Canine C-reactive Protein

Note: We have recently switched C-reactive protein assays. Therefore, our reference interval and interpretations have changed slightly. Marshal Covin, who was one of our summer DVM students, performed an extensive validation of the new assay and we are pleased to say that it performs very well. The big advantages of the new assay are that is quicker to run and more cost-effective. Because of this, we have been able to significantly reduce the price we charge. Although there is very good agreement between the two assays in terms of how patients are classified, the numerical values are not directly comparable, especially for very high concentrations. Therefore, please contact the lab if have been using our old C-reactive protein assay to serially assess a patient.

Reference Interval (dogs only)

Canine < 10 mg/L

Sample

400 ┬Ál fasting (8-12 hours) serum; DOGS ONLY. Refrigerate serum as soon as possible and store and ship frozen.

C-reactive protein is an integrated marker of systemic inflammation. C-reactive protein is a member of the acute phase reactant family of proteins in the dog. The synthesis of this group of proteins is dramatically increased during inflammatory disease. These proteins are typically involved in regulation of the early response of the patient to the agent causing the inflammation, and in the regulation of immune system activity. During inflammatory disease, hepatic synthesis of C-reactive protein is dramatically up-regulated (up to a 1000-fold increase).

The ability to determine the severity of the disease is helpful in planning the clinical approach to the case and in discussions with owners/clients involving prognosis. In diseases that are predominantly inflammatory in nature, integrated measurement of the severity of inflammation may be superior to the measurement of organ-specific marker enzymes when trying to answer the second question. Canine C-reactive protein is a marker of systemic inflammation that is receiving increasing attention and has been shown to reflect the severity of canine small intestinal disease.

The greatest clinical utility of this assay is likely to be in the monitoring of response to treatment for inflammatory bowel disease in dogs. It is reasonable to expect that the institution of effective dietary or medical therapy will be associated with a decrease in serum C-reactive protein in the patient.

C-reactive protein or protein C: which test do I need?

It is crucial to recognize that C-reactive protein and protein C are two different molecules and that the measurement of each provides very different clinical information. C-reactive protein (CRP) is a positive acute-phase reactant protein that is produced by the liver. CRP is a biomarker of systemic inflammation in dogs that may be useful for monitoring response to treatment in dogs with inflammatory bowel disease. Protein C is an anticoagulant protein that is also produced in the liver. Measurement of serum protein C activity may help distinguish between dogs with congenital portosystemic shunts and dogs with microvascular dysplasia.

Recently several practices have mistakenly submitted samples to us for measurement of serum CRP concentration when they actually intended to measure serum protein C activity to help distinguish between a portosystemic shunt and microvascular dysplasia in a canine patient. The Gastrointestinal Laboratory does offer measurement of serum CRP concentration in dogs. However, we do not currently offer measurement of protein C, although we are planning to offer this service shortly. One of the laboratories that currently offer the measurement of protein C activity in canine plasma is the Comparative Coagulation Laboratory at Cornell University (https://ahdc.vet.cornell.edu/sects/coag/test/proteinC.cfm).