Pamela A. Davol, 76 Mildred Avenue, Swansea,
Canine Nutrition Slide Show
Nutrition Letters - A compilation of selected letters from my archives addressing issues pertaining to nutrition.
Want to incite a riot among an otherwise amiable group of dog breeders, commercial nutritionists, veterinarians and pet food salespersons within a relatively short amount of time? Begin a conversation about which brand of dog food one should be feeding their puppy or adult dog. Among dog breeders, brand of food is an extremely sensitive topic, mainly because many breeders base their evaluation of dog food on many years of experience and performance among their dogs. In many cases, the best dog food isn't always the most expensive or the most socially acceptable dog food on the market.
At the heart of the controversy, many nutritionists and pet food salespersons take the stand that puppies require expensive, specially formulated high protein, calorie-dense diets to maximize skeletal development. However, clinical research on the occurrence of skeletal diseases in growing dogs have veterinarians and canine orthopedic specialists taking the opposite side that high plane nutrition increases risk of skeletal diseases in medium and large breeds predisposed to developmental bone disorders (including hip dysplasia, osteochondritis dessicans, panosteitis, hypertrophic osteodystrophy, etc.). To minimize occurrence of these disorders, they recommend that foods encouraging rapid and maximized growth in puppies be avoided with the premise that a gradual, progressive growth curve obtained through restriction of high-calories and avoidance of rapid weight gain, particularly between the ages of 4-8 months, ensures less stress on developing joints and bones.
The following article addresses the nutritional requirements of the dog for the purpose of selecting good-quality dog food. Additionally, common misconceptions regarding feeding and supplementation are discussed in regard to medical findings.
Dogs are considered carnivores--meat eaters--however, to acquire complete nutrition, a dog must eat a wide variety of cereals and vegetables as well as meat. Therefore, meat-only diets, particularly those which must be supplemented with excessive amounts of vitamins and minerals are not recommended since they often do not provide the critical balance of nutrients required.
To take the guess-work out of canine nutrition, recommendations for the daily nutrient intake for proper growth and maintenance of dogs is outlined by the National Reasearch Council's Nutrient Requirements of Dogs (NRC). The latest NRC publication provides a guideline for the manufacturing of good-quality commercial brand dog foods. 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, a more reliable assurance of nutritional quality is given by labels that state that the food has passed American Association of Feed Control Officials' (AAFCO) feeding trials.
Unfortunately, there is no one superior brand of dog food on the market which will work best for all dogs. This is primarily because nutritional requirements differ from dog to dog based on factors related to breed, genetics, body weight, level of activity, environment, pregnancy or lactation, and age. It is, therefore, important to take these factors into consideration when selecting a commercial dog food that will provide the necessary levels of protein, fats, vitamins, and minerals.
When acquiring a puppy from a breeder, it is recommended that the brand of dog food and feeding guidelines be discussed with the breeder. Unlike dog food salespeople who have a vested interest in selling expensive dog foods, breeders usually recommend dog food based on years of experience with the performance of their own dogs on a particular brand of dog food. If a breeder is pleased with a particular brand of dog food, it is usually because her dogs have exhibited signs of good health and nourishment while on that brand. Such signs include alertness, vigor, good appetite, regular urination and defecation habits, proper weight, glossy haircoat, unblemished skin, and bright eyes and indicate that a dog food is providing the necessary nutritional requirements.
Sometimes, however, advice pertaining to dog food may not be available from a breeder. In such cases, pet owners may have to make decisions based on little or no experience. Therefore:
Proteins contain essential amino acids which are the building blocks for growth and repair of the body. The average dog requires a minimum of 22% protein in dry dog food for basic maintenance; higher levels are required in pregnant or lactating bitches. Unlike fat, very little excess protein is stored by the body. Most excess protein is degraded and excreted by the kidneys. (Therefore, feeding expensive, high-protein performance dog foods to the average dog is equivalent to "urinating"-away money!) Dogs, however, with high daily energy requirements, such as working dogs, require higher protein levels. In this case, high performance dog foods are required because they are specially formulated with highly digestible sources of protein to provide energy requirements and prevent protein depletion. It is important to note, however, that high protein content listed on a dog food label does not guarantee a nutritional advantage. Nutritionally, the source of dietary protein is perhaps more important than the percentage of crude protein listed on the side of the bag. Animal protein sources (meat) are better than plant protein sources (soy). Therefore, a dog food claiming 28% crude protein derived from soy, would not be a better source of nutrition than a dog food claiming 22% crude protein derived from meat.
Feeding quality sources of protein, particularly in working dogs, is essential. If a dog is expending high energy but fails to meet the dietary intake of nutrient protein, the body will metabolize functional protein required for normal cellular processes. As a result, anemia, increased susceptibility to disease, loss of body weight and eventually death can occur.
If there is sufficient clinical evidence to suggest that high protein levels are essential for dogs with high energy output, there is equal evidence to suggest that high protein levels may be contraindicated in breeds which undergo rapid growth phases. Increase in nutritional skeletal diseases has closely paralleled the increase of high calorie, high protein diets in growing puppies. Besides producing a source of energy, protein intake directly effects growth rate. However, a direct relationship between high protein and bone disorders has not been clinically demonstrated. Rather, the correlation between high protein diets and skeletal diseases may lie in other related factors. For example, it has been clinically demonstrated that when puppies at risk for developing hip dysplasia were allowed to eat ad lib, they had a greater incidence of hip dysplasia than littermates who were placed on maintenance diets. Since protein content increases palatability, protein rich dog foods encourage an increase in food consumption. Therefore, puppies fed higher protein diets who are not limited in regard to the amount of food they consume are more prone to rapid growth phases and consequently skeletal disorders.
Another concern regards protein levels in the relationship to kidney dysfunction in adult dogs. Because degraded protein products are excreted by the kidneys, erroneous conclusions were made which blamed excess dietary protein for kidney damage in adult dogs. There is no clinical evidence to suggest that high protein levels increase occurrence of kidney disorder in dogs. In fact, in one clinical trial, placing dogs diagnosed with kidney disease on high protein diets did not increase kidney damage or accelerate the disease process compared to those fed low level protein diets. Therefore, there is no medical evidence supporting protein-restricted diets in the treatment of dogs with kidney dysfunction. Furthermore, since protein is essential for repair of the body during and after illness, protein restriction may be contraindicated.
Dietary fatty acids are critical for growth, reproduction, and maintenance of healthy skin and coat. Additionally, fat plays a role in inflammation and immune regulation. A minimum of 5% fat in dry dog food is recommended, however, most commercial dog foods contain about 10% fat. Because working dogs may require up to twice as many calories as the average dog and because fat contains twice as many calories per weight as protein, fatty acid supplements are sometimes used to increase caloric intake without the need to increase amount of food intake. However, use of fat supplements beyond caloric needs can cause obesity, flatulence, and degeneration of red blood cells and the heart. Therefore, fat supplementation should be used under the direction of a veterinarian only.
VITAMINS AND MINERALS
Processing and storage of pet food usually leads to a reduction in essential vitamins and minerals. Therefore, most manufacturers of commercial dog foods address this issue by overcompensating the vitamin and mineral content prior to processing. Nowadays, most good quality dog foods contain a proper balance of vitamins and minerals and healthy dogs rarely require supplementation. Before this practice began, many pet owners adopted the practice of supplementing their dogs' diets. Because old practices die hard, some pet owners and breeders continue to supplement already-balanced diets.
Interestingly, oversupplementation may contribute to increase in correlation between skeletal disorders and increased use of high protein, as previously discussed. Since most high-protein diets have complete vitamin and mineral nutrition, continued use of diet supplementation may be a primary contributor to skeletal disorders. The most common abuse of supplementation involves calcium and vitamin D.
Owners and breeders of medium and large breeds continue to use calcium supplement probably as a prophylactic measure against eclampsia in pregnant bitches and skeletal problems in puppies. There is no medical evidence that calcium supplement prevents eclampsia in pregnant bitches. In fact, increased calcium intake prior to delivery for the purpose of increasing calcium production for lactation seems to have the exact opposite effect since it was found that excessive calcium intake prior to birth resulted in decrease in calcium once lactation began. It is hypothesized that supplementation interferes with normal homeostatic responses which allow the body to compensate for the calcium drain.
In dogs and in growing puppies, maintaining the appropriate calcium:phosphorus ratio is essential for bone integrity. Imbalances in this ratio can lead to increased resorption or mineralization of bone resulting in skeletal abnormalities and disorders. To ensure that the appropriate calcium:phosphorus ratio is maintained, many owners and breeders insist upon supplementing nutritionally balanced dog food with calcium. Clinically, however, oversupplementation with calcium is associated with skeletal disorders such as osteochondritis. Additionally, increased calcium intake causes a disease process in dogs related to zinc deficiency, since excess calcium inhibits absorption of zinc. Furthermore, when calcium is supplemented with vitamin D, there is a greater risk for causing imbalance of the calcium:phosphorus ratio since vitamin D increases calcium absorption by the gastrointestinal tract. Therefore, administering calcium supplement, particularly with vitamin D, is a dangerous practice and is not recommended.
Once the pet owner decides on a quality brand dog food, the next question becomes, "How much food should be fed?" Most dog foods list the recommended amount for feeding based on weight of the dog, however, in most cases, following this guideline would lead to a very obese dog.
In my own litters, puppies are usually eating between 1/2 to 1 cup of food at each feeding (4 times/day) between 8 and 16 weeks of age. Between 16 weeks and 6 months, they are up to between 1 to 1-1/2 cups at each feeding (3 times/day). At 6 months and through adulthood, they are fed 2 cups at each feeding (2 times/day). This tentative feeding schedule I provide as a guideline to my new puppy owners with the understanding that it is to serve only as a starting point and should be adjusted based on metabolism, activity and requirements of the individual dog. When judging amount of food to feed, it is important to evaluate the results by appearance of the dog. Though puppies should be kept on the lean side during 4-8 months of age while they are going through the rapid growth phase, they should not appear emaciated. One should be able to feel the rib cage and the back bone, but not see them. Looking down on the dog, there should be a slight indentation between the end of the rib cage and the hip bones.
FREQUENTLY CHANGING FOODS ENCOURAGES FINICKY EATING HABITS
Once a dog is started on a particular brand of dog food, unless there is a problem with reaction or performance to the food, it is best not to change dog foods frequently. Such practice can lead to gastrointestinal upset which may contribute to finicky eating behavior. Additionally, during feeding time, the dog should be allowed only 10 minutes to eat and then the bowl should be removed even if there is food left over. When it is necessary to change foods, always make the change a gradual one, mixing old dog food (in decreasing amounts) with the new (in increasing amount) to prevent gastrointestinal irritation. Be aware, however, that it can take anywhere from 6 weeks to 3 months to see improvements related to switching to a new dog food from one which was not tolerated.
SMALLER, MORE FREQUENT FEEDINGS ARE BETTER
Feeding smaller portions more frequently is an important factor both in terms of nutritional intake and to avoid potential gastrointestinal complications. Bloat, a condition in which the stomach becomes distended due to excess food consumption, excess water intake, or build up of gas is a common problem among puppies who are fed too much food at one feeding. This condition, however, can also afflict adult dogs, particularly deep-chested breeds of which Labradors are considered to be a part. Dogs who develop bloat and who are allowed to exercise are further at risk to a serious and often fatal condition known as gastric volvulus and torsion in which the distended stomach actually flips over cutting off its own vital blood supply. It is for this reason that dogs should not be allowed to drink large volumes of water or exercise immediately after eating.
SAVE LAMB-BASED DOG FOODS AS A RESORT FOR FOOD ALLERGIES
Some dogs have a genetic predisposition for developing food alergies. Symptoms of food allergies vary widely, however, common symptoms include weight loss, diarrhea, hair loss, skin lesions, dull coat, and chronic ear infections. Because these symptoms can be caused by a multitude of disorders, it is important for a veterinarian to rule out other causes first. When food allergies do occur, they commonly do so when the dog reaches about 2 years of age. For years, veterinarians have used lamb-based dog foods for treatment of dogs who have developed hypersensitivity to common dog food because lamb-based diets were uncommon and thus the dog less likely sensitized to the diet. Nowadays, however, lamb-based commercial diets are widely fed to puppies and young dogs making this alternative diet ineffective if the dog, as an adult, should develop a food allergy. For this reason, it is recommended that lamb-based diets be avoided until a dog is over 2 years of age.
FEEDING PREGNANT BITCHES
It is not necessarily required to change the food a Lab is eating should she become pregnant. However, 4-5 weeks into the pregnancy the puppies will begin to undergo the most rapid development and will begin drawing required nutrients from the dam if the demands of their nutritional requirements exceed the level of nutrients in her diet. One way to increase the dam's nutrient intake is to increase the amount of food she is being fed. One drawback to this is that the growing pups will be taking up more abdominal space, therefore, excess food in her stomach may cause her discomfort and she may refuse to eat. To prevent this, the total amount of food is increased but divided into small portions and fed more frequently. Since many bitches also have problems with upset stomach during the pregnancy due to increased stomach acidity, the more frequent feedings will help to reduce this upset, as well. For my own girls, on the average, I will increase by 1 to 2 cups per day between the 5th and 9th week of the pregnancy (that's a total of 5 to 6 cups per day since my adults get a total of 4 cups per day for a normal feeding). By the last two weeks of the pregnancy, my bitches are usually eating about 8 times per day (about 3/4 of a cup at a time). No vitamin supplementation or calcium supplementation during pregnancy is required. Alternatively, some breeders will feed puppy-food (which is higher in vitamins, protein, and calories) to the dam during the pregnancy. In this way, the food content need not be increased.
Occassionally, as whelping draws near, the dam may refuse solid food. This may be one indication that whelping is imminent within the next 24-48 hours. However, if the dam begins to refuse solid food prior to the last week of her pregnancy, one can attempt to entice her to eat by grinding the solid food in a blender and then mixing it with warm water to make a gruel. Though other foods such as canned food, cat food, or table scraps may present a more palatable temptation, gastrointestinal upset may occur as a result of substituting these other foods and may only encourage her loss of appetite.
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Donoghue, S.: Nutritional recommendations for reproductive performance. In Kirk, Robert W. (ed.), Current Veterinary Therapy XI, pp. 971-980. Philadelphia, W.B. Saunders Company, 1992.
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.
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