The liver is a vital organ. Responsible for filtering toxins from blood, a dog's liver maintains a healthy coat, digestion and immune system. When it's damaged, the whole dog suffers. Broadly speaking, liver damage is either primary, due to causes such as improper food, medications, trauma or birth defects, or secondary to disease. In both cases there are steps you can take to minimize the risk of liver damage in your dog.
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Primary Causes for Liver Damage
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Primary liver damage may be congenital. Some dogs (like Bedlington terriers and Dalmations) are born with an inability to filter copper in food and water, and the resulting chronic hepatitis leads to an enlarged liver. Proper diet is essential for susceptible breeds.
Since the liver filters toxins, some medications cause liver damage. Steroids and NSAIDs (non-steroidal anti-inflammatory drugs) used for pain control are well-documented as causing liver disease and even death in some dogs.
Antifreeze, rat poison, household chemicals and pesticides can all cause liver damage. According to a 1989 World Health Organization study, allethrin, a common ingredient in household bug sprays and lawn treatments, has been linked to liver damage and cancer in dogs.
Dogs' livers metabolize some substances differently than ours. Never give your dog onions, garlic, vitamins containing iron, or artificial sweeteners like xylitol. Some dog foods have also been responsible for illness and death from liver damage. This is usually due to molds like aflatoxin, or contaminated pet food ingredients like the melamine-tainted gluten that sickened and killed many dogs in 2007.
Parasites, Bacteria and Viruses
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Intestinal parasites originating in the gastrointestinal tract can invade the liver. These are diagnosed by checking a fecal sample for parasites and treated with the appropriate paraciticide. Leptospirosis is a virus that invades the liver, causing multiple small lesions. Adenovirus is another virus that can attack a dog's liver and cause hepatitis. Most puppy vaccines include those against leptospirosis and adenovirus.
When the liver is damaged in any way, it's also more susceptible to bacterial infections. A damaged liver cannot ward off infection from even a normal load of bacteria.
Secondary Causes for Liver Damage
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While occasionally cancer of the liver is primary, usually liver cancer in dogs originates elsewhere and spreads to the liver. Severe bowel disease and pancreatitis can damage the liver by infiltrating the liver bile ducts with toxins and bacteria from the bowel and pancreas.
Several illnesses, including Cushing's disease, diabetes and hepatitis, all affect the liver.
Trauma and Injury
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According to data collected by the Long Beach Animal Hospital, dogs who have suffered abdominal trauma from abuse or car accidents often have bruised or ruptured livers. A ruptured liver may bleed internally and, if untreated, will cause anemia and shock, possibly leading to death. Even if there are no outward signs of injury, after an accident take the dog to the vet to check for internal injuries.
Symptoms
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Because the liver can be affected in so many different ways, there are numerous possible symptoms of liver damage or disease, and all should be checked by a veterinarian.
According to the Long Beach Animal Hospital, classic symptoms of liver damage include loss of appetite, weight loss, excessive water consumption and urination, and lethargy. Other signs may be light-colored stools, orange urine and any behavioral changes indicating that the dog may be in pain.
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