This article was updated on September 8th, 2023
Our furry friends can’t talk to us, and when they have red, irritated skin, we worry about their comfort. As a veterinarian, I see multiple dogs every week with red spots or rashes. Luckily, with a little investigation, we can typically determine the cause and formulate a treatment plan that will have their dog feeling better in no time!
Why did my dog’s skin turn red?
Your dog’s skin may appear red for many reasons. Most commonly, an allergy of some sort is the culprit. This could be a food allergy or an environmental allergy. Other possible causes include parasites, toxin exposure, bleeding under the skin, and autoimmune conditions.
Top causes of red skin issues in dogs (red spots and rashes)
1. Moist dermatitis (Hot Spots)
Hot spots, technically known as acute moist dermatitis, are red, inflamed areas of skin that can seem to appear overnight. These spots may occur anywhere on a dog but are most common behind and under the ear and on the hips. Though not life-threatening, these lesions can make dogs absolutely miserable.
Typical symptoms include:
- The area will be moist and typically have some purulent oozing.
- Often there is matted fur covering and hiding the hot spot.
Treatment consists of shaving the hair from around the edges and on the hot spot, antibiotics if an infection is present, and anti-inflammatories. The most important part of treatment is addressing the underlying cause, as the dog will get more hot spots if this cause is not addressed. It is important to note that hot spots are a result of an issue, not the cause. Causes are varied and include fleas, allergies, and other infections.
If your dog has a hot spot, you need to take them to see their veterinarian as soon as possible. In the meantime, you can try putting an Elizabethan collar on them to keep them from further traumatizing the hot spot, as well as a soothing topical such as Benadryl cream. View more pictures of hot spots.
2. Red skin issues due to environmental allergies
Allergies to substances in the environment (Atopy/Allergic dermatitis) can manifest as skin lesions in dogs – including red spots or rashes, as shown in the picture below:
Typical symptoms include
- Redness and inflammation of the skin.
- Hair loss or hot spots on the skin.
- Frequent scratching and itching.
- Watery or itchy eyes.
- Sneezing and coughing.
- Excessive licking or chewing of paws.
- Runny nose and nasal congestion.
- Ear infections or constant head shaking.
These allergies are typically genetic and appear for the first time between 1 and 3 years of age. However, a move to a new area may trigger allergies in an older dog. The signs are most commonly observed seasonally, meaning they come and go throughout the year as the allergens in the environment change.
Diagnosing atopy can be difficult. Though the signs may point to an allergy, deciphering the offending substance can be nearly impossible because these allergens are typically airborne. Allergy testing is available through board-certified veterinary dermatologists in the form of skin prick testing.
There are many strategies for treating atopy. First, any current skin infection needs to be treated. Then your veterinarian will prescribe medicines, supplements, and shampoos that are appropriate for your individual dog. Some trial and error is typically involved in finding out what works the best for your dog. It is very important to remember that allergies in dogs, like humans, are never cured, only managed.
If you cannot see your veterinarian right away, call and ask them about temporary comfort measures such as over-the-counter oral antihistamines and shampoos. Never give your dog any medication without your veterinarian’s approval. View more pictures of dog skin allergy rashes with veterinarian advice.
3. Red bumps from food allergies
Food allergies in dogs present differently than environmental allergies. Food allergies tend to manifest as redness or bumps on the dog’s abdomen or gastrointestinal issues such as diarrhea.
Another distinguishing feature is that food allergies tend to occur year-round, in contrast to atopy, which is typically seasonal.
- Redness or inflammation of the skin / red bumps
- Itchy skin, especially around the face, paws, and ears.
- Recurrent ear infections.
- Gastrointestinal problems such as vomiting, diarrhea, or excessive gas.
- Poor coat quality or excessive shedding.
- Chronic licking or chewing of paws or other body parts.
- Swollen or inflamed paws.
To diagnose a food allergy, your veterinarian will have you feed either a nonallergenic, hydrolyzed or a novel protein diet to your dog for at least eight weeks. This is called a food trial. It is essential not to feed our dog anything else during this trial, including treats and flavored medications. It may take the entire eight weeks to see a difference, so do not stop early. These foods are available by prescription from your veterinarian. Once the dog has ceased showing allergy signs, your veterinarian may have you slowly add in new proteins and foods to see what triggers the dog’s signs. Beef, chicken, and dairy are the most common food allergens in dogs [Reference 1].
If you cannot see your dog’s veterinarian immediately, you can try changing their food and seeing if the signs of food allergy resolve. However, many over-the-counter foods may be contaminated with unknown allergens, and guessing about different proteins can be expensive and time-consuming. View more pictures of dog skin allergy rashes with veterinarian advice.
Disclaimer: This content is not a substitute for veterinary care. Always consult with your vet for health decisions. Learn more.
4. Red rashes & hair loss from Mange (dog mites)
There are two main types of mange that affect dogs, demodectic and sarcoptic. Demodectic mange is caused by the Demodex mite and most commonly causes patchy hair loss in younger dogs. This condition is not itchy and not contagious. Sarcoptic mange, caused by Sarcoptes mites, is very itchy and is contagious to both other animals and humans.
Typical symptoms include:
- Redness, inflammation, and thickening of the skin.
- Intense itching and scratching.
- Hair loss, typically starting around the face, ears, and paws.
- Formation of scabs, crusts, or sores on the skin.
- Presence of mites or their eggs on the skin or in fur.
Diagnosing mange in dogs involves a veterinarian scraping the hair follicles and examining the scraping under a high-power microscope. Demodex mites are fairly easy to find, while Sarcoptes mites may not be seen. Treatment will include medications to kill the mites, as well as antibiotics for secondary infections and pain. Costs vary from $100-$300.
Mange must be diagnosed and treated by a licensed veterinarian. Home remedies are dangerous and ineffective. Learn more about Mange (Dog Mites).
5. Red skin issues from bacterial infections
Bacterial infections often cause redness, pustules, and discharge. You may also notice your dog itching, chewing, or excessively licking. In the picture below, a bacterial infection caused redness (erythema), crusts, scaly flakes, and mild hair loss.
6. Ringworm’s red spots
There are multiple fungal infections, but the one that worries most pet owners is ringworm (caused by Microsporum species). Despite the name, ringworm is not, in fact, a worm. Ringworm is a fungal infection that is contagious between animals and humans. The lesions are typically red, and circular and lose hair in a concentrical widening outwards. The very outer ring is often scaly. Dogs may have one lesion or up to hundreds. See our article with pictures of ringworm in dogs.
Treatment of ringworm will depend on the size and number of lesions, as well as the dog’s overall health. Typically oral medications, topical creams, and shampoos will be prescribed. Costs range from $100-$300.
Owners that suspect ringworm may try treating the lesions with an over-the-counter antifungal cream, but be careful as this may not be effective, and it is not a good idea to treat a lesion unless you are sure you are treating the right thing. Not seeking professional help right away may result in unneeded suffering for your dog, a worsening of their condition, and the spread of contagious disease to others.
WATCH: 3 Important Tips To Care For an Old Dog [VET VIDEO]
Related post: skin infections in dogs.
7. Other common causes of red skin issues or rashes in dogs
Dogs who are having an issue with blood clotting, whether from exposure to a toxin such as rat poison, or due to an autoimmune disease, may bleed into the area under the skin. These lesions are classified by their size and appearance but can appear as small red spots under the skin, as shown in the picture below. This condition is always an emergency and the dog should be taken to a veterinarian urgently.
Related post: Best Creams and Home Remedies for a Red Rash on a Dog
Signs that your veterinarian needs to look at your dog
If your dog has red skin, they are likely uncomfortable. Allergies should be addressed with your vet as soon as possible, but are not typically an emergency. An exception would be an anaphylactic allergic reaction where the dog has hives, facial swelling, and difficulty breathing. Bleeding under the skin points to a serious health issue and is always an emergency.
How much will it cost to diagnose a red skin issue at the vet?
Because the possible causes of red skin in a dog vary widely, the costs for diagnosis do as well. Your dog may require a simple examination and consultation along with medication or a food trial. Others may require allergy testing, blood work, skin scrapes, cultures, and other diagnostics to pinpoint the root causes of their red skin. Costs will typically range between $100-800, but are highly variable.
Related post: pictures of 21 common dog skin issues in dogs.