Veterinary Care by Mazomanie Animal Hospital, Mazomanie, Cross Plains, Black Earth, Mt. Horeb, Spring Green, Arena, WI, Vet / Liver Disease in Dogs

My dog has raised liver enzymes, what does that mean?

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So, your vet has told you that your dog has raised liver enzymes. Understandably, you’ll probably have a few questions.; is it serious? What might have caused it? And, what exactly does it mean? As is often the case, there isn’t a single answer to any of these questions. So in this article, we look at some of the most common causes, the underlying conditions and the role of the liver in your dog.

What does a dog’s liver actually do?

First of all, let’s talk about what livers do. A lot of confusion surrounds this: we all know that livers are important, but many people find it hard to explain why. This is probably because they have a variety of different complicated jobs, mostly connected to metabolising food.

I like to think of them as the body’s boiler. Not because they literally generate heat, although they certainly do. But they are also a hotbed of metabolic reactions, releasing energy and other products from food, so that the body can use them. They also clear dead blood cells, toxins, poisons and waste products from the blood and make bile and some essential vitamins and minerals.

In short, our livers are vitally important and luckily, they are regenerative. That is, animals can grow new liver tissue when their livers are damaged. As the liver starts to struggle, lumps of extra tissue grow on the side. Sadly, the capacity of the new liver tissue is often limited. In severe, ongoing cases, the liver can become large with increasingly few useful cells and additional lumps on the side.

As an aside, this explains why it can be difficult to tell the difference between a cancerous liver and one that isn’t working but has tried to regenerate. A vet might tell you that a liver looks irregular or lumpy, but it may be regeneration or may be cancer, so biopsies are often needed.

Liver Enzymes

Anyway, back to liver enzymes, which are made by the liver and found in the blood. They have slightly confusing names which are usually shorted to initials. The concentration (amount per ml) of these chemicals reflects what’s going on in the liver. I’ll focus on two basic ones:

ALT (alanine aminotransferase)

This is found in liver cells. If liver cells break down for any reason, it is released into the blood. When ALT levels in the blood are high, it tells us that liver cells are breaking down more quickly than usual. What it doesn’t tell us, is why. The liver might be perfectly healthy, but the metabolism too fast: this is common in Hyperthyroid cats. The animal may have recently had a dose of a drug that the liver finds difficult to cope with, such as a steroid. But it may also be a sign of a serious breakdown of liver cells.

ALKP (Alkaline Phosphatase)

Is found on the cell membranes (the outer borders) of liver cells and the bile duct. The ALKP in the blood will increase when bile is not flowing properly out of the liver. This may be because the liver is inflamed and thus preventing it. It will also increase with certain drugs, hormonal diseases and bone growth in young dogs.

Liver enzymes are a piece of the puzzle

The problem with liver enzymes is that they don’t tell us which of these things are causing the elevation. They are useful for ‘screening,’ i.e. for looking out for pets that might have a problem with the liver. If the vet knows of a possible reason for the increase in liver enzymes e.g. hyperthyroidism or poisoning, they may treat the underlying cause rather than investigating further and run the liver test again later on. Very often, however, further tests are needed in order to work out more.

These tests may include an ultrasound to look directly at the liver tissue, or a bile acid stimulation test (BAST). This evaluates how well the liver is working and whether it needs extra support. Another way to get a better idea of what’s going on in the liver is a biopsy; in which a small amount of liver is removed and examined under a microscope.

So in short, having raised liver enzymes isn’t a diagnosis, but a small piece of the jigsaw to find out what is going on with your pet.

You may also be interested in;

raised, lowered, causes, blood norm, de Ritis coefficient

The article was checked by the chief veterinarian
Konchevoi Elizaveta Sergeevna

Contents

1. ALT in dogs
   • Norm
   • ALT in a dog is elevated
   • Reduced ALT
2. AST in dogs
   • Norm
   • AST in a dog is increased
   • Reduced AST
   • Variance table
3. De Ritis coefficient in dogs
4. Summing up
5. Answers to frequently asked questions

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ALT in dogs

ALT (alanine aminotransferase) is a specific enzyme, a substance found in the liver cells of animals, and also, albeit in much smaller quantities, in the tissues of the intestines, kidneys, muscles and red blood cells. That is why ALT in dogs is used primarily to assess liver tissue damage and is included in the standard biochemical profile, but is not considered as an isolated, single study.

Norm

The norms of different laboratories may differ, since the largest of them use their own norms, obtained during long research. That is why it is advisable to donate blood to the same organization if you need to control the performance.

For reference, here are the norms for the age of the dog used in such a large laboratory as Vet Union:

• 0-6 months. – 10-32 U/l;
• 6-12 months – 10-45 U/l;
• Older than one year – 10-65 U / l.

It is worth mentioning the concept of an individual norm inherent in each particular patient. You can find it out by examining the blood of an adult healthy pet, after which it is worth saving this data for further comparison.

The dog’s ALT is elevated

You may have heard that “tests don’t cure”. This means that in all cases of deviations, it is necessary to pay attention to the patient’s condition, the presence of complaints from the owner, and also take into account the results of other studies. And the overestimation of ALT is no exception.

Causes: if ALT in the dog’s blood is more than three times higher, then most often this indicates problems in the liver due to damage to its tissues. In some individuals, the level of the indicator is affected by the use of steroid drugs. In more rare cases, this indicator is overestimated against the background of serious diseases of the intestines, muscle tissue, pancreas, or against the background of hemolysis. Destruction of red blood cells – erythrocytes. An overestimation of less than three times, most often considered insignificant, but it requires constant monitoring if the disease has nevertheless been diagnosed or the owner notes any alarming changes in the pet’s condition. It is important to note that, according to studies, in working greyhounds, the normal level of the indicator is significantly higher than the upper limit of the standard limit.

Symptoms: A dog with liver disease may experience vomiting, diarrhea, poor appetite, weight loss, and yellowing of the skin. Bowel disease is most often manifested by problems with appetite, vomiting, diarrhea, and pain in the abdomen. Muscle problems can be expressed in pain or lameness, and hemolysis in a dog is manifested by slight weakness and intolerance to exercise up to fainting.

What to do: a face-to-face examination by a veterinarian is important here, who, after collecting information, will prescribe additional diagnostics and, after a thorough analysis of all the data, will establish a diagnosis and prescribe treatment.

Low ALT

A subnormal reading is the same cause for investigation as a high ALT in a dog, although this happens much less frequently. This is due to the fact that this enzyme is found in various organs, which complicates its critical decrease.

Causes: a persistent decrease is considered as a sign of atrophy. Eating disorder, lifetime decrease in the size of cells, tissues, organs of the liver, but at the same time, the level of other indicators in biochemical analysis, such as albumin, total bilirubin, urea and glucose, is also evaluated. This happens in the presence of a portosystemic shunt, an abnormal vessel that carries blood around the liver, to which certain breeds of dogs, such as Yorkshire, Toy, and West Highland White Terriers, are predisposed. Vitamin B6 deficiency will reduce the activity of this enzyme.

Symptoms: vomiting, constant weakness, continued emaciation, problems with appetite. Seizures are possible.

What to do: it is extremely important not to make a diagnosis on your own and go to a veterinary clinic, where the doctor will examine the patient, listen to all complaints, clarify the dog’s living conditions and, possibly, prescribe additional studies in order to then choose the treatment.

AST in dogs

Less informative indicator is AST (aspartate aminotransferase). This enzyme no longer predominates in one particular organ, but is found in significant quantities in the same muscles, liver, intestines, blood cells, while at a lower concentration it can be found in almost all organs and tissues. These factors make it an additional indicator, not as specific as ALT, and optional for a standard biochemical profile.

Norm

For dogs of various ages, the Vet Union laboratory uses the following norms in its work:

• Neonatals (first three days of life, colostrum nutrition) – 44-194 U / l;
• 0-6 months – 10-23 U/l;
• 6-12 months – 10-20 U/l;
• Older than one year ‒ 10-50 U/l.

AST in a dog is increased

An increase in this indicator is found in the results of biochemical analyzes of many dogs of various breeds and ages. But does this overestimation always mean a disease, what else should you pay attention to in the analysis, and how to understand what exactly hurts the pet?

Causes: AST in the blood can be elevated in a dog for a number of reasons: most often the increase is associated with problems with the liver, muscle tissue, intestines, pancreas, and the level is too high due to hemolysis and against the background of taking steroid drugs such as Prednisolone .

An increase in AST does not always indicate problems in a pet.

Sometimes the destruction of cells occurs due to improper selection of the blood itself – excessive shaking or freezing. This phenomenon is called a preanalytical error, and blood resampling is necessary to adequately evaluate the results of the analysis. Again, working greyhounds normally have significantly higher levels of AST than other breeds.

Symptoms: Vomiting, diarrhoea, weight loss and yellowness of the skin are frequent companions of liver disease. The same vomiting and diarrhea, together with abdominal pain, often accompany intestinal problems, pain and lameness can indicate muscle disease, and the destruction of blood cells in a dog sometimes manifests itself as mild weakness, and sometimes results in an extremely dangerous condition.

What to do: if your dog has elevated AST, then he needs to see a doctor, take an anamnesis, order additional studies, such as ultrasound of the abdominal cavity to assess the condition of the liver and other organs, a complete blood count to rule out hemolysis as a disease, and additional biochemical CPK (creatine kinase) index to assess muscle damage.

Decreased AST

Decreased AST, just like low ALT, occurs infrequently for the same reasons – the enzyme is very common and is normally found in a fairly large number of organs. However, there are a number of diseases that can cause this result.

Causes: liver atrophy, vitamin B6 deficiency.

Symptoms: diseases that cause atrophy of the liver tissue are characterized by problems with appetite, weight loss, vomiting, diarrhea, convulsions and jaundice are possible. Vitamin B6 deficiency can be manifested by diseases of the skin, reproductive system, less often by convulsions and anemia. Anemia.

What to do: In all cases where the test results are out of range, it is important to evaluate the condition of the pet and, if necessary, conduct additional diagnostics in order not to prescribe treatment to a healthy animal.

Deviation table

De Ritis coefficient in dogs

At the dawn of the development of veterinary laboratory diagnostics, most of the research was borrowed from human medicine, and the norms were copied from humans. But the difference between us and pets is obvious, so some indicators were not applicable. This is what happened with the de Ritis coefficient in dogs. Initially, this parameter was an attempt to determine the ratio of the activity of AST and ALT enzymes, which of the organs containing these substances is affected by the disease. A veterinarian will receive much more information from the results of an ultrasound scan of the liver and other abdominal organs, as well as from a general blood test.

But if the de Ritis coefficient in dogs is lowered, then for the attending physician this does not mean liver damage to his patient and does not carry any prognostic value. To detect heart diseases, in addition to ultrasound and ECG, additional analyzes have been developed, whose accuracy is many times higher than the inherently uninformative coefficient.

Let’s summarize

1. If a dog has elevated ALT, the reasons for this are quite specific. After all, ALT is an enzyme, the content of which is highest in liver cells. At the same time, its slight increase in dogs may be associated with breed and individual characteristics, and a threefold overestimation most often indicates liver pathology.
2. But if AST is elevated in the blood of a dog, the reasons are ambiguous: this is a rather non-specific indicator, which is equally overestimated, both against the background of hemolysis and in diseases of the muscles, intestines and liver, against the background of taking steroid drugs, can be high in greyhound dogs are normal.
3. The de Ritis coefficient is not applicable in veterinary medicine and has no diagnostic value.
4. Each organism is unique, and not all patients fit the generally accepted norms, so it is desirable to take into account the breed and individual characteristics.
5. It is impossible to establish a diagnosis only on the basis of the results of one biochemical analysis – one cannot ignore the examination of the animal, the collection of anamnesis, and often ultrasound diagnostics and other studies are required.

Answers to frequently asked questions

Sources:

1. Shishkanova SV webinar on the topic “Biochemistry of blood. What is important for a practicing veterinarian to know”, 2015
2. Sahan B. “The importance of detailed biochemical profiles”, Laboratory diagnostics in veterinary medicine, St. Petersburg, 2020
3. Article by E. B. Bazhibina “Methodological approach to the interpretation of the results of biochemical studies” in the Russian Veterinary Journal “Small Domestic and Wild Animals”, No. 2, 2012, pp. 8-14.

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Study of bile acids in blood serum in TBA animals.

Serum Total Bile Acids

Bile acids are the main component of bile. They are formed in the liver, in hepatocytes as a result of cholesterol metabolism. The process of formation of bile acids from cholesterol is multistage. This process is catalyzed by the enzyme 7α-hydroxylase. The activity of this enzyme will depend on the period of fasting of the animal, the presence of cholestasis, liver failure, exposure to glucocorticoids. There are primary (cholic and chenodeoxycholic) and secondary bile acids (deoxycholic and lithocholic). Bile acids accumulate in the gallbladder, enter the intestines with bile, and their excess is removed from the body with urine.

Studies often do not reveal changes in the main “liver” indicators. In birds, an increase in liver enzymes (especially AST) is not always associated with liver disease. In horses, hepatobiliary disease is very often accompanied by an increase in the level of bile acids. Bile acid levels can be very variable in cows, so this test is not always effective in animals of this species.

As a rule, many liver diseases are diagnosed very late, with severe damage to the liver parenchyma. Routine biochemical studies often do not reveal changes in the main “liver” indicators.

When should a serum bile acid test be used in cats and dogs?

1. In dogs of breeds predisposed to the development of congenital porto-caval anastomosis (anastomoses), as a method of early diagnosis of shunting with subsequent closure of the abnormal vessel.

2. In puppies of miniature breeds with a lag in growth and development, as a method for diagnosing congenital portosystemic shunts.

3. In cases of suspected latent liver diseases in animals with a single-chamber stomach and birds.

4. When ammonium urate crystals are found in the urine (with the exception of Dalmatian and English Bulldog breeds).

5. In animals with neurological disorders.

6. To monitor patients with established liver disease.

Dog breeds predisposed to congenital extrahepatic anastomosis

– Yorkshire Terrier (surpasses other dog breeds by 36 times)

— Cairn Terrier

— Maltese

— Shih Tzu

– Miniature Schnauzer

— Dachshund

— Jack Russell Terrier

— Pug

– Lhasa Apso

— Chihuahua

Dog breeds predisposed to congenital intrahepatic anastomosis

– Irish wolfhound (autosomal recessive inheritance)

– Bernese Mountain Dog

— Dogs of the Retriever group

— Samoyed husky

— bobtail

In cats, congenital porto-caval anastomoses are rare; cases of this disease in Persian and Himalayan cats are described in the literature.

Advantages of the test

The test is easy to use and highly sensitive. There are few factors that are not related to the liver, and they cannot affect the results of the test.

Test flaws

It is impossible to accurately differentiate between different liver diseases.

How to test blood serum for bile acids?

Blood sampling from the animal is carried out strictly on an empty stomach (at least 12 hours of strict fasting). During this period, the animal is forbidden to give treats and even chew on toys. Blood is taken into a special biochemical test tube with a separating gel (with a red or yellow cap) in a volume of 0.5-1 ml (only 50 µl of serum is required for the study), the second blood sample is taken 2-4 hours after giving food to the animal. The main thing is that at least 2 hours have passed after eating and no more than 4! It is acceptable, but undesirable, to conduct a study 6-8 hours after ingestion of food. Samples must be delivered to the laboratory within 24 hours. If this is not possible, it is recommended to obtain serum by centrifugation and freeze it yourself (frozen serum can be stored for 5-7 days).

The animal is offered its normal diet or canned food with moderate or even high levels of fat and protein.

Ready meal options:

— Hill’s a/d

Roal Canin Convalescence or Recovery

— Purina CN

For an animal weighing less than 5 kg, it is recommended to give 2 teaspoons of food, for the rest ¼ of the usual portion.

To avoid post-prandial lipemia, it is important not to overfeed the animal (otherwise, it will lead to a false positive result)! In horses and birds, the test is performed once on an empty stomach.

Reference intervals for the content of bile acids in blood serum for animals of different species (enzymatic method)