Hyperlipemia in 9 miniature horses and miniature donkeys

Basic Postoperative Care of the Equine Colic Patient

The 3 time periods around colic surgery (preoperative, operative, and postoperative) are all critical to successful outcomes. Although much focus is often paid to the first 2 time periods, the importance of sound clinical judgment and rational decision-making in the postoperative period cannot be overstated. This article will outline the basic principles of monitoring, fluid therapy, antimicrobial therapy, analgesia, nutrition, and other therapeutics routinely used in patients following colic surgery. Discussions of the economics of colic surgery and expectations for normal return to function will also be included.

Obesity-Related Metabolic Dysfunction in Dairy Cows and Horses: Comparison to Human Metabolic Syndrome

Obesity has become a serious health problem with frequent occurrence both in human and animal populations. It is estimated that it may affect over 85% of the human population and 70–80% of horses and cows by 2030. Fat cow syndrome (FCS) is a combination of metabolic, digestive, infectious, and reproductive disorders that affects obese periparturient dairy cows, and occurs most frequently in loose-housing systems, where periparturient and dry cows are fed and managed in one group disregarding the lactation stages. Equine metabolic syndrome (EMS) was named after human metabolic syndrome (MetS) and has insulin dysregulation as a central and consistent feature. It is often associated with obesity, although EMS may occur in a lean phenotype as well. Other inconsistent features of EMS are cardiovascular changes and adipose dysregulation. Laminitis is the main clinical consequence of EMS. MetS holds a 30-years old lead in research and represents a clustering of risk factors that comprise abdominal obesity, dyslipidemia, hypertension, and hyperglycemia (impaired fasting glucose or type 2 diabetes mellitus—T2DM), which are associated with doubled atherosclerotic cardiovascular disease risk, and a 5-fold increased risk for T2DM. The main aim of this review is to provide critical information for better understanding of the underlying mechanisms of obesity-related metabolic dysfunction in animals, especially in cows and horses, in comparison with MetS. Human medicine studies can offer suitable candidate mechanisms to fill the existing gap in the literature, which might be indispensable for owners to tackle FCS, EMS, and their consequences.

Refeeding syndrome in a miniature donkey

OBJECTIVE

To describe refeeding syndrome in an equid without a history of recognized risk factors.

CASE SUMMARY

Refeeding syndrome with marked hypophosphatemia developed in an aged miniature donkey gelding during treatment of suspected enterocolitis. Hypophosphatemia (manifested clinically as ileus and neuromuscular weakness) developed despite a short (3 day) history of hyporexia, increased body condition (7/9), and adherence to nutritional recommendations for critically ill equids. Nutritional support included nasogastric enteral feeding with a commercial equine nutrition product claiming to provide 100% of the National Research Council's daily recommended protein, vitamin, and mineral requirements for equids. Hypophosphatemia developed despite this enteral supplementation and was ultimately corrected by intravenous administration of sodium phosphate solution.

NEW OR UNIQUE INFORMATION PROVIDED

This case report suggests that risk factors for refeeding syndrome in equids may be broader than previously recognized. Specifically, critically ill equids at risk for insulin dysregulation may have unique nutritional co-morbidities and requirements. This report highlights the need for both broader recognition of risk factors for refeeding syndrome, and revised best-practice nutritional guidelines and supplementation products to improve equine critical care.

Variations in haematological and biochemical parameters in healthy ponies

Background

Breed specific reference ranges for selected blood parameters are recommended for proper interpretation of blood tests, but there are only few reports dealing with ponies. The purpose of this study was to investigate if blood parameters differ among ponies’ classes and to check if general normal values for equine species are applicable to ponies.

Results

All, except total protein concentration, biochemical parameter significantly (p < 0.05) differed among ponies’ classes. The most pronounced difference was noted in blood lactate concentrations, higher (p < 0.001) in the smallest ponies (class A). In all groups of ponies muscle enzymes (aspartate aminotransferase and creatine kinase) and urea were high when compared to normal values for equine species, but triglycerides and creatinine were low. Blood lactate concentration was high in comparison with normal values for horses only in class A ponies’.

Conclusions

In healthy ponies, blood lactate concentration significantly differs between height classes. Normal values for equine species should not be directly applied to interpret the lactate, triglycerides, aspartate aminotransferase and creatine kinase values in ponies.

Effects of feed deprivation on physical and blood parameters of horses

The objective of this study was to evaluate the effect of feed restriction on some physical and blood parameters in horses kept outdoors under natural conditions. Twenty horses were deprived of food for 48 h. They were closely monitored and examined, and blood samples were taken at the beginning (0) of the experiment and 6, 12, 18, 24, 30, 36, 42 and 48 hours afterward. During the experimental period, the control group (12 animals) had free access to water and hay, while the restricted group had free access to water only. Data were submitted to two-way analysis of variance with repeated measures, and statistical significance was P ≤ 0.05. The horses tolerated feed restriction without complications. Feed restriction had no effect on body mass and body condition score, heart rate, respiratory rate, capillary filling time and body temperature. However, feed restriction decreased the intensity of gastrointestinal sounds (P<0.05) compared to the control horses. Feed restriction did not cause any changes in erythrocyte variables and gamma glutamyl transferase, creatinine, total protein, and albumin concentrations. During fasting, there was a reduction in the leukocyte response (P<0.05). Feed restriction significantly raised the levels of blood urea nitrogen (24 to 48 hours), aspartate aminotransferase (36 to 48 hours) and total cholesterol (42 to 48 hours). During 48 hours of fasting, there was a continuous increase in triglyceride concentration. Feed restriction for 48 h had a marked effect on the intensity of gastrointestinal sounds and was responsible for important metabolic changes in the healthy horses of our sample.

Determination of lipid profiles in serum of obese ponies before and after weight reduction by using multi-one-dimensional thin-layer chromatography

Obesity is a key component of equine metabolic syndrome, which is highly associated with laminitis. Feed restriction and/or exercise are known to alleviate the detrimental effects of insulin resistance in obese ponies. However, little is known about changes in the serum lipid patterns due to weight reduction and its association with disease outcomes. Therefore, the lipid patterns in the serum of 14 mature ponies before and after a 14-week body weight reduction program (BWRP) were investigated by multi-one-dimensional thin-layer chromatography (MOD-TLC). Additionally, sensitivity to insulin (SI), body condition scores (BCS) and cresty neck scores (CNS) were measured. A BWRP resulted in a significant loss of body weight (P<0.001), which was associated with beneficial decreases in BCS and CNS (both, P<0.001). Serum lipid compositions revealed significantly increased free fatty acid (FFA), sphingomyelin (SM; both P<0.001), total cholesterol (C) and cholesterol ester (CE) (both P<0.01) and triacylglycerol (TG; P<0.05) densities. Improvement of SI after the BWRP was associated with increases in neutral lipids (C, CE and TG, all P<0.01), FFA and the phospholipid SM (both, P<0.001). The results show that a BWRP in obese ponies was effective and associated with changes in the concentrations of neutral lipids and the phospholipid SM, indicating that SM may play a role in insulin signaling pathways and thus in the pathogenesis of insulin resistance and the progression of metabolic syndrome in obese ponies.

Blood lactate concentrations in ponies and miniature horses with gastrointestinal disease

REASONS FOR PERFORMING STUDY

Clinical impression suggested that pony and miniature breeds (collectively referred to as ponies) presenting to a referral hospital for investigation of gastrointestinal disease had higher blood lactate concentrations on admission than large breed horses.

OBJECTIVES

The study tested the hypothesis that ponies with gastrointestinal disease had higher blood lactate concentrations on admission than large breed horses with similar disease severity.

STUDY DESIGN

Retrospective case-control study.

METHODS

Medical records from September 2006 to July 2011 were reviewed for ponies with a primary presenting complaint of gastrointestinal disease. Two larger breed horses with gastrointestinal disease were selected as controls for each case. Data collected included case details, historical and clinicopathological findings, diagnosis and outcome.

RESULTS

Information was collected on 50 ponies and 100 horses. Ponies had higher mean ± s.d. respiratory rates (27 ± 13 vs. 21 ± 13 beats/min; P = 0.01) and rectal temperatures (37.9 ± 0.6 vs. 37.4 ± 0.6°C; P = 0.006) and a longer median duration of clinical signs prior to presentation (10 h [1-72 h] vs. 6 h [1-120]; P<0.001). Median blood lactate concentrations on admission were higher in ponies than in horses (2.8 mmol/l [0.7-18.0] vs. 1.6 mmol/l [0.4-8.1]; P = 0.001). All other parameters relating to colic severity were not significantly different between groups, although more horses underwent exploratory laparotomy (19/50 ponies and 55/100 horses; P = 0.05). Median blood lactate concentrations in ponies with large intestinal disease, nonstrangulating lesions, undergoing medical treatment and surviving ponies were significantly higher than in horses in the same category. In contrast to horses, no differences in blood lactate concentrations exist between ponies with medical vs. surgical treatment, strangulating and nonstrangulating lesions and surviving and nonsurviving ponies.

CONCLUSION AND POTENTIAL RELEVANCE

Ponies might present with higher blood lactate concentrations than horses and might falsely be suspected of having a surgical lesion or a poorer prognosis if veterinarians are not aware of breed differences.

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

REASONS FOR PERFORMING STUDY

Sporadic 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.

HYPOTHESES

1) 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.

METHODS

The 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.

RESULTS

Severe 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.

CONCLUSIONS

Severe 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.

POTENTIAL RELEVANCE

Hypertriglyceridaemia could perpetuate inappetance and depression in clinically ill horses and potentially predispose to fatty infiltration of the liver and other organ systems.

Nutrition for critical gastrointestinal illness: feeding horses with diarrhea or colic

Horses with GI diseases such as colic and diarrhea are often intolerant of adequate enteral nutrition. Nutritional intervention should be an early part of therapeutic management in such cases. Protein and energy malnutrition in critically ill horses can have deleterious effects, including poor wound or incisional healing, reduced immunity, and weight loss. Early enteral or parenteral support should be provided to supply resting DE requirements in the equine ICU.

β-Adrenergic stimulated lipolysis in pony adipocytes is exclusively via a β2-subtype and is not affected by lactation

Catecholamines are important lipolytic agents in horses and ponies but the nature of the adrenergic receptor subtype distribution in their adipocytes is uncertain. A first objective was to identify the beta-adrenergic receptor subtype(s) present in adipocytes from horses and ponies. A second objective was to evaluate if the lipolytic responsiveness of isolated adipocytes to beta-adrenergic agonists is altered during lactation, a condition known to affect markedly maternal fat metabolism. Isoproterenol and salbutamol elicited strong lipolytic responses in adipocytes isolated from horse and pony subcutaneous adipose tissue. There were weak lipolytic responses to norepinephrine, dobutamine and BRL37344. The weak lipolytic response to NE compared to isoproterenol or salbutamol suggests an antilipolytic action from alpha2-adrenergic receptors. The relative order of potency for the beta-adrenergic agonists was isoproterenol>/=salbutamol>>dobutamine=BRL37344. There was expression of beta2-adrenergic receptor mRNA in pony and horse adipose tissues, as estimated by relative RT-PCR, but no expression of mRNAs for beta1- or beta3-adrenergic receptors. Early lactation did not alter the lipolytic responses to beta-adrenergic agonists, nor the expression of beta2-adrenergic receptor mRNA. Thus, these results indicate a dominant if not exclusive presence of beta2-adrenergic receptors in pony and horse adipocytes that is not affected by lactation.

Results of surgical treatment of colic in miniature breed horses: 11 cases

OBJECTIVE

To report on the outcome of surgical treatment of acute abdominal crises in miniature breed horses.

DESIGN

Retrospective case series of miniature horses presented to the University Veterinary Centre, Camden with an acute abdominal crisis.

METHODS

Hospital records of all miniature horses that underwent ventral midline laparotomy for acute abdominal crisis between 1997 and 2001 were reviewed. The signalment, history, clinical signs, results of ancillary diagnostic procedures, location and type of intestinal lesion, treatment and outcome were retrieved from each case record. Long-term survival was determined by telephone interview of owners.

RESULTS

Eleven miniature horses including five females and six males underwent ventral midline laparotomies for acute abdominal crisis during the study period. Ages ranged between 1 month and 19 years. Surgical findings included faecalith obstruction (seven horses), enterolith (one horse), strangulating lipoma of the descending colon (one horse), jejunal infarction (one horse), and caecal infarction (one horse). Long-term survival rate (minimum 12 months post surgery) was 55%. Six of eight horses with simple intraluminal obstructions survived, while the three horses with gastrointestinal lesions associated with vascular compromise were euthanased either at surgery (caecal infarction), or postoperatively, due to complications (strangulating lipoma of the descending colon, jejunal infarction). Postoperative complications in this study included impaction of the descending colon (two horses), diarrhoea (two horses), peritonitis (one horse), hyperlipaemia (two horses), incisional infection (two horses) and abdominal adhesions (one horse). Hyperlipidaemia was present in five of seven horses in which serum triglycerides were measured at presentation.

CONCLUSIONS

Simple intraluminal obstructions of the large intestine were frequently encountered during exploratory laparotomy in miniature horses presented for acute abdominal crises, and their surgical treatment was associated with a good prognosis. In contrast, this study suggested that abdominal pain associated with vascular compromise of gastrointestinal tissues in miniature horses was associated with a poorer prognosis, consistent with reports in other horse breeds. Possible contributing factors to faecalith formation, including poor quality roughage, dental disease, and inadequate water consumption, should be recognised and avoided in miniature horses. Serum triglyceride concentrations should be measured in miniature horses presented for acute abdominal pain. If elevated, nutritional supplementation should be provided.

Pituitary pars intermedia dysfunction: equine Cushing's disease

PPID in older equids has become a major health concern of horse owners. In response, equine practitioners have made greater efforts at understanding, diagnosing, and treating this disorder. Although PPID is recognized to be a different form of pituitary-dependent hyperadrenocorticism than is seen in canine or human patients, relatively little is known about the pathophysiology and natural progression of the disease. At present, the diagnosis is best supported by manifestation of characteristic clinical signs and endocrinologic test results, preferably a supportive DST result. Treatment must focus on improving overall health care, including body clipping, dentistry, and nutrition. As the condition progresses, administration of pergolide or a combination of pergolide and cyproheptadine is currently considered the best medical treatment. The time point at which medication should be added to improved health care and management changes is not currently known, but loss of body condition and development of hyperglycemia suggest more advanced PPID that would likely benefit from drug therapy. Whether medical treatment needs to be continuous or could be intermittent is also unknown. As the demand for treatment of affected equids continues to increase, clinical response and endocrinologic testing data as well as pharmacologic data for currently used drugs and other agents should be expected. Similarly, novel medical, and perhaps surgical, treatment strategies for this condition should also be anticipated in the future.

A preliminary report on a fat-free diet formula for nasogastric enteral administration as treatment for hyperlipaemia in ponies

A fat-free liquid diet was formulated to be administered by nasogastric tube as therapy for hyperlipaemia in ponies. The liquid diet provided energy, protein, minerals, trace elements, and vitamins in accordance with the requirements of ponies. As sole source of nutrition, the liquid diet fully counteracted fasting-induced hyperlipaemia in two healthy ponies. The liquid diet was also used in hyperlipaemic patients, but only in combination with conventional therapy, consisting of intravenous administration of glucose, insulin, and heparin. Although no patients were treated with the liquid diet alone, the liquid diet has potential in the treatment of hyperlipaemia - it is easy to prepare and to administer by nasogastric tube and it provides energy and nutrients to counteract the negative energy balance and low nutritional status of patients. Experience is needed with hyperlipaemic patients that are treated with the liquid diet only.