Why does my kitten have lumps under his skin after vaccinations?

Great question! This lump could be a localized reaction to the vaccine if the lump is in the area where the vaccine was given. Other options could be a cyst or a benign tumor. Given it's not painful and if she is otherwise acting normally, this isn't an emergency. Keep an eye on this lump, and if it doesn't go down over the next couple of days or gets bigger, then I would have Poppy seen by a vet. Good luck, I hope this helps!

If it is hard a raised (try looking underneath if it is red as well) it could be an allergic reaction, an infection or possibly an autoimmune disease that is quite common in cats (EG granuloma). If this line seems to get worse or doesn't get any better within a week give or take, I would recommend having it checked by your vet, it might need medical treatment (either steroids, antibiotics or anti-fungal therapy).

It does not look like post-injection reaction. I would rather suspect an insect bite, reaction to a tick, cat bite (if Ori goes out at all) or self-inflicted small wound from scratching the area. Please, keep an eye on it, small skin wounds often heal rapidly without treatment. If there is any discharge from the wound you can use 4% chlorhexidine skin solution to clean it. If it gets bigger or starts bothering Ori, take her to your local vets for a check.

Hello and welcome to Petco Pet Education Center, formerly Petcoach. Soft masses that are part of the skin can be either abscesses (pockets of infection), small bits of swelling from vaccine injections (these can last a few months sometimes), fatty masses, and less commonly in a 4 month old kitten, cancers. I would monitor it, if Bean is painful or if it is growing or changing get it looked at right away, otherwise just monitor for now and have it assessed by your vet next time you are in. Best of luck with Bean!

Poor girl. Due to her age a mass here would be less likely as the cause for this hard lump. This may be an abscess or even a cyst. It is difficult to tell without feeling it in person, however, if it does not go down on its own within a few days to a week, then I would recommend having your vet check it out further. If it is an abscess, then cats typically will start to act ill (decreased appetite, low grade fever, lethargy) after a few days, in which case the abscess would need to be drained by your vet and then KitKat would need a short course of antibiotics to get things to heal well. Otherwise, I would recommend monitoring this for now to see what happens. I hope that Kit Kat's strange lump heals well soon! : ) Best wishes and take care.

Normally, there will be a small bump where a vaccination is given and this can persist for several weeks to months. If it persists for longer than 3 months and / or continues to grow in size, I would recommend having a veterinarian examine Simba so that the most appropriate diagnostic and treatment recommendation can be made. Sometimes, vaccines can cause cancerous tumors to grow in the area where the vaccine was administered. This is less common now, but still a risk. I hope this helps! Please let me know if you have any further questions / concerns and I would be more than happy to help you further.

Cats typically do not receive vaccines on their belly, they are given over the shoulders on their back; therefore, I do not think this mass you felt is due to her vaccines. It could be that Lucy has a benign tumor, cyst, abscess, or a malignant tumor (unlikely in a young cat) causing the lump, and I would have her seen by a vet for it. The vet can examine and diagnose it, and let you know if any treatment is needed.