Why Blood Work Can’t Evaluate Homemade Dog Food

The last two posts have highlighted my worry of a potential surge in medical problems in dogs caused by improperly formulated homemade dog food. My concern in writing the articles was that the various strategies of those feeding homemade were based on assumptions that would necessarily lead to unbalanced diets. Moreover, 95% of all homemade dog food recipes found online and in popular books have been shown to be nutritionally inadequate. Thoughtful comments from a reader highlighted why routine veterinary monitoring, especially blood tests, will not detect most dietary insufficiencies.

 Blood Test Can't Detect Nutrition Deficiencies

What Are the Essential Nutrients for Dogs?

Daily dogs need adequate quantities of:

  • Total Protein and Specific Amino Acids (from protein) – arginine, histidine, isoleucine, leucine, lysine. methionine, phenylalanine, taurine, threonine, tryptophan, valine
  • Total Fat and Specific Fatty Acids – linoleic acid, alpha linolenic acid, docosahexaenoic acid (DHA) and eicosapentaenic acid (EPA)
  • Vitamins – A, D, E, K, B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B9 (folic acid) and B12 (cobalamin)
  • Minerals– calcium, chloride, copper, iodine, iron, magnesium, manganese, phosphorus, potassium, selenium, sodium and zinc

What Routine Canine Blood Tests Do Not Include:

  • No measurements of essential amino acids
  • No measurements of total dietary fat or specific essential fatty acids
  • No measurements of any vitamins
  • No measurements of 6 of the 12 essential minerals

What Do Routine Canine Blood Tests Evaluate?

Complete Blood Count (CBC): Measures the number, size and hemoglobin (molecule responsible for transporting oxygen and carbon dioxide) content; the number and type of infection fighting white blood cells; the number of platelet cells (important for clotting). Certain types of anemia, or decreased red blood cells, can suggest iron or vitamin B12 deficiencies.

Serum Biochemistry: Evaluates liver, kidney, and pancreas function; measures cholesterol, total blood protein, albumin (protein important for retaining water in blood vessels), glucose, chloride, calcium, magnesium, potassium, sodium and thyroid hormone.

Why Are Routine Blood Test Inadequate to Evaluate the Diet?

  • As you can see blood levels of very few nutrients are included in routine blood tests. Each nutrient requires individual tests that are more expensive the entire routine blood panel.
  • With the exception of iron or vitamin B12 deficiencies, a CBC tells little about dietary balance.
  • Constant blood levels of calcium, phosphorus and magnesium are necessary for heart and nerve function. Dietary deficiencies will cause a release in hormones to dissolve bone to maintain vital blood levels. Uncorrected this will result in eventual osteoporosis but the blood work will always be normal until all bone is gone. The condition is generally diagnosed by x-rays because a dog spontaneously breaks one or several bones or is showing severe weakness.


Blood vessels must maintain a certain level of protein or water will leak from the veins into the abdominal or thoracic cavity. Muscle provides an adequate source of protein if the diet does not contain adequate amounts. The body will continue to take protein from muscle to maintain adequate blood amounts. Low levels of protein in the blood will not show-up until muscle is depleted to critically low levels.

Potassium, sodium and chloride levels are also important for heart, nerve and other body functions so the body will maintain deficiencies in the diet by altering kidney function to reabsorb these minerals from the urine. It is not until very late stages of deficiency when heart, nerve and other organs fail that indications of deficiency may be suspected. But it cannot be proved by the blood tests.

Taurine deficiency causes congestive heart failure like that in the bulldog on an incomplete vegan diet. On admission to the emergency hospital the routine blood work was normal and it required an echocardiogram and a special test for taurine levels to diagnosis the dietary deficiency.

I could go on with other examples, but I think you probably get the point.

The Bottom Line

I did not write these posts to discourage homemade dog food. Quality, nutritious homemade dog food is my business because I think it is the best dog food. The point is that deficient homemade diets cannot be detected by routine veterinary monitoring and are generally discovered after a problem arises to a critical level. Nutritious homemade diets are not as easy to formulate as internet chatter would suggest. Providers of homemade recipes should be able to demonstrate the exact amount of all 42 daily essential nutrients in recipes and supplement recommendations. We do that with all of our recipes and hope others will also.

~Dr Ken Tudor,


Homemade Dog Food Recipes and Supplements

There are 4 comments

  1. proplus888

    Reblogged this on Mylo in HK! and commented:
    Following on from his previous 2 articles, Dr. Ken Tudor follows up with how blood tests cannot give you the full story of if your dog’s homemade diet is adequate for its health needs.

  2. Run A Muck Ranch

    Here’s where I’m perplexed from conflicting info, from the vets, the labs, vet and vet tech textbooks and now you.

    Be another source to educate me:

    I didn’t see, and my vet confirmed long ago, a B12 indicator on the CBC. My understanding is a separate test, at least a year after starting the diet, is required, B-12 deficiencies not necessarily showing for up to a couple of years, maybe more in some cases. Where would a deficiency be indicated? I would certainly not object to paying less for my labs!

    The assumption on protein and minerals is now confusing to me. As was explained, and from research I gleaned from vet and vet tech texts on lab reports, if the levels remain constant, or within normal range, (this assumes levels would be checked regularly, no less than once a year), there are no nutritional problems {with those elements} to note. My understanding is that genetic predisposition throws a monkey wrench in the works for some disease states in that all the proper feeding in the world won’t prevent problems.

    Vitamins (except for B12, possibly) will not show on ‘regular’ reports, however, symptoms of deficiencies or toxicities are usually pretty evident on a physical exam. If the patient shows no physical signs, and no disease state exists, vitamin adequacies are assumed.

    Since organ function is a function of overall health, nutrition being the primary driver, normal readings on those line items would also support at least adequate nutrition.

    While I agree a single blood draw will not prove adequacy of a diet, I humbly submit that if a person monitors on a regular basis, both with veterinary exams AND blood draws, blood work can evaluate a home made diet.

    I very much appreciate your blog and your thoughts.

    1. Dr Ken Tudor

      You are absolutely right that the confirmation of a vitamin B-12 deficiency requires a separate blood test. What does show up on a CBC with this condition is a “macrocytic anemia” or a shortage of red blood cells but the cells are larger than normal. So if a pet has this type of anemia, a blood B-12 level is run to confirm the condition or rule it out. The same would be true of an iron deficiency. The only thing that would show up on a CBC would be a “microcytic anemia” or an anemia with small blood cells. Blood iron levels would then have to be run, because this type of anemia can have causes other than iron deficiency.

      Just as you said, a single blood test will not necessarily indicate a dietary problem. That is the point of these articles. The body is marvelously equipped to compensate for inadequacies. If the body is deprived of calcium, the body will continue taking it from the bone. Blood tests will be normal despite the fact that osteoporisis is occurring. With sodium, potassium deficiencies the kidneys will work overtime reabsorbing them to maintain proper blood levels until the shortages reach critical mass levels and then symptoms will occur. I won’t go on with all of the other examples, but the science is the same, the body will compensate for shortages of vital nutrients at the expense of other organs. Blood test could be normal yet something is very wrong (the bulldog whose heart progressively got worse until heart failure occurred. Before heart failure it would be unlikely that the veterinarian would have been suspicious unless the owners reported coughing and exercise intolerance or other symptoms that would suggest a heart problem).

      The symptoms of nutritional deficiencies are not specific. The same symptoms can be caused by many other non-dietary conditions. Because of this and the fact that routine blood work is not reliable, nutritional deficiencies go undiagnosed until in some cases it is too late. That is why I wrote the articles. Dietary analysis is the only way to ensure that a diet is adequate, complete and balanced.

      Any homemade diet needs to be checked against the USDA database of nutrient quantities of foods to ensure that sufficient amounts of all of the 42 required daily nutrients are present. As I tried to point out, routine veterinary visits and blood tests are not an adequate substitute for diet analysis. Again, that is why I wrote the articles. Most dog owners feel that making healthy homemade dog food is easy. It is not. That is why studies have shown that 95% of homemade dog food recipes online and in popular books are nutritionally deficient. That is why I am fearful of a potential health crisis. That is why I founded Hearthstone Homemade. I have done the research so owners can relax and know they are feeding a healthy diet.

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