Archive for April, 2012

Yes, well sort of, it depends, is that clear? Actually chocolate poisoning is not unusual in dogs, maybe because many dogs will eat almost anything. Cats are more discerning. I found one reported case of chocolate poisoning in a horse. That is weird because the toxic dose of chocolate is dependent on body weight. The published toxic dose is 100-200 mg/kg. (a mg, milligram, is 1/1000 of a gram, a kg, kilogram, is 1000 grams, a kilogram is equal to 2.24 pounds, 16 ounces to the pound. Let your fourth grader do the math.) To complicate matters veterinarians at the Poison Control Center of the ASPCA have reported problems with doses as low as 20mg/kg, of theobromine. So we will go with the lower toxic dose.

Chocolate comes from the beans of the cacao tree. The beans contain methylxanthines, a class of drugs that include theobromine and caffeine. Most humans can metabolize, break down, both theobromine and caffeine without much difficulty, in two to four hours. The half-life of theobromine in dogs is 17.5 hours, the half-life of caffeine about 4.5 hours, about the same in cats.

To complicate matters further the levels of theobromine depend upon the type of chocolate. Dry cocoa powder has the most theobromine, about 800 mg/ounce. If your five-pound Chihuahua (about 2.25 kg) ingests an ounce of cocoa powder, he will have ingested 800 mg of theobromine. Anything more than 45 mg could cause problems for him. Unsweetened Baker’s chocolate, contains about 450 mg/oz of theobromine, an ounce is still very toxic to your Chihuahua. Semisweet and sweet dark chocolate contain about 150-160 mg/oz and milk chocolate about 44-64 mg per oz so your Chihuahua could still be in trouble. However, your 70-pound Golden Retriever (much more likely to snarf down your chocolate) will have to consume about 14-16 oz of milk chocolate to get sick on it. A 400 kg horse would need to ingest about 8,000 mg of theobromine, that’s about 17-18 oz of Baker’s chocolate. If caught feeding Baker’s chocolate to a race horse you will be banned from the track, maybe prosecuted, it’s considered a stimulant. White chocolate contains very small quantities of the methylxanthines.

Both caffeine and theobromine are readily absorbed from the gastrointestinal tract and distribute throughout the body. Both compounds are metabolized in the liver. The metabolites are excreted in the urine along with small amounts of the original, un-metabolized, compounds. So, if your pet is old, or has liver or kidney disease, the toxic effects can be intensified. With normal liver and kidney function, it will take about two days for your pet to eliminate a toxic dose from its system.

Signs of chocolate toxicity in dogs and cats include diarrhea, vomiting, increased urination, muscle twitching, excessive panting, hyperactivity, whining and when severe, seizures, rapid heart rate and circulatory collapse. Treatment is to induce vomiting and use activated charcoal in an attempt to bind the theobromine and prevent its absorption from the GI tract. You can induce vomiting with 1-2 teaspoons of hydrogen peroxide, repeated two or three times every 15 minutes, if needed. One to,3 teaspoons of syrup of Ipecac, based on the size of the pet, will also do the trick. If your pet is showing signs of intoxication, get it to your veterinarian. S/he can sedate the animal to control seizures and flush with intravenous fluids to hasten elimination from the body.

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Epistaxis (bleeding from the nose) is more common in dogs than in cats, in my experience, probably because most cats are indoor pets these days. It can occur from one or both nostrils and can vary from slight bleeding that usually stops without treatment to profuse, possibly life threatening bleeding, that resists treatment. As with most abnormal conditions your pet may suffer, proper treatment depends upon establishing the cause.

Some incidents start with sneezing and traces of blood in the discharge from the nose while others can start with alarming, and profuse, bleeding. Any cause of persistent and/or violent sneezing can result in a nosebleed. The most common cause is a foreign body such as a foxtail, grass seed (awns), a small blade of grass or a burr. Other causes of sneezing are nasal infections from bacterial and/or fungal organisms and, of course, allergies that initiate sneezing episodes. In rare cases, the infection from a rotten tooth can extend into a nasal sinus and/or the nasal cavity and cause bleeding. Of course, trauma to the head or nose can result in a bleed and cancers of the nasal cavity, particularly hemangiosarcoma, frequently invade the nasal cavity and result in persistent bleeding.

Less common causes include problems with blood clotting that can result from hemophilia or von Willebrand’s disease (a specific type of hemophilia) and hypertension (high blood pressure). The ingestion of warfarin-based rodent poisons, either directly or after eating a rodent poisoned by one of these agents, can be a cause, as well as systemic infections that involve the blood (septicemia) or bone marrow. The bacteria that responsible for Rocky Mountain Spotted Fever and Ehrlichiosis can cause epistaxis. Other infectious causes include the feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV) in cats. Very ill animals can develop disseminated intravascular coagulation (DIC) with nosebleeds, as can animals with immune-mediated thrombocytopenia. The use of some drugs including methimazole (a drug used to treat animals with a hyperthyroid condition), estrogens, sulfa drugs and some chemotherapeutic treatments for cancer can cause bleeding as well.

If your pet has a nosebleed first try to keep it calm, then hold an ice pack on top of the muzzle. If the bleeding stops then returns, or does not stop, take it to your veterinarian. Do not treat your pet with aspirin or non-steroidal anti-inflammatory agents (NSAIDs). Tell your vet if the animal has been on any kind of medication, been exposed to rat poison or other pesticides, dead rodents, or to a place where s/he could have sniffed up a grass awn or other seed head. You must tell your vet if your pet has been roughhousing with other animals, sustained a trauma to the head or face, been sneezing or rubbing at the nose, had blood in the mouth or gums, a black tarry stool or had “coffee-ground” vomiting. Any of these signs could help with the diagnosis.

After a thorough physical exam, your veterinarian may need to examine the nasal cavities with a small endoscope, do blood work, radiographs, nasal swab cultures and antibiotic sensitivity tests and/or fungal cultures and possibly allergy testing. In cases of neoplasia (cancer), a CT or MRI scan may be necessary. The good news is that most nosebleeds are not serious and once the cause is determined and removed the nosebleed will no longer be a problem.

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