Since the relationship between refractive index and specific gravity is different for almost every fluid, accurate, specific gravity tests must be completed with a measurement scale developed explicitly for that fluid. Although humans, dogs, and other large animals share the same urine properties, this is not the case for cats, rabbits, and guinea pigs. Unless you use a special scale to test these smaller animals’ urine specific gravity, the refractometer measurements will provide erroneously low readings.
Below are models with options for both large and small animals. The PA203X allows for programming with up to 5 measurement scales for versatility and convenience in the laboratory or clinic and is the ideal for field use.