“A lot of owners want to change their dog’s diet if they see any signs” that something’s not right with the liver, says Tufts veterinary nutritionist Cailin Heinze, VMD, DACVM. “But a change in liver enzyme values on blood work does not necessarily mean that a dietary change is appropriate.” Indeed, there are only two main instances where dietary change has been shown to be beneficial for liver disease.
When the liver disease is severe and the dog has protein intolerance
One of the two reasons to change a dog’s diet in the event that she has liver disease is that the disease has become severe, meaning the dog has essentially gone into liver failure and that organ is no longer able to do what it’s supposed to — filter toxins from body tissues and serve as the “control panel” for metabolism.
Some dogs with advanced liver disease can show signs of “hepatic encephalopathy,” which basically means a problem with the brain related to the liver. They include the dog’s walking as if she is drunk, feeling really sleepy after meals — “kind of spacy or zoned out,” Dr. Heinze says — seizures, and staring at the wall or even pressing her head into the wall.
If you see any of those signs, it’s obviously an emergency, and the dog has to be evaluated right away. Frequently, a liver biopsy will be necessary to assess the exact nature of the situation as well as the extent of disease.
These concerning signs appear because the liver is less and less able to metabolize protein properly. Normally, the liver breaks down the amino acid building blocks of protein to separate out the nitrogen they contain. This process produces ammonia, which is eventually excreted in the urine as urea. But if the liver substantially loses its ability to function normally, the ammonia remains in the bloodstream with other toxins, and that’s what causes all the neurological issues.
“We can adjust the diet to help reduce the levels of some of those toxins,” Dr. Heinze says, “and one of the ways that we do that is by reducing the total amount of protein in the diet. Every dog has a minimum amount of protein she has to ingest to have normal body function. But in dogs with really severe liver disease, if you give them a lot more than they need, you’re fueling the fire.”
The type of protein counts, too. “Certain types of protein seem to cause worse issues,” comments Dr. Heinze. “Things like organ meats and fish contain higher levels of certain compounds (purines, some of the amino acids) that can be particularly harmful for dogs with bad liver disease. Many do better on plant-based protein or egg- and dairy-based proteins, both because of differences in the amino acid composition and differences in the tissues that the protein is coming from.”
Fortunately, there are therapeutic diets for dogs available by prescription from veterinarians that provide the right kinds of protein in the right amounts. These products are generally egg or soy-based. Owners needn’t worry about the quality of the protein. Both eggs and soy contain high-quality proteins that will provide the necessary nutrition at the same time that they prove more gentle to a failing liver.
Even so, pet owners should note that for a dog in the later stages of disease, there’s a lot of trial and error. “The amount of protein that is tolerated is individual to the patient,” Dr. Heinze says. “How much protein is tolerated depends on the degree of disease, what’s causing it, and also the medications the pet is on.” The aim is to maintain blood protein levels in the normal range and to feed the highest level of protein that is tolerated without causing abnormal blood ammonia or clinical signs. Diet is typically not used alone, however. Medications are frequently used along with diet to improve a dog’s protein tolerance. The combination is what will help control the clinical symptoms.
It is important to stress that most dogs who have problems with the liver based solely on increased liver enzyme levels on bloodwork have reasonably normal overall liver function and do not show signs of hepatic encephalopathy. For dogs with no clinical signs, such as a dog who had increased liver enzyme levels on a blood panel taken before going under anesthesia for something routine like dental work, no dietary change is indicated. Typically the abnormal values are monitored, and if they continue to fall outside the normal range, a biopsy is likely called for to understand the nature of the liver problem.
To emphasize the point, dietary modification using a veterinary therapeutic diet will likely not help a dog with mildly elevated liver enzymes (which can very well go back to normal on their own) or even with mid-stage liver disease. The disease has to be quite far along for a special low-protein diet to have a beneficial effect. The evidence is simply not there to change a dog’s diet in the case of mild or even moderate liver problems.
Excess copper in the liver
The other reason to change the diet of a dog with liver disease is if the disease is caused by an excess copper build-up. Over time, if a dog is unable to clear excess copper from her liver (it is a genetic condition in some breeds such as Bedlington terriers), it damages the liver cells, and she can develop severe liver disease and even liver failure. As with liver disease in general, a biopsy may be performed even if the dog seems fine if blood liver enzymes are found on a routine exam to be much higher than they should be and do not improve with conservative treatment. If it’s found via biopsy that excess copper in the liver is the problem, dietary changes should be instituted immediately — you don’t want to wait for the dog to reach the point of liver failure to make a difference. Dogs with excess copper in their liver can act completely normally, be mildly sick, or even go into full-blown acute liver failure, depending on the severity of the copper accumulation and how long it has taken to build up.
Once copper toxicity is identified as the problem, medications are administered to help remove the excess from the liver. Instituting a low-copper diet is a complementary measure to help prevent further copper build-up. How do you find one?
The same low-protein therapeutic diets prescribed by veterinarians for dogs with severe liver disease are also low in copper. “It’s kind of one size fits all,” Dr. Heinze says.
The problem, however, is that one size doesn’t always fit all very well. “The challenge,” says Dr. Heinze, “is that many dogs with too much copper don’t need a low-protein diet because their livers aren’t that bad off. If what’s available commercially is not a good fit for the dog, I may recommend carefully adding protein to a therapeutic liver diet or recommend a home-cooked diet for which I’ll provide a specific recipe,” that is, higher in protein but low in copper. Alternatively, there may be non-liver focused commercial diets that are lower, but not the lowest, in copper that might work for a specific dog.
High-copper foods tend to be red meats and organ meats like liver. A lower-copper diet might contain, for example, chicken instead of beef. “We assess the individual patient,” Dr. Heinze says. “The hope is that the liver wasn’t so damaged by the copper that it can’t regenerate. Liver tissue can regenerate to a significant degree if the liver as a whole isn’t too far gone.”
Like for protein, a veterinary nutritionist may alter the copper intake to suit the individual dog — an important point because strictly speaking, the therapeutic low-copper foods available for dogs are so low in that mineral that they could theoretically make a pet deficient in copper, particularly if they are used for long periods of time along with copper-reducing medications. You have to look at the situation in front of you. “Imagine a 2-year-old dog with too much liver copper showing signs of clinical disease who has been eating a lower-copper diet already,” Dr. Heinze says. “Compare that to a dog who at age 10 is diagnosed with excess liver copper and has been eating a high-copper diet her whole life but has no clinical signs. The 2-year-old will have built up her copper levels much more quickly and will need more severe copper restriction, and copper-reducing medications as well.”