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Pamela A. Davol, 76 Mildred Avenue, Swansea, MA  02777-1620.


Nutrition Letters

A compilation of selected letters from my archives addressing issues pertaining to nutrition.



Nutritional Supplements

What type of supplements should I give my dog? Also, I’ve heard that feeding a raw meat diet is better for my dog. What do you think?

The average pet dog eats a more balanced and nutritional diet than his owner and does not require supplementation if fed a dog food that has been stamped with the AAFCO approval (indicating the food has been tested in the American Association of Feed Control Officials' feeding trials and meets the nutrient requirements for all stages of growth). Very rarely, typically only when a dog is fed a homemade diet to address a particular health issue or in cases of certain illnesses, will a dog require supplementation.

Raw meat and other fad diets rarely provide a balanced source of nutrition for dogs, and I would not recommend raw meat especially for puppies, geriatric or immunosuppressed dogs or for dogs living in households with young children, elderly or immunocompromised humans. There is a wealth of literature that indicates that animals, including dogs, that eat raw meat are susceptible to infections with a multitude of pathogens (including E. coli, Listeria, Arcobacter, Helicobacter , Cryptosporidium, Cyclospora, Salmonella, and Campylobacter species). Though normal immune response to such infections in healthy dogs may ward off infection without presence of clinical symptoms, infected dogs may transmit these pathogens and thus present a health risk to their human companions or other dogs that may be immunocompromised.


Should I be giving my dogs calcium?

Calcium supplementation may be indicated on an individual basis and in some conditions; however, calcium supplementation, in general, is discouraged for the following reasons:

Because calcium supplementation has been found to interfere with the normal calcium homeostasis in some species (actually increases risk for eclampsia because high exogenous levels of calcium interferes in the body's normal processes for maintaining calcium balance), calcium supplementation in pregnant bitches is contraindicated (in fact, anecdotal observations in small breed dogs corroborates the likelihood that supplementing with calcium or feeding foods high in calcium poses a higher risk for these dogs to develop eclampsia).

In puppies, excessive calcium predisposes to orthopedic disorders such as osteochondritis dissecans (OCD) and hypertophic osteodystrophy (HOD) (excessive calcium interferes with the normal processes of bone resorption required for proper bone modeling during bone development).

In adult dogs, excessive calcium inhibits absorption of zinc and can lead to zinc-deficiency disease in dogs (symptoms include: hyperkeratosis, pyoderma, lymphadenopathy).

In those breeds with higher incidences of developing calcium oxalate uroliths (kidney stones), calcium supplementation is considered a risk factor in these dogs.

In light of the potential risks associated with diets high in calcium, calcium supplementation of nutritionally balanced dog foods should only take place under the guidance of a veterinarian, and only when laboratory diagnostics are indicative of abnormal serum calcium values warranting treatment with exogenous calcium.


I have heard that selenium deficiency can cause fertility problems in dogs, and that many dog foods do not contain enough selenium. Should breeders supplement with selenium?

As most individuals probably know by now, I am not an advocate of supplementing balanced diets for dogs (humans need supplements; dogs fed a AAFCO tested diet do not—and yes, I am also against fad or homemade diets for dogs, except in those situations in which a health condition may require a special diet [and even then, I believe a prescription diet is a better option for providing balanced and adequate nutrition]). In most instances dietary supplements cause more problems in our dogs by disturbing the balance of nutrients provided by an already balanced diet. Case in point: one may find that the breeders who are most likely to suggest supplementing with selenium are the breeders who are more often than not also recommending supplementing with vitamin C. Well, they probably wouldn’t need to supplement with selenium if they would stop supplementing with vitamin C (because vitamin C interferes with absorption of selenium); therefore, they probably wouldn’t have a selenium deficient dog in the first place if they just fed the correct balanced diet and left things alone. This is typically one of the limitations encountered when using exogenous supplements or these feeding fads that come along: a breeder/owner cannot possibly take into consideration all the nutrient interactions or contraindications. Add to this the fact that although providing benefits (yes, early studies suggest that selenium may play a role in prevention of prostate cancer—a current national clinical trial is underway to determine if this may be the case—as well as play a role in numerous other biochemical pathways including immune response and prevention of cellular damage from reactive oxygen species), like many other dietary nutrients, selenium has the potential for causing adverse side-effects (hair loss, gastrointestinal upset, spinal cord inflammation, paralysis, bone marrow toxicity, dermatitis, alteration of thyroid hormone metabolism, decreased sperm motility, etc.). My recommendation is that if one fears that their dog has a nutrient deficiency (any nutrient deficiency) have the dog tested first to confirm the deficiency before supplementing (when one considers the acute cost of testing to the cost of chronic medicating, there is an advantage to testing even beyond the medical implications of oversupplementation).

Natural Diets

I would prefer to feed a natural diet but I am worried that many natural diets may not be nutritionally balanced. Is there a way to assure balanced nutrition in natural diets?

Even some "unnatural" commercial diets are not nutritionally balanced. Many dog foods claim to meet the National Research Council's (NRC) Nutrient Requirements of Dogs, however, dog food labels are misleading because although many of them claim to meet or exceed NRC recommendations for nutrients, the quality and thus the digestibility (bioavailability) of these nutrients are often undetermined in these dog foods. Therefore, when purchasing either standard or natural dog food, the best assurance of nutritional quality is given by labels that state: "Complete and balanced nutrition for all stages of a dog's life as substantiated by feeding trials performed in accordance with the procedures established by the Association of American Feed Control Officials (AAFCO)."

Also, a warning about diets labeled as "natural": many pet foods that claim to be natural may not be natural at all. Some do contain chemically synthesized preservatives. The AAFCO has established recommended guidelines for "natural" dog foods which states that natural refers to " A feed or ingredient derived solely from plant, animal or mined sources, either in its unprocessed state or having been subjected to physical processing, heat processing, rendering, purification extraction, hydrolysis, enzymolysis or fermentation, but not having been produced by or subject to a chemically synthetic process and not containing any additives or processing aids that are chemically synthetic except in amounts as might occur unavoidably in good manufacturing practices." The only exception to this is that the AAFCO does allow for certain synthetic vitamins and mineral additives to these dog foods (but no synthetic preservatives).

There are AAFCO tested natural foods available. When in doubt, these may be the safest choice for assuring both natural and balanced nutrition.

Food Allergies

I’ve tried feeding my dog different hypoallergenic diets but she is still chewing herself raw (she doesn’t have fleas, though). What can I do?

It is a widely held misconception that "food" allergies are responsible for the majority of skin ailments in dogs. Though food allergies can cause skin problems, clinical studies indicate that food allergies only account for about 10-30% of adverse skin reactions in dogs. The major culprit is environmental allergens. In fact, even in those dogs that have genuine food allergies, more than 80% will have atopy (skin reactions associated with environmental allergens). It is for this reason that hypoallergenic diets are, more often than not, incompletely effective for controlling allergic skin reactions in dogs.

For diagnosis and treatment options for atopy, please refer to:



My dog has received allergy treatments but still scratches (not severe, but noticeable). My vet recommended a hypoallergenic diet, either commercial or fish and potato. I’ve tried a couple of different diets but I haven’t noticed any change. Is there a hypoallergenic diet that may help with the symptoms?

Changing from one hypoallergenic diet to another may not make any difference in terms of the mild itchy symptoms that you are observing. Even with immunotherapy (allergy treatments) some dogs will require additional anti-inflammatory treatment to control symptoms. In severe cases, glucocorticoids (prednisone) are typically prescribed, but for milder symptoms the side-effects of glucocorticoids usually outweigh any benefits. If you feel the mild symptoms you are observing are unacceptable, you might discuss "essential fatty acid" treatment, which has anti-inflammatory properties that have been found to control symptoms associated with atopy, with your veterinarian. EFAs are frequently used in combination with immunotherapy (hyposensitization treatment) to circumvent the need for adjuvant glucocorticoid therapy. Because your dog is only having mild symptoms, EFAs combined with the hypoallergenic diet you are currently feeding may be sufficient to control these symptoms. For more info on EFAs and other treatment options for atopy, please refer to:


Additionally, a word of caution regarding diets containing fish products. Some dogs are predisposed to developing "non-allergic food reactions" to fish products. Many types of fish contain high levels of vaso-active chemicals that can cause spontaneous histamine release (immune reaction) or can lower the threshold for immune response and thus actually exacerbate symptoms associated with atopy or food allergies. In fact, I've had several Lab owners contact me with reports of their dogs exhibiting facial swelling following feeding their dogs fish-containing dietary supplements for the purpose of improving coat. This does not mean that all dogs will exhibit a contraindication to fish supplements, however, if one is feeding fish supplements or decides to try to incorporate fish-containing supplements one should remain vigilant for potential adverse reactions that might suggest hypersensitivity.


More information on Food Allergies:


Protein Issues

When selecting a brand of dog food, how much emphasis should I place on protein content? What happens if my dog gets too much or too little protein from the dog food?

Protein requirement will depend on the individual dog and the level of activity. It is estimated that the average dog requires a minimum of 22% protein from an animal protein source (meat). Working and pregnant dogs will require higher protein intake. However, it is important to note that studies to assess the protein quality of commercial dog foods have shown no correlation between "crude protein content" with protein quality (evaluated as net protein ratio [NPR] and net protein utilization [NPU]). Simply put, just because a dog food claims 28% crude protein doesn't mean that the dog is able to digest and utilize this protein, therefore, crude protein levels are not a means for evaluating protein quality of any particular dog food brand. The range of NPR and NPU among commercial dog foods is quite broad suggesting that protein quality is quite variable even among premium brand dog foods. For reasons mentioned here, nutritionists are now recommending that NPR or NPU values be reported in place of crude protein %.

Because the body will excrete and not store excess protein, there is no reason to be concerned about high protein levels in a dog's diet. At one time, high protein diets were erroneously believed to be associated with kidney disorders, however, clinical studies have clearly demonstrated that no association exists between high protein diets and kidney disease in dogs. Additionally, high protein levels are contraindicated only in specific cases of liver dysfunction (unfortunately, low protein diets are frequently and incorrectly used in regard to liver disorders). Furthermore, no direct correlation between high protein diets and orthopedic problems have been demonstrated in growing dogs. An indirect correlation between these two factors has been reported and is postulated to occur as an effect of increased palatability related to high protein diets with increased calorie intake (that is, high protein diets tend to taste better and dogs that are allowed to consume ad lib will eat more food and thus consume more calories--it is the calorie intake that directly correlates with orthopedic problems, particularly in growing dogs).

In regard to evaluating dog food, the best method remains to assess based upon individual performance of the dog while on a particular commercial dog food (i.e. alertness, vigor, good appetite, regular urination and defecation habits, proper weight, glossy haircoat, unblemished skin, and bright eyes are assurance of healthful nutrition).


My dog has been diagnosed with kidney disease and was found to have protein in her urine. She is currently on a protein-restricted diet. Was her condition caused by a high protein diet?

In a recent study by Finco DR et al. examining the progression of chronic renal disease (CRD) in canines, the data suggests that there is no correlation between levels of proteinuria (UPC) and degree of renal dysfunction. This suggests that proteinuria does not play a causative role in the etiology of CRD. However, because UPC levels positively correlate with renal injury, it is postulated that proteinuria is rather a marker of the rate of renal injury occurring during CRD, and therefore proteinuria is an effect of renal dysfunction rather than a cause.


Therefore, how high your dog's protein levels rise are more of an indicator of renal injury that she is sustaining as a result of underlying disease.

This is consistent with the data over the past decade that has refuted earlier research that suggested high protein diets were causative factors for CRD. Does increased protein in diet put more stress on the diseased organ? Apparently not. In perhaps the most noted clinical trial examining effects of high protein diet on progression of CRD, groups of dogs diagnosed with CRD were fed either high protein diets or low protein diets. No significant difference was observed in the rate of progression of CRD in the high-protein group compared to the low protein group. Therefore, excess protein in the diet did not appear to compromise renal function even in the presence of high endogenous levels of protein associated with the disease. In fact, on an individual basis some of the CRD dogs in the high protein diet group faired better. This finding was postulated to be associated with the fact that protein is required for cellular repair and function. Endogenous proteins that accumulate as a side effect of renal injury may not necessarily be available for utilization as exogenous dietary proteins. Thus, lowering dietary proteins may reduce availability of "utilizable" proteins that may be needed for cellular repair processes. This, however, is merely speculation.

(reviewed in: Finco, D.R. and Brown, S.A.: Inappropriate dietary protein and mineral restriction in dogs and cats. In Kirk's Current Veterinary Therapy XII (ed. J.D. Bonagura), pp. 958-961. W.B. Saunders Company, Philadelphia, 1995.)

Additional references pertaining to CRD and high protein diet:

1) http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7848181&dopt=Abstract

2) http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1476305&dopt=Abstract

3) http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1941208&dopt=Abstract

4) http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1410855&dopt=Abstract

5) http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9308397&dopt=Abstract

From a dietary standpoint, evidence suggests that more emphasis should be applied to controlling dietary phosphorus and polyunsaturated fats in the CRD dog since these dietary supplements appear to play a direct role as causative factors in renal injury and CRD progression:


1) http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10711867&dopt=Abstract

2) http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9842114&dopt=Abstract

Protein-restricted diets are frequently prescribed for hepatobilliary disorders, however, evidence suggests that protein-restriction may be contraindicated in these disorders as well

see: http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9868254&dopt=Abstract

Protein restriction is currently recommended for only some cases of hepatic encephalopathy

see: http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10488912&dopt=Abstract

If your dog is currently on a protein restricted diet and is doing well, however, there would be no reason to change it.

My best hopes for your dog.

Feeding Growing Puppies

I’ve heard that restricted feeding of puppies can lead to improper bone structure. Should I free-feed my show puppy?

It has been well established in clinical studies that ad libitum (unrestricted) feeding induces a state of overnutrition and is associated with numerous developmental bone abnormalities in the medium, large and giant breeds. In regard to your question pertaining to structural development, studies suggest that during growth and development larger breeds are inherently predisposed to having less dense and, as such, weaker bones compared to the small breeds. As such, over-feeding during the growth period will only increase risk for structural deformities because accelerated growth and accelerated bone remodeling induced by overnutrition (due to ad libatum feeding or over-feeding) results in these inherently weaker bones being unable to support the articular cartilage of joints. As a result, overloading of the joint occurs and secondary complications take place in the form of disturbances in the nutrition, metabolism, function and structure of the developing joint (therefore, in many instances, overnutrition equates to less nutrition to developing bones). Additionally, because of the predisposition for bone weakness in these breeds, excessive weight during the growth and development period may lead to structural deformities of the bones (i.e. bowing); such deformities are usually irreversible (this should not be confused, however, with the appearance of uneven growth/development patterns. Keep in mind, however, that many structural traits during growth and development are related to uneven growth patterns and will fall into place once the growth/development phase has been completed).

Feeding a well-balanced, commercial diet (without additional supplementation) and monitoring/curbing excessive calorie intake (I'll avoid use of the word "restricted" feeding since this term is often inappropriately interpreted as being synonymous with "starvation" or "inadequate nutrition") are the recommendations of those who have been studying the effects of nutrition on orthopedic development in the dog.

Stool Eating (Coprophagy)

My dog is eating his own stools. Does this mean he has a vitamin deficiency?

Stool eating (a.k.a. coprophagy) in rare instances may indicate an enzyme deficiency (such as thiamine deficiency) or an underlying endocrine disorder (diabetes, hypothyroidism, hyperadrenocorticism. etc.), but in most instances it is caused by an instinctive behavior passed down through many generations. In regard to this latter, up to 40% or more of the stool is undigested and thus remains a potential source for nutrients. It is proposed that this behavior originated from the early ancestors of the canine living in the wild; during periods of famine, stool contained a source of protein and nutrients for these dogs. Dogs that adapted the behavior had an evolutionary selective advantage toward survival and thus were able to live and pass on their genes, while those who did not adopt this behavior experienced a higher rate of death due to starvation during periods when food was scarce.

Not all evolutionary advantages are pleasant, however! In any event, in addition to keeping the yard free of feces (before your pup does, that is), certain products are available that can be added to your dog's food which will help curb this behavior by making the stool less palatable (bet you never thought you'd hear something like this). Drs. Foster and Smith offers the product "Dis-taste":


(Petco or other pet supply stores will offer similar products)

Other additives that work similarly: Yogurt or the digestive enzyme papain (derived from papaya and found in meat tenderizers).  However, it is advisable for the health of one's dog to consult with one's veterinarian before administering any treatments. Your veterinarian will be able to provide you with a correct dosing schedule based upon the weight and age of your dog. Keep in mind that any product may be potentially harmful if administered over the recommended dosage (in the case of meat tenderizer, potential side-effects of lung injury may occur if the product is used in higher than recommended doses or is used for too long a period of time because these factors increase risk for inhalation of papain during ingestion).

Copyright 1998-2003. Pamela A. Davol. All rights reserved. Copyright & disclaimer.

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