Canine liver disease is one of the causes of death in dogs and is something to be taken seriously by dog owners. The liver is responsible for a number of essential, important body functions and a problem with the liver will affect the overall health and well-being of your dog
The liver has several important functions to maintain the health of your dog. Blood detoxification, waste removal and the production of bile to aid digestion of food are just some of these vital functions. The liver is involved in nearly all body processes and is a strong resilient organ that continues working even though liver disease in your dog may be present in early stages.
The liver plays a role with almost all biochemical pathways that allow growth, fight disease, supply nutrients, provide energy, and aid reproduction. Liver cells go through thousands of chemical reactions every second in order to perform all of this work. As the liver is involved with so many processes, it is an obvious target to be affected by different diseases. Liver function is vital to life.
Day after day for every second of life, the liver processes raw materials and manufactures the building blocks of the body. It recycles old material to make new, and detoxifies body waste. Because of its importance in the dog’s body and the far-reaching effects of its activity, symptoms of liver disease are usually non-specific and unpredictable. The liver is susceptible to a wide range of diseases including degenerative disease, viral and bacterial infections, neoplastic disease (tumor), and toxicity.
Liver conditions are difficult to diagnose as it has an incredible life preserving capacity, which means it can easily continue to perform its function with up to 70 or 80% of the liver affected by disease. It has a phenomenal reserve capacity, which often means that by the time liver disease is diagnosed; it is very advanced meaning the condition may be untreatable in the worst cases. While it is of tremendous benefit that the liver can keep your dog alive despite an overwhelming infection or a tumor, it means the option of treating symptoms early is rare when a better outcome could be expected. However, the liver is the only organ in your dog’s body that is capable of complete regeneration, so if treatment is successful, the chances of complete recovery are high.
LIVER FUNCTIONS DEFINED
The liver is the organ that co-ordinates the metabolism of fat, carbohydrate, and protein. This is performed alongside the circulatory system, the lymphatic system, and the endocrine (hormone) system. Metabolism is dependent on a healthy liver.
The liver produces all proteins except for those synthesized by the immune system. It does this by assembling amino acids into protein. The main protein produced by the liver is called albumin.
Normal albumin in the bloodstream is important for many bodily functions. Without it being produced by the liver properly, it can cause fluid in arteries and veins to leak out and pool in the abdominal and chest cavities. Albumin also transports calcium, vitamins, hormones, fatty acids, bilirubin, and many drug medications through the bloodstream.
One consistent finding with liver disease is low protein levels. This low level occurs only when the liver has been diseased over a long period of time as aforementioned; the liver has a remarkable capacity to continue working while diseased.
With the aid of the hormones insulin and glucagon, the liver maintains normal blood glucose levels. Abnormalities that affect blood glucose level result from insulinoma or diabetes mellitus (sugar diabetes).
Glucose that is stored in liver cells is called glycogen. It acts as reservoir during times when carbohydrate intake is low (fasting or starvation). The liver can also manufacture glucose from proteins or fats. When your dog has liver disease, his body may have difficulty regulating blood glucose levels which leads to hypoglycemia (low blood glucose). Because of these abnormalities, intake of calories and diet are an important aspect of liver disease.
The liver regulates fats (called fatty acids) in the bloodstream. Excess amounts of carbohydrate and protein are converted into fatty acids. From the fatty acids, the liver produces cholesterol, which is necessary for many functions particularly the sex hormones, and cortisone.
There are times when your dog’s liver may have to fight very hard against toxicity. Any type of poisoning from weed killer or car anti-freeze your dog may ingest will have a serious effect on the liver as it tries to flush out the poison. Often the impact of poisoning is too severe for the liver to fight back and sadly the outcome usually results in death or the dog being euthanized. It is important to protect your dog from access to any toxic substances and to be aware that dogs do not tolerate some drug medications like humans so care must be taken not to give any medication that has not been prescribed by your vet. Even then, some drugs are quite aggressive and may affect your dog’s liver if he is undergoing some other kind of treatment.
Detoxification is an important liver function. In the liver cells, a complex process occurs depending on the substance being detoxified. The offending toxin is inactivated and eliminated by the body. It will either pass through the kidneys and excreted in urine or, secreted into bile and passed out in the feces.
Bile is made up of electrolytes, cholesterol, bile acids, bilirubin, and globulins. It is produced by hepatocytes, secreted into channels in the liver called and stored in the gall bladder. Drugs are eliminated in the bile, red blood cells are re-circulated through the bile system, and fats are absorbed from the intestines into the bloodstream only in the presence of bile.
When red blood cells break down and are recycled, they release bilirubin from their hemoglobin. The liver, along with spleen and bone marrow, recycle this bilirubin, salvaging some of the compounds and excreting the rest in the bile. Bilirubin, which is toxic, binds to albumin and is detoxified and excreted. Eventually this will reach the intestines and be broken down by intestinal bacteria, where it imparts the dark color to stools. If this bilirubin cannot be excreted from the gallbladder (when there is an obstruction in the bile duct), there will be very light colored stool.
Excess amounts of bilirubin that build up in the bloodstream will cause jaundice, the yellow discoloration of the mucous membranes and skin that can occur with liver disease.
The fat-soluble vitamins, A, D, E, and K, require bile for proper absorption from the intestines. These vitamins are stored in the liver, and are converted to active compounds as part of the liver’s job.
Proteins initiate and maintain blood clotting and are synthesized by the liver. A diseased liver is unable to synthesize these proteins, leading to potential bleeding problems. Vitamin K is also an essential component of these clotting mechanisms.
Red Blood Cell System
The liver removes old or damaged red blood cells from the circulation, and is involved with the storage of iron and the breakdown of hemoglobin. Because of this, chronic liver disease causes anemia in most cases. The liver (along with the spleen), is a storage organ for blood. If there is a severe blood loss, the liver expels this blood into the bloodstream to help make up for the loss.
Specific cells called Kupffer cells line the inside of the liver. These cells are part of the immune system. They eliminate and degrade the substances that are brought into the liver by the portal vein. Some of these substances are bacteria, toxins, nutrients, and chemicals. When the liver is diseased, it will not be able to perform this function resulting in a build up of toxic substances such as bacteria, chemicals, or drugs. This can lead to further complications such as septicaemia where there are excess bacteria in the bloodstream. Anti-biotics are commonly used in the treatment of liver disease precisely for this kind of reason depending on specific diagnosis.
Many vitamins are stored in the liver, and perform their functions only when the liver activates them when needed. These include some of the B vitamins and Vitamin C, along with A, D, E, and K previously described.
Canine liver disease may be caused if your dog receives a blunt blow to the front of the abdomen and is injured. The most common cause of this type of injury is where a dog is injured in a road accident. A liver lobe can be fractured and bleed into the abdomen, even leading to death from internal bleeding. A more common occurrence is a bruise (contusion) that heals itself. Heatstroke, diaphragmatic hernia, and liver lobe torsion can also cause liver problems.
This severe inflammatory disease can cause digestive enzymes to spill over into the liver causing disease. The close proximity of the pancreas to the liver and the bile ducts results in some degree of hepatitis whenever there is a case of pancreatic inflammation. The liver disease will regress when the pancreatitis is treated.
Anemia decreases the oxygen available to liver cells and leads to their death.
Inflammation of the liver is called hepatitis. Hepatitis may be caused by many antagonists include trauma, bacteria, virus, poison or bile.
Adenovirus or herpes virus causes infectious hepatitis. It is transferred from dog to dog by oral contact and ingestion of contaminated materials. It usually causes a transient non-specific illness characterized by lethargy, vomiting, diarrhea, and fever. It sometimes develops into a full-blown case of severe hepatitis. Treatment supports your dog while he fights off the virus. Infectious hepatitis can be prevented by routine vaccination.
Bacteria, viruses, and fungi
Bacterial infection is common in many liver problems so antibiotic therapy is often the first line of defence. Specific diseases include Infectious canine Hepatitis, canine Herpes virus, Leptospirosis, abscesses, histoplasmosis, coccidiomycosis, and Toxoplasmosis.
There are several known bacterial causes of hepatitis. Treatment is based on proper diagnosis and administration of antibiotics. Research shows that bacteria is a normal inhabitant of the liver and only becomes a problem when the liver is under attack from other causes.
Leptospirosis is one bacterial infection common in wildlife and transferable to domestic dogs and people through contaminated water. It is very dangerous and sometimes fatal but routine vaccination is the preventative measure to take.
Unfortunately, some kinds of parasites will infect the liver in your dog. A lot depends on your geographical location as some regions have a higher risk factor. Diagnosis is usually symptom based accompanied by fecal examination, and standard diagnostic techniques for liver disease. Treatment is the appropriate parasiticides.
Some breeds of dog have a genetic predisposition to chronic hepatitis. This disease is primarily found in Bedlington Terriers, Doberman Pinschers, and West Highland White Terriers. The liver stores abnormal and toxic levels of copper. The course of the disease is variable, with some dogs presenting with acute hepatitis, and some presenting in end stage cirrhosis of the liver.
Diagnosis is made after a liver biopsy. Treatment requires the use of copper binding and anti-inflammatory drugs to decrease liver inflammation with dietary modification to limit copper intake.
These worms can block blood flow into the liver and cause liver failure. A routine and regular de-worming programme for your dog can prevent this. In general, any disease that can cause failure of the right side of the heart can also cause liver problems.
Disease to the liver is caused by the ingestion, injection, or inhalation of a toxic substance, which adversely affects the liver. Due to the nature of the liver, that has a detoxification function, it is to be expected that an overload will be harmful.
There are some factors contributing to a greater likelihood of toxicity. Female dogs are more at risk than males, fatty diets are more dangerous, and high exposure to toxic chemicals, pesticides and so forth are all factors that put your dog at risk. Continuous exposure to these toxins could result in death but certainly, there will be severe inflammation of the liver cells. The damaged tissue resulting from the inflammation will be replaced with fibrous scar tissue. This could lead to cirrhosis of the liver in severe circumstances.
Toxins include many common drugs, such as anabolic steroids, chemotherapy drugs, some antibiotics, glucocorticoids, anaesthetics, parasite control drugs, and phenylbutazone.
Some of drug-induced hepatitis is a predictable side effect of the drug, while other incidences of hepatitis are considered an unpredicted or abnormal side effect of a given drug. This is difficult to diagnose unless there is a known exposure to the drug or toxin and the testing has been done. A biopsy will confirm liver destruction, inflammation, and fibrosis, but it will not single out the causative agent.
Different dogs have different tolerances to drugs and insecticides and so forth. For example, collie sheep dogs who ingest ivermectin a common parasite control product for worms in cattle horses and sheep, will be fatally poisoned, yet the rest of their canine friends will not be affected at all.
Drugs that cause liver damage
Dogs are extremely sensitive to cortisone and will develop lesions in the liver after long term or multiple dose therapy for a disease such as like Cushing’ disease. While cortisone is an effective treatment for Cushing’s disease, the side effects may cause liver damage. If signs of liver disease are noticed during treatment, the cortisone therapy can be stopped, the liver disease will improve, but the lesions may take months to heal.
Anti convulsant drugs such as Phenobarbital, primidone, and phentoin, may cause liver disease in 6 to 15 % of all dogs on anti-convulsant therapy. Inflammation of the liver varies according to the drug dosage. The extent of liver disease is variable and unpredictable. Treatment for the liver is removal of the drug treatment.
There are so many chemical compounds toxic to the liver and quite common treatments for ailments such as arthritis, heartworm, worms, parasites; epilepsy to name a few may cause some degree of liver damage.
Portal Vascular Abnormalities
This is a congenital defect is usually seen in young dogs and puppies where blood is passed from the digestive tract into the bloodstream without being detoxified by the liver. Symptoms of this condition are inconsistent but warning signs are youth, malnourishment, and chronic unwellness, poor tolerance to medication and anaesthetic and pica (eating unusual items). Diagnosis is based on a full veterinary work up with specialized X-rays, laboratory tests, and history. The only treatment is surgical intervention to correct the circulation abnormality.
Cancer can arise directly within the liver (primary) or spread from elsewhere (metastatic or secondary) through the circulatory or lymphatic systems. There are two blood supply routes to the liver through the portal vein and hepatic artery. This additional blood supply makes it likely that a tumor in a different organ will spread to the liver. Liver cancer is normally diagnosed long after the cancer is well established due to the remarkable powers of endurance the liver has.
Other than cancer, Hypothyroidism, Diabetes Mellitus, Pancreatitis, Cushing’s disease, and Inflammatory Bowel Disease may cause secondary liver disease for example.
Cirrhosis of the Liver
Cirrhosis of the liver occurs as the end result of several liver diseases. Cirrhosis can occur as a result of many different liver diseases. It is likely to occur in copper storage diseases of the liver, as the end result of chronic hepatitis, as a breed related disorder (Terrier breeds, Dobermans, Labradors, Cocker Spaniels and Standard Poodles), side effect of anti-seizure, and some de worming treatment. Cirrhosis sometimes appears after leptospirosis or infectious canine hepatitis although it is a rare complication in these cases.
Summary of Diseases
Amongst all of these various medical conditions your dog may suffer, the one that appears without much warning is chronic hepatitis, so awareness of symptoms is important for dog owners. This disease can be present for a long time without displaying symptoms. When clinical signs are present, it is likely the liver is markedly decreased in size and function. Even when things get this bad, it is possible to manage the condition. Recommendations include a low to moderate protein diet, drug therapy, supportive therapy with vitamins and natural products such as milk thistle.
All of the diseases mentioned that your dog could suffer from progress and slowly destroy the liver cells resulting in scarring and fibrous tissue in the liver or cirrhosis. Many dogs live for extended periods of times even if cirrhosis present. At this stage, it is difficult to identify the underlying cause for the disease.
New and Emerging Liver Diseases
This syndrome is characterized by degeneration of the skin cells probably caused by nutritional imbalance caused by metabolic abnormalities as the result of pancreatic tumors or severe liver dysfunction.
It affects mainly older dogs who show clinical signs a syndrome primarily of skin disease although some dogs will exhibit symptoms of illness such as lethargy, poor appetite, and weight loss prior to the skin eruptions. The skin lesions frequently appear on the muzzle, lower legs, and footpads. Lesions can also appear on the mouth, earflaps, elbows, and genitalia. Most lesions consist of crusting, erosions, or ulcerations, but blisters may also occur. Footpads are often severely thickened and fissured and are often painful and the dog is lame.
Diagnosis is based on your dog’s history, physical examination, blood tests to identify abnormalities such as elevated liver enzymes and low protein levels, and skin biopsy. Abdominal ultrasound may show a “honeycomb” pattern of the liver due to liver degeneration or less commonly a pancreatic tumor.
If a pancreatic or liver tumor is identified and able to be surgically removed, the skin lesions will normalize. This type of tumour spreads to other parts of the body quickly so surgery is not a total solution. In cases of end stage liver disease, surgery is not possible, so the aim of therapy is to increase quality of life and decrease uncomfortable skin lesions with supportive care, good nutrition. Milk thistle is helpful as a natural support element. Your vet will advise on a program of care that may involve fluid therapy, amino acid infusions, and a tailored course of minerals, protein, and enzymes. Unfortunately, despite the supportive care, the disease will progress and has a poor outcome with a survival time of around one year in most cases.
Idiopathic Vacuolar Hepatopathy
This is a condition observed in older dogs. The liver in these older dogs contain excess glycogen. Because of improved nutrition, vaccination, and de worming, dogs are now living longer and beginning to acquire geriatric diseases and other conditions previously unknown. There is speculation that increases in progestin steroid hormones may result in liver changes. It appears that almost every dog diagnosed with this condition live a prolonged life without illness from his or her liver disease. Recently studies have shown that a disproportionate number of Scottish Terriers have liver changes suggesting a breed predisposition for this condition. They may have a genetic defect in ALP production.
Gallbladder mucocele is seen in smaller breeds and older dogs with Cocker Spaniels being most commonly affected. Most dogs have nonspecific clinical sign, such as vomiting, lack of appetite and lethargy. Abdominal pain and hyperthermia are common findings. Most dogs will show elevated serum elevations of total bilirubin. An ultrasound will confirm diagnosis.
General Symptoms of Liver Disease
Liver disease symptoms are very subtle and your dog may show very little in the way of signs. The alert owner can learn to recognize any unusual signs and advanced symptoms. If you have any concerns about your dog, do not wait and see but consult your veterinarian early as the earlier liver disease is caught, the quicker it can be treated successfully.
Dogs with liver disorders show many types of physical symptoms. Very few of the symptoms are specifically for liver disease, but are signs of multiple diseases and conditions that can affect the liver. Symptoms of liver disease are extremely subtle in the early stages. Your dog may experience all of the following symptoms, some of them or one of them.
- Loss of appetite. Loss of appetite is always cause for concern and a veterinary surgeon should be contacted without delay.
- Recurrent abdominal or gastrointestinal upsets. Any vomiting, diarrhea or constipation should be taken seriously especially if they are intermittent attacks.
- Progressive depression or lethargy. When your dog does not want to play or go for walks and has a lethargic demeanor this can be a symptom to be taken seriously.
- Swollen abdomen. This may mean there is fluid in the abdomen due to alterations in your dog’s circulation.
- Pale gray feces. Bile is what gives feces its characteristic brown color. If the liver is not processing bile properly, the feces will be unpigmented and a grayish color.
- Orange urine. Improper bile processing results in high levels of bilirubin excretion in the urine, which results in an orange color.
- Jaundice. Any pale or white skin or visible tissue takes on a yellow hue. This is because the biliary pigments are accumulating in the body because the liver is not processing them.
- Bleeding problems. Many of the proteins required for proper blood clotting are created in the liver. When these proteins are low or not present, the ability to clot blood decreases. Any signs of bleeding that do not stop easily should be cause for concern and your veterinarian should be contacted immediately. If your dog has any small swellings or bruises it may indicate blood-clotting problems.
- Neurological symptoms. Behavioral changes, seizures, aimless pacing or circling, pressing the head against a wall or stargazing are frightening symptoms that may be caused by toxicity causing the liver to fail. Contact your veterinarian immediately as an emergency.
- Abdominal Pain. This is due to the stretching of the liver capsule. The liver is sore and tender and you are likely to notice this when your dog is lifted up. Your vet will also be able to tell the liver is swollen by examining your dog.
- Chronic weight loss. The liver processes all the essential life force building blocks. If it is not working correctly, bodily systems are compromised and the body cannot maintain itself.
- Increased Water Consumption And Urination. These symptoms are likely to be caused by large shifts in serum and kidney salt balances.
- Blood Pressure. Recent studies concluded that dog liver disease could also cause high blood pressure. This will need monitoring if your dog is diagnosed with canine liver disease.
At the Veterinarian
If you notice your dog showing any of the symptoms described, make sure you consult your veterinarian as soon as possible. Because your dog’s liver is such an amazing organ, it can function even with severe disease. This essential organ is closely involved in all other bodily functions. The liver is very resilient to attacks by viruses and bacteria, but symptoms will show up, even though another condition is causing the primary illness. Dog liver disease is very often therefore a secondary condition brought about by a primary illness in another area of your dog’s body.
Your veterinarian will use his or her expertise and knowledge of anatomy and disease to make a diagnosis. Taking known facts into account like the age and breed of the dog, his vaccination status, worming program, toilet habits and so forth, they will be able to eliminate certain diseases and use tests to arrive at a diagnosis and how affected your dog’s liver is by disease.
Early signs of liver disease are subtle and it is a good idea to get into the practice of taking your dog for annual routine check ups that include blood work especially if he falls into a high risk category for canine liver disease e.g. breed pre-disposition or is over eight years of age. It is important to remember that your dog may not show any explicit signs of canine liver disease, which is why a regular blood or urine test may give you an early warning. Often indirect evidence from laboratory tests can lead to the presence of liver disease.
Always provide your veterinarian with all relevant facts. Nothing is too small or insignificant and the more facts you can provide the better the chances. If for example you have been using weed killer in the garden or spilled some anti freeze in the garage the dog may have ingested or you have to admit his diet is less than healthy go ahead, your veterinarian needs to know all the facts you have because at the end of the day you know your dog best.
When your veterinarian examines your dog, physical examination findings may include a distended abdomen due to enlargement of the liver. This symptom can also be indicative of other diseases it should be borne in mind. There may be enlarged lymph nodes, which could indicate secondary bacterial infection or the spread of a primary liver tumor. Bruising may be seen under the skin or after a blood sample is taken which is due to the liver’s effect on your dog’s blood clotting mechanism.
Sometimes canine liver disease is accompanied by fever indicated by a rectal temperature of 103 degrees when inflammation or infection is present. Your veterinarian will notice all of the signs and symptoms present by a full body examination and routine blood and urine tests.
Sometimes if results are inconclusive, it may require some more extensive blood and diagnostic testing to be certain of the diagnosis. Many different levels of liver enzymes are tested and compared against normal levels.
X rays can show increased liver size, decreased liver size liver abscesses, abnormal mineralization, and circulatory abnormalities (using special dyes).
Ultrasound is one of the better techniques for diagnosing dog liver disease as the circulation of the liver, the bile duct system, the density of liver tissue and the size of the liver can be seen.
Biopsy of the liver
While this is surgery, it is most useful for diagnosis of canine liver disease as liver tissue can be examined and tested to give a conclusive diagnosis and a treatment regime based on the findings. Your dog’s liver biopsy can be taken by a full laparotomy where the whole liver can be looked at by the veterinary surgeon or by a needle biopsy. The liver will regenerate these tiny pieces of liver taken for testing so it is a low risk procedure for your dog.
The course of treatment required in a case of canine liver disease will depend upon the cause of the condition. For example, if trauma was the trigger, hospitalization while the dog recovers from the impact of the trauma may be all that is required. On the other hand, antibiotics may be needed if a bacterial infection is at the root of the disease. Furthermore, when liver disease is caused by another medical condition such as cancer or anemia, these additional medical circumstances will need to be taken into account.
In addition to certain medications, dietary adjustments and supplements can be very useful when attempting to treat canine liver disease. Dietary changes can include adjusting the amounts of proteins, vitamins, carbohydrates, fats, and minerals that a dog eats. This will then ensure that your dog is receiving the nutrition he needs and will also help to decrease the stress and workload of the liver. Vitamin K can be helpful with respect to controlling bleeding disorders while vitamin E, as an antioxidant, helps to remove free radicals and to prevent continued damage to your dog’s liver.
Certain natural remedies can also be very helpful when treating canine liver disease. Natural herbs and substances have properties that assist with the purification of blood, the stimulation of digestive enzymes, and the protection of the liver from toxic substances. Some of these substances have anti-inflammatory and antibacterial properties. Milk thistle is another natural ingredient that is known to be very effective in cases of canine liver disease. This natural substance acts as an antioxidant like vitamin E, stimulates production of new liver cells, and helps to prevent certain toxins from attaching to the liver. Thus, many natural substances and remedies can be very beneficial for dogs suffering from liver disease.
Never use alternative therapies until you have received a proper and specific diagnosis from your veterinarian.