The treatment of heartworm infection is something of an art. There are several strategies that can be used depending on the dog’s medical condition, including the gold standard of a 3-injection protocol versus 2-injections versus not killing the adults but preventing reinfection (not recommended). The important concept to realize is that arsenic based drugs are necessary to kill adult heartworms and that appropriately treating for heartworm disease requires skill on the part of the veterinarian, work on the part of the owner and while safer than ever, there are still risks. The best option of all is prevention!

Patient Evaluation in The Heights

Prior to therapy, the heartworm patient is assessed and rated for risk into one of four categories. Important factors include: how many worms are thought to be present based upon the tests performed, the size of the dog, the age of the dog, concurrent health factors, severity of the heart disease, and the degree to which exercise can be restricted in the recovery period. Some hospitals use computerized formulas to categorize heartworm infected patients. The categories into which patients are grouped are as follows:

  • Class I: Lowest Risk. These dogs are typically without symptoms and their infection is a surprise discovery during a routine annual health examination when a positive test comes up. Other blood tests are normal and radiographs show mild changes if any change at all.
  • Class II: Moderately Affected. Healthy dogs with minimal signs as above, occasional coughing, fatigue only with exercise but with radiographs that show definite evidence of heart disease. Lab testing shows mild anemia, urine dipsticks show some protein present but not severe urinary protein loss.
  • Class III: Severely Affected. Dog is suffering from weight loss, cough, difficulty breathing, blatant damage to the vasculature is apparent on radiographs, lab work reveals a more severe anemia and marked urinary protein loss. The damage to the lung blood vessels from the worms, creates extra resistance for the heart to pump against and often episodes of collapse occur with exercise. If the damage is severe enough, the heart can actually fail trying to pump through all the clogged up blood vessels. Class III dogs are expected to die without treatment but are, unfortunately, sick enough that treatment itself is not without risk.
  • Class IV: Caval Syndrome. Dog is collapsing in shock with dark brown urine evident. Heartworms visible by ultrasound in the AV valve of the right side of the heart, very abnormal bloodwork. These dogs are dying and can only be saved by the physical removal of adult heartworms via an incision through the jugular vein. If such a dog can be saved from this crisis, further heartworm infection treatment cannot be contemplated until the dog is stable enough to fit into one of the other categories above.View the physical removal of adult heartworms from the jugular vein of a dog with caval syndrome.

Houston Heights Veterinary Clinic
Urban Animal Veterinary Hospital is here to help you prevent your pet getting heartworms. Call us today to schedule an appointment!

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