B. Dunkel

Severe hypertriglyceridaemia in clinically ill horses: diagnosis, treatment and outcome

REASONS FOR PERFORMING STUDYnSporadic measurement of serum triglycerides in depressed and inappetant clinically ill horses revealed severe hypertriglyceridaemia without visible evidence of lipaemia on several occasions, leading to the inclusion of serum triglyceride concentrations in the routine serum biochemistry evaluation of our hospital. Since then, more cases have been identified and treated for hypertriglyceridaemia, raising questions about the prevalence, predisposing factors and significance of these findings.nnnHYPOTHESESn1) Severe hypertriglyceridaemia without visible opacity of the serum occurs more commonly in clinically ill and inappetant horses than previously described and 2) appropriate treatment using i.v. dextrose and/or partial parenteral nutrition would decrease serum triglycerides to normal limits and might result in improved appetite and attitude of the patient.nnnMETHODSnThe laboratory computer database from 2000 and 2001 was searched for increased serum triglycerides (> 5.65 mmol/l) in any horse breed, ponies and miniature breeds excluded. Data analysed included subject details, diagnosis, clinical and laboratory parameters, treatment, response to treatment and outcome.nnnRESULTSnSevere hypertriglyceridaemia was identified in 13 horses, with serum triglyceride concentrations 6.17-18.29 mmol/l, while none showed visible lipaemia. All horses had clinical and laboratory findings consistent with systemic inflammatory response syndrome and all but one had an increased serum creatinine concentration. Treatment with i.v. dextrose and/or partial parenteral nutrition resulted in decrease of the serum triglycerides to normal limits.nnnCONCLUSIONSnSevere hypertriglyceridaemia occurs in inappetant and clinically ill horses without evidence of serum opacity more commonly than previously described. The presence of systemic inflammatory response syndrome might predispose horses to hypertriglyceridaemia, while the increased creatinine concentration might be a predisposing factor or result of the condition. Horses identified in our study readily responded to treatment and appetite and attitude improved coincident with decrease of the serum triglycerides to normal limits.nnnPOTENTIAL RELEVANCEnHypertriglyceridaemia could perpetuate inappetance and depression in clinically ill horses and potentially predispose to fatty infiltration of the liver and other organ systems.

Association between hypercoagulability and decreased survival in horses with ischemic or inflammatory gastrointestinal disease.

BACKGROUNDnCoagulopathies are common in horses with ischemic or inflammatory gastrointestinal (GI) disturbances. There is indirect evidence suggesting that early stages of these diseases are characterized by hypercoagulability (HC).nnnHYPOTHESIS/OBJECTIVESnHC, assessed via thromboelastography (TEG), is common in horses with ischemic or inflammatory GI diseases. The degree of HC is correlated with nonsurvival and thrombotic complications.nnnANIMALSnThirty client-owned horses with ischemic or inflammatory GI disease, 30 client-owned horses with nonischemic or inflammatory GI disease, and 30 healthy horses (control group).nnnMETHODSnProspective, observational clinical study. TEG profiles of 30 horses with ischemic or inflammatory GI disease were obtained on admission and 48 hours after admission, and these were compared with profiles from 30 horses with nonischemic or inflammatory GI disease and 30 healthy controls. Prothrombin time (PT), activated partial thromboplastin time (aPTT), antithrombin activity (AT), and D-Dimer concentrations were also determined in horses with GI disease.nnnRESULTSnHorses with ischemic or inflammatory GI disease had shorter R times compared with healthy horses (14.8±8.3 versus 22.8±12 minute; P=.011). However, changes were subtle and TEG profiles did not resembled those obtained from animals or humans presumed to be hypercoagulable. Although conventional coagulation testing supported the presence of HC (decreased AT and increased D-Dimer concentrations), TEG and coagulation abnormalities were rarely found in the same horses and the methods were not statistically related.nnnCONCLUSIONS AND CLINICAL IMPORTANCEnThere is evidence of HC in horses with GI disease but techniques for diagnoses require refinement.

Acute lung injury/acute respiratory distress syndrome in 15 foals.

REASONS FOR PERFORMING STUDYnFew reports exist in the veterinary medical literature describing clinical and pathological findings resembling conditions described as (ALI) and acute respiratory distress syndrome (ARDS) in man.nnnOBJECTIVESnTo document history, clinical, laboratory and diagnostic findings, treatment and outcome of foals age 1-12 months diagnosed with ALI/ARDS at a referral hospital.nnnMETHODSnMedical records, including radiographic, cytological, microbiological, serological and post mortem findings, were reviewed in a retrospective manner to identify foals with acute onset of respiratory distress, a partial pressure of arterial oxygen (PaO2) to fraction of oxygen in inspired gases (FiO2) ratio of < or = 300 mmHg, pulmonary infiltrates on thoracic radiographs or post mortem findings consistent with ALI/ARDS.nnnRESULTSnFifteen foals age 1.5-8 months were included in the study. Seven foals had previously been treated for respiratory disease, and all foals developed acute respiratory distress <48 h prior to presentation. Findings on presentation included tachycardia and tachypnoea in all foals, with fever recorded in 8 cases. Eight cases met the criteria for ALI and 7 for ARDS. Radiographic findings demonstrated diffuse bronchointerstitial pattern with focal to coalescing alveolar radiopacities. An aetiological agent was identified in foals ante mortem (n = 6) and post mortem (n = 4). All foals were treated with intranasal oxygen and antimicrobial drugs; 13 received corticosteroids. Nine patients survived, 4 died due to respiratory failure and 2 were subjected to euthanasia in a moribund state. Follow-up was available for 7 foals; all performed as well as age mates or siblings, and one was racing successfully.nnnCONCLUSIONSnA condition closely meeting the human criteria for ALI/ARDS exists in foals age 1-12 months and may be identical to previously described acute bronchointerstitial pneumonia in young horses.nnnPOTENTIAL RELEVANCEnALI/ARDS should be suspected in foals with acute severe respiratory distress and hypoxaemia that is minimally responsive to intranasal oxygen therapy. Treatment with systemic corticosteroids, intranasal oxygen and antimicrobials may be beneficial in foals with clinical signs compatible with ALI/ARDS.

Platelet activation in ponies with airway inflammation

REASON FOR PERFORMING STUDYnPlatelet activation occurs in human obstructive airway diseases and in laboratory animal models. However, there is limited evidence that platelets may be involved in equine recurrent airway obstruction (RAO) and other inflammatory diseases. This study investigated whether platelet activation also occurred in RAO.nnnHYPOTHESISnPlatelet function is altered in ponies with active RAO. This alteration can be detected ex vivo by measuring platelet adhesion.nnnMETHODSnAn in vitro platelet adhesion assay measuring acid phosphatase (AcP) activity colorimetrically was adapted for use with equine platelets and responses to selected agonists were established. Platelet adhesion and aggregation was evaluated in vitro on platelets isolated from 6 ponies with RAO before, during and after a 7 h natural antigen challenge. Three ponies with no history of airway disease were also studied.nnnRESULTSnAdhesion of equine platelets to serum coated plastic was detected at concentrations of 10-100 radicaló 10(9)/l. Adhesion increased in response to stimulation with platelet activating factor and thrombin, but not equine interleukin 8. Prior to the antigen challenge, adhesion of nonstimulated platelets was low and increased significantly (P<0.05) 24 h after initiation of the challenge in RAOs, but not in the normal animals. No changes in platelet aggregation were noted in either group.nnnCONCLUSIONSnThe described assay offers an alternative method to evaluate platelet function in healthy and diseased horses and can detect changes not observed using a classic aggregation assay. Circulating platelets are activated 24 h after antigen challenge of ponies with RAO and may play a role in pulmonary inflammation and/or the pathophysiology of RAO.nnnPOTENTIAL RELEVANCEnInvestigating platelet function in RAO and airway inflammation may reveal new aspects of the pathogenesis of inflammatory lung disease in the horse.

Putative intestinal hyperammonaemia in horses: 36 cases

REASONS FOR PERFORMING THE STUDYnIntestinal hyperammonaemia (HA) has been infrequently reported in individual horses; however, there have been no studies describing clinical and laboratory data as well as short- and long-term outcome in a larger number of cases.nnnOBJECTIVESnTo describe clinical and laboratory data and short- and long-term outcome in a large group of horses with intestinal HA.nnnMETHODSnMulti-centred, retrospective study; case records of horses with HA were reviewed and any horse with a clinical or post mortem diagnosis of intestinal HA was included. Hyperammonaemia was defined as a blood ammonium (NH(4) (+)) concentration ≥60 µmol/l and horses with a diagnosis of primary hepatic disease were excluded. Relevant data were recorded and, if appropriate, data from survivors were compared to nonsurvivors to identify potential prognostic indicators.nnnRESULTSnThirty-six cases, 26 mature horses and 10 foals with intestinal HA were identified. Case histories included diarrhoea, colic and neurological signs and the most common clinical diagnosis was colitis and/or enteritis. The most common clinical and laboratory abnormalities included tachycardia, increased packed cell volume, hyperlactataemia and hyperglycaemia. Fourteen horses (39%) survived to discharge; NH(4) (+) concentration on admission was the only parameter significantly associated with survival. All surviving horses and foals for which follow-up information was available recovered completely and returned to their intended use without further complications.nnnCONCLUSIONS AND POTENTIAL RELEVANCEnIntestinal HA occurs in mature horses and foals and can be associated with severe clinical and laboratory abnormalities; further studies are required to investigate predisposing factors and delineate possible differences in aetiologies.

Neutrophil and platelet activation in equine recurrent airway obstruction is associated with increased neutrophil CD13 expression, but not platelet CD41/61 and CD62P or neutrophil–platelet aggregate formation

Recurrent airway obstruction (RAO) in mature horses is characterized by reversible airway obstruction and neutrophilic inflammation; there is also functional activation of circulating platelets and neutrophils. This study was undertaken to determine if changes in activation marker expression and heterotypic aggregate formation can be used as an indicator of this increased functional responsiveness. In vitro conditions for flow cytometric measurement of CD13, CD41/61 and CD62P expression on activated cells and heterotypic aggregate formation were established. Values were then compared before and after antigen challenge of RAO and healthy horses. Platelet adhesion to serum-coated plastic was measured as a functional marker of platelet activation. In vitro activation resulted in increased expression of neutrophil CD13 and platelet CD41/61 and CD62P. Activation of both cell types caused a significant increase in neutrophil-platelet aggregates. In horses with RAO, but not controls, there was a significant increase in the percentage of CD13 positive neutrophils at 10h and 24h and in the mean fluorescence intensity at 10h. This was accompanied at 24h by an increased mean platelet side scatter and thrombin-stimulated platelet adhesion. In conclusion, CD13 expression can be used as an indicator of equine neutrophil activation both in vitro and in vivo. Equine platelet activation in vitro can be detected by measuring CD41/61 or CD62P expression, and PAF-activated platelets and neutrophils form aggregates. However, despite evidence of circulating platelet activation, neither a change in expression of platelet activation markers, nor heterotypic aggregate aggregate formation could be detected.

Rater Agreement on Gait Assessment during Neurologic Examination of Horses

Background Reproducible and accurate recognition of presence and severity of ataxia in horses with neurologic disease is important when establishing a diagnosis, assessing response to treatment, and making recommendations that might influence rider safety or a decision for euthanasia. Objectives To determine the reproducibility and validity of the gait assessment component in the neurologic examination of horses. Animals Twenty‐five horses referred to the Royal Veterinary College Equine Referral Hospital for neurological assessment (n = 15), purchased (without a history of gait abnormalities) for an unrelated study (n = 5), or donated because of perceived ataxia (n = 5). Methods Utilizing a prospective study design; a group of board‐certified medicine (n = 2) and surgery (n = 2) clinicians and residents (n = 2) assessed components of the equine neurologic examination (live and video recorded) and assigned individual and overall neurologic gait deficit grades (0–4). Inter‐rater agreement and assessment‐reassessment reliability were quantified using intraclass correlation coefficients (ICC). Results The ICCs of the selected components of the neurologic examination ranged from 0 to 0.69. “Backing up” and “recognition of mistakes over obstacle” were the only components with an ICC > 0.6. Assessment‐reassessment agreement was poor to fair. The agreement on gait grading was good overall (ICC = 0.74), but poor for grades ≤ 1 (ICC = 0.08) and fair for ataxia grades ≥ 2 (ICC = 0.43). Clinicians with prior knowledge of a possible gait abnormality were more likely to assign a grade higher than the median grade. Conclusion and Clinical Importance Clinicians should be aware of poor agreement even between skilled observers of equine gait abnormalities, especially when the clinical signs are subtle.

Severe hypertriglyceridaemia in horses and ponies with endocrine disorders

REASONS FOR PERFORMING THE STUDYnSevere hypertriglyceridaemia in horses and ponies with endocrine disorders has been reported anecdotally but has not been documented in the literature.nnnOBJECTIVESnTo describe historical and clinicopathological findings as well as progression and outcome in horses and ponies with severe hypertriglyceridaemia (serum triglyceride concentration >5.65 mmol/l) secondary to an endocrine disorder that were otherwise apparently healthy.nnnMETHODSnCases from 6 participating institutions were identified and case details extracted from the medical records.nnnRESULTSnCase details of 3 horses and 4 ponies were available. Presenting complaints included weight loss despite good appetite in 4 animals, while in 3 hypertriglyceridaemia was identified incidentally. All animals were bright and alert and showed a normal or increased appetite. Serum triglyceride concentrations ranged from 10.5 to 60.3 mmol/l. Other abnormalities included hyperglycaemia in 6 animals, suspected insulin resistance and mild to severe increases in hepatic enzyme activities. In 2 animals, moderate hepatic lipidosis was confirmed histologically. Three horses and 3 ponies were diagnosed with pituitary pars intermedia dysfunction based on clinical signs and basal adrenocorticotropic hormone (ACTH) concentrations or dexamethasone suppression test results. In 5 of these, type 2 diabetes mellitus was also confirmed, while one pony suffered from type 2 diabetes mellitus without concurrent pituitary pars intermedia dysfunction. Laboratory abnormalities improved in 4 animals with treatment (pergolide and/or insulin), in one horse specific treatment was not attempted, and in 2 ponies treatment was impaired by the owner or only partly effective. In one of the latter cases, biochemical abnormalities persisted for 7 years without apparent ill effects.nnnCONCLUSIONS AND POTENTIAL RELEVANCEnHorses and ponies may develop severe hypertriglyceridaemia secondary to endocrine disorders that are associated with insulin resistance. Hypertriglyceridaemia can resolve with treatment of the endocrinopathy. Although biochemical evidence of hepatic compromise was present, clinical abnormalities were not noted in these animals.

Comparison of two antimicrobial regimens on the prevalence of incisional infections after colic surgery.

Appropriate durations of perioperative antimicrobial therapy following exploratory coeliotomy in horses are controversial, and with the rising prevalence of multiresistant bacteria there is a strong incentive to use antimicrobials for the shortest time possible. Following exploratory coeliotomies, incisional infections are an important cause of morbidity in horses and could be influenced by the duration of systemic antimicrobial therapy. The aim of this study was to investigate whether 72u2005hours of perioperative antimicrobial therapy is as effective as 120u2005hours at preventing the development of postoperative incisional infections. Horses undergoing exploratory coeliotomy at two referral hospitals were assigned randomly into Group 1 (receiving 72u2005hours of perioperative antimicrobial therapy) and Group 2 (receiving 120u2005hours of perioperative antimicrobial therapy). Only horses recovering from surgery and surviving for >120u2005hours were included in the study. Ninety-two horses met the criteria for inclusion in the study, 42 in Group 1 and 50 in Group 2. The overall incisional complication rate was 42.2 per cent, and no significant difference in the number of incisional complications in the two groups was identified. Results of the study suggest that there is no benefit in using 120u2005hours over 72u2005hours of perioperative antimicrobial therapy to prevent incisional infections.

Stimulus-dependent release of tissue-regenerating factors by equine platelets.

REASONS FOR PERFORMING THE STUDYnPlatelet-rich plasma (PRP) is increasingly used for treatment of orthopaedic injuries. However, the effects of different stimuli on the release pattern of regenerative and proinflammatory factors from equine platelets are largely unknown and an optimal treatment protocol remains to be established.nnnOBJECTIVESnThe aim of this study was to identify a stimulus that enhanced release of histopromotive factors (platelet-derived growth factor BB [PDGF] and transforming growth factor 1β[TGF]) without causing concurrent release of a proinflammatory mediator (CCL5).nnnMETHODSnWashed platelets were prepared from 6 healthy ponies and release of growth factors and CCL5 measured using commercially available ELISAs for human proteins following incubation with or without thrombin, chitosan or equine recombinant tumour necrosis factor (erTNF) over 24u2003h and subsequently over 96u2003h. Additionally, noncoagulated samples were analysed.nnnRESULTSnRegardless of whether a stimulus was present or what stimulus was used, PDGF and TGF release was maximal by 0.5-1u2003h when clot formation took place and very little release was observed after 24u2003h. Growth factor release was minimal in noncoagulated samples. In contrast, CCL5 release was not associated with coagulation and appeared to persist for much longer. High concentrations of erTNF caused significantly greater release of CCL5 at 6u2003h than any other stimulus tested.nnnCONCLUSIONSnGrowth factor release from equine platelets is dependent on coagulation but independent of the initiating stimulus, and is accompanied by more sustained release of proinflammatory mediators.nnnPOTENTIAL RELEVANCEnSupernatants collected from coagulated platelets could be an alternative treatment to PRP.