Experienced and professional animal trainer provide their insights in answering this question :
A. It could be an allergic reaction or an infection. If it doesn’t subside after a few hours or gets worse then you should see your vet.

How to Identify Common Pet Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced pet care professionals :

Balanoposthitis = inflammation of the penis & prepuce (the sheath of skin that covers the penis). The causes include: injuries, bacterial microbe infections, phimosis (constriction of the prepuce opening so that the prepuce cannot be drawn back to expose the penis), & tumors.
These swellings are typically the result of an engorged bulbus glandis. They represent a normal anatomical structure that can become swollen with sexual arousal or any other form of excitement.
This tissue is a normal part of a male dogs anatomy, which can swell up when the dog is excited or aroused, in both entire and desexed dogs. The two `lumps` you can see either side of the penis are the `bulbis glandis`. They should reduce in size on their own when your dogs arousal is reduced.
The most common preputial tumors in dogs include SCC, transmissible venereal tumor (TVT), and mast cell tumor (MCT). Any skin tumor common to haired skin may occur within the prepuce. Papilloma, hemangioma, fibroma, sebaceous adenoma, fibrosarcoma, and HSA have been reported within the prepuce.
Acute inflammation of the testis and/or epididymis is most commonly infectious (bacterial, fungal or viral). The source of infection can be hematogenous or urologic or by direct inoculation. Clinical signs include pain and enlargement of the testis or epididymis.
Treatment. Various medications including steroids, anti-inflammatories, antibiotics, anti-parasitics, and even chemotherapy may be recommended depending on the reason for the lymph node enlargement. Surgery or radiation are other treatment possibilities, especially for low-grade, localized lymphomas.
Lipomas (fatty lumps)

Lipomas are the most common benign mass dogs can get; they`re often found under the skin of older dogs, and are more common in obese dogs. They tend to be round, soft tumours of fat cells that grow very slowly and rarely spread, so it can take up to six months before you see any change.

The most common types of lumps or bumps found on puppies are warts, skin tags, button tumors, and abscesses. In these cases, your vet may recommend a wart ointment or other skin treatment. There are also some products that claim to help dissolve normal fatty skin lumps on dogs.
Warning signs of testicular tumors include soft swellings in one or both testicles, a single enlarged testicle or asymmetric testicles, generalized scrotal enlargement, and infertility in the breeding stud.
Lumps, bumps, or growths that are located in or around a dog`s vulva are not normal and may be associated with injuries, infections, anatomic abnormalities, inflammation, cysts, or tumors.
The recommended treatment of malignant PNST is the same as with dogs, with surgical excision, including amputation, the treatment of choice. Adjuvant radiotherapy is also recommended, as it may also be beneficial for local control and long-term survival.
Hepatoid tumor or hepatoid [adeno]carcinoma are terms for a number of uncommon or rare neoplasms in humans, named for a visual resemblance of the cells under the microscope to those of hepatocellular carcinoma, the most common form of liver cancer.
Perineal hernias are usually very easy to identify. Dogs with perineal hernias will have a telltale swelling adjacent to the rectum (on one or both sides). Constipation, lethargy, difficulty urinating, and a change in how they carry their tail are also typical of this condition.
Hydrocele (pronounced hy-dra-sel) is when your scrotum fills with extra fluid, making it look swollen. It usually develops on only one side and tends to be painless. It`s much more common in babies, but sometimes you can get it as an adult. Hydrocele usually goes away on its own.
Mild swelling may resolve on its own, but you still need a vet to check your pet out and determine why their face swelled up. If the cause is due to dental disease, treatments can range from cleaning to tooth removal.
Mast cell tumors are quite serious when identified in dogs. If untreated they can cause anaphylactic shock or if they progress into a more aggressive form they can metastasize and ultimately lead to death.
Lipomas are the most common masses found on pets. These “fatty tumors” are almost always benign growths, and are usually just under the skin. They remain relatively mobile (skin moves around them freely) unless they invade local muscle and connective tissue.
A mild dog shampoo and a bit of gentle scrubbing will do the trick. Be sure to always use a fresh water rinse when cleaning your puppy`s privates. Dried soap or shampoo can cause irritation.
A tumor can either be benign or malignant. Dr. Whittenburg notes, “Cancerous masses may be rapidly growing and therefore seem to appear suddenly.
Histiocytoma tumors are often referred to as button tumors because they are usually less than an inch in size, red, raised, and hairless. Often seen in English Bulldogs, Scottish Terriers, Greyhounds, Boxers, Boston Terriers, and Chinese Shar-Peis these tumors typically regress on their own within two to three months.
Cysts – A cyst develops when one of your dog`s oil glands becomes blocked. These are similar to a zit on a human, although these cysts can grow much larger. Generally, they aren`t anything you need to worry about or seek treatment for, and they should go away on their own.
Testicular tumors in dogs may not be painful—which means your dog may not show any signs that something is wrong. However, swelling and pressure from a growing tumor may cause signs of pain.
Dog Cyst vs Tumor: How Do I Tell The Difference? Cysts are fluid-filled sacs under the skin that are usually easy to move around, while tumors are typically more solid. A cyst also may drain a white, yellow, or green discharge.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Q. My Maltese is not a female his penis /sheath is swollen and has a growth on it. It could be a allergic reaction but I do not know what to do.
ANSWER : A. It could be an allergic reaction or an infection. If it doesn’t subside after a few hours or gets worse then you should see your vet.

Q. Dogs eyes swollen 10hrs after given rabies shot. Also put on 3 different meds for ear infection given 10hrs ago. Is it an allergic reaction?
ANSWER : A. It sounds like he could be having an allergic reaction to something. Please call your vet and give him/her an update. Your vet may want to re-examine your dog to make sure everything looks ok. If your vet thinks it is an allergic reaction, he/she can prescribe an anti-inflammatory and an antihistamine, if needed.

Q. What would cause sudden swelling around the outside of my dog’s mouth
ANSWER : A. Several things could cause it, but two things are more common than others. It could be some type of allergic reaction to something that’s new in the environment – the skin around the mouth is pretty sensitive to things like that, and sometimes allergic reactions will result in swelling in that area.

The other possibility is some type of insect sting. Bees are really common culprits here, and dogs are famous for biting at them and getting stung. Hopefully it’s not too serious, but do monitor for continued swelling and take her in if you see anything concerning, especially difficulty breathing or signs that the reaction is becoming more generalized (swelling or focal “wheels” in other parts of the body).

Also I’ll just mention that I’ve seen dogs get bitten by snakes in the area around the mouth, so if you live anywhere where that’s a possibility this time of year, definitely go right in to see a vet ASAP.

Q. Cats legs and paws are swollen. In the morning her chin is but it goes away after a couple hours. Have any idea what’s going on?
ANSWER : A. If multiple body parts are swollen, or your cat’s head, face or neck are swollen it may indicate a severe allergic reaction. In these cases it is best to contact your local vet or emergency clinic as soon as possible for treatment.

If the swelling is minor, it may be caused by a number of things ranging from scratches or stings from bugs, allergies or a minor allergic reaction to a medication, food or treatment. Your vet can provide you with an over the counter antihistamine dosage to treat acute minor swelling.

Swelling in the body such as the chest and abdomen, or extremities can also sometimes indicate problems such as heart disease or other internal organ disease. If your cat is experiencing chronic swelling, scheduling a complete wellness exam with your vet is best.

Q. My dog is bleeding out of rearend after
going to vet for a leg trouble the vet says
it is stres
ANSWER : A. It could be many things causing the problem. If it is an unneutered female it could be a season, if it is in the urine it could be a cystitis which could be set of by stress amongst other things. It could be from the anal glands or it could be from the lower intestinal tract. If it is the latter I would be careful what pain relief medication you are giving as some can cause bleeding in the GI tract such as meloxicam. I would recommend having a recheck with your vet to establish where the bleeding is coming from as some causes may require treatment or a change in current treatment.

Q. Just came home from work and noticed my 12 year old mutt has a swollen face. I believe its an abscessed tooth. My vet is closed. Can I wait till morni
ANSWER : A. If your dog looks well and is not in pain you can wait until your vet is open. NB: swollen face is often related to allergic reaction in dogs. If you notice that your dog has breathing problems which could be a case in allergic reaction you should contact your emergency vet without delay.

Q. Our female dog dog had a lump in her nipple but it kept growing over the years and became big now its become painful and she is unable to sit
ANSWER : A. If your dog has a lump or growth on her nipples or belly that has been growing in size, it is best to have your local vet examine her. Sudden growths on the body can be caused by a number of things ranging from lipomas (benign fatty tumors that are common in older dogs) to more serious problems such as mammary or mast cell tumors. Your vet can take a sample of the growth and send it to a Lab for analysis. Depending on the cause, treatment may range from leaving the growth be, removing the growth, or removing the growth and beginning additional treatment therapies.

Q. I have a shitdzu breed 5year old and about months ago she started to have red itchy skin and loose hair from middle of body to the end fully
ANSWER : A. This is probably caused by an allergic reaction. first of all make sure you flea your dog regularly every month with a high quality spot on (ex. Advantage) as fleas are by far the most common reason for these reactions.

If the fleas are not the problem, it could be an allergic reaction to food or an environmental factor. this is more complicated to treat and will sometimes require medications such as Steroids, anti histamines, cyclosporine or Apoquel in order to stop the allergy.