Don’t Go Breaking My Heart: Protecting Pets From Caval Syndrome
Caval syndrome is the final stage of heartworm disease, and only a small percentage of pets with heartworms are at risk of developing the condition.
With summer comes mosquitos, and with mosquitos can come heartworms. Even one or two of these dangerous parasites can have serious consequences for pets, but the threat becomes even greater when there are enough to create a blockage inside the heart and cause a life-threatening condition called caval syndrome.
Caval syndrome is the final stage of heartworm disease, and only a small percentage of pets with heartworms are at risk of developing the condition.
Texas A&M College of Veterinary Medicine and Biomedical Sciences associate professor Dr. Sonya Wesselowski and first-year resident Dr. Sukjung Lim explain the dangers of caval syndrome and the importance of heartworm prevention for dogs and cats.
Understanding Caval Syndrome
Pets contract heartworms after being bitten by a mosquito infected with heartworm larvae, which then mature into adult worms inside an animal’s heart and lungs.
“Heartworms usually live in the pulmonary arteries (which carry blood from the heart to the lungs), but if there are enough, they can start backing up into the heart and cause obstruction to blood flow and red blood cell damage,” Lim said. “This is what causes caval syndrome, the worst complication of heartworm infection a pet can get.”
One of the major indicators of caval syndrome is anemia, which occurs because red blood cells are damaged or destroyed when trying to move past the blockage.
Other symptoms of caval syndrome include:
- Lethargy
- Weakness
- Heavy breathing
- Collapse
- Bloody or discolored urine
If left untreated, caval syndrome can also lead to death within a matter of days. For this reason, it’s very important that owners noticing any of the symptoms in their pet seek veterinary care quickly, especially if the animal has previously been diagnosed with heartworms.
A Multi-Step Treatment Process
The recommended treatment for caval syndrome is performing surgery as soon as possible to physically remove the worms.
This procedure is only available at select veterinary hospitals and is ideally performed by experienced cardiologists.
“Heartworm retrieval surgery is minimally invasive but can still carry some risks in addition to the typical risks associated with anesthesia,” Wesselowski said. “We go in through the jugular vein, which is the large vein in their neck, and feed tiny equipment down into the right side of the heart so we can grab the worms and pull them out. We always warn owners that a potential complication of this procedure is bleeding or damage to normal cardiac structures during the extraction, but with careful planning and an experienced team, these complications are relatively uncommon.”
For about two weeks after surgery, owners will also need to monitor the small incision site on a pet’s neck to watch for signs of infection.
Although the majority of heartworms are removed during the procedure, affected pets must still undergo standard heartworm treatment to kill any worms remaining in the lungs. This includes a course of antibiotics, two months of heartworm prevention to kill larvae, and a series of three injections to kill adult heartworms.
During this multi-month process, it’s important that pets are kept calm and confined to a crate because of an increased risk for a pulmonary thromboembolism (PTE) — a condition that occurs when blood clots or fragments of worms dislodge and block an artery in the lungs.
“If a PTE is severe enough, it can result in the sudden onset of breathing distress or even sudden death in the worst-case scenario,” Wesselowski said. “Strenuous activity and exercise increase the risk of PTE in dogs with heartworm disease and can also worsen the degree of inflammation within the lungs. These are some of the important reasons why exercise restriction and crate rest is a crucial part of the management plan while heartworm treatment is ongoing.”
Prevention Is Key
Fortunately, despite their serious consequences, heartworms can be easily prevented with medications that kill any larvae transmitted through a mosquito bite.
“You just need to give a pill once a month, and it’s really not expensive, especially compared to surgery or heartworm treatment,” Lim said.
Heartworm preventatives are also available as topical and injectable medications, and some even include additional protection against intestinal worms, fleas, and ticks. A veterinarian can help you choose the most appropriate option for your pet and lifestyle.
By preventing pets from contracting heartworms in the first place, you’re also avoiding the risks that come with surgery or standard heartworm treatment. Prevention is the safest, easiest, and cheapest way to protect pets from heartworms and caval syndrome. While mosquitos will always be a nuisance, you can ensure that they pose no significant threat to your beloved pet this summer.
