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Basics ⬇

Outline

BASICS

Definition!!navigator!!

Can be defined as loss of body weight over time (>4–5 weeks) due to decreased fat and muscle mass or loss of GI content and total body water, or a combination of these factors.

Pathophysiology!!navigator!!

Weight loss can result from many causes—lack of adequate food and/or water, poor quality food, inability to prehend or swallow, maldigestion or malabsorption of food, increased loss of nutrients once absorbed, and increased catabolism. Inadequate caloric intake is likely the most common cause of weight loss, and may also be due to specific nutrient deficiencies, chronic liver disease, neoplasia, malabsorption, and chronic infections. The pathophysiologic events leading to weight loss are manifold and depend on underlying causes. For details, see specific problems.

Systems Affected!!navigator!!

GI

  • Dental diseases.
  • Parasitism.
  • Oral ulcerations.
  • Tongue paralysis.
  • Pharyngeal paresis or paralysis.
  • Retropharyngeal masses.
  • Esophageal strictures.
  • Gastric ulceration.
  • Intestinal malabsorption.
  • Maldigestion.
  • Intestinal infections and noninfectious inflammatory, infiltrative, and neoplastic disorders.
  • Intestinal motility disturbances.
  • Intra-abdominal abscesses.
  • Chronic grass sickness.
  • Sand enteropathy

Endocrine/Metabolic

  • Pituitary adenoma of the pars intermedia in the horse due to increased metabolic rate, including muscle wasting induced by hyperadrenocorticism.
  • Diabetes mellitus due to endocrine pancreatic insufficiency.
  • Nutritional secondary hyperparathyroidism

Hemic/Lymphatic/Immune

  • Lymphoma, leading to cancer cachexia.
  • Inflammatory bowel disease leading to malabsorption.
  • EIA.
  • Chronic piroplasmosis

Hepatobiliary

  • Chronic hepatic failure.
  • Cholangiohepatitis.
  • Hepatic abscess

Cardiovascular

  • Congestive heart failure, leading to decreased liver and GI function.
  • Valvular endocarditis due to occult infections

Renal/Urologic

Chronic renal failure.

Neuromuscular

Equine motor neuron disease and associated muscle wasting.

Behavioral

  • Cribbing.
  • Oral stereotypy

Respiratory

  • Heaves.
  • Chronic pleuropneumonia.
  • Lung abscesses

Skin/Exocrine

  • Pemphigus foliaceus.
  • Pythiosis

Musculoskeletal

Chronic painful lameness (e.g. severe laminitis).

Nervous

Neurologic conditions that impair prehension, chewing, and swallowing.

Signalment!!navigator!!

Varies according to the underlying cause of weight loss.

Signs!!navigator!!

Signs vary according to the primary condition, but, commonly, decrease in body condition and reduced appetite are observed.

Causes!!navigator!!

See Systems Affected.

The most common causes (Consultant®, Maurice White, Cornell University, 2016) include occult infections, malabsorption syndromes, chronic renal failure, liver failure, parasitism, chronic viral infections (EIA), and endocrinopathies.

Risk Factors!!navigator!!

Any condition leading to catabolic situations.

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

CBC/Biochemistry/Urinalysis!!navigator!!

A minimal database includes CBC, serum biochemical profile, and fibrinogen. CBC findings may be nonspecific, but total protein might be increased (e.g. due to hyperglobulinemia in occult infections) or decreased (e.g. due to protein-losing enteropathies). Anemia of chronic disease might be present. There might be leukocytosis. Biochemistry should help to differentiate between specific organ failure problems such as hepatic or renal diseases. Serum electrophoresis might assist in characterizing dysproteinemias and in separating conditions such as occult infections from neoplasia or parasitism.

Other Laboratory Tests!!navigator!!

Hyperfibrinogenemia in inflammatory or neoplastic disease.

Diagnostic Procedures!!navigator!!

  • Abdominocentesis can be useful in identifying the abdomen to be the site of occult infections.
  • Ultrasonography is used to detect abscesses (abdominal, pleural, wall thickening of jejunum and colon, etc.).
  • In individual cases, exploratory laparotomy/laparoscopy might be required.
  • Glucose and xylose absorption tests when small intestine malabsorption is suspected.
  • When stomach ulcers are suspected, gastroscopy should be performed.
  • Echocardiography in cases of congestive heart failure

Treatment ⬆ ⬇

TREATMENT

See specific conditions.

Medications ⬆ ⬇

MEDICATIONS

Drug(s) of Choice

See specific conditions.

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Reports of case studies indicate a survival probability of around 70%.

Patient Monitoring!!navigator!!

Monitor feed intake and body weight of the animal.

Possible Complications!!navigator!!

Secondary infections due to the debilitated immune system of the horse.

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Age-Related Factors!!navigator!!

Poor dentition might be a major factor in weight loss in geriatric horses.

Zoonotic Potential!!navigator!!

Chronic salmonellosis.

Abbreviations!!navigator!!

  • EIA = equine infectious anemia.
  • GI = gastrointestinal

Suggested Reading ⬆ ⬇

Metcalfe LVA, More SJ, Duggan V, Katz LM. A retrospective study of horses investigated for weight loss despite a good appetite (2002–2011). Equine Vet J 2013;45:340–345.

Stämpfli H, Oliver OE. Chronic diarrhea and weight loss in three horses.Vet Clin North Am Equine Pract 2006;22:e27–e35.

Author(s) ⬆

Author: Olimpo Oliver-Espinosa

Consulting Editors: Henry Stämpfli and Olimpo Oliver-Espinosa