220 I Unit 2 Nutrition

ANIMAL NUTRITION

Objective

■ Explain the General Principles in Animal Nutrition

Many factors considered in nutrition are consistent among the species. The basic goal of nutrition is to meet all the needs of the animal and maintain good body weight and condition. As discussed in the previ­ous chapter, water quality and quantity must be con­sidered in the animal's nutrition.

Several considerations influence the nutritional demands on an animal. When developing a diet, we begin by considering a resting animal in a comfort­able environment. Dietary needs in this condition are referred to as maintenance requirements. Any change from these factors alters the needs of the animal. Increasing the level of activity immediately increases the animal's needs. The activity level can be dramatic for working animals. Race horses, draft horses, and hunting dogs serve as examples of animals that have nutritional needs much higher than maintenance lev­els. The environment also influences requirements. The same animal in cold wet conditions must expend more energy to maintain body temperature. This increase in energy must be supplied in the diet or the animal will mobilize fat to provide this energy.

Animals in other stages of life also require different levels of nutrients. Growth, pregnancy, and lactation increase the demands that must be supplied through the diet. A dog in peak lactation may have an energy requirement two to four times that needed for mainte­nance. Likewise, a young rapidly growing puppy may have twice the nutritional requirement of an adult dog of the same weight and size. Additionally, it is impor­tant to recognize the tremendous variation among individuals. Even littermates sharing the same envi­ronment can have quite different needs. It is common to see, in two pets in the same household, one that is dramatically overweight and the other in good body condition. Finally, the health status of an animal can dramatically change the requirements of the animal. Certain disease conditions can increase the metabolic needs of an animal.

Several methods are available to deliver feed to an animal. One of the simplest methods is to provide a free choice diet. The goal is to have good quality feed available for the animal at all times. Using the dog as an example, free choice feeding requires the least work and helps to eliminate any competition between animals. The pet can eat at any time. This can be help­ful in quieting a confined dog. Free choice feeding is )ften beneficial in dogs with high requirements such 1s in pregnancy, lactation, or high physical acti~ity. -Iowever, there are drawbacks to this type of feedmg.

I multiple pet households, it can be difficult to d n .. dt . ete ine when a pet is ill an s ops eating. The most r-:on problem, h~wever, is ~hat with free_ choice fee~:­comes a higher nsk of obesity. Many animals eat Ill g more feed than is required. The excessive ener Uc.h converted to fat and deposited in the fat tissue. gy 1s

The diet can also be delivered by controllin · th ff g the time allowed for eatmg or e amount o eed supplied

This allows much greater control over the amo · consumed by the animal. A pet that begins t~ gain: much weight can be fed less or allowed less time to . ·t eat, This does require more time comm1 ment as meals are supplied multiple times throughout the day. The pet may also show more food hunting or begging behavior between meals.

Most animals should also have free access to water throughout the day. The diet should then provide all the necessary nutrients ( carbohydrates, fats, protein, vitamins, and minerals) in the proper amount and pro­portions. The caloric need of ~he ~al can be used to determine how much food 1s reqmred. The resting energy rate (RER) is the amount of energy required by an animal at rest in a comfortable environment (temperatures not requiring the animal to heat or cool itself). Numerous formulas exist to calculate RER, based on the animal's body weight. An example of such a formula is:

RER (kcal) = 70 x (Weight in kg0-75)

Notice that the formula does relate to the animal's weight, but that the weight is raised to the power of 0.75. The resting energy rate is impacted more signifi­cantly by the animal's body surface area than by its weight. This formula attempts to relate body weight to surface area.

The maintenance energy requirement (MER) accounts for the RER, plus any additional energy required for the normal activity of the animal. The MER for the typical or average dog is usually twice the RER. Cats, on the other hand, typically have an MER that is 1.4 times the RER. Although inactivity decreases the requirements, many of the other factors discussed create an extra need for calories. For example, a dog in peak lactation with a large litter may have energy needs two to four times that of a typical MER.

Every animal has a limit to the volume or weight of food that can be consumed in a day. To meet the high energy needs of the lactating or working dog, each amount o~ food may need to contain a higher amount of calones. Energy density describes the calo­ries supplied by each weight unit of food ( e.g., kcal per P?und). Whereas th~ lactating dog may benefit from a higher energy density food, the overweight inactive d~g will benefit from a lower energy den;ity food. With the lower energy density, the fat dog will feel

satisfied with the volum.e consumed, while obtajning fewer calories.

pET FOOD LAB~~~

Objective Describe the Important Features Found on Pet Food Labels 1 and Compare and Contrast the Nutritional Requirements for Dogs and Cats

Anyone who has walked down the pet food aisle in the arocery store will recognize that a wide variety exists ~ the types of foods available for pets (Figure 13-2). In addition to purchasing commercial feeds, it is pos­sible to make diets for pets at home. For the sake of convenience, the vast majority of pet owners elect to purchase commercially available foods. The three basic feed types available are moist or canned, semi-moist, and dry foods (Figure 13-3).

Canned foods in general are about 75% water. These moist foods tend to be more palatable and digestible than dry food. Palatability describes how well the animal likes the food. Palatability is affected by several factors: odor, texture, nutrient content, and habit. Canned foods tend to have a higher level of water, protein, and fat, which also influences the odor. Fat plays a large role in the palatability of a food. The role of smell in the sense of taste is very important. An animal with an upper respiratory tract infection and a congested nose may become anorexi~ (have a poor appetite). Cleaning the nose and warming the_ food to increase the smell released can often help to improve the appetite of such an animal.

Dogs in general prefer canned food to dry. Cats are not so consistent. Cats often develop a preference for one type or shape of food. Manufacturers attempt to

,~

RE 13_2 A tremendous variety of foods are available. Making a FIGU d ·tt· It selection can be , ,cu .

Chapter 13 Species Comparison I 221

FIGURE 13-3 Three major varieties of food: canned, semi-moist, and dry.

take advantage of this habit of cats, by producing foods with a distinctive shape or texture. Cats can become such creatures of habit that it can be difficult to get them to switch foods if the need arises.

Canned foods have the advantage that any type of feed ingredient can be used (wet or dry). Once opened, canned foods should be refrigerated, because they can spoil. In general, canned foods are the most expensive on a dry matter basis. Because of the high palatabil­ity, canned foods are not often used on a free choice basis. Pets often eat food well beyond their needs, and obesity becomes a common problem if intakes are not regulated.

Semi-moist or soft-moist foods are generally pack­aged in a sealed foil or plastic package. This type of food generally contains about 15% to 35% water. The small pieces of food are coated with a carbohydrate and treated with an acid, which helps to retain mois­ture and prevent spoilage. Because of the external treatment, this type of food does not require refrig­eration. The soft texture and high sugar content of semi-moist food make it a very palatable food source for dogs.

In general, similar ingredients are used in semi­moist and dry foods. Some wetter protein (meat) sources can be used in semi-moist food because of the

tU

222 / Unit 2 Nutrition

higher water content. The cost of semi-moist food can approach the cost of canned food .

Dry food is most commonly used and is gener­ally the least expensive of the three types of food. For many pets, dry foods are used free choice. The hard food particles also provide an abrasive action on the teeth. This helps to slow the accumulation of tartar on the teeth. Tartar is a hard mineral plaque that builds up on the teeth. Excessive accumulation allows for bacteria to invade the gums and can eventually lead to tooth loss.

Most commonly, the dry foods are packaged in paper bags or cardboard boxes. These foods are very stable, have a long shelf life, and do not require refriger­ation. The fat in the food can become oxidized, lowering

its nutritional value. It is recommended that the food be

used within six months of when it is made. Because

this date may not be known, it is ideal to purchase only

amounts that can be used within a month or two. The ingredients are limited in dry food, because

the moisture content must be controlled. Because of

this limitation, cereal grains are typically used to pro­

vide a high percentage of the carbohydrate supply. Dry

foods typically have 10% to 14% moisture. This limits

the amount of fat and fresh meat that can be used in

manufacturing dry food. With the type of ingredients

needed, dry food tends to be the least palatable and

least digestible of the three food types.

9cean whitefish 1n gravy

The government establishes rules for the labeJin pet foods (Figure 13--4). Obviously, the label needs tog~! the name of the product, the words dog food or catfi

. h In dd. . h ood and the net we1g t. a 1hon, t e name and ad,L '

d. .b '-lfess of the manufacturer or 1stn utor must be identifi The label must also include a description of the desiS:d. usage or purpose of the food . This may describe van ed

h dul. 0~

life stages, sue as puppy, a t, mactive and ov . er.

weight, or semor. Many foods may also be labeled to b "complete and balanced for all life stages." e

The Association of American Feed Control Offi.

cials (AAFCO) is an organization that helps to monito pet foods and establish national standards. Two meth~

ods are available t~ meet these _standards. The simplest and most inexpensive method 1s based on calculations.

In this method, the food can be evaluated in the labo­

ratory to arrive at the nutrient content. This analysis is

then compared to the nutrient requirement of a pet at

a given life stage. The drawback of this method is that

palatability and bioavailability of the food are not eval­

uated. The second method to evaluate the suitability of

a pet food is to do feeding trials. This method is more

time consuming and expensive to perform, but is con­

sidered to be more reliable. The feed trial must follow

guidelines established by AAFCO. A statement may be

placed on the pet food label stating that feeding trials

were performed to evaluate the food. This provides

the consumer the ability to compare how foods were

ID -0

118 -INGREDIENTS: WATER SUFFICIENT FQR PROCESSING, MEAT BY-PRODUCTS; OCEAN WHITEFISH1

POULTRY BY-PRODUCTS, SOY PROTEIN CONCENlllATE, RSH BROTH, WHEAT FLOO~ SOYBEAN R.OUR1

MODI/ID STARCH, 5700/ED BONE ME41., TITNIIUM DIOXIDE GUAR GUM, SALT, MIIWL rue, SODIUM TRIPOLYPHOSPHATE, GLYCINE POTASSIUM CHLORIDE CHOLINE CHLORIDE, VIT~INS

~ITAMIN E SUPPLEMENT, VITAMIN A SUPPUMM, THIAMINE MONONJTllATE, NJACIN SUP!UfllT,

D-CALCIUM P,ANTOBTEi RIBOFIAVJN SUPPI.EMENT, PYRIDOXINE HYDROCHI.OffiDE, IBAJ)IONE

(J) NmONAL STATEMEIIT: --------- Animal leedinglBstsusingMECOprocedures

~iiiiiiiiiiiiiii•m subslantialethat lb~ product provides complete

SODIUM BISUl.FITE C0MPLEX VITAMIN _D, SUPPlEMENT, f,OUC AOIDi 81011~ SUPPLEMENT)1 TAI/RINE, C4RMfEI. COLO~ MINMS (fERROOO SUtFA~ZINOOXI~ OXIDE, COPPER S/JlJATf, C~CJUM IODA1F, iDIUM SELENm), RID 3. ~ BUAMED AKAL YS/8: CRUDE RR01c1N:MIN. 9.0%, CRUDE f!!M 1:D'/4, MOfmlRE·WX 10%JSl!M.IXA!~, TAlJRlN&MIN. 0,00%

FIGURE 13-4 An example of a pet food label.

= 0 and lunced nulritlOn for growth and maintenance. fHDllG INSlRIICllONS;

t() feed:an adult6U 12tor3 Utten 0119 can OJ · asnQSS8.lytryourcafs LO

------~ ~~ 0

iirtb~ .

evaluated. Even food trials have certain limitations; they are performed under specific conditions and have a specific trial length. Results may differ if the animal is held under other conditions or when fed this diet for extended periods of time.

Also on the label is the guaranteed analysis of the pet food. The guaranteed analysis does not define the absolute quantity of nutrients, but rather certain minimums and maximums. The label lists the min­imum for crude protein and fat. The actual amount may be higher than that listed on the label. Maximum values are listed for moisture and crude fiber. For these nutrients, the actual content may be less than that listed on the label. The minimum and maximum values assure the consumer of a certain quality of the food. The manufacturer can, for example, formulate the food with a higher level of protein. If the qual­ity of the ingredients used in the food declines, the manufacturer is still safe in producing an acceptable product. If the moisture level is over 14% it too must be included on the label.

The label must also include the ingredients, listed in descending order. This can be somewhat confus­ing, however. Consumers may choose a pet food because it lists meat sources as the first ingredient, but the ingredients are listed based on weight. Although meat products may be listed as the first ingredient, this source may contain much higher water content than the second ingredient, which might be a grain source. Multiple forms of a similar ingredient may also be listed (such as corn grain, flaked corn, corn byproduct, ground corn, and so on). Again this gives the appearance that the grain source is lower in t_he list. Furthermore, meat by-products may vary sig­nificantly in their nutritional content, based on the sources are used.

Many terms are used on the packa~ing and_ in the ingredient list. Some terms are legally defmed while oth­ers are used as a promotion. The complete list of termi­nology is quite long. A sample of common terms follows.

1. Meat by-products and poultry by-products: These are high-protein sources derived from meat scraps, blood, bone, and other organs such ~s the heart and liver. This term is often characterized in a negative light in pet foo_d comm_ercials. ~t is important to recognize that m the wild, carnivores often eat the organs before eating the meat (i.e., skeletal muscle). AAFCO clarifies ~he use of the

t b ducts which does not mclude feather, erm y-pro , h h ms Or the intestinal contents. ooves, o ,

2 N. I· Th' term refers to products de.rived

. atura . is d · 1 'th f

1 t animals an mmera wi -solely . romhp a1: s,lly synth~sized. These foods out bemg c emica d f h . th tic vitamins an o ten ave may contam syn e

Chapter 13 Species Comparison 223

an added antioxidant to stabilize the fat in the product.

3. Organic: The U.S. Department of Agriculture (USDA) has clear rules defining the production of organic animals and plants. There are specific restrictions on the use of pesticides, herbicides, and antibiotics. More than 95% of the ingredients must be from organic sources to qualify.

4. Premium: Although this term implies a higher level of quality it is not legally defined. There­fore, the term premium cannot be used to compare products from different companies.

5. Soybean meal: This is a highly digestible protein source obtained from processed soybeans. Much of the starch and oil is removed in the process, resulting in the high protein concentration.

6. TBHQ (tertiary butyl hydroquinone): This is an antioxidant used to prevent rancidity in the fat.

7. Tocopherols: Chemical terms are often alarming to consumers, but in this instance tocopherols are a natural vitamin E source and function as an antioxidant to prevent fat from becoming rancid.

8. Veterinarian approved: This is another term that is not legally defined.

9. Whole grain: As the term implies a whole grain source includes the entire grain. It is typically pro­cessed in some manner, such as grinding. Whole grains provide a significant source of starch but also contain protein, fat, vitamins, and fiber.

In 2007, many pets were sickened by the addition of melamine and cyanuric acid in commercial pet foods. These products were added to artificially raise the protein level in some processed feeds purchased for use in dog food. It took time to isolate the source of the problem and many foods had to be recalled. This had a major impact on pet owners' confidence and trust in commercial pet foods. In response, some people chose to make their own pet's food, ensuring that they know the contents.

A raw food diet is one method of self-preparation. Supporters suggest this is a more natural way to feed pets and also raise concerns that cooking in the prep­aration of commercial foods decreases the digestibility and destroys important nutrients. It is true that over­cooking may decrease the availability of protein but ~or some plant ingredients the digestibility is actually increased by proper cooking. Additionally, infectious agents ~e.g., Salmonella and Escherichia coli) can be ~resent m raw meats. This contamination has potential nsks for both the pet and the owner handling the meat.

224 I Unit 2 Nutrition

Veterinarians are commonly asked, "How m~c~

should I be feeding my pet?" This is a very diffi­

cult question to answer completely and directly. The

labels on pet foods give an estimate ~f how much

to feed. However, this recommendation needs to

be adapted to the individual pet. Variations in the

energy requirement of an individual have already

been discussed. The goal of the diet is to provide enough fo~~ to

maintain an ideal body weight and body condition.

Body condition is a term that describes the outer appea~­

ance of an animal. Body weight is very helpful, but it

is important to realize that muscle tissue is more d~nse

than fat. Two animals with the same body weight

could have quite different appearances and body com­

position. Body condition is used in many species to

judge the amount of fat on the animal.

In pets, a simple evaluation of body condition is

to feel the flesh over the ribs. It should take only gentle

pressure to feel the individual ribs. If firm pressure is

required to feel the ribs, the animal is becoming too

fat. There should be enough flesh over the rib cage that

the ribs are not visible. The animal is too thin if the

ribs are visible. (It is important to realize that long hair

can mask this sign.) Pets should also have a waistline

(Figure 13-5). That is, the abdomen should be smaller

than the ribs. When the abdomen protrudes beyond

the ribs, the animal is becoming too heavy. The dog

in Figure 13-6 illustrates a body condition score of

1. This dog has basically no body fat and had been

neglected. Although cats and dogs share a very similar diges­

tive system, they do have distinct differences in their

nutritional demands and habits. Several generaliza­

tions can be made; however, many exceptions exist.

Dogs do not require a change in foods to provide vari­

ety. This may actually create a finicky eater. Often the

dog can train the owner! When the dog learns to expect

feed changes often, it eats poorly for a few days and the

owner responds with a new food. It is better to main­

tain the dog on a consistent diet. If changes do need to

be made, it is best to gradually make the transition to

the new diet over several days to prevent upsetting the

digestive system.

Cats can become very fixed on a particular food

type. It is best to provide a diet with multiple protein

sources, which makes transitioning to a new diet easier

if the need arises. Cats can also be made into finicky

eaters by frequent feed changes. Cats often eat small

amounts frequently, unlike many dogs that eat large

meals. Typically, cats even prefer to eat alone and tend

to be erratic in their appetite. One day they may eat a

large amount and eat very little the following day.

More important than the behavior involved, cats

and dogs have distinct nutritional differences. Cats are

true carnivores (meat eaters), whereas dogs fit more

2

3

4

5

~:G~RE _13-5 Evaluating body condition in cats on a scale of 1 to '

, ~s _rations ~how cats ranging from emaciated (1) to obese 5) N 3 '\'d~al. This cat will still have a visible waistline and the ~bs ·ca

eas, Y e felt but not seen. Long hair can make vi;ual evaluation c

FIGURE 13-6 A dog with a body condition score of 1. This dog was being

neglected and was rescued. Fortunately, the dog recovered very well.

into the 0111nivore (eatiI1g both m.eat and plant) cate­

gory. Dog foods are not designed to be nutritionally

sound for cats. Cats have a higher demand for protein

and require much higher levels of the amino acids

arginine and taurine than the dog. Cats cannot convert

linoleic acid to arachidonic acid like the dog. Arachi­

donic acid and taurine are found only in animal tissues

and therefore must be included in the cat's diet. Cats

cannot survive on a complete vegetarian diet without

appropriate supplementation. Dogs can produce the B vitamin niacin from the

amino acid tryptophan and can produce vitamin A

from beta-carotene. Cats are unable to make either of

these conversions. As a result, the cat's requirements

for niacin and vitamin A are much higher than those

of the dog. To ensure proper nutrition for a dog or cat, it is

essential to feed a good quality food designed for that

animal in that stage of life and activity level. Cat and

dog foods are not interchangeable. The volume of food

to provide is the amount necessary to keep an animal

in good body condition and at ideal body weight and

maintain its health. Supplements are generally not

needed for healthy animals on a balanced diet.

FIGURE 13-12 A TMR mixer being loaded with feed.

grain can often make a cow go off feed (have a poor

appetite) and actually result in a more negative energy

balance. Even in diets in which normal amounts of grain are

fed, feeding too much at one time can cause the same

pH changes in the rumen. This is called slug feeding.

To prevent this, many farmers feed a total mixed ration

(TMR). In a TMR, all the feed ingredients are combined

in a mixer and blended together (Figure 13-12). The

goal of this feeding method is to supply a uniform feed

to the cattle throughout the day. With each mouthful,

the cow is consuming the proper balance of fiber,

protein, and energy.

CLI NICAL PRACTICE

Objective

■ Link the Clinical Significance of the Academic Material

Learned in This Chapter to Veterinary Practice

Obesity is the most common nutritional disorder that

veterinarians see in dogs and cats. Certain disease

conditions, such as hypothyroidism and hyperadreno­

corticism, may contribute to an animal's obesity. How­

ever, most cases are associated with an excessive intake

of calories relative to the animal's needs. Several fac­

tors can contribute to this problem. The animal may

be fed too much or fed a diet not designed for its

activity level. Many pets confined to a kennel or to the

house just do not get enough exercise to utilize all the

calories consumed. Most pets will spend a majority

of their time resting when there is no interaction with

owners. Spaying and neutering also reduce the energy

demands of the animal. Additionally, many pets are

given too many snacks or treats (both animal treats and

table food) that add calories. Weight regulation in healthy pets requires strong

Willpower by the owner. Often when treats are taken

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owners need to recognize that they are trying to helJ

the dog. Increasing the pet's activity level also require:

a significant time commitment by the owner.

Obesity may contribute to or worsen other dis·

eases. A common presentation is an overweight dog

that is having difficulty rising or getting around. Many

elderly pets develop arthritis, and adding extra weight

increases the stress on the joints. As muscles weaken

and the arthritis worsens, the extra weight can become

quite crippling. The added weight also puts more stress on the

circulatory and respiratory systems. The extra fat puts

a higher demand on cardiac output and oxygen usage.

This can worsen an existing problem, such as heart fail­

ure. These problems also make obese pets more of an

anesthesia risk if surgery is required. Obesity may also

have a relationship to controlling diabetes. Diabetes is

much more readily regulated when weight is brought

under control. Recent studies have shown a decreased

life span in overweight animals. As a veterinarian, it is common to hear about the

increased variety of food items that pets are fed . Many

owners are quite proud when they can say that their

pets will eat anything. Unfortunately, many items that

humans consume regularly can be toxic to small pets.

Chocolate is one such food. Pets often find chocolate

very tasty and will consume large quantities if given

the opportunities. Chocolate contains theobromine and

caffeine, both of which can be toxic when consumed

in high levels. These toxic components have effects on

the cardiovascular and central nervous systems. Signs

of toxicity often begin with increased thirst and urine

production, vomiting, diarrhea, and urinary inconti­

nence. If the dosage is high enough, the signs progress

to excitability, muscle twitching, seizures, and coma.

Chocolate toxicity can be fatal.

The amount of theobromine and caffeine varies

among types of chocolate. As a result, the type and

amount of chocolate consumed impacts the likelihood

of having a toxic reaction. Table 13-1 lists the theobro­

mine and caffeine levels in several common products.

Often clinical signs will begin with ingestion at levels

of 20 mg/kg of body weight and usually becomes life

threatening at 60 mg/kg of body weight.

Cats happen to be very sensitive to a toxin in

onions. If consumed in high enough quantities, the

onions cause a defect in the red blood cells. The red

blood cells break down in the bloodstream, producing

hemolytic anemia. These animals develop darkened

urine from the free hemoglobin along with a fever.

The combination of anemia and damage to the kid­

neys can result in death if sufficient amounts are eaten.

232 1 Unit 2 Nutrition

Table 13-1 Chocolate

Theobromlne Caffeine Type of Chocolate (mg/oz) (mg/oz)

Unsweetened cocoa 737 70 powder

Baker's chocolate 393 35-47

Chocolate chips 140-240 22

Instant cocoa 135 15-20

Milk chocolate 44-58 22

Oreo cookies 2.4 0.85

The role of fiber in the nutrition of both horses and ruminants has been emphasized. It is possible to overfeed concentrates and cause digestive disorders. But animals can accidentally gain access to grain and eat extreme amounts in a short period. The result is grain overload. In the horse, grain overload results in a dramatic decline in the pH within the colon. Many of the natural organisms die and are replaced by other bacteria that can survive in those conditions. The death of such a large number of bacteria releases toxins that are absorbed into the bloodstream. In moderate levels, the result is typically diarrhea and anorexia.

In more severe cases, the toxins can have a dam­aging effect on the blood supply to the hooves. The third phalange (P3) is suspended within the hoof by a tissue rich in blood supply, called laminae. The lam­inae become inflamed, resulting in a disease called laminitis. With laminitis the horse has a great deal of pain with each step and develops swelling at the top of the hoof. The gait of these horses is often described as "walking on eggshells." An interesting side note is that horses bedded with black walnut shavings may also develop laminitis. The walnut shavings have a toxin that can cause laminitis.

Horses with mild laminitis improve with rest and medications to reduce the inflammation. More severe cases can result in permanent lameness. The disease can be so severe that the point of P3 rotates downward. The laminae are so inflamed that they are unable to suspend the bone. It is possible that the entire hoof can become detached. Many of these horses do not recover.

Nutrition is often used in combination with treat­ment or as a follow-up to treatment in many diseases. Bladder stones and urinary blockage in cats were dis­cussed in Chapter 6. Diet can play a significant role

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in preventing recurrences of these diseases. The diet change must be adapted to the specific cause. Many different types of bladder stones may develop. Some are more likely to occur in low pH, whereas others occur in high pH. Each has specific mineral composition. Diets can be adapted to control both the pH and the mineral content of the urine. This modification must be care­fully balanced to prevent deficiency and yet restricted enough to minimize crystal formation. Initially these types of diets were sold only by prescription through veterinarians. Now many foods are available over the counter to help control such problems. Many diets are now labeled with the claim of promoting urinary health in cats.

Other diseases that can benefit from attention to nutrition include kidney and heart failure. In kidney failure, nitrogen-containing waste from protein metab­olism builds up in the blood. Diets used to control kid­ney failure contain a very high-quality protein source in limited amounts. Other minerals, such as phospho­rus, are also restricted to help limit the accumulation in the blood. In heart failure, the diets often restrict the amount of sodium, which helps prevent excessive blood volume from accumulating.

Earlier it was mentioned that high-producing dairy cattle often have a negative energy balance early in lactation. In response, the cow mobilizes body fat in an attempt to meet the energy demands. Molecules of triacylglycerols are broken down into the component glycerol and three nonesterified fatty acids (NEFAs). NEFAs can be used by the mammary gland to produce milk fat. The liver absorbs much of the NEFAs to capture the energy available in these molecules.

To complete the process of oxidizing NEFAs, the liver needs glucose. Cattle absorb very little glucose directly from the intestinal tract (unlike monogastrics). As a result, cattle must create glucose from VFAs and amino acids (a process called gluconeogenisis). When glucose is in a limited supply, the NEFAs are incom­pletely oxidized, creating ketones or ketone bodies. As levels increase in the bloodstream, the cow will have a depressed appetite and suppressed milk production. This clinical condition is called ketosis.

Ketones are eliminated by the kidney in the urine and exhaled through the lungs. This excretion produces a "sweet" smell to the breath and urine. (Sh1dents may be familiar with the smell of the ketone acetone, found in many fingernail polish removers.) Quick dipstick tests are available to test the urine for those people who are not sensitive to the smell. Treatment of ketosis revolves around providing the cow with glucose or glucose precursors. This allows the cow to completely metabolize the ketones.

......

Materials to complete activities:

Moist and dry pet food labels

1. Research the association of American Feed Control Officials (AAFCO). Report the scope of their oversight

2. Compute your resting energy rate by multiplying your body weight times 10 (keep in mind that variations will exist, but this simple equation will give a ballpark figure). Example 155 x 10 = 1550 calories. The resulting number would increase your energy needs. Expected answers could be sports or physical labor. If you have an animal, explain how much feed you provide to the animal and why you chose that amount.

3. Based on the display of pet food samples, guess the percentage of water in each. Suggest an ingredient list for each. Pick a favorite from a pet’s perspective.

4. Compare and contrast the ingredients found on the dog and cat food labels. Refer to the chapter content to identify the differences.

5. Ms. Goodchef call your office Saturday evening at 6pm to tell you that her French poodle, Pierre, just at 2 oz of chocolate chips that had gotten knocked off the counter. She tells you that Pierre weighs 11 pounds. Ms. Goodchef is very busy preparing a banquet and wonders if she need to worry. You tell her that you will need to do some calculations and will call her right back

a. What is Pierre’s weight in kilograms? (Multiply pounds by 2.2) b. Using table 13-1, how much theobromine did Pierre ingest if he at 2 ox of chocolate

chips? c. How much theobromine would have to ingest for you to start treatment using the

20mg/ kg level? d. How much theobromine would he have to ingest for you to be concerned that he could

have life-threatening problems using the 60mg/kg level? e. What will you tell Ms. Goodchef when you call her back?

Option 1 You hope her meal turns out well and she should check with your office Monday morning to set up an appointment Option 2 You tell her that you are very concerned with the levels of theobromine that Pierre has ingested and that she should come to your office immediately