Chemistry

The different types of acid-base disturbances are differentiated based on: Origin: Respiratory or metabolic Primary or secondary (compensatory) Uncomplicated or mixed: A simple or uncomplicated disturbance is a single or primary acid-base disturbance with or without compensation. A mixed disturbance is more than one primary disturbance (not a primary with an expected compensatory response). Acid-base […]

To detect an acid-base disturbance, both a blood gas analysis and chemistry panel should be performed. This combines traditional blood gas analysis (Henderson-Hasselback equation) and the strong ion approach (by evaluating the contributions of electrolytes, in particular). The blood gas analysis and chemistry panel provide information on most of the variables responsible for acid-base disturbances and

Results of chemistry tests provide information on the function of various body systems and yield clues or even diagnosis as to the presence of underlying disease. Chemistry tests should always be interpreted with respect to what is known about the patient (signalment, history, clinical signs, results of other diagnostic testing) and should not be interpreted

Chemistry testing is usually performed on serum or plasma samples. To optimize results of testing, serum or plasma should be separated from cells as soon as possible after collection to minimize artifacts that occur with storage. Note that some chemistry tests can also be run on urine (e.g. protein to creatinine ratios, fractional excretion of

Physiology Lactate dehydrogenase (LDH, LD) is an enzyme that catalyzes the conversion of lactate to pyruvate. It is not tissue-specific, being found in a variety of tissues, including liver, heart and skeletal muscle. The enzyme is tetrameric and is composed of four subunits of two molecules, M (muscle) and H (heart). Various combinations of these

Physiology Creatine kinase (CK) is a “leakage” enzyme present in high concentrations in the cytoplasm of myocytes (skeletal and cardiac primarily) and brain and is the most widely used enzyme for evaluation of muscular disease. In muscles, CK functions by making ATP available for contraction by phosphorylating ADP from phosphocreatine. Phosphocreatine is the major storage

Physiology Lipases hydrolyze triglycerides. There are several forms of lipase found in various tissues: pancreatic lipase, colipase, hepatic lipase, gastrointestinal lipases, renal lipase and lipoprotein lipase. Lipoprotein lipase is produced by vascular endothelium and is essential in triglyceride metabolism. Based on sequential decreases in lipase activity in ill horses, lipase (as measured by the DGGR

Physiology Amylase is a calcium dependent enzyme which hydrolyzes complex carbohydrates at alpha 1,4-linkages to form maltose and glucose. Amylase is filtered by renal tubules and resorbed (inactivated) by tubular epithelium. Active enzyme does not appear in urine. Small amounts of amylase are taken up by Kupffer cells in the liver. In healthy dogs, 14%

Physiology Bile acids are a group of amphipathic steroids synthesized by hepatocytes from cholesterol and excreted into bile. They function to emulsify fat in intestine and facilitate nutrient absorption and are highly conserved via enterohepatic circulation as outlined below. This emulsification is possible because of their amphipathic nature and tendency to form micelles.  To produce

Physiology Ammonia is produced from dietary amino acids and by catabolism of amino acids, amines, nucleic acids, glutamine and glutamate (nitrogenous wastes) in peripheral tissues (especially skeletal muscle). Gastrointestinal micro-organisms (primarily coliforms and anaerobes in the colon and cecum) convert dietary amino acids and urea into ammonia in the gastrointestinal system. The ammonia is absorbed