Yes! They are harmful

Some foods, which are edible for humans, are hazardous to dogs because of their different metabolism. Some may cause only mild digestive upsets, whereas, others can cause severe illness, and even death. There are some foods that are bad for both dogs and cats as shown in figure. It’s the responsibility of every pet parent not just to provide them nutritionally balanced, wholesome and adequate food, but also to see that they do not eat anything harmful.

Onions and garlic: highly toxic

We must remember that what is great and tasty for us can be extremely harmful to our pets. Onions contain an ingredient called thiosulphate which is toxic to cats and dogs. Onions and garlic are very common seasonings and even major ingredients in common household recipes. Onion in any form – either cooked, raw, powdered, etc can be harmful to pets.
Onion toxicity can cause rupture of the red blood cells circulating through your pet’s body. Symptoms of this condition include animal going off feed, breathlessness, lethargy, diarrhoea and vomiting. It may take up to two to four days after your pet eats the onion for symptoms to appear. Consumption of as little as five g/kg of onions in cats or 15 to 30 g/kg in dogs has resulted in clinically important haematologic changes. Onion toxicosis is consistently noted in animals who ingest more than 0.5 percent of their body weight in onions at one time. About 600 to 800 gm of onions can cause acute toxicity in large dogs. Your pet can also become poisoned by eating extremely small amounts of onions over a period of time.
Garlic is the partner of onion because of its incrementing factor allyl sulfide, which is harmful to dogs. Over time, garlic and onions in a pet’s diet can lead to severe stomach and intestinal damage. Acutely it causes a haemolytic anaemia (destroys the blood cells) and animals can suffer or perish from the lack of oxygen to the brain, as well as develop problems that affect clotting, and they can bleed excessively.

Grapes or raisins: bad for kidneys

Grapes and raisins can be toxic to dogs when ingested in large quantities. According to the American Society for the Prevention of Cruelty to Animals’ (ASPCA) Animal Poison Control Center, grapes and raisins have been known to cause acute renal (kidney) failure in dogs who have ingested large amounts. With kidney failure, a pet’s ability to produce urine decreases, which means they are unable to filter toxins out of their system. Depending on the size of the dog, as little as four grapes/raisins can have an adverse effect on your furry friend.
Though it’s still unclear what makes grapes/raisins dangerous to pets, bacteria or fungi that grow on grapes and the pesticides or fertilizers used in the growing process have been named as culprits for the onset of renal failure. Most affected dogs who have ingested grapes have various symptoms, including lethargy, decreased appetite, muscle weakness, diarrhoea, abdominal pain and shivers.
Raisins are dried grapes. Though not all dogs seem to suffer the effects of eating grapes and raisins, those who do, will suffer severe and possible permanent kidney damage if not treated immediately. For this reason, it’s unwise to feed these to your pet, even if small amounts are tolerated.

Mushroom: fatal to pets

Mushroom toxicity does occur in dogs and it can be fatal if certain species of mushrooms are eaten. They can cause severe liver disease and neurological disorders. Various species of mushrooms are toxic to dogs, and can cause shock and death. Mushrooms contain toxins that trigger numerous organ systems, including the kidneys, liver and brain. Nervous system abnormalities, seizure, coma, vomiting, and death can result when a dog ingests mushrooms.

Chocolate: sweet toxin

There are several compounds in chocolate which are toxic to pets and all seem to affect the heart and gastrointestinal tract. Theobromine is the toxic ingredient in chocolate, a xanthine compound, theobromine and other xanthine compounds are caffeine and theophylline. Theobromine serves to stimulate the central nervous system, resulting in rapid heart rate, seizures, tremors, vomiting, diarrhoea, drooling, panting and extremely fast pulse.
This is a ‘dose-dependent’ poisoning, meaning the more pure chocolate that is ingested, the more serious the toxicity, though a toxic dose will vary depending on factors like whether the dog ate the chocolate on an empty stomach, if the dog is particularly sensitive to chocolate and type of chocolate (dark chocolate is more toxic whereas milk chocolate less so, and white chocolate are dangerous when consumed in very large quantity).

Coffee: toxic too

Because of xanthine compound, the same compound found in chocolate (theobromine), coffee is toxic in sufficient quantities for dogs. It contains caffeine which is also toxic.

Poultry and fish bones: bad for pets

Poultry meat (chicken) is one of the delicacies for many non-vegetarians and fish adds to taste, be aware of feeding poultry bones which can splinter and puncture the stomach or intestines of your pet. Poultry bones are particularly dangerous, as they become brittle when cooked. Chicken bones though not toxic, get stuck in the roof of the mouth, throat and intestines, and should be avoided; splinters of chicken bones can also become lodged internally. Fish bones are very spiny and may lead to glossities (inflammation of tongue); they can also pierce through stomach and rupture the intestines.

Xylitol: lethal for dogs

This is a sugar substitute found in many types of candy, chewable vitamins, sugarless baked goods, and in sugarless gums. As little as three grams (for example, about five pieces of gum) can kill a 25-30 kg dog, with smaller dogs succumbing to just one or two sticks. Within 15-30 minutes of ingesting xylitol, a dog’s insulin levels will surge and blood sugar levels will drop, resulting in lethargy, seizures and loss of balance. Permanent brain damage can occur and without treatment, liver failure will result in death within 24 hours.

Raw fish: life threatening

Eating raw fish may lead to salmon poisoning, a life threatening syndrome that can cause diarrhoea, dehydration, and depression in your dog. Salmon is the common name for several species of fish of the family Salmonidae. Salmon poisoning disease (SPD) is a fatal disease of dogs and other canids caused by infection with a type of rickettsia, Neorickettsia helminthoeca. The disease is caused from a deadly bacteria carried by some free swimming-parasites called flukes. If your dog eats raw fish that carry fluke, the parasites can attach to the walls of your dog’s intestine, releasing the bacteria. The bacteria can enter the blood stream and spread to other organs. It is preventable by cooking all fish before feeding your dog. Eating raw fish can also result in thiamine (a type of Vitamin B) deficiency leading to loss of appetite, seizures, and in severe cases, death. It is more common if raw fish is fed regularly.

Alcohol toxicity: bad for pets too

Dogs cannot tolerate alcohol, even in small amounts. Alcohol ingestion by dogs can result in intoxication, liver failure, coma, seizures and death.

Miscellaneous food toxic to pets

Other miscellaneous foods that are toxic to dogs include: raw eggs and egg whites (contains antivitamin avidin which destroys Biotin), nutmeg, tobacco, trash items, persimmons, yeast and dough containing yeast, excessive liver (Vitamin A toxicity), human iron supplements, chewing gum and candies (contains xylitol). Also, avoid the seeds and pits from apricots, cherries, peaches and plums. These pits contain a natural form of cyanide.
Provide your dog with nutritionally balanced food, specially formulated for him. Speak to your veterinarian who will advice you about the various options available.

(The authors belong to College of Veterinary Science and Animal Husbandry, Navsari Agricultural University, Navsari).