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Lump Appeared Overnight on Dog: How to Treat It

Dogs are lovely but they are not free from mishaps. Or should I say, illnesses.

The pooch that you saw in a perfect state yesterdaydevelops a lump overnight and you are at a loss wondering what to do with it.

There are perhaps a thousand questions crowding your mind at that point.

Did the dog hurt itself? Is it some serious illness? Should I rush the dog to a vet? Is the lump malignant? Am I overthinking? Should I just wait a little longer? And so on.

A lump appearing overnight on your dog can beoverwhelming indeed, but definitely not uncommon.

Many dog owners over the world have faced this atleast once in a lifetime with their canines. Lumps can appear anywhere – legs,body, neck, and just about anywhere.

There are countless reasons behind a lump formation onyour pet. And these appear all of a sudden and out of nowhere, more often thannot. Lumps can be both benign and cancerous.

However, the good news is that about 60%-80% of lumps in dogs arenon-malignant,meaning there is nothing to worry about.

But the problem is, you cannot tell if a lump is serious just by looking at it or by touching it. It can only be diagnosed by a veterinarian after biopsy.

Therefore, if you find a lump growth on your dog overnight, take it to a vet after you get over your overwhelmed initial state. Treatment starts thereafter.

Types of Fast Growing Lump on Dog

In case you are curious and would like to know about a dog’s lumps better, you may be interested to know that lumps can be of many types.

Most of these bumps are fatty tumors and less than 50% of these lumps are cancerous. While some are less problematic, some call for more attention and care. Here is a list of identified lumps in our four-legged friends:

  • Lipomas
  • Liposarcomas
  • Histiocytomas
  • Sebaceouscysts
  • Sebaceousadenomas
  • Basalcell tumor
  • Mastcell tumor
  • Warts
  • Abscess

Lump Appeared Overnight on Dog, What Should You Do?

Lipomas are the commonest kind of lumps and are basically just fatty growths under your dog’s skin. They do not attach to the skin and can hence be moved over the body of the dog with slight hand pressure.

This kind is benign, but grows bigger in size, sometimes affecting mobility and posture of the pet. If a lipoma appears, another is expected to appear soon in some other part of the body.

Although not harmful, why allow a lump to grow on the dog, making it uncomfortable? Best, seek advice from the vet.

Liposarcomas look similar to lipomas, but are fundamentally different. When touched externally, these can feel both soft and firm.

Firm lumps are less likely to be moved around over the skin. They may or may not be serious lumps.

Therefore, consulting a vet can be the safest choice to initiate treatment.

The vet will, most probably, conduct a fine needle aspirate (FNA) test to determine the next course of action. This kind is more common in older dogs than young ones.

Unlike lipomas and liposarcomas, histiocytomas are more common in younger dogs. They are also known as button tumors due to their button-like appearance.

They develop abruptly and are round, hairless growths on a dog. Histiocytomas mostly appear and disappear all by themselves and there is not much to be done.

However, they sometimes cause inflammation and release pus from the tumor, which is when you need to consult a vet.

Also, if lumps change size, structure or texture/color, it is always wise to get professional help.

So, for all lumps and this, you may mark the area with a marker or paint to observe for a few days if it grows, transforms, or deteriorates. Based on that, report your findings to the vet and get treatment started.

Sebaceous cysts can grow anywhere on the dogs body where there is hair. These are formed as a result of blocked hair follicles.

They have a roundish appearance and are generally about an inch or more in size. They are prone to getting infected easily and therefore, needs more attention than the above 3 kinds.

If you suspect a sebaceous cyst, visit a vet immediately. The doctor may start your dog on antibiotics to restrict any chance of infection and may also drain out the lump surgically.

Sebaceous adenomas are again more common in older dogs and are a benign kind of tumor. These mainly form on the dog’s eyelids and legs.

They have a smooth and hairless appearance and occur in numbers. So you would often spot more than one at a time.

In these lumps, a little wait before a vet visit is still okay, but make sure you check with a vet in case redness or inflammation accompanies the lumps.

Basal cell tumors are generally firm at external feel and benign upon biopsy, although malignancy is possible in some cases. They usually occur at the neck and beneath the furry coat of your dog.

In basal cell tumors, it is absolutely advisable to get a biopsy done and diagnosis confirmed before any treatment is started.

Also, it is always a good idea to remove basal cell tumors surgically, be it benign or malignant.

Mast cell tumors are mostly malignant and they are the commonest kind of skin cancers in dogs. It accounts for about 20% of all skin cancers in canines.

These are sometimes quite invasive and often pop up even after surgical eradication. Some mast cell tumors also secrete histamine that leads to inflammation, swelling, and bruises around the lump.

Generally, these are singular lumps, but may sometimes bear multiple masses too. One easy way to identify a mast cell tumor is that their size changes fast – first enlarges and then shrinks.

Of course, the surest way to know is through an FNA examination by the vet. These lumps can occur in any breed of dog, but some breeds are at higher risk.

These include the Labradors, schnauzers, Boston Terriers, beagles, and boxers.

Warts are tumors of the mouth, also known as oral warts or canine oral papillomas. Unlike other lumps, these are caused by viral infections (the papilloma virus).

They are generally small in appearance and benign in nature. Oral warts usually develop in or around the mouth of the dog – in the tongue, throat, lips, or gums.

These are more common in puppies and dogs under 2 years. Hence, these are also loosely referred to as puppy warts.

Mostly, you do not have to do anything about these as they subside on their own within 2-3 months. But some warts can turn malignant. So why take a chance? Get the vet’s advice as soon as you can.

If these warts occur in aged dogs, surgery might be necessary if they persist long.

Abscesses are nothing but pus accumulation under the dog’s skin and consequent swelling with a lump-like appearance.

Wound infections or insect bites are the usual suspects behind abscesses in dogs. Infection-oriented abscesses are caused by bacteria like Pasteurella multocida, Staphylococcus intermedius, etc.

Abscesses grow bigger over time and also, more complicated if left untreated.

So you must take your dog to the vet and have it treated. Alternatively, if you are really keen on doing it at home, make sure you do it under the vet’s guidance and in absolutely sterile conditions.

Flush the abscess with sterile saline solutions and apply wound creams as many times as you can in a day. Remember to wear gloves and also sanitize your hands and everything else in contact with the abscesses.

As it appears, lumps are not simple matters, although they are common. A veterinary intervention is almost always necessary and it’s better if you do not begin treating your dog off your head.

The reasons are obvious – there is no one-size-fits-all solution to every lump that your dog may have. And not all lumps are of similar nature or severity.

Some lumps appear one at a time, some in multiples. Some lumps are small, some are large.

Some are cancerous, while some are benign. Some lumps disappear on their own, some lead to more serious skin infections.

There are so many varieties, causes, and consequences that it would not be easy for any dog owner to diagnose it accurately without medical examinations. Home remedies to lumps are, therefore, not a good idea – neither for you, nor for your dog.

Although you can wait and observe certain lumps and map their growth for some days, do not delay if symptoms worsen (redness, inflammation, etc.).


Observation is important if your dog develops lumps overnight. Watch it closely for a few days and take him to the vet thereafter.

In the meanwhile, you can always chart the growth, size and color of the lump to help the vet understand it better.

Also, if you spot one lump, try to look for others to be extra sure there aren’t any more. In any case, your first most important action should be to report the lump to the vet.