Endocarditis in Macaws: Infection of the Heart Lining and Valves

Endocarditis is inflammation and infection of the inner lining of the heart, especially the valves. In macaws, it is considered uncommon, but when it happens it is serious because infected material can damage the valve, disrupt blood flow, and strain the heart. Over time, that can lead to poor circulation, weakness, fluid buildup, or sudden decline.

In many birds, endocarditis does not start in the heart. It often develops after bacteria or other infectious organisms enter the bloodstream from another site, then attach to damaged or inflamed heart tissue. Because birds tend to hide illness, early signs may be subtle. A macaw may only seem quieter, less interactive, or less willing to fly before more obvious breathing or circulation problems appear.

This condition is not something pet parents can confirm at home. Your vet will need to sort out whether the problem is truly endocarditis or another cause of weakness and breathing changes, such as respiratory disease, liver disease, generalized infection, or another form of heart disease.

Endocarditis usually happens when infectious organisms travel through the bloodstream and settle on the heart lining or valves. Bacteria are the most likely cause, especially when there has already been inflammation, tissue injury, or another infection somewhere else in the body. In veterinary species, organisms such as Staphylococcus, Streptococcus, E. coli, and Klebsiella are recognized causes of infectious endocarditis, and similar bloodstream spread is the concern in birds.

In macaws, the original source may be hard to find. Possible starting points include respiratory infection, gastrointestinal infection, skin or foot wounds, reproductive tract disease, liver disease, or a chronic infection that weakens the bird over time. Some infectious diseases of parrots can also cause body-wide illness and secondary cardiovascular problems.

Risk may be higher in birds under chronic stress, with poor nutrition, recent exposure to new birds, or delayed treatment of another infection. Newly acquired birds and birds exposed to outside birds are more likely to encounter infectious disease, and malnutrition can make secondary infections more likely. That does not mean a pet parent caused the problem. It means your vet may need to look beyond the heart to find the underlying trigger.

Diagnosis usually starts with a careful history and physical exam. Your vet will ask about appetite, droppings, activity, breathing, recent stress, travel, and exposure to other birds. In birds, subtle changes like reduced vocalizing, sleeping more, or less interaction can be important early clues. On exam, your vet may hear a murmur, notice poor body condition, or see increased breathing effort.

Testing often includes a complete blood count and chemistry panel, because bloodwork is especially important in birds and may show inflammation, infection, anemia, or organ involvement. Depending on the case, your vet may also recommend blood culture, cloacal or choanal testing for infectious disease, and radiographs to assess heart size and look for other problems.

Echocardiography can be especially helpful when endocarditis is suspected because ultrasound lets your vet look at the valves and internal heart structures in real time. In other veterinary species, echocardiography is the diagnostic test of choice for infectious endocarditis because vegetative, thickened valve lesions may be visible even when blood cultures are negative. In a macaw, your vet may combine echo findings with bloodwork, imaging, and response to treatment to reach the most likely diagnosis.

Not every case can be prevented, but lowering infection risk matters. Good prevention starts with routine avian wellness care, prompt treatment of wounds and infections, and a balanced diet that supports immune function. Malnutrition can predispose birds to secondary infections, so diet review with your vet is worthwhile, especially for macaws eating mostly seed or an unbalanced homemade diet.

Quarantine new birds before introducing them to your household flock, and be cautious about exposure at bird shows, stores, boarding situations, or homes with other birds. Newly acquired birds and birds exposed to outside birds are more likely to encounter infectious disease. Clean cages, food bowls, and perches regularly, and avoid sharing supplies between birds without disinfection.

Pay attention to subtle changes. Birds often show only small behavior shifts early in illness, such as less vocalizing, sleeping more, or reduced interaction. Early veterinary care for those changes may help catch bloodstream infections or other systemic disease before the heart becomes involved. If your macaw has already had a serious infection, ask your vet whether follow-up bloodwork or imaging is appropriate.