One of your dogs is acting really tired. It doesn’t want to take a walk, or, when it does, it has to stop to catch its breath. It’s not interested in fetching a ball or chasing that pesky squirrel in the backyard. Then you notice that when it urinates on a sidewalk the urine is amber-colored or looks like port wine.
Lots of conditions can make a dog less energetic than usual, but if you see a dramatic color change in the urine, your dog may have hemolytic anemia. Blood loss, inadequate production of new red blood cells or destruction of the cells result in anemia, with the latter being “hemolytic” anemia.
One of the conditions that cause destruction of red blood cells is more complicated. It’s immune-mediated hemolytic anemia. In years past, you may have heard it called “autoimmune hemolytic anemia.” Same thing. The fact that it has to do with the immune system is a clue to what’s happening. Your dog’s own immune cells are attacking its red blood cells, which are essential for carrying oxygen around the body. Made in the bone marrow, red blood cells live for about 100 days in the bloodstream, then die. As the immune cells destroy the red blood cells, the bone marrow can’t replace them quickly enough.
When you get the dog to your veterinarian, pale gums, jaundice, an elevated heart rate, a heart murmur or an enlarged spleen, and any combination of these clinical signs, will point the vet toward immune-mediated hemolytic anemia.
“Anemia with jaundice really makes us think that it may be immune-mediated,” says Audrey K. Cook, BVM&S,MRCVS, DACVIM, an associate professor of small animal internal medicine at Texas A&M University’s College of Veterinary Medicine and Biomedical Services. The other big indicator? Urine the color of port wine, she says.
“Some cases are very, very classic,” she explains, adding that the Texas A&M vet school sees a case about every couple of weeks, or about 25 a year. And she sees more cases in the summer for a reason not yet identified. While “it’s a very familiar disease for internists to see,” she says, “we see way more dogs with diseases like cancer or pancreatitis.”
Several diagnostics determine that the clinical signs do, indeed, indicate IMHA. “We look at the red blood cells under the microscope. Sometimes you can actually see where they have been ‘bitten’ by the cells of the immune system. Sometimes the red blood cells stick to each other.”
Veterinarians also can use special tests to identify antibodies on the surface of the cells and look for autoagglutination, or that clumping together of the cells. A positive result for either test strongly suggests IMHA.
The first step in diagnosis, Cook says, is to rule out other possible causes of anemia in general, and then investigate other types of hemolytic anemia. Some of the conditions that look like IMHA include certain infections and zinc toxicity. How would a dog get zinc into its system? Usually by swallowing a penny, Cook says, adding that a single penny can kill a Yorkshire Terrier.
If after testing, you learn that your dog has IMHA, you’ll naturally want to know the cause. It’s unlikely, though, that you ever will know what brought on the condition.
In the “vast majority of cases, we don’t find causes,” Cook says. Despite that, studies have shown that Miniature Schnauzers and Cocker Spaniels are the most susceptible.
Some dogs have what veterinarians call “secondary” IMHA where an underlying disease is identified as triggering the hemolytic anemia. This could be a tumor, a medication or an infectious disease, such as those transmitted by ticks.
Without a known cause, in what is known as “primary IMHA,” treatment includes a blood transfusion to address the anemia and “aggressive” drug therapy to suppress the immune system, such as prednisone, and perhaps cyclosporine or azathioprine.
“If they’re eating and drinking, they don’t need fluids,” Cook says, while other dogs may need anti-nausea medicine and supportive fluids.
A blood clot lodged in the lung, or pulmonary thromboembolism, is one risk of IMHA, according to the Merck Veterinary Manual. “Fluids are important to maintain renal perfusion [the passage of blood through the kidneys] and to protect the kidneys from the high concentrations of circulating bilirubin,” the yellowish pigment found in bile, made by the liver. If blood clots are suspected or the risk for forming them is high, heparin may be added to the treatment. Fresh frozen plasma may be administered if the time it takes for blood to clot is longer than normal or if the proteins that control blot clotting are too active, Merck says. Pointing to a poor prognosis are a rapid drop in packed red-cell volume, high bilirubin concentration, rupture of red blood cells within vessels, red blood cells sticking together and blood clot complications, according to Merck, which goes on to suggest that referral to a specialist or veterinary school clinic may increase the chance of survival.
Not all cases of IMHA are the same. “The disease is very variable in its severity,” Cook says. “Some dogs crash very fast” and “a fair number of acute cases don’t survive.”
“They get worse so quickly,” she says, however, if they can make to Day 7, it’s more likely they’ll recover.”
Overall, about half of dogs will survive the first “attack,” Cook says. That means the other half won’t, of course. Treating acute IHMA gets “very, very costly very quickly.” Sometimes owners simply admit, “I can’t keep watching my dog suffer like this,” she says. Merck Veterinary Manual puts the mortality rate between 20 to 75 percent, “depending on the severity of initial clinical signs.”
Cook says, “Some dogs will get through an attack, then relapse in a year. We look again for a cause, but in the ones that were primary [with no known cause for the first attack], we usually find no explanation the second time,” she says. At the time of a second attack, many owners will decide it’s time to let their dogs go.
Although people get IMHA as well, no big breakthroughs in diagnosis or treatment have been made in the last 10 years, Cook says.
Because there does seem to be some breed predisposition, Cook recommends that dogs whose family members have had IMHA not be used for breeding. While no proven connection with vaccination exists, Cook also suggests that owners give careful consideration to vaccine protocols with the consultation of their dog’s veterinarian.
Fortunately 25 cases a year at Texas A&M, multiplied by all the vet schools in the country, plus those treated by veterinary internists, makes this a somewhat rare disease. However, knowing the signs can help you get your dog into treatment sooner than later.
“This is not a wait-until-Monday-morning thing,” Cook says. “If a dog looks yellow [in the nostrils, gums, genitals or skin] or its urine looks amber-y or like port wine,” it’s an emergency.