8 substances that can result in toxicoses in certain species

Some toxins are specific to cats, dogs, horses, and ruminants. We'll break down these eight for you in an easy-to-remember list.
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Mar 12, 2013

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Some toxins are specific to cats, dogs, horses, and ruminants. We'll break down these eight for you in an easy-to-remember list.

Xylitol is a threat to dogs. Xylitol is a natural sugar-alcohol normally found in small amounts in many fruits and vegetables. Because of its sweet taste and natural plaque fighting properties, it is frequently used as a sugar substitute in chewing gum, breath mints, multivitamins, baked goods, and dental products like toothpaste and mouthwash. Its use is rapidly growing in popularity and it’s now turning up in some pretty interesting places--nasal sprays, multi-vitamins, and smoking cessation chewing gums. Non-toxic amounts are even found in some pet dental products. The amount of xylitol typically found in most pet oral-care products is very small and, when used properly, is not expected to cause toxicoses unless the dog ingests a very large amount.

Xylitol may cause a life-threatening drop in blood sugar as well as causing liver damage to dogs. Cats and people do not experience this problem. Typically, the dose needed to cause toxicoses is at least (0.05 grams of xylitol per pound of body weight (0.1 grams of xylitol per kilogram of body weight). The signs of poisoning include hypoglycemia, loss of coordination and vomiting within 10 to 60 minutes of ingestion. Collapse and seizures may quickly follow. In rare cases, these signs won't appear until hours after ingestion. Liver damage will become evident within 1-2 days of ingestion.

The treatment is inducing vomiting or performing gastric lavage in dogs that are asymptomatic and have a normal blood sugar level. If the dog is hypoglycemic, intravenous fluids containing dextrose needs to be given first. The prognosis is excellent if the ingestion is caught early.

Dunayer EK. New findings on the effects of xylitol ingestion in dogs. Veterinary Medicine 2006;101(12):791-796.

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Pyrethroids are a threat to cats. . Pyrethrins and their synthetic derivative, pyrethroids, are commonly found in squeeze-on topical flea/tick treatments, household insecticide sprays, flea shampoos, and flea collars. Common chemical names include permethrin, cypermethrin, cyphenothrin, bifenthrin, etc.

Cats are significantly more sensitive to this group of insecticides than dogs and people. The biggest concern comes with the application of canine spot-on pyrethrin/pyrethroid-based insecticides to cats. The most notable signs are twitching, tremors, and seizures. The twitching in cats may start at the head—ear flicking, jaw snapping, excessive skin twitching, and full head tremors are common. As the poisoning progresses, the twitching and tremors become more severe.

The tremors are responsive to injectable muscle relaxants. Once the tremors have been stopped, it's important to bathe the cat thoroughly to fully remove the flea/tick product. Remember never to bathe a tremoring cat because that may push the cat into seizures. Prognosis is excellent with appropriate treatment.

Linnett PJ. Permethrin toxicosis in cats. Aust Vet J. 2008 Jan-Feb;86(1-2):32-5.

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Grapes, raisins, and currants are a threat to dogs. Grapes, raisins, and currants found in a host of food products including cereals, trail mixes, cookies, breads, and bagels. As we all know, they're equally delicious on their own and are popular snacks. Vomiting may spontaneously occur within hours of ingestion. Then, within 1-4 days of ingestion, the kidneys began to shut down causing increased urination, increased thirst, lethargy, and a reduced appetite. If not treated, these dogs will likely die. The treatment is decontamination by inducing vomiting and giving activated charcoal is helpful to prevent absorption of the toxins. Following this, diuretic doses of IV fluids (to protect the kidneys), frequent monitoring of kidney laboratory values, anti-vomiting medication and in-hospital care is needed for at least 2 days. The prognosis is excellent if the dog is treated before signs begin.

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Lilies—Lilium spp. and Hemerocallis spp. There are two common species of lilies that are of specific concern--Lilium spp. (true lilies) and Hemerocallis spp. (Day lilies). They are commonly know as the Easter lily, tiger lily, Japanese show lily, stargazer lily, rubrum lily, and day lily. In the United States, they are very common perennial garden plants and also frequently sold in fresh bouquets and floral arrangements for all seasons.

Cats develop acute kidney failure and possibly pancreatitis from ingesting this plant. Humans, on the other hand, can enjoy lily blossoms in their salads or in cooked meals with no concerns. Clinical signs may start within a few hours of ingestion and often include vomiting, depression, and a reduced appetite. The kidneys will begin to shut down and stop producing urine within in 3 days.

If caught in time, vomiting may be induced in cats. Next, activated charcoal is given and diuresis with IV fluids begins. If available, dialysis may also be used. Cats should be hospitalized for at least two full days on IV fluids. If fluid therapy is initiated within 18 hours, the overall response to therapy is good. However, if treatment is delayed beyond 18-24 hours, or the kidneys have stopped producing urine, the prognosis is grave.

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Macadamia nuts are a threat to dogs. Edible macadamia nuts come from trees native to Australia but are now grown in Hawaii, California and areas of similar climate. They are often snacked upon, covered in chocolate or baked into cookies. Within 12 hours of ingestion, dogs will become weak, especially in the hind limbs, and can develop joint pain, a lack of coordination, a slight increase in body temperature, and mild abdominal pain. In serious cases, hind limb paresis, and tremors can occur. Pancreatitis from the high concentration of fat is also a risk.

There is no antidote for macadamia nut poisoning. Decontamination by inducing vomiting and giving activated charcoal is helpful if a toxic dose was ingested. Pain relievers and medications to manage tremors may be needed. The prognosis is excellent and signs will typically resolve during the first two days.

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Fluoroquinolone antibiotics warrant caution in cats. The class of fluoroquinolone antibiotics includes enrofloxacin, marbofloxacin, and orbifloxacin; these drugs have been commonly used in veterinary and human medicine for more than 20 years. While considered safe at labeled dosages, caution is still warranted as retinal degeneration is a rare but serious side effect that has been associated with fluoroquinolone use in cats only. Most cases resulting in blindness occurred after cats received high doses (10 times the labeled dose)1,2 of these antibiotics. Signs of blindness in cats may include dilated pupils, bumpinginto furniture, misguided jumps, etc. There is no antidote for the retinal damage; the first line of treatment is to immediately stop giving the fluoroquinolone. Following this, a thorough eye exam is needed to rule-out other causes of blindness such as retinal detachment secondary to hypertension. Intravenous fluid therapy may be helpful to aid in drug removal, especially if the cat has kidney problems. The prognosis is poor; vision cannot often be regained after retinal degeneration.

1. Ramirez CJ, Minch JD, ay, JM, et al. Molecular genetic basis for fluoroquinolone-induced retinal degeneration in cats. Pharmacogenet Genomics. 2011 Feb;21(2):66-75.

2. Ford MM, Dubielzig RR, Giuliano EA, Moore CP, Narfström KL. Ocular and systemic manifestations after oral administration of a high dose of enrofloxacin in cats. Am J Vet Res 2007 Feb;68(2):190-202.

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Nitrate is a threat to ruminants. Plants take up nitrogen from the soil in the form of nitrate. Plants can accumulate higher levels of nitrate under certain conditions such as excessive fertilization, drought, some herbicide use, and low sunlight. After ingestion of plants, microorganisms in the rumen convert nitrates (NO3) to nitrites (NO2) and then to ammonia, which is used for microbial growth. If the amount of nitrates ingested exceeds the capacity of the microorganisms to form ammonia, nitrates and nitrites can accumulate and be absorbed into the blood. It is important to note that nitrate is not toxic but it becomes toxic when it is converted to nitrite.

Clinical signs occur when methemoglobin concentrations reach 40 percent. Signs include weakness, cyanosis of mucous membranes, ataxia, and collapse. Blood can appear chocolate brown in color. When methemoglobin concentrations reach 70-80 percent, death can occur. Nitrate poisoning can also cause abortions.

The treatment is intravenous methylene blue in a 1 or 2 percent aqueous solution at a rate of 1-2 mg/kg BW. In severe cases, up to 10 mg/kg BW can be administered. Tissues of treated animals will be stained and the urine will appear dark green. Treated animals should not be slaughtered for 180 days. Prognosis is good when the ingestion is caught early and methemoglobin is reconverted to hemoglobin. However, in many instances, animals are found dead in the field.

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Red Maple is a threat to horses. Red maple (Acer rubrum) is a deciduous tree native to North America. It is frequently planted as an ornamental because of its vibrant fall colors. Ingestion of the leaves can cause red blood cells to rupture (hemolytic anemia) with methemoglobin and Heinz body formation. Hemoglobin from ruptured red blood cells can precipitate within the tubules of the kidney leading to renal failure. There are no reports of other animal species having this problem except for one case report in two alpacas.

Nonspecific signs such as depression and anorexia appear initially. During the next few days, icterus, hemoglobinuria and brown discoloration of mucous membranes and blood develop. Lack of oxygen from methemoglobin formation can ultimately lead to death.

Activated charcoal can be given if ingestion is recent. IV fluids should be given to prevent dehydration and support renal function. Ascorbic acid, 20-50 mg/kg, given twice daily in IV fluids has been used successfully in two horses to reduce methemoglobinemia. A blood transfusion might be necessary. Prognosis is guarded even with early, appropriate treatment.