H is for heartworm.
April is National Heartworm Awareness Month.
Heartworms prefer dogs, but can also infect cats, ferrets, and humans. They are transmitted through infected mosquitoes, either outside or inside -- the skeeters don't care. Since cats are smaller than dogs, it doesn't take as many of the worms to get us sick. There is no cure, only prevention of infection and some treatment of symptoms. Some of the drugs that work on dogs are fatal to cats (where have we heard that before?). And it's not as easy to diagnose in cats, as they can infect us before they show up on diagnostic tests. In dogs, the worms infect the heart. In cats, they seem to prefer the pulmonary artery or vena cava, which carry oxygen-poor blood to the lungs and heart respectively.
Signs of heartworm infestation in cats include coughing, labored raspy breathing (known as dyspnea), vomiting, diarrhea, loss of appetite, weight loss, lethargy, and greater susceptibility to other feline disorders. It may be confused with feline Asthma. Respiratory problems and vomiting are the predominant symptoms in cases of chronic infestation. A physical examination may also reveal a heart murmur or otherwise irregular heart rhythm.
Some of the flea and tick preventatives available also contain an anti-heartworm ingredient, so that is the best way to prevent it. Talk to your vet for more information; they may require a prescription.