Cardiomiopatia dilatada em cães: sinais, diagnóstico e cuidados

What happens in the heart

A healthy heart muscle squeezes firmly with every beat. In DCM the muscle cells weaken or are lost, so the walls get thinner and the chambers enlarge. The heart works harder but moves less blood. Fluid can then back up into the lungs, the chest, or the belly. This stage is called congestive heart failure.

The disease usually has a long hidden phase. A dog can have a weakening heart for months or even years and still seem normal at home. Signs often show up late, which is why screening matters for breeds at high risk.

In most dogs the exact cause is unknown. Known causes and links include inherited gene changes in some Dobermans and Boxers, a shortage of the nutrient taurine, certain diets, some cancer drugs, and some viral infections.

Which dogs are at risk

DCM is seen most often in large and giant breeds, usually in middle-aged and older dogs. Males are affected more often than females. Breeds with a known higher risk include:

• Doberman Pinschers and Boxers
• Great Danes, Irish Wolfhounds, Scottish Deerhounds, Newfoundlands, and Saint Bernards
• German Shepherds and Labrador Retrievers
• American and English Cocker Spaniels, even though they are smaller dogs
• Portuguese Water Dogs, in which an inherited form can affect young puppies

The link with diet

In 2018 the US Food and Drug Administration began looking into reports of DCM in dogs eating certain foods. Most of the reported diets were labeled grain-free, and most contained peas or lentils. Golden Retrievers and mixed-breed dogs were among those reported most often, even though they are not known for inherited DCM. The FDA has not found proof that these foods cause DCM. Its last public update came in late 2022.

Veterinary nutrition researchers now link the problem to diets high in pulses, such as peas, lentils, chickpeas, and beans. These diets can be grain-free or contain grain. Most affected dogs have normal taurine levels, and a lack of taurine does not appear to explain these cases. The exact cause is still being studied.

Some dogs with diet-linked DCM slowly improve after a change of food, especially when the problem is found early. Recovery can take months and is not always complete. If your dog eats a food with pulses among the main ingredients, it is reasonable to ask your vet whether a different diet makes sense. It is best to talk to the vet before adding supplements.

Sinais a observar

Early DCM often causes no signs at all, and some affected dogs have no heart murmur. Mild signs are easy to put down to age or hot weather. Watch for:

• Tiring quickly on walks or losing interest in play
• Faster or harder breathing at rest or during sleep
• A cough
• Weakness, wobbly spells, or fainting
• A swollen belly from fluid build-up
• Weight loss and loss of muscle

For a dog at risk, it helps to count breaths during sleep. Count one breath for each full rise and fall of the chest over 30 seconds, then double the number. In most healthy dogs the sleeping rate stays under 30 to 35 breaths a minute. Your vet can tell you what count is normal for your dog and when a rising number means you should call.

Quando é uma emergência

Get veterinary help straight away, day or night, if your dog has any of these signs:

• Labored or very fast breathing at rest
• Breathing with the mouth open while lying still
• Gums that look pale, gray, or blue
• Fainting or collapse
• A sudden increase in coughing

These can be signs of fluid in the lungs or a dangerous heart rhythm. Some dogs with DCM die suddenly from an irregular heartbeat, sometimes before any other sign appears. In Dobermans with the disease, up to about one in five collapse or die suddenly.

How vets diagnose it

The vet starts with your dog's history and a physical exam. With a stethoscope they may hear a soft murmur, an extra heart sound called a gallop, or an irregular rhythm. A normal exam does not rule DCM out, especially in the early phase.

Chest X-rays show the size of the heart and whether fluid has built up in the lungs. An electrocardiogram (ECG) records the heart's electrical activity and picks up rhythm problems. An ultrasound of the heart, called an echocardiogram, is the key test. It shows the size of each chamber and how well the muscle squeezes.

For breeds prone to rhythm problems, the vet may suggest a Holter monitor. This is a small recorder the dog wears for a day at home to capture every heartbeat. A heart blood test called NT-proBNP is sometimes added as an extra check, and the ultrasound remains the main test. Other blood tests check the kidneys and other organs before treatment, and in some dogs the vet also measures taurine. Many dogs are referred to a veterinary cardiologist for the heart ultrasound and ongoing care.

Treatment and daily care

Most forms of DCM cannot be cured. Treatment can slow the disease, ease the signs, and help many dogs live more comfortably. Your vet sets the plan based on the stage of the disease and the heart rhythm.

Vets use medicines that help the heart muscle pump more strongly, medicines that clear extra fluid from the lungs and body, medicines that ease the strain on the heart, and medicines that control abnormal rhythms. When screening finds early disease, some dogs start treatment before any signs appear. A dog in crisis may need oxygen and a stay in hospital, and fluid in the chest or belly may be drained.

The vet may recommend a change of diet, especially if the current food is high in pulses. Taurine may be suggested for dogs with low levels or for breeds known to respond, such as American Cocker Spaniels, Golden Retrievers, and Dalmatians. Any benefit from taurine can take a few months to show. Fish oil is sometimes suggested to help with weight and muscle loss. It usually helps to avoid salty treats and table scraps, and a lower-salt diet may be advised in advanced stages.

At home, it helps to give medicines on schedule and to check with the vet before changing or stopping any of them. Walks can stay gentle, at a pace the dog sets. A simple log of the sleeping breathing rate, appetite, and energy is useful at rechecks, which often include repeat heart scans and blood tests.

The outlook varies. It is usually guarded once heart failure has started, and it is often poorer in Dobermans. Dogs whose DCM is linked to diet or to low taurine can do much better, and some improve over time. Your vet or cardiologist can give you a realistic picture for your own dog.

Prevention and screening

Inherited DCM cannot be prevented. Screening can often find it before signs start, which gives time to begin treatment and plan ahead. For Dobermans, veterinary cardiology guidelines advise a heart ultrasound and a Holter recording every year, starting at about three years of age. In Boxers, a related inherited heart muscle disease mainly causes rhythm problems, and a yearly Holter recording is a common check. Your vet can suggest a schedule for your own dog.

For any dog, a complete and balanced diet and a talk with your vet before feeding a food rich in pulses are sensible steps. DCM itself is not contagious, so other pets and people in the home cannot catch it from an affected dog.

Notes for adopters

At Paw Squadron, the first stops after every rescue are the vet and a bath. Every dog gets a checkup, treatment against parasites, vaccinations, and a microchip before adoption. Early DCM can stay hidden even during a careful exam, so it helps to keep the heart in mind in the months after adoption.

If you adopt a large-breed dog, or one that looks like a Doberman, Boxer, or Great Dane, mention it at your first vet visit and ask whether heart screening makes sense. Bring the dog's records and tell the vet what food you are feeding. Heartworm disease also occurs in southern Europe and can cause similar signs, such as coughing and tiring quickly, so your vet may want to rule it out in a dog that has lived there.

If you are thinking about giving a dog a home, our Adoptions page shows the dogs waiting now, and you can find more health guides in PawPedia.