The liver is the largest internal organ. In the specific case of carnivores, it represents up to 4% of their body weight. It is an organ that performs important functions of metabolism, synthesis, storage and purification, so any injury to it may trigger the imbalance of various organic functions.
If you are interested in learning more about liver problems in dogs,we recommend that you do not miss the following article on our site, in which we treat the causes, symptoms, diagnosis and treatment of liver diseases in dogs.
Causes of liver problems in dogs
Before talking about the causes of liver problems, we must clarify that liver diseases can be classified into 4 large groups:
- Alterations of liver parenchyma: both inflammatory (hepatitis with or without cirrhosis) and non-inflammatory (hepatic amyloidosis, hepatic lipidosis and steroid liver disease).
- Tumoral diseases: lymphoma, hepatocellular carcinoma, cholangiocarcinoma or liver metastases. If you want to know more about Lymphoma in dogs: treatment and life expectancy, read this other article that we recommend.
- Alterations of the biliary system: cholangitis, cholecystitis or mucocele.
- Hepatic circulation disorders: portosystemic shunts and hepatic congestion.
Once we know the different groups in which liver diseases are classified, we will explain in detail the different causes that can originate them.
Congenital abnormalities
They are defects that are present from birth One of the liver diseases caused by congenital alterations are the Congenital portosystemic shunts. Dogs born with this alteration present a vessel that abnormally communicates the portal vein with the vena cava.
Portal hypertension
Portal hypertension consists of the increase in the pressure of the portal venous system, which is responsible for transporting blood from the intestine up to the liver. Portal hypertension can give rise to the appearance of acquired portosystemic shunts,consisting of multiple vessels that abnormally communicate the portal vein with the vena cava.
Endocrine diseases
Some endocrine diseases can secondarily lead to liver damage. Some examples are:
- Cushing's syndrome: it is associated with the appearance of a steroid liver disease, as a consequence of the high levels of glucocorticoids that dogs present with this disease. Find out more about Cushing's Syndrome in dogs: symptoms and treatment in this article on our site that we suggest.
- Diabetes mellitus: is associated with the development of hepatic lipidosis, which consists of the pathological accumulation of triglycerides within hepatocytes.
Infectious diseases
In dogs, there are various pathogenic microorganisms capable of affecting the liver and producing hepatitis. The main infectious and parasitic diseases associated with chronic hepatitis in dogs are:
- Canine Viral Hepatitis (adenovirus type 1).
- Ehrlichiosis: to learn more about canine Ehrlichiosis: symptoms and treatment, take a look at this post.
- Leishmaniosis: don't hesitate to find out the life expectancy of a dog with leishmaniasis, here.
- Leptospirosis: See more information about Leptospirosis in dogs: causes, symptoms and treatment in this article on our site that we suggest.
- Neosporosis.
- Histoplasmosis.
- Toxoplasmosis: we also have more information on Toxoplasmosis in dogs: symptoms and contagion.
Drugs and toxics
There are certain drugs and toxic compounds that can cause liver disorders. Here are some examples:
- Glucocorticoids: lead to steroid liver disease, although this reverts when treatment is withdrawn.
- Hepatotoxic drugs: such as phenobarbital or lomustine, which cause chronic hepatitis, followed by cirrhosis and liver failure.
- Cobre: Accumulation of copper in the liver leads to chronic hepatitis. There are some breeds predisposed to copper accumulation, such as the Bedlington Terrier, the Labrador, the Dalmatian, the West Highland Terrier or the Skye Terrier. You may be interested in this post from our site on Hepatitis in dogs: symptoms and treatment.
- Aflatoxins: Consumption of moldy feed containing these toxins can lead to the development of chronic hepatitis.
Tumors
Among the leading liver problems in older dogsUnlike what happens in cats, in dogs most liver tumors are usually malignant Specifically, hepatocellular carcinoma is the most common liver tumor in dogs, followed by biliary tract carcinoma.
Symptoms of liver problems in dogs
The clinical presentation of liver problems in dogs, as in other animal species, is conditioned by two fundamental characteristics of the liver:
- Its enormous regeneration capacity: this capacity is such that the liver can regenerate completely from just 30 % of its size.
- Its large functional reserve: which means that, under normal conditions, the liver does not need to use its full capacity to carry out its own functions. Using its role in albumin synthesis as an example, only 30% of the liver needs to work to maintain normal albumin levels, which means that the liver has a functional reserve capacity of 70%.
For these reasons, it is common to observe patients with liver injuries who remain completely asymptomatic, since these injuries have not yet given rise to to a functional alteration in the liver. Generally, when symptoms suggestive of a liver problem are observed, more than 70% of the liver parenchyma is affected.
Knowing these particulars about the liver, we are going to explain the three situations that we can find in dogs with liver problems are the following.
Asymptomatic patients
They are those who are in the early stages of a chronic diseaseBeing asymptomatic, we are only able to detect the existence of a liver problem by performing a blood test with a liver profile, which usually occurs when dogs undergo general anesthesia for any other reason (for example, for neutering). or a mouth cleaning).
Take a look at this post on how to castrate a dog: price, postoperative, consequences and benefits.
Patients with nonspecific signs
In these patients one begins to observe nonspecific clinical signs, that is, a priori they are not suggestive of liver disease. The symptoms that we can appreciate in these dogs are:
- Digestive signs: bilious vomiting and, less frequently, diarrhoea. Check out this article on our site about Types of Diarrhea in Dogs.
- Urinary signs: polyuria (increased urine volume) and polydipsia (increased water consumption), hematuria and dysuria.
- Anorexia and weight loss: here you can find more information about Anorexia in dogs: causes, diagnosis and treatment.
- Low body condition.
- Apathy and depression: discover more about Depression in dogs: symptoms, causes and treatment.
- Growth retardation in young animals.
Patients with signs suggestive of liver disease
These are patients who have more advanced symptoms of liver disease, in which the functional reserve capacity of the liver has been exceeded. Even if the animal suffers from a chronic disease, the symptoms usually appear acutely when the liver cannot carry out its functions because its functional reserve has been exceeded.
Specifically, the clinical signs that we can observe in these dogs are:
- Jaundice: yellowish discoloration of the mucous membranes. It is due to an excess of bilirubin (a yellow pigment) that is deposited on the tissues. In dogs it is usually detected initially in the sclera. To learn more about Jaundice in dogs: causes, symptoms and treatment, do not hesitate to take a look at this article that we recommend.
- Ascites: abdominal dilation due to the presence of free fluid in the abdomen. Find out more about Ascites in dogs: causes and treatment, here.
- Hepatic encephalopathy picture: When the liver loses its purification capacity, ammonia enters the circulatory system and, in ultimately, to the central nervous system, giving rise to a neurological picture. Signs that may be seen in these dogs include altered level of consciousness (lethargy, stupor, and eventually coma), weakness or ataxia, pressure of the head against the wall or floor, circling, and seizures.
- Bleeding tendencies: since the liver is responsible for synthesizing coagulation factors.
- Urinary signs: such as dysuria (painful urination) and hematuria (bloody urine). They usually appear in dogs with portosystemic shunts, as a consequence of the formation of ammonium urate stones in the urine.
Diagnosis of liver problems in dogs
The diagnostic protocol for liver problems in dogs includes the following points:
- Medical history and general examination: In asymptomatic dogs or those with only non-specific signs, it is difficult to suspect a liver problem. In the case of patients with signs suggestive of liver disease, it is easier to guide the diagnosis; however, it should be borne in mind that the signs are very similar in most liver problems, so the clinical picture does not usually provide information about the specific liver disease. In addition, the symptomatology does not help to know whether it is an acute or chronic case, since, as we have explained, in patients with chronic disease the signs usually appear acutely when the functional capacity of the liver is exceeded.
- Blood analysis with liver profile: when the animal's clinical signs are suggestive of biliary disease, a blood test should be performed to measure values such as total protein, albumin, liver enzymes (ALT, GGT and alkaline phosphatase), ammonia, glucose and bile acids.
- Urinalysis:must measure urine density and bilirubin, especially when the urine is very strong and pigmented. In addition, it is convenient to analyze the urine sediment for ammonium urate crystals.
- Other laboratory tests: In addition, more specific laboratory tests can be performed, such as the measurement of fasting bile acids or the ammonia overload test.
- Abdominal ultrasound: This imaging test can assess the liver parenchyma, the biliary system and the vascular system. Allows you to diagnose some liver diseases such as portosystemic shunts or extrahepatic biliary obstructions. However, obtaining a negative ultrasound does not rule out the presence of liver disease, since alterations of the liver parenchyma do not produce a diagnostic ultrasound image.
- Abdominal x-ray: the purpose of the x-ray is to provide information on the size of the liver, since the ultrasound usually gives a somewhat subjective idea. In acute pathologies the size of the liver will be normal or increased, while in chronic cases it will be decreased.
- MRI: is an advanced imaging test that is especially useful for the diagnosis of vascular pathologies of the liver (such as portosystemic shunts), pathologies of the biliary system and tumors.
- Fine Needle Aspiration (FNA): to perform a cytology. This test can detect abnormalities within hepatocytes (liver cells) such as lipidosis, steroid liver disease, amyloidosis, or tumors. However, in dogs this test is only diagnostic in 30% of cases
- Biopsy: to perform a histopathological analysis in those dogs in which FAP is not diagnostic. The sample can be taken percutaneously (with biopsy needles) or surgically (by laparotomy or laparoscopy).
Treatment for liver problems in dogs
Treatment of liver problems in dogs may include one or more of the following:
- Medical treatment: depending on the specific pathology, it will be necessary to correct hydro-electrolyte imbalances with fluid therapy, supplement in cases of vitamin deficiency (with vitamin K, thiamine, cobalamin), treat digestive and/or neurological signs, administer hepatoprotective drugs (such as ursodeoxycholic acid), etc. Read more about Vitamin K for dogs: dosage and uses, in this other post on our site that we recommend.
- Dietary management: in general, a highly digestible diet should be administered, rich in easily assimilated carbohydrates and low in fat. The level of protein, sodium and copper in the diet should be adjusted according to the specific pathology of the patient. Do not hesitate to consult this article on the Diet for dogs with liver problems.
- Surgical treatment: it will be necessary in some pathologies, such as portosystemic shunts or liver tumors.
In addition, for the treatment to be successful, it is important to consider whether the liver disease is primary (that is, it originates from the own liver) or if it is caused secondarily by another disease. In the latter case, we will also have to treat the primary pathology in order to solve the liver problem.
Prevention of liver problems in dogs
For the prevention of liver problems in dogs, the following factors must be taken into account:
- Vaccination and deworming: As we have explained, there are multiple microorganisms and parasites capable of generating liver disorders. For this reason, always keeping the vaccination and deworming program for dogs up to date will be a key tool to prevent these pathologies. Check here the schedule of vaccinations for dogs.
- Control of other pathologies: those pathologies that can secondarily cause liver alteration must be controlled.
- Control of pharmacological treatments: Patients treated with hepatotoxic drugs must undergo periodic controls and maintain doses within therapeutic ranges.
- Prevention of poisoning: due to mycotoxins, hepatotoxic plants, etc.
