Liver Biopsy in Dogs

The liver is an amazing organ that plays a multitude of roles in maintaining good health. Given the number of duties the liver undertakes, a rise in liver enzymes alone on a blood test tells the clinician very little as to the cause of the problem. Indeed, because the liver 'cleans' the blood, the rise may even be due to pressure on the liver due to non-liver-related illness. 

What's for sure is that untreated liver disease progresses more rapidly than treated, with the risk of complications and extensive scar tissue formation. The gold standard for diagnosing the exact nature of liver disease remains taking a biopsy sample. This enables a histologist to examine the structure on a cellular level to determine the problem and the best treatment for it. 

There are several options for obtaining a sample of liver tissue. These methods vary in invasiveness and the size of sample obtained. However, regardless of which method is used, it's important to check the dog does not have a coagulopathy (difficulty clotting blood) prior to sampling, as the liver has a large blood supply and is prone to bleeding. 

Ultrasound guided biopsy

Usually performed under deep sedation or full anesthesia. An ultrasound image is used to guide placement of a large bore biopsy needle. This is the least invasive method as it only requires a small nick in the skin. However, the sample harvested is small, and there is a risk of missing relevant pathology. 

Laparoscopic biopsy

Also known as keyhole surgery, this is performed under anesthesia and involves passing a laparoscope through a small incision in the skin. A small camera allows the surgeon to see the liver and identify the best area to harvest. This is moderately invasive and collects a sample size intermediate between a needle biopsy and wedge biopsy. 

Wedge biopsy taken during a laparotomy

A laparotomy (surgically opening into the abdomen) is performed under general anesthesia. The surgeon can directly examine all the abdominal organs, and chose the exact piece of liver they wish to harvest. This allows for collection of wedges of liver, which are of high diagnostic value. 

Liver biopsy is a tool that facilitates the clinician reaching a diagnosis. How useful a biopsy sample is for diagnostic purposes depends on the size of the sample and the area sampled. For example, an ultrasound guided biopsy is most useful for generalized liver disease, where the chances of sampling an area affected by the process is high. That said, if the disease is localised, the ultrasound image helps guide the clinician to the relevant area. 

To reach an accurate diagnosis the histologist needs to see 16 triads (an architectural landmark within the liver) worth of tissue. This is easily achieved with the second two methods of sampling. 

Unfortunately, the implication is that if too small a sample is obtained, or it is harvested from an area that doesn't represent the ongoing pathology, that a 'normal' sample can be obtained despite the dog having liver disease. The chances of this are minimized via laprascopic or laparotomy collection. 

The recovery time to a large extent depends on how sick the patient was initially, and the method of collection. For a fit dog that has a sample collected via ultrasound guidance, they may be bouncing around again within 2 - 3 days of the anesthetic. 

For dogs that undergo laparotomy, the recover time is around two weeks, which is also the time until the skin incisions is healed. However, it may be necessary to rest the dog and avoid vigorous exercise for 3 - 4 weeks, since some types of liver disease can result in delayed healing times. 

The cost of a liver biopsy needs to be considered as part of a larger procedure, since it will invariably involve imaging (such as ultrasound) or invasive surgery (such as laparotomy), plus anesthesia. 

The cost of an ultrasound scan varies depending on the experience of the operator, but a fee of around $200 is to be expected. The cost of histology by an outside laboratory is typically around $80 - $100, with specialist stains looking for copper or the like being additional to this. 

The cost of a  full general anesthesia and laparotomy depends on the dog's size and how long the procedure takes. A minimum fee of $750 is to be expected. 

Because a liver biopsy is liable to be performed on a sick dog, anticipate extra fees such as intravenous fluids (estimated $50) or drugs such as vitamin K injections. 

The are risks associated with liver biopsy, of which the greatest is hemorrhage. This is because the liver is richly served with blood vessels, added to the fact that a disease liver may not produce enough clotting factors which leads to a tendency to bleed. 

The clinician will carefully screen the dog prior to surgery, to identify any bleeding tendencies. If a problem is detected, this can mean postponing surgery until that issue is corrected. Action may mean giving vitamin K injections or a transfusion of plasma-rich with clotting factors. 

Other considerations include balancing the invasiveness of the procedure against the size of sample obtained and visualization to choose the most useful piece of tissue. Thus, although laparotomy is the most invasive method, it is also the one most likely to harvest a diagnostic sample. 

Prevention of the need for a liver biopsy is largely a matter of preventing liver disease and promoting good health. Conditions such as infectious canine hepatitis are largely preventable through regular vaccination, so keeping up to date with innoculations is advisable. 

Some pedigree breeds such as Bedlington terriers are prone to an inheritable form of liver disease, so screening of parent stock prior to breeding is essential. When carriers of inherited liver disease are detected, then they should not be breed from. 

Liver enzymes can be elevated due to non-liver disease, such as Cushing's disease or even dental infections. With this in mind, the clinician may need to running tests screening for these other problems, in order to rule them out (or reach a diagnosis which makes the need for a liver biopsy redundant).