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The Daily Insight

Does heartworm medication make a dog lethargic

Author

Isabella Wilson

Published Feb 15, 2026

ADVERSE REACTIONS: The following adverse reactions have been reported following the use of HEARTGARD: Depression/lethargy, vomiting, anorexia, diarrhea, mydriasis, ataxia, staggering, convulsions and hypersalivation.

How long will my dog be lethargic after heartworm treatment?

When discharged after the third injection, your dog must remain as quiet/inactive as possible for the next 4 weeks, as noted above. After 4 weeks, limited activity may be slowly increased. Respiratory symptoms are important, as described above. Continue giving heartworm preventative on a monthly basis.

What to expect after dog has heartworm treatment?

The dog may be required to stay at the hospital for 3-4 days. After treatment, the adult worms die and are carried by the blood to the lungs where they lodge in small blood vessels. There they decompose and are absorbed by the body over a period of several months.

What are the side effects of heartworm medication?

Oral Heartworm Medications There are rarely side effects, if given at the proper dosage, but some dogs may experience vomiting, diarrhea, or incoordination. In the case of an allergic response to the heartworm medication, a dog may experience itching, hives, swelling of the face, or even seizures or shock.

Can I walk my dog after heartworm treatment?

Most dogs can be safely leash-walked during the treatment recovery period and providing appropriate chew toys can help relieve some of that stored up physical energy.

Should Heartgard be given with food?

Heartgard Plus may be offered by hand or added to the food. It does not need to be given with food to be effective. Heartgard Plus should be given in a manner that encourages the dog to chew, rather than swallow without chewing. Chewables may be broken into pieces and fed to dogs that normally swallow treats whole.

Is heartworm medication harmful to dogs?

The treatment for heartworm disease is not easy on the dog or on the owner’s pocket book. Treatment can be potentially toxic to the dog’s body and can cause serious complications, such as life-threatening blood clots to the dog’s lungs.

What is the success rate of heartworm treatment?

What is the treatment? There is some risk involved in treating dogs with heartworms, although fatalities are rare. “A new drug is available that does not have as many side effects, allowing successful treatment of more than 95% of dogs with heartworms.”

Can my dog jump on the bed after heartworm treatment?

There is no reason to allow running, jumping, or other physical activity at any time for 8 weeks after the start of the injectable heartworm adulticide treatment.

Why is my dog panting after heartworm treatment?

The injections are given within the muscle and can indeed be uncomfortable, but the inflammation that develops within the days following creates the most discomfort. Restlessness, panting, trembling and reduced appetite can all be signs that the dog is uncomfortable.

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Does Heartgard have side effects?

ADVERSE REACTIONS: The following adverse reactions have been reported following the use of HEARTGARD: Depression/lethargy, vomiting, anorexia, diarrhea, mydriasis, ataxia, staggering, convulsions and hypersalivation.

Can dog climb stairs after heartworm treatment?

Stairs should be avoided if possible. The dog should always be walked on a leash when outside, and he or she should only be walked for the purposes of going to the bathroom. These restrictions should start immediately after the first melarsomine injection is given and continue until 6-8 weeks after the last injection.

How often should I give my dog heartworm medicine?

Because heartworms must be eliminated before they reach this adult stage, it is extremely important that heartworm preventives be administered strictly on schedule (monthly for oral and topical products and every 6 months or 12 months for the injectable).

How long does heartworm medicine stay in the dog's system?

Monthly heartworm preventative medications do not stay in your dog’s bloodstream for 30 days. The active ingredients work to kill any larvae that have been in the system for the past 30 days, clearing the body each month.

Can you give your dog heartworm and flea medicine at the same time?

No more sticky, smelly topicalls. It can be given at the same time as their monthly Heartgard- ONCE-a- MONTH! They are so easy to give, dogs think they are treats. For cats, we recommend Vectra, a once-a-month flea prevention, or Frontline for fleas and ticks.

Is it OK to cut Heartgard in half?

When splitting oral heartworm medication (especially soft chews), it is possible that you will not divide it evenly thereby resulting in one dog getting a smaller or larger dose. … In this case, giving your Collie a dose of Heartgard prescribed for another dog could result in a serious adverse reaction.

How long should my dog take Heartgard?

immitis for a month (30 days) after infection and, as a result, prevent the development of the adult stage. HEARTGARD Plus Chewables are also effective against canine ascarids (T. canis, T.

How long does it take Heartgard to start working?

Because it is administered orally, most roundworms and hookworms begin to die almost immediately, but it may take up to 3-5 days to have complete clearance of worms. You may recheck a stool sample in 10 days to ensure there are not more parasites noted. Hope this helps and best of luck.

How do I comfort my dog after heartworm treatment?

Try a game of stationary catch or use a clicker to train him to follow quiet commands while he’s in his crate. Keeping your treated dog calm and quiet is one of the most important responsibilities a pet owner has during heartworm treatment.

Is heartworm treatment painful?

Treatment involves using very harsh arsenic-based drug to kill the adult heartworms. This medication is painful to administer and can lead to injection site reactions in some patients.

Is heartworm a death sentence?

Most everyone knows heartworms are a threat to dogs, especially in the warm climate of the South. But what many people might not realize is that heartworm disease is seldom a death sentence. In fact, dogs with this condition can live happy, high quality lives as long as they are given appropriate care.

Do dogs poop out heartworms?

Although many worm types, such as roundworms and tiny hookworms, are shed in your pet’s feces, heartworms do not live in the gastrointestinal (GI) tract, and are not found in feces.

Why do dogs get prednisone after heartworm treatment?

During this treatment your pet will begin taking Prednisone (a steroid) to help reduce inflammation in the lungs and vessels, caused by the worms before and after they die. Prednisone also helps reduce the risk of an acute pulmonary embolism (clot) that can cause sudden death.

How long is exercise restriction after heartworm treatment?

After treatment, a dog with mild to moderate heartworm disease is generally kept on at least 4-8 weeks of exercise restriction, but then can gradually return to normal activity as recommended by your veterinarian.

Does NexGard make dogs sleepy?

The safety studies for NexGard had a good outcome with a very small percentage of dogs experiencing minor adverse effects. The most frequently reported adverse reaction was vomiting; less frequent reactions included dry skin, diarrhea, lethargy, and anorexia.

Is heartworm medication toxic?

Given at the proper doses and under the supervision of a veterinarian, ivermectin is safe for most dogs and is very effective in treating and preventing a number of parasites. However, a dog with the mutation who ingests the drug can have a severe, life-threatening reaction called ivermectin toxicity.

Does Heartgard interact with other medications?

Drug interactions Ivermectin and pyrantel, the main ingredients in Heartgard and Heartgard Plus, may interact with the following drugs [6, 7]: Anti-fungal medications (ketoconazole, itraconazole) Immunosuppressive medications (cyclosporine) Antibiotics (erythromycin)

Can dogs eat before heartworm treatment?

Heartworm treatment patients will usually go home with 6-7 days of prescription food recommended by the veterinarian. When you only have a few servings of the prescription food left, start mixing it with your dogs’ usual food. This will make the transition easier for your dog. Your dog also needs to be kept calm.

Does Heartgard make dogs sleepy?

The following adverse reactions have been reported following the use of HEARTGARD: Depression/lethargy, vomiting, anorexia, diarrhea, mydriasis, ataxia, staggering, convulsions and hypersalivation.

Can you give a dog too much heartworm medicine?

It’s most commonly used in monthly heartworm prevention. It is also used to treat ear mites as well as hair mites, which can cause mange. It is used to treat some internal parasites as well. Toxicity can occur if a dog is given an excessive dose of the medication (10 to 20 times the recommended dose).

Is it OK to skip a month of heartworm medicine?

Most of the monthly heartworm medicines have a safety factor of at least 15 days of protection if a dose is missed. This means that if you’re just a week or two late, your pet is likely still within that window of protection and would be unlikely to become infected during that time.