Application of Biomarkers in Animal Health

Many of the advances in human healthcare are being applied to animal health. Some of the new technologies were tested in experimental animals before they were introduced into human medicine. Biomarkers are studied in animal models of human diseases. Table 5.4 shows some examples of biomarkers used in animal healthcare.

Dogs suffer from many of the same disease as humans. The value of measuring blood levels of the myocardial protein cardiac troponin I (cTnl) has been tested for the diagnosis of congenital and acquired heart disease in the dog and in the evaluation of the severity of heart failure. Serum samples obtained from healthy dogs and from dogs diagnosed with a variety of congenital and acquired heart conditions can

Table 5.4 Examples of use of biomarkers in animal health


Relevant clinical conditions

Biomarkers of cartilage degradation and synthesis measured by ELISA assays

Canine osteoarthritis

Biomarkers of endothelial cell activation

Drug-induced vascular injury

Cardiac troponin I

Heart failure in dogs

Cross-sectional brain imaging

CNS trauma and infections

Telomeres lengths and expressed telomerase activity in lens epithelium

Canine cataract

© Jain PharmaBiotech

be assayed for cTnl concentration using an automated immunoassay method. Results can also analyzed according to the degree of heart failure as assessed using the International Small Animal Cardiac Health Council’s scheme. Healthy dogs have very low or undetectable blood cTnl levels, as do dogs with congenital heart disease. However, cTnl levels are significantly elevated in dogs with acquired mitral valve disease, dilated cardiomyopathy and pericardial effusion. Blood cTnl levels also vary with severity of heart failure. Measurement of blood cTnl levels may be a useful aid in the diagnosis of dogs with suspected heart disease and in indicating the severity of heart failure.

Cataracts in small animals are shown to be at least partially caused by oxidative damage to lens epithelial cells (LECs) and the internal lens. Therefore, biomarkers of oxidative stress in the lens are considered as general biomarkers for life expectancy in the canine and other animals. Telomeres lengths and expressed telomerase activity in canine LECs may serve as important monitors of oxidative damage in normal LECs with documented higher levels of telomerase activity in cataract. Loss of functional telomere length below a critical threshold in LECs of canines during the effect of UV and chronic oxidative stress or metabolic failure, can activate programs leading to LEC senescence or death. Telomerase is induced in LECs of canines at critical stages of initiation of cataract pathogenesis and exposure to oxidative stress through the involvement of transition metal ions such as, ferrous ions- catalytic oxidants (Babizhayev and Yegorov 2014). Early detection is important as treatment with 1% N-acetylcarnosine lubricant eye drops is beneficial for prevention and dissolution of ripe cataracts in canines.

Cross-sectional imaging techniques have facilitated diagnosis of central nervous system (CNS) diseases in companion animals. However, there is still frequently a lack of definition of the cause of neurologic lesions, because tissue sampling from the pathologic site is often difficult and there are few clinical diagnostic tools to assist diagnosis. Biomarkers can assist in understanding the cause, diagnosis, severity, and prognosis for neural injury. Integration of conventional testing and new diagnostic techniques will overcome shortcomings in understanding infectious diseases of the CNS. Diagnostic tests may be limited by poor positive and negative predictive values, which must be recognized when interpreting test results (Nishida 2014).

FDA researchers are trying to find and identify biomarkers for inflammatory diseases in cows, as well as proteins that could serve as alternatives to antibiotics for use in food animals. The goal is to develop tools that will allow the FDA to regulate new drugs for diseases for which no treatments exist, or better treatments than currently exist.

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