Side Effects of Sentinel for Dogs

Sentinel for dogs protects against heartworm, common intestinal worms and fleas. There are even some studies that find Sentinel can help with mange mites. Veterinarians recommend it because it offers broad-spectrum protection. It's a safe parasite preventative, as long as the dog or puppy weighs more than two pounds and is at least four weeks of age. As is true with any prescription medication, Sentinel does have side effects.

Make sure you give your pet the chewable tablet after a meal. One of the active ingredients in Sentinel is best absorbed when taken as food is digesting. Monitor for side effects for the next day or two.

Key Ingredients in Sentinel for Dogs

Sentinel contains lufenuron and milbemycin oxime. The active ingredients enter the dog's pores and are stored in the fat cells. When a parasite ingests blood, they receive a dose of the medications that alter their health, leading to death.

Lufenuron prevents larvae from forming an exoskeleton. Without this exoskeleton, the fleas cannot mature into adults and lay more eggs to continue the life cycle.

Milbemycin opens specific channels within the parasite's neurons. This causes the cells of the central nervous system to function improperly. As a result, the cells die and paralysis occurs, eventually leading to death.

Gastrointestinal Side Effects

Side effects after taking Sentinel for dogs are extremely rare. However, of those dogs that do experience adverse reactions, diarrhea, excessive drool, loss of appetite and vomiting are common. Let the dog rest and avoid strenuous activity, especially following a meal, because activity can increase the possibility of regurgitation. Make sure he's drinking to avoid dehydration.

Skin Reactions Following Sentinel for Dogs

Though Sentinel is an oral medication, it may cause itchy skin, oily skin and hives. Shampooing your dog with an oatmeal-based pet-safe shampoo can help relieve the irritation. If the condition continues, contact your veterinarian.

Signs of an Allergic Reaction to Sentinel

If your dog is having an allergic reaction to at least one of the active ingredients in Sentinel, symptoms include:

  • Cold extremities
  • Coma
  • Facial swelling
  • Pale gums
  • Severe vomiting
  • Sudden, explosive diarrhea

If any of these symptoms occur, seek immediate veterinary care. Your vet will likely keep your dog in his clinic to monitor his health for a day or two.

Collies and collie mixes may have a higher susceptibility to adverse reactions. Studies find that taking a normal dose has no effect, but collies given a higher than normal dose did begin to show signs of seizures.

Test for Heartworm before Giving Sentinel for Dogs

Heartworm is a serious disease transmitted through the bite of an infected mosquito. The eggs hatch in the dog's bloodstream and grow inside the lungs and occasionally the heart. If you have mosquitoes in your area, your dog should be on a preventative heartworm medication. Even if your dog is kept indoors, mosquitoes can easily come in when a door or window is opened.

Before taking Sentinel, your dog must be tested for heartworm. If heartworm is present, Sentinel is more likely to cause dangerous side effects. Many pet owners report that their heartworm-positive dog reacts to the medication with seizure-like symptoms, including convulsions.