Most people know what they are supposed to feed their pets, but not enough owners are aware of foods that make cats and dogs very ill. Did you know, for example, that milk is more of a "trick" than a "treat" for cats, given the havoc it can wreak on the feline gastrointestinal system? Study this list of forbidden foods carefully and you may save you and your pet from a lot of grief.

Don't throw him a bone

In the cartoons and in the folklore, the good dog gets the bone. But bones are bad for animals! Most people know that chicken bones aren't healthy for pets, but they will freely offer steak or pork chop bones as a treat. The fact is, NO bones should be fed to your pet. They splinter easily and can traumatize the mouth and esophagus.

Even if well-chewed, the bony spicules lodge in the stomach and can require surgical removal. As a veterinarian, I have had to cut round steak bones off of lower jaws, and I have extricated T-bones that got jammed in the backs of dogs' mouths. Worst of all, I have seen dogs that have swallowed pork chop bones, which became stuck in the esophagus. A veterinary specialist had to open the chest to retrieve these bones. Even if the bones don't get stuck going through, they can cause an awful lot of discomfort coming out as well.

People who give dogs bones have the best of intentions. Maybe they want to reward good behavior, share their meal with the pet, supplement the animal's diet, or help clean teeth. There are safer ways to accomplish these goals, though. If the dog has tartar or you want to keep his teeth clean, brush them. If you feel like the dog's jaw needs exercise, get him a nylabone. If you are concerned that your pet doesn't have enough of the calcium and minerals found in bones, buy him vitamins. However, keep in mind that dogs that are fed a complete and balanced diet will not need supplementation.

Onions will give you something to cry about

Did you know that onions are toxic to cats and dogs? However you like to serve them--cooked, fresh, or even dehydrated--onions pose a threat because they contain allyl propyl disulfide. This substance damages red blood cells by causing the hemoglobin to break apart. Once the hemoglobin is damaged, the body works to rid itself of the damaged cells.

Loss of the red blood cells results in anemia, which has serious consequences for companion animals. Pets that are anemic may have pale gums, show difficulty breathing, and seem weak and depressed. The urine may have reddish brown color. This occurs when the hemoglobin from the destroyed red blood cells from the bloodstream is filtered by the kidneys. One result is damage to the kidneys, eventually leading to kidney failure.

A veterinarian should immediately see any dog or cat that has eaten onions.

Got milk? Don't give it to your pet!

Just like many people, dogs and cats frequently are lactose intolerant. Many pets lack the enzyme that is required to break down the milk sugar. Over the years, a number of clients have come to me complaining that their cats had severe diarrhea and were stunned when I told them that it was probably from that dish of milk the animal got as a treat.

Despite what the old wives' tales say, it simply isn't true that cats have a nutritional need for milk. Although most cats like the taste of milk, many cannot tolerate it and get diarrhea, vomiting, and gas. Once again, a complete and balanced diet is your ally: if the pet is fed properly, supplementation won't be necessary.

Even when a puppy or kitten is deprived of its mother's milk, the cow's milk we drink will not be beneficial. If the puppy or kitten is orphaned, or if the mother is not able to feed the litter, you will need to consult with your veterinarian about getting a milk substitute that is species-specific. The gallon from Acme just is not going to suit your purpose.

Like seizures for chocolate

These days, many more people are aware that chocolate can be deadly to pets. Chocolate contains the methylxanthine alkaloids, theobromine and caffeine. These compounds cause constriction of blood vessels and an increased heart rate. Consumption of chocolate results in vomiting, diarrhea, restlessness, and increased urination. More advanced symptoms of toxicity include excitability, increased respiratory and heart rate, stiffness, and even seizures.

All chocolate is not made the same. No, I am not referring to the difference between a luxurious Godiva truffle and a good old-fashioned Mars bar. Rather, the darker the chocolate is, the more likely it is to contain toxic compounds. If your Labrador eats a bag of Hershey kisses he may vomit and consume a lot of water; if he eats a bar of baking chocolate, he may end up in the hospital on IV fluids. About a half ounce of baking chocolate per pound or less is toxic for dogs.

Cats also can become gravely ill from eating chocolate, but they are less likely to want anything to do with the sweet substance. However, if your dog can get to chocolate, it will it eat it. Kids and dogs both love chocolate.

Because eating chocolate can have serious consequences, such as heart failure, seizures, coma, and even death, if your pet ingests chocolate, contact your veterinarian immediately. If treated promptly, most cases of chocolate toxicity do well.

Giving up the grapes

A new study has found that grapes and raisins can lead to renal failure in pets, so keep those keep those Sunmaids to yourself.  If you're looking for a healthy, natural treat to give to your dog, try carrots instead. 

Pet + coffee = coffin?

Caffeine is a real drug that usually causes problems in pets. Most people have the common sense not to give the dog a cup o' joe in the morning, but pets do have their ways of getting into the owners' No Doz, drinking cola, and tea. Some even will eat the coffee grounds from the trash.

Caffeine is a methylated xanthine that results in stimulation of the central nervous and cardiovascular systems. After ingestion, clinical signs usually develop within hours and include vomiting, restlessness, hyperactivity, unsteadiness, muscle tremors, heart problems, seizures, increased thirst and urination, increased body temperature, respiratory distress, and even coma.

These are worst-case scenarios, of course. Most cases of caffeine ingestion simply cause your pet to shake and bounce off the walls. However, some pets will require supportive treatment by your veterinarian because of the side effects listed above. Death from caffeine overdose has not been reported, but it is theoretically possible. Next time, order decaf.

Friends don't let pets get drunk

Just like with caffeine, most people don't actually give their pets alcohol. However, if they discover that Fifi likes to lick the beer cans, they may find this amusing and give Fifi a can of her own. Big mistake.

Dogs and cats obviously have much less body weight than humans and become intoxicated very quickly. Some people may think it is funny when the dog starts staggering around the house, but they will stop laughing when the dog begins to urinate uncontrollably on the rug. As many people know, alcohol is a diuretic. Once a pet is drunk, it will have lost its inhibitions, so all that house training goes right out the window.

There are worse consequences. Ingestion of larger amounts of alcohol causes behavioral depression, depressed respiration, cardiac arrest, and death. Next time you have a party, lock your pet in a room where it can stay safe and alcohol-free. If your pet should imbibe, call your veterinarian immediately. This way, laughing at your drunken pet is expensive but not fatal.

* Article courtesy of VetCentric.com
Originally published July 10, 2005
Written by: Elizabeth L. DeLomba, DVM @ VetCentric
For more information on this article, please visit http://www.vetcentric.com