenesis. Most GCTs in human beings are derived from Schwann cells, and rat meningeal GCTs are believed to originate in the neural crest. Three equine pulmonary GCTs from aged horses were studied immunohistochemically with primary antibodies directed against vimentin, cytokeratins (AE1/AE3), S-100, Leu 7, desmin, and neuron-specific enolase (NSE) using a steptavidin-biotin procedure. All three tumors stained similarly with strong and diffuse staining of neoplastic cells for vimentin and S-100 and negative staining ...
Effect of maturation and aging on material and ultrasonographic properties of equine superficial digital flexor tendon. Results of studies in human beings and other species have indicated that aging significantly influences the strength, modulus of elasticity, and energy storage ability of tendon. We wanted to determine the effects of aging on the material and ultrasonographic properties of equine superficial digital flexor (SDF) tendon. Ultrasonographic measurements of left forelimb SDF tendon cross-sectional area and mean echogenicity were made in 23 standing horses ranging in age from 2 to 23 years. All horses had not been in work for a minimum of 6 months prior to the study. After euthanasia, left forelimb ...
Age-related morphometrical changes of arteries of uterine wall in mares. To investigate the morphological changes of uterine wall arteries associated with the progression of age in Thoroughbred broodmares, uterine wall arteries from 13 mares, aged 2 to 31 years, were studied by routine histomorphometry. The ratio of intimal thickness to external diameter increased due to hyperplasia of elastic fibers and was significantly correlated with age (r = 0.95, P < 0.001). The ratio of medial thickness to external diameter decreased and was also significantly correlated with age (r = -0.84, P < 0.001). Using electron microscopy, it was determined that the cross-sectional ar...
Pheochromocytoma in two horses. A 12-year-old Standard-bred mare and a 21-year-old Quarter Horse gelding were treated for signs of abdominal pain and sweating. The mare also had muscle fasciculations, azotemia, and ataxia, and was euthanatized after signs of pain became refractory to analgesics. The gelding died when ventricular tachycardia developed during general anesthesia for exploratory celiotomy. Adrenal pheochromocytomas (bilateral in the mare), associated with retroperitoneal and intra-abdominal hemorrhage, were found on postmortem examination. Pheochromocytoma should be considered in older horses with signs of abdom...
Diagnostic testing for pituitary pars intermedia dysfunction in horses. Pituitary pars intermedia dysfunction is a slowly progressive disorder that afflicts most breeds of horses. Because it shares features with human Cushing disease, it has been referred to as equine Cushing disease. A variety of tests of pituitary-adrenocortical function were performed on horses with evidence of pituitary pars intermediate dysfunction, and results were compared with those in healthy control horses. Diurnal variations in plasma cortisol concentration were not statistically different between control horses and those with pituitary pars intermedia dysfunction. An ACTH stimulation (...
The frequent occurrence of thyroid tumours in aged horses. Thyroid tumours have been described as "moderately common" in horses, but diseases associated with them are rare and the actual incidence has not been reported. A survey of thyroids from 29 horses aged 12 to 32 years revealed gross lesions in 11 animals, all older than 17. Most lesions were microfollicular adenomas. There was no evidence that the horses suffered from long-standing iodine deficiency or diffuse hyperplasia. Adenomas were more common than hyperplastic nodules and it is unlikely that the former arose from the latter. One thyroid adenocarcinoma was discovered. Progression from thyr...
[The former place of execution of the Lucerne herd in Emmen (1562-1798)(1562-1798) and slaughter yard belonging to it (1562-1866): pathologico-anatomic findings in excavated animal bones]. During archaeological excavations of the former knackers yard in Emmen (Canton Lucerne) skeletons and individual bones of more than 700 animals were recovered. 110 bone samples had lesions and were examined macroscopically and radiologically, 100 were from horses, 9 from dogs and only one from cattle. According to morphological and etiopathogenetical criteria, lesions are presented in the following groups: tooth irregularities (10), degenerative changes in bones and joints due to overload and aging (80), trauma and infection (10), other lesions (10). Over 80% of pathological bone samples prese...
Diffuse cerebral encephalopathy associated with hydrocephalus and cholesterinic granulomas in a horse. Cholesterinic granulomas, commonly found at necropsy in aged horses, may cause neurologic signs by obstructing the interventricular foramina, resulting in hydrocephalus. Diffuse cerebral disease in horses may not always result in rapid progression of clinical signs. Intermittency of neurologic signs may be associated with intermittent increases in CSF pressure.