Laminitis is a complex and painful condition affecting the hooves of horses, characterized by inflammation and damage to the laminae, the soft tissue structures that secure the hoof wall to the coffin bone. This condition can lead to severe lameness and, in chronic cases, permanent structural changes within the hoof. Factors contributing to laminitis include metabolic disorders, excessive intake of carbohydrates, and mechanical overload, among others. The condition is diagnosed through clinical signs, radiographic imaging, and sometimes histopathological examination. Management strategies often involve dietary modifications, pain relief, and corrective hoof care. This page compiles peer-reviewed research studies and scholarly articles that explore the pathophysiology, risk factors, diagnostic approaches, and management strategies for laminitis in horses.
Minnick PD, Brown CM, Braselton WE, Meerdink GL, Slanker MR.An aqueous extract of the heartwood of black walnut (Juglans nigra) was given via stomach tube to 10 horses. Eight developed Obel grade 3 or 4 laminitis within 12 hr. Limb edema and mild sedation were the only other clinical signs observed. One horse was euthanized due to severe signs. The other 7 recovered within 6 days. Gas chromatography/mass spectrometry of aqueous extracts of heartwood, bark and nuts of black walnut identified juglone in the bark and nuts, but not in the heartwood. It was concluded that the aqueous extract of heartwood is laminogenic to horses, but the active ingredient i...
Rugh KS, Garner HE, Sprouse RF, Hatfield DG.Systemic arterial hypertension is associated with equine laminitis, a disease precipitated by gross over-ingestion of carbohydrates. We examined the hearts from nine chronically hypertensive (161 +/- 11/99 +/- 6 mmHg) laminitic ponies and nine normotensive (128 +/- 2/76 +/- 3 mmHg) ponies postmortem for signs of left ventricular hypertrophy. The hypertensive ponies had hearts which were significantly larger (7.77 +/- 0.26 g/kg bodyweight (BW) vs. 5.67 +/- 0.22 g/kg BW), as well as increased combined left ventricle and septum weight (4.99 +/- 0.21 g/kg BW vs. 3.67 +/- 0.20 g/kg BW) and left ven...
Markel MD, Pascoe JR, Sams AE.The medical records of 13 horses with strangulated umbilical hernias were reviewed. Typical history included increased swelling, warmth, and firmness of the hernial sac. Enterocutaneous fistulas had developed in 2 horses. Four horses had signs of abdominal pain. Surgery was performed on all horses, and the hernia was reduced by an open reduction technique. Incarcerated tissue included omentum (1 horse), jejunum (5), ileum (4), cecum (1), and ventral colon (2). All horses survived and were discharged from the hospital. Follow-up information on 9 horses (5 to 52 months after discharge) revealed ...
Baxter GM.Clinical data from 12 cases of equine laminitis characterized by distal displacement of the distal phalanx (P3) were reviewed. Clinical features of horses that survived the syndrome were compared with the nonsurvivors to obtain prognostic indicators. Animals affected included 8 Quarter Horses, 2 Welsh ponies, 1 Thoroughbred, and 1 Arabian. Eight of the animals were females (67%), 2 were stallions, and 2 were geldings. The mean age of affected animals was 8.6 years (2 to 14 years), and the mean body weight was 442 kg. The survivors weighed less than the nonsurvivors (384 kg vs 473 kg, respectiv...
Hunt JM, Edwards GB, Clarke KW.A survey of 259 surgical colic cases revealed that over 50 per cent of fatalities occurred in the postoperative period. Postoperative ileus and circulatory/endotoxaemic shock accounted for 70 per cent of these deaths. Other less important complications were salmonellosis, long bone fracture, adhesions, haemorrhage, laminitis, wound infection and ischaemic muscle damage. Close monitoring of postoperative progress is necessary to enable early diagnosis and treatment. Recent developments in understanding of the pathophysiology of endotoxic shock and ileus may lead to more successful treatment reg...
Jeffcott LB, Field JR, McLean JG, O'Dea K.The existence of an innate insulin insensitivity in ponies was investigated and compared with the situation in larger breeds of horse. Ponies that were fat or had previously suffered laminitis were found to be far more intolerant to oral glucose loading (1 g/kg bodyweight [bwt]) than normal ponies or Standardbreds. These ponies also exhibited a far greater response in plasma insulin levels after glucose loading. Insulin response tests (0.4 iu/kg bwt insulin intravenously) showed only a minimal and very protracted response in both the fat and laminitic groups. The relevance of these findings in...
Jeffcott LB, Field JR.Hyperlipaemia is an important condition in ponies, not just because of the seriousness of the clinical signs and biochemical changes involved, but because of the distress it causes owners and breeders that have had animals suffer from it. Hyperlipaemia occurs most commonly in fat ponies in late pregnancy and is rarely seen in larger horses. The syndrome has similarities with conditions in other species but the definitive aetiologies are not yet known. The condition in ponies is undoubtedly related to stress. The biochemical mechanisms involved in equine hyperlipaemia are considered and an hypo...
Lazary S, Gerber H, de Weck AL, Arnold P.A new, non-MHC linked alloantigenic membrane antigen on the equine lymphocytes is described. This antigen was characterized with alloantisera in the two-stage microcytotoxicity test and designated as ELy-1 antigen. The frequency of ELy-1 antigen positive animals in various populations is close to 50%. ELy-1 shows an autosomal, dominant inheritance. Since an allelic antigen (s) could not be demonstrated in family studies, it is assumed that only two alleles ELy-1+ and ELy-1- exist. The ELy-1 antigen in positive animals is expressed on both T and B lymphocytes but it is not present on erythrocyt...
Ek N.Studies of transferrin (Tf) concentration in sera of sick horses were carried out using Mancini’s immunodiffusion technique. Relative values against a chosen reference serum were determined for a total of 112 horses. Horses with acute infections had Tf values significantly below the normal. The lowest individual Tf value in this group (46%) was found in a six-months-old foal with temperature 41°C and watery diarrhoea. Horses suffering from acute laminitis also had decreased Tf values. The lowest value in the whole material (45%) was found in a horse belonging to this group. There was a posi...
Coffman JR, Hammond LS, Garner HE, Thawley DG, Selby LA.A COMMON progression of chronic laminitis is ischaemic
necrosis with secondary infection a frequent complication.
For 6 years we have performed a complete blood count
(CBC) on all hospitalised horses (at the University of Missouri
Veterinary Hospital) every Monday, Wednesday and Friday.
Preliminary scrutiny of the results indicated that persistent
elevation of the total white blood cell count (WBC) and
neutrophilia was consistent with poor prognosis in horses
affected with laminitis. Because of these considerations we
decided to perform a retrospective examination of the blood
cell d...
Ek N.Studies of Pr protein concentrations in sera of sick horses were carried out using ’s (1965) immunodiffusion technique. Relative values against a chosen standard of 100 were determined for a total of 102 horses. Horses with acute infections had Pr protein values significantly above the normal. The highest individual Pr protein value recorded in this group was 202. Horses suffering from acute laminitis and malignant tumours also had increased Pr protein values. There was a positive correlation between the Pr protein value and the blood leucocyte count and a negative correlation between the P...
Moore JN, Garner HE, Berg JN, Sprouse RF.Cecal fluid from two adult horses was assayed by the limulus amebocyte lysate system for endotoxin before and after carbohydrate overload of the gastrointestinal tract. There were increases in cecal fluid endotoxin concentrations at the 3-, 6-, and 12-hour samplings when compared with base-line values. Concomitant cecal fluid lactate concentrations and pH values increased and decreased, respectively. Both horses subsequently developed clinical signs of acute laminitis.
Ackerman N, Garner HE, Coffman JR, Clement JW.The angiographic appearance of the normal equine foot was compared with the appearance of equine feet affected with chronic laminitis. The normal foot was characterized by complete filling of the terminal arch, 8 to 10 main branches between 0.1 and 0.2 cm in diameter, a symmetrical netlike vascular pattern in the corium of the hoof, and numerous fine vessels in the corium of the coronary band. The feet affected with chronic laminitis were characterized by poor filling of the terminal arch, larger and less numerous primary branches, an irregular vascular pattern in the corium of the hoof, areas...
Freeman DE, Richardson DW, Tulleners EP, Orsini JA, Donawick WJ, Madison JB, Ross MW, Beroza GA.Loop colostomy was performed in 10 horses as treatment for grade-III rectal tears (n = 6 horses), small-colon infarction (n = 2 horses), perirectal abscess and stenosis (n = 1 horse), and small-colon stricture (n = 1 horse). In 7 horses, the colostomy was constructed through a single incision low in the left flank, with closure of the incision around the stoma (single-incision technique). In 3 horses, 2 of which had colostomy performed as a standing procedure, the selected segment of small colon was placed from a flank incision into a separate, small incision low in the left flank (double-inci...
Owens JG, Kamerling SG, Keowen ML.The eicosanoids are a family of lipid-derived autocoids that are released in response to a variety of physical and hormonal stimuli. In this study, prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) were measured in the digital veins of clinically normal horses and horses with chronic laminitis to determine whether these arachidonic acid metabolites have a role in mediating signs of hoof pain and lesions associated with chronic laminitis. Horses were evaluated at rest and after a brief exercise period, to determine whether eicosanoids are released into the circulation after mild concussion. Dig...
Borer-Weir KE, Bailey SR, Harris PA, Menzies-Gow NJ, Elliott J.Digital vasoconstriction, ischaemia and hypoxia may predispose to acute laminitis. Laminitis incidence varies seasonally, peaking in spring and summer. Direct seasonal influences on equine digital artery (EDA) contractility have not been investigated. This study assessed seasonal variation in maintenance of phenylephrine (PHE)-induced tone in isolated EDAs under hypoxic (95% nitrogen) and hyperoxic (95% oxygen) conditions. The objective was to measure change in arterial tone over time after constriction to a plateau with PHE. Tone was measured at plateau and over time and percentage change cal...
Fortin-Trahan R, Sjolin E, Lack A, de Arbina CL, McFadden-Bennett A, Wang L, Baird JD, Rikihisa Y, Arroyo LG.Potomac horse fever (PHF) is characterized by fever, depression, anorexia, ileus, diarrhea, and occasionally, laminitis. The disease is caused by infection with and/or . Equids of all ages may be affected; however, the condition has not been well-characterized in foals. This report describes clinical signs, laboratory findings, and treatment of 2 foals diagnosed with PHF in southwestern Ontario. Feces submitted for an equine PCR panel tested positive for spp. and were subsequently confirmed to be (Case 1) and (Case 2). Both foals recovered following hospitalization and intensive care. Key ...
Jayathilake WMNK, de Laat MA, Furr M, Risco C, Lacombe VA.Hyperinsulinemia is the key feature of equine metabolic syndrome (EMS) which leads to debilitating sequelae. Hyperinsulinemia-associated laminitis (HAL) is one of the major sequelae of EMS, although the pathophysiological mechanisms are not well elucidated. Using an equine model, we hypothesized that expression of inflammatory markers would be increased in digital lamellae and striated muscle following prolonged hyperinsulinemia. Healthy Standardbred horses (5.4 ± 1.9 years) were alternately assigned to a prolonged euglycemic-hyperinsulinemic clamp (pEHC) or control group (n = 4 per group...
Ward AB, Harris PA, Argo CM, Watson CA, Burns NM, Neacsu M, Russell WR, Grove-White D, Morrison PK.Native ponies are at increased risk of obesity and metabolic perturbations, such as insulin dysregulation (ID), a key risk factor for endocrinopathic laminitis. Management and feeding practices can be adapted to maintain healthy body condition and support metabolic health, but owners may inadvertently provide their ponies with inappropriate management leading to obesity and exacerbating risk of metabolic disease. Adoption of preventative weight management approaches (WMAs), including regular monitoring of body condition, providing appropriate preserved forage, promoting seasonal weight loss, a...
de Laat MA, Fitzgerald DM, Harris PA, Bailey SR.High plasma concentrations of insulin can cause acute laminitis. Ponies and horses with insulin dysregulation (ID) exhibit marked hyperinsulinemia in response to dietary hydrolyzable carbohydrates. Glucagon-like peptide-1 (GLP-1), an incretin hormone released from the gastrointestinal tract, enhances insulin release, and is increased postprandially in ponies with ID. The aim of this study was to determine whether blocking the GLP-1 receptor reduces the insulin response to a high glycemic meal. Five adult ponies were adapted to a cereal meal and then given two feed challenges 24 h apart of a me...
Macon EL, Harris P, McClendon M, Perron B, Adams A.Hyperinsulinemia-associated laminitis (HAL) is the primary concern for insulin dysregulated (ID) equids and their insulin response to the consumption of oral, nonstructural carbohydrates (NSC) has been shown to be a risk predictor for HAL development. This randomized, crossover study's objective was to examine the insulinemic responses to 3 forage pellets (1 g/kg BW) (timothy hay, TH, 9.5 % CP & 10 % NSC DM; alfalfa hay, AH, 16.3 % CP & 9.8 % NSC DM; timothy-alfalfa hay; TAH, 17.2 % CP & 9.8 % NSC DM) along with a positive (dehulled oats; OG, 14.7 % CP & 59.7 % NSC DM) and negative dietary cha...
Paraschou G, Xue C, Egan R, Bolfa P.Lymphoma is a common neoplasm in horses but is reported much less commonly in donkeys. In this case report, we describe the macroscopic, microscopic and immunohistochemical features of a multicentric lymphoma with intestinal and bone marrow involvement. Methods: A geriatric female donkey with history of chronic lameness was found dead. Post-mortem examination revealed advanced emaciation, periodontal disease, left front foot laminitis and multiple, soft, white to yellow tan intestinal transmural masses, up to 12 cm in diameter. Cytology suggested a round cell intestinal neoplasm. The femur of...
Khaledi KA, Mirshahi A, Sardari K, Azizzadeh M, Ghasemi S.The Turkmen horse is one of the oldest breeds in the world with unique characteristics in agility, endurance and jump, being publicly acclaimed. Laminitis affects the limbs and decreases athletic performance. Radiographic evaluation is essential to confirm the sinking diagnosis in every breed of a horse suffering from laminitis. Since no information about distal phalanx radiographic measurements in this breed has been reported, the current study was designed and conducted. In the present study, 24 clinically sound registered Turkmen horses of both sexes (15 mares and nine stallions) were selec...
Menzies-Gow NJ, Knowles EJ.Laminitis is a common and painful condition of the equine foot and approximately 90% of cases are associated with insulin dysregulation (ID) that is a central feature of the common endocrine disorder equine metabolic syndrome (EMS) and occurs in a subset of animals with pituitary pars intermedia dysfunction. Additional features of EMS include obesity, altered circulating concentrations of adipokines (particularly adiponectin and leptin) and hypertriglyceridaemia. Obesity, ID, hypoadiponectinaemia, hyperleptinaemia and an altered plasma lipid profile are also features of human metabolic syndrom...
Lopes MAF, Hollenbach E, Schliewert EC, Murphy MA, Corrêa F.A mare was admitted for progressive swelling of the neck, lethargy and anorexia. Radiography revealed perilaryngeal, peritracheal, and periesophageal emphysema. Endoscopy revealed pharyngeal and tracheal roof collapse, and a small laceration on the trachea. Treatment with antimicrobials, fluids, and flunixin was initiated. To prevent exacerbation of the emphysema, temporary tracheostomy was performed. Clipping for the tracheostomy revealed a hoofprint mark on the ventral neck. Subsequent endoscopies revealed laceration of the esophagus and guttural pouch septum communicating with the visceral ...
Tuniyazi M, Tang R, Hu X, Zhang N.Laminitis is a serious health condition that can cause severe pain and lameness in horses. Due to lack of understanding of laminitis, treatments often fail to achieve the desired results. In recent years, we have begun to recognize that laminitis may involve a complex interaction between local and systemic inflammation. Dysbiosis of the gut microbiota has been linked in the development of systemic inflammation, and our previous findings suggest that the development of laminitis is closely linked to the production of harmful metabolites of the gut microbiota. In addition, it was found that loca...
Kaufman KL, Suagee-Bedore JK, Johnson SE, Ely KM, Ghajar SJ, McIntosh BM.Forage is essential for equine health and performance, but intake of elevated pasture nonstructural carbohydrates (NSC) may exacerbate metabolic disorders. This study aimed to investigate the influence of laminitis history on metabolic and morphometric responses in grazing horses. Twelve non-pregnant mares (15 ± 3.4 yrs) were selected based on previous diagnosis of laminitis (PRELAM; n=6) or not (NOLAM; n=6). Horses were maintained on 8.5-ha pasture. Weekly pasture samples were clipped at random for nutrient analysis. Monthly blood samples were collected and analyzed for glucose and insulin c...
McGuire CJ, Knowles EJ, Harris PA, Menzies-Gow NJ.Circulating insulin concentrations are used to quantify risk of laminitis in currently non-laminitic ponies. Basal serum activin A (AA) concentration has previously been positively correlated with serum insulin concentrations 60 minutes (T60) following an oral sugar test (OST) in ponies with equine metabolic syndrome. Therefore, circulating AA might be a useful marker for insulin dysregulation (ID) and laminitis risk. Objective: To explore the relationship between circulating AA concentrations at baseline (T0) and T60 in ponies that developed laminitis within six months and non-laminitic ponie...
Johnson A, Karam B, Schroeder O, McKaig L, Loesch K.A 12-month-old miniature horse filly was presented because of laminitis, suspected lymphangitis, and pyrexia. Although the filly's initial physical examination and diagnostic tests suggested an infectious etiology, ultrasonographic findings were suspicious for generalized steatitis. This was confirmed histopathology. The filly experienced full recovery with continued resolution of clinical signs at 18 mo after presentation. This case included aspects similar to those of previously reported clinical presentations, as well as long-term follow-up in a breed that is not overrepresented, providing...
Mlyneková E, Zaťko S, Halo M, Imrich I, Halo M.This study aimed to examine the seasonal dynamics of non-structural carbohydrates in pasture and their relationship to metabolic indicators in horses with a history of laminitis. Thirty Hucul mares were divided into a laminitis group (LG, = 15) and a control group (CG, = 15). Insulin, glucose, fructosamines concentrations and body weight were monitored during four sampling periods (S0-S3), while pasture variables were analyzed during three periods (S1-S3). The concentration of water-soluble carbohydrates was highest in May (126.8 g/kg DM) and measured lower in October (57.9 g/kg DM), while s...
Page AE, McPeek JL, Carattini S, McGreevy E, Adam E.The goal of this project was to examine the metabolic effects of IA methylprednisolone acetate (MPA) following injection into multiple low-motion joints. Unassigned: Six 3-year-old geldings without pituitary pars intermedia dysfunction or insulin dysregulation were randomly injected with 20 mg of IA MPA/joint (80 mg total; bilateral distal hock joints) or an equal volume of saline. Serial blood samples were collected for resting ACTH, cortisol, insulin, and glucose, as well as insulin and glucose following repeated low-dose oral sugar tests. Treatments were crossed over after a 6-week washout,...
Hargitaiova K, Maleas G.To describe outcomes following high-metacarpal deep digital flexor tenotomy (DDFT) combined with Steward clog application in horses and ponies with refractory chronic laminitis. Methods: Retrospective observational study. Methods: Client-owned horses and ponies (7 horses, 8 ponies) with severe refractory laminitis. Methods: Medical records (2018-2019) were reviewed. All underwent standing high-metacarpal DDFT tenotomy proximal to the accessory ligament (AL-DDFT) junction, followed by customized Steward clogs application. Preoperative assessment included radiography and venography. Postoperativ...
Stapley E, Gillespie-Harmon C, Waxman S, Farr A, Bertin FR.The frequency of comorbidities in horses with pituitary pars intermedia dysfunction (PPID) in first-opinion practice is unknown. It is hypothesized that horses with PPID would have more frequent medical events and be euthanized at a younger age. Unassigned: This was a case-control retrospective study. Medical records ranging from 1996 to 2024 including 132 horses diagnosed with PPID and 274 controls matched by age and breed were reviewed. Variables associated with PPID were evaluated with a Fisher exact or Mann-Whitney U test followed by conditional logistic regression. Results were reported a...
