Owners often give table scraps to their pets as a special treat. This seems to be especially true on holidays, because owners often include their pets in their celebrations. Unfortunately, some types of human food can be toxic to pets, so it it important that owners be aware of these dangerous foods and try to avoid allowing their pets to have them.

A mixture of cocoa beans and cocoa butter, chocolate contains theobromine and caffeine, which are both classified as methylxanthines, which competitively inhibit cellular adenosine receptors, resulting in central nervous system (CNS) stimulation and tachycardia. Depending on the amount consumer, methlxanthines can cause increased heart rate, hyperactivity, tremors, and potentially death. Other effects seen with chocolate overdose include diarrhea, lethargy, increased thirst, increased urination, and vomiting. Although theobromine and caffeine have and LD50 of 100 to 200 mg/kg; signs can manifest well below this does: Mild signs can be seen at does higher than 20 mg/kg, moderate signs above 40 mg/kg, and severe signs about 60 mg/kg.

The amount of methylxanthines in chocolate varies with the type of chocolate. Generally, the more bitter the chocolate is, the more toxic it can be (Table 1). In fact, unsweetened baking chocolate contains about seven times more theobromine than milk chocolate, while white chocolate (a combination of cocoa butter, sugar, butterfat, milk solids, and flavorings but no cocoa beans) contains negligible amounts of methylxanthines.

Some types of grapes and raisins have been shown to cause kidney failure in dogs when consumed in large amounts. The basis of this kidney failure is unclear but is currently being studied in the veterinary community. The exact amount of grapes or raisins that may cause renal failure is not known, so any amount could potentially be dangerous.

According to a retrospective study, clinical signs commonly reported in dogs ingesting macadamia nuts include ataxiz, depression, hyperthermia, tremors, vomiting, and weakness. In most cases, dogs developed clinical signs within the first 12 hours after ingestion. These signs have only been seen in dogs, and the exact cause for dogs'sensitivity to macadamia nuts is unknown. The lowest does reproted to cause clinical effects is 2.4 g/kg.

Moldy foods may contain certain tremorgenic mycotoxins such as penitrem A and requefortine C. Classified as neurotoxins, tremorgenic mycotoxins can induce ataxia, muscle tremors, and convulsions that can last for several days. While the exact mechanism of action is unknown, studies have shown that penitrem A inhibits the neurotransmitter glycine in mice. Severity of signs can vary from mild to severe, depending on the particular strength of the mycotoxin ingested. Intoxications have been reported in many species; however, dogs that roam or have access to spoiled foods are more at risk than other pets.

Onions (raw, powdered, or cooked) can be harmful to dogs and cats. Onions are members of the genus Allium. Other members of this genus include chives, garlic, leeks, and shallots. The primary toxic principle in onions and other members of the Allium family is n-propyl disulfide, which is thought to cause oxidative damage to erythrocytes, resuting in hemolysis and potentially anemia.

Ingestion of rising bread dough can be life threatening to dogs. The animal's body heat will cause the dough to rise in the stomach. Ethanol is produced during the rising process, and the dough may expand to several times its original size. Signs seen with bread dough ingestion are associated with ethanol toxicoses and foreign body obstruction and may include severe abdominal pain, bloating, depression, incoordination, and vomiting.

Tobacco preducts contain varying amounts of nicotine; cigarettes contain 13 to 30 mg and cigars 15 to 40 mg. Butts ontain abut 25% of the total nicotine content. The minimum lethal dose in dogs and cats is reported as 20 to 100 mg. Signs often develope quickly (usually within 15 to 45 minutes) and include diarrhea, emesis, excitation, salivation, and tachypnea. Cardiac arrest, collapse, coma, depression, muscle weakness, shalow respiration, tachycardia, and twitching can follow the period of excitation. Death occurs secondary to respiratiory paralysis.