Many types of foods can cause illness in pets. Some of the most common examples are discussed below.
All parts of the avocado—the fruit, leaves, stems, and seeds—can cause poisoning in animals. The leaves are the most toxic part. Horses, rabbits, guinea pigs, budgerigars, canaries, cockatiels, and fish are susceptible. Caged birds appear more sensitive to the effects of avocado. Budgerigars fed very small amounts of avocado fruit (0.04 ounces [1 gram]) can become agitated and begin feather pulling. An amount of 0.3 ounces (8.7 grams) of mashed avocado fruit can cause death within 48 hours.
In mammals and birds, heart muscle can be damaged within 24 to 48 hours of eating avocado. Horses may develop swelling of the head, tongue, and brisket. Birds develop a lack of energy, difficulty breathing, loss of appetite, swelling beneath the skin of neck and chest, and death. In nursing mammals, the mammary glands become inflamed within 24 hours of eating avocado. Affected mammary glands are firm and swollen, and milk production decreases by 75%.
Diagnosis of avocado poisoning relies on history of exposure and signs. There is no specific test to confirm the diagnosis. Treatment includes nonsteroidal anti-inflammatory drugs, pain relievers, and medications for congestive heart failure.
Raw bread dough made with yeast poses hazards when eaten, including bloated stomach, metabolic abnormalities, and central nervous system depression. Although all species can be affected, dogs are most commonly involved because of their tendency to eat anything.
The warm, moist environment of the stomach serves as an efficient incubator for yeast to replicate, which expands the dough mass. The distended stomach reduces the flow of blood to the stomach wall and can result in breathing difficulties. The products of yeast fermentation include ethanol, which is absorbed into the bloodstream and results in poisoning and metabolic abnormalities.
Early signs can include unproductive attempts at vomiting, a distended stomach, and depression. As poisoning progresses, the animal becomes disoriented and uncoordinated. Eventually, severe depression, weakness, coma, dangerously low body temperature, or seizures may be seen. The expanding dough can also cause the digestive tract to twist abnormally in susceptible dog breeds.
A presumptive diagnosis is based on history of exposure, signs, and increased ethanol levels in the blood.
In animals that have eaten dough but are not yet showing any signs, inducing vomiting may be tried. However, the glutinous nature of the dough makes it difficult to vomit up. If vomiting is unsuccessful, the stomach may be flushed with cold water to slow the rate of yeast fermentation and help remove the dough. In some cases, the dough mass may need to be removed by surgery. Additional treatment includes medications to correct metabolic abnormalities and disturbances in heart rhythm, as well as to maintain normal body temperature. Fluids are administered to increase urine output and elimination of alcohol.
Ingestion of chocolate can result in potentially life-threatening heart rhythm abnormalities and central nervous system disturbances. Many species are susceptible, but chocolate poisoning is most common in dogs because of their tendency to eat anything and the fact that chocolate is readily available. Deaths have also been reported in animals that have eaten mulch containing cocoa-bean hulls.
The toxic substances in chocolate are theobromine and caffeine. The following products are listed in order from highest to lowest of the amount of toxic substances they contain: dry cocoa powder, unsweetened (baker's) chocolate, cocoa bean hulls, semisweet chocolate and sweet dark chocolate, and milk chocolate. White chocolate contains insignificant amounts of theobromine and caffeine.
Theobromine and caffeine stimulate the central nervous system, increase urine output, and cause a rapid heartbeat. Severe signs and deaths vary depending on individual sensitivity to theobromine and caffeine. One ounce of milk chocolate per pound of body weight is a potentially fatal dosage in dogs.
Signs of poisoning usually begin within 6 to 12 hours of eating chocolate. The animal may become excessively thirsty, vomit, have diarrhea, and become restless. Signs may progress to hyperactivity, lack of coordination, tremors, and seizures. The animal may pass large amounts of urine. A very rapid and irregular heartbeat, rapid breathing, a bluish tinge to the skin and mucous membranes, high blood pressure, fever, and coma may develop.
Diagnosis is based on history of exposure and signs.
Animals showing signs of chocolate poisoning are stabilized with medications for tremors, seizures, and heart rhythm abnormalities. Fluids are given to increase urine output and excretion of theobromine and caffeine in the urine. In animals that are not yet showing signs, vomiting can be induced, followed by repeated doses of activated charcoal. Signs may persist up to 72 hours in severe cases.
Dogs are the only species in which illness after eating macadamia nuts has been reported. Within 12 hours of ingestion, dogs may vomit and become weak, depressed, and uncoordinated. Tremors and a fever may also be seen. Signs generally resolve within 12 to 48 hours. Diagnosis is based on history of exposure, signs, and excluding other possible conditions.
If the dog has eaten the nuts recently and is not yet showing signs, vomiting should be induced. Activated charcoal can also be helpful. Fortunately, most dogs recover without specific treatment. Severely affected dogs may need supportive treatment, including fluids, pain relievers, and medications to control the fever.
Raisins and Grapes
Ingestion of grapes or raisins has led to kidney failure in some dogs, and it has been reported in 1 cat. The amount of grapes associated with kidney injury in dogs is about 32 grams per kilogram. The amount of raisins associated with signs ranges from 11 to 30 grams per kilogram.
Dogs develop vomiting and/or diarrhea within 6 to 12 hours of eating grapes or raisins. Other signs include lack of energy, loss of appetite, abdominal pain, weakness, dehydration, excessive thirst, and tremors. Kidney failure develops within 1 to 3 days and usually results in death.
Diagnosis is based on history of exposure, signs, and excluding other causes of kidney failure.
If the animal has eaten the grapes or raisins within the last 15 to 20 minutes, vomiting can be induced, followed by administration of activated charcoal. If the animal has eaten a very large amount, or if vomiting or diarrhea has developed, fluids are given for 48 hours to increase urine output. If the dog is producing a small amount of urine, medications can be given to stimulate more urine production. If the dog is not producing any urine, survival is unlikely.
Last full review/revision July 2011 by Barry R. Blakley, DVM, PhD; Cheryl L. Waldner, DVM, PhD; Rob Bildfell, DVM, MSc, DACVP; William D. Black, MSc, DVM, PhD; Herman J. Boermans, DVM, MSc, PhD; Cecil F. Brownie, DVM, PhD, DABVT, DABT, DABFE, DABFM, FACFEI; Raymond Cahill-Morasco, MS, DVM; Keith A. Clark, DVM, PhD; Gregory F. Grauer, DVM, MS, DACVIM; Sharon M. Gwaltney-Brant, DVM, PhD, DABVT, DABT; Larry G. Hansen, PhD; Safdar A. Khan, DVM, MS, PhD, DABVT; Garrick C. M. Latch, MASc, PhD; Gavin L. Meerdink, DVM, DABVT; Lisa A. Murphy, VMD; Frederick W. Oehme, DVM, PhD; Gary D. Osweiler, DVM, MS, PhD, DABVT; Mary M. Schell, DVM; David G. Schmitz, DVM, MS, DACVIM; Norman R. Schneider, DVM, MSc, DABVT