My dog gained weight. Was heartworm prevention dose too low?

Yes! These medications are based on weight and this is usually the manufacturer’s recommendation. If your dog is a little overweight this might be an incentive to get him under 100 lbs. Heartworm is a serious disease and the cost of treatment would by far exceed the cost of the extra pills.

If he has always been on it and hasn't missed any doses, then he should be fine to continue with the prevention. Now, that being said, no prevention is 100% effective so the reason we test every year is to check and make sure there was no break-though issues with the product. If a dog has heartworm disease there is a chance the prevention could cause a medical problem. In this case, I think the benefit of him taking the heartworm prevention outweighs the very tiny risk that he could be positive and have a reaction to the medication. Hope this helps. If you have more questions you can always opt for a private consultation where we can chat back and forth. That way you can ask as many questions as you'd like. Best wishes!

Yes, it would show up even if on prevention. The test is only checking for the presence of the adult heartworms in the heart. It takes approximately 6 months from the time the dog is bitten by a positive mosquito to the time they would show up positive on a test. I suggest you not wait and get a confirmatory test now. If Shiloh truly is heartworm positive you should have him treated. The prevention is only going to keep him from getting more worms. It does nothing for treatment. Hope this helps. Best wishes.

She'll probably be fine for this month if she's just a pound or two over. But in the future, if she's gained a bit of weight and is now borderline or just over the maximum weight for her current dose, I would get the next size up. Nexgard has a very wide margin of safety, so the manufacturer recommends "rounding up" if a dog is near the upper limit of the weight range. :)

If heartworm is a problem in your area, which is may be considering the mosquitos that carry it have been found in your country according to the paper I gave you earlier, she should be protected against it regardless if she is showing signs or not. A dog can have heartworm without showing signs, and the only way to know for sure if to have a blood test done on her. Even if it's negative, you can't prevent mosquitos from biting her, so she should be protected against it. Heartworm is fatal without treatment, and it can still be fatal even with treatment if the infection is severe enough. I'm glad to hear Bella may be getting spayed this spring! I remember from earlier questions you were debating having it done. Before getting spayed, you can have routine blood tests and a urinalysis done on her. That tells the vet who her organs are functioning, and gives an anesthetic risk assessment for the surgery. An anesthetic risk assessment lets the vet know how she will likely handle being under anesthesia. As with any surgery, as we've talked about before, there is always a risk, but as long as Bella is healthy, that risk is quite small :-)

A Light positive is still a positive. I would ask your vet to send out test to an outside Lab to confirm the results using a different type of test. You can also have an ultrasound done to see if your dog has any adult worms at this time. Your dog should currently be a heartworm preventative every month like Heartgard. Most heartworm tests are actually looking for antibodies in the bloodstream, so when they come up positive (even light positive, this means that your dog has antibodies or that your dog has been exposed. It may be that your dog doesn't have any adult worms of his/her own at this exact moment, but that he/she has baby heartworms floating around in the bloodstream because he/she is constantly being exposed to them (be it from another dog in the area who is infected and mosquitoes are passing it around or you live in a rural area where there are a lot of coyotes who are infected?? These are very far fetched reasons.. The most likely cause is that your dog is infected but has what we call a "low case load" and is producing a small amount of antibodies and therefore shows a light positive. Further testing will show you how advanced the disease is (like I said, ultrasound, xrays, etc) but regardless, you should treat your dog. One heartworm WILL eventually become two, three four etc. The longer the problem is left untreated, the worse it will become and the more damage they will will do to your dog's heart, lungs and overall health.

Hello, sorry to hear about Zoey. It truly depends on the dose your dog got. If the weights are similar then Zoey may not experience any side effects. If the weights are different, then it truly does depend on what dose in mg/kg Zoey ingested. If you think this dose is high then you could expect to see vomiting, diarrhea and a decreased appetite. If you note any of these, then contact your veterinarian for an appointment as Zoey may need medications to control these side effects. Hope this helps and best of luck.