ISSN 2398-2977      

Hyperlipemia syndrome

pequis

Synonym(s): Fatty liver syndrome


Introduction

  • Hyperlipemia syndrome is a metabolic disease of ponies, miniature horses and donkeys; it rarely occurs in horses.
  • Hyperlipemia refers to the condition-disease, while hyperlipidemia refers to the increase in serum triglyceride concentrations (hypertriglyceridemia).
  • It can   →    organ failure   Liver disease: overview   (liver failure, renal failure, multiorgan dysfunction) and death.
  • Cause:
    • Any condition that results in a negative energy balance or is associated with anorexia can   →    hyperlipemia, eg anorexia, illness, neoplasia, stress, pregnancy, lactation and parasitism.
    • Typically these are obese animals with a recent history of stress, weight loss, parasites, sepsis, gestation/lactation, colic, endotoxemia, azotemia, Cishing's disease or any debilitating disease.
    • A decrease energy intake   →    increased blood triglycerides and deposition of fat in the liver and other organs.
    • The excessive deposition of fat may   →    organ dysfunction (liver, renal, intestine).
    • Breed and obesity are predisposing factors.
  • Signs: depression, anorexia, weakness, diarrhea, ataxia, seizures and other signs of liver or multi-organ failure may be present.
  • Diagnosis: history, clinical findings, blood biochemistry, transabdominal ultrasonography, post-mortem examination.
  • Treatment: supportive therapy, including fluid therapy, parenteral glucose administration (with or without insulin), partial parenteral nutrition, treatment of concurrent disease.
  • Prognosis: guarded; depending on how severe the increase in triglycerides is and how rapidly the condition is recognized and treated, the mortality can be up to 70%.

Pathogenesis

Etiology

  • Negative carbohydrate balance.
  • Factors that   →    decreased uptake.
  • Factors that   →    insulin resistance.
  • Factors associated with decreased energy intake.

Predisposing factors

General
  • Overweight ponies and donkeys.
  • Starvation.
  • Pregnancy.
  • Lactation.
  • Transportation.
  • Illnesses (diarrhea, pneumonia, etc).
  • Any stressful condition.
  • Any disease that reduces food intake.
  • Parasite burden.

Pathophysiology

  • A decrease in energy intake increases fat mobilization.
  • Stress = increased catecholamines, increased cortisol = lipolysis = increased free fatty acids   →    liver   →    triglycerides production (VLDLs).
  • Liver triglycerides   →    blood (ponies are efficient in releasing VLDLs into circulation, which is not good).
  • Lipoprotein lipase removes VLDLs from blood.
  • Lipoprotein lipase activity is normal or elevated in hyperlipemic ponies, so it is unlikely to be important in the pathogenesis of the disease.
  • Problem in ponies = increased liver VLDL production   →    fatty infiltration of various organs (liver, kidney, intestine).
  • In severe cases hepatic lipidosis/rupture may occur.
  • Insulin inhibits hyperlipemia by inhibiting lipolysis.
  • Insulin increases gluconeogenesis.
  • Rather than a lack of insulin it is insulin insensitivity (resistance) that are important in the pathogenesis of hyperlipemia.
  • Ponies and donkeys are relatively insensitive to insulin   Protamine zinc insulin   (insulin resistance).
  • Insulin effects are opposed by glucocorticoids   Prednisolone  , catecholamines, ACTH, TSH, vasopressin, growth hormone and progesterone   Progesterone   = predispose/induce insulin resistance.
  • Azotemia predisposes hyperlipemia by decreasing VLDL uptake.
  • These processes are exacerbated by obesity.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Durham A E (2006) Clinical application of parenteral nutrition in the treatment of five ponies and one donkey with hyperlipaemia. Vet Rec 158 (5), 159-164 PubMed. 
  • Hammond A (2004) Management of equine hyperlipaemia. In Pract 26 (10), 548-552 VetMedResource.
  • Mogg T D et al (1995) Hyperlipidemia, hyperlipemia and hepatic lipidosis in American miniature horses; 23 cases (1990-1994). JAVMA 207 (5), 604-607 PubMed.
  • Moore B R et al (1994) Hyperlipemia in 9 miniature horses and miniature donkeys. J Vet Intern Med (5), 376-381 PubMed.
  • Watson T D, Murphy D & Love S (1992) Equine hyperlipemia in the United Kingdom; clinical features and blood biochemistry of 18 cases. Vet Rec 131 (3), 48-51 PubMed.
  • Poso A R et al (1989) Exercise-induced transient hyperlipidemia in the racehorse. Zentralbl Veterinarmed 36 (8), 603-611 PubMed.
  • Gilbert R O et al (1986) Congenital hyperlipemia in a Shetland pony foal. Equine Vet J 18 (6), 489-500 PubMed.
  • Jeffcott L B et al (1985) Current concepts of hyperlipemia in horses and ponies. Vet Rec 116 (17), 461-466 PubMed.
  • Jeffcott L B et al (1985) Epidemiologic aspects of hyperlipemia in ponies in south eastern Australia. Aust Vet J 62 (4), 140-141 PubMed.
  • Naylor J M et al (1980) Hyperlipemia in horses; effects of undernutrition and disease. Am J Vet Res 41 (6), 899-905 PubMed.
  • Gay C C et al (1978) Hyperlipemia in ponies. Aust Vet 54 (10), 459-462 PubMed.

Other sources of information

  • Barton M H (2004) Disorders of the Liver. In: Equine Internal Medicine.Eds: Reed S M, Bayly W M & Sellon D C. 2nd edn. Saunders, USA. pp 951-994.
  • Naylor J M (1999) Nutrition - stress and hyperlipaemia in donkeys and ponies. In: Proc 38th BEVA Congress. pp 119.
  • Wayson T (1998) Ed. Equine hyperlipemia. In: Metabolic and Endocrine Problems of the Horse.W B Saunders, UK. pp 23-40.

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