One of the challenges of being a vet is that there are differences between the kinds of patients that we see. There are some pretty big differences between dogs and cats, including their physiologies, tendencies for diseases, normal laboratory values and so on. There can also be significant differences between breeds within a species. Some examples...
*Cavalier King Charles spaniels have giant platelets. These platelets are larger than in other dogs, but function normally. The problem is that the automatic blood analyzers we use in our hospitals measure cells based on size. Because these platelets are larger than the machine is expecting, it will give a lower platelet value than actually exists.
*Greyhounds have a higher percentage of red blood cells in their blood than other breeds. A high percentage of cells can indicate dehydration or certain diseases, but is normal in greyhounds.
*Asian breeds can have a higher than normal potassium level. This includes chows, Akitas, and others.
As far as I am aware, differences this significant don't really exist among human races. There are some racial and regional differences, but some of the largest ones are due to environment and not genetics. For example, people who live at higher elevations have a higher density of red blood cells than people who live at lower altitudes; but this can change the longer you live at a given elevation and so is a physiological adaptation and not a genetic difference. I would be very interested if anyone has examples of true racial differences as significant as those seen in animal breeds.
Such differences can make a veterinarian's job challenging. When we're interpreting lab values the analyzers will give us a range of "normals" and will let us know when something is outside of that normal range. We then have to figure out of that out-of-range value is truly significant, incidental, or related to the breed. Determining disease is not as straightforward as it may sometimes seem.
Remember a veterinarian's motto: "Real doctors treat more than one species!"
