The short answer is YES! Unfortunately, age does not make you immune to fleas, mosquitoes, or ticks and the respective diseases that they can carry. I have kept all my senior pets on year round heartworm medications and flea medications. Although, I live in the Midwest where winter temps get cold enough to kill off fleas but it’s still important to continue treatment. If you live in the South the cold winter doesn’t kill off fleas, so my best advice is to use these medications year round.
The other part to this question is about them going outside. Again, even short walks outside exposes your dogs to everything and it only takes one flea to jump on and hitch a ride to lead to a full flea infestation in your house. So, let’s say your dog doesn’t go outside at all, can they stop flea, heartworm, and tick preventatives? No! We see mosquitoes all the time inside and fleas are very adept to latch on to our pants and find their way inside, they can even latch on to another one of your pets and come inside this way as well.
What we do know is that the treatments for a lot of the diseases that mosquitoes and other parasites carry can be very rough on a senior pet. I really think that preventatives are the best way to go rather than subjecting your pet to the suffering of having to be treated for the nasty pests. The preventative treatments are safe, effective, and relatively inexpensive – especially when compared to the treatments for the diseases they cause. However, the final thing I will say is that it might be worth speaking with your vet about what preventatives they recommend for your pet. There are certain conditions (like seizures) that might require that we suggest a different product. It should all be part of your regular senior pet well visit!