Why Is My Dog So Itchy? Common Causes of Canine Pruritus

It’s the middle of the night, and suddenly you hear jangling. It’s not Santa, though – it’s just the dog, scratching her neck again. An hour later, she’s at it again. And an hour after that. Whether it’s sleepless nights from constant jangling and thumping or you’re fed up with walks being punctuated with scratching, it might be time to ask, “Why is my dog so itchy?”

As a vet, I’ve seen plenty of dogs with itchiness – which is medically termed ‘pruritus’ – and my own dog is pretty itchy too. While occasional scratching is normal, if you’re noticing frequent licking, chewing, scratching, or headshaking, it’s probably a sign of an underlying disease. In this article, I’ll cover the common causes of itchiness in dogs, how to tell what’s causing your dog’s pruritus, and when you need to schedule an appointment with your veterinarian.

Fast Facts on Canine Pruritus

• Itching in dogs is very common, and vets like me deal with this on a daily basis
• Allergies and parasites (usually fleas) are the top causes of canine itchiness
• Constant scratching isn’t just annoying – it can cause infection and sore skin
• It’s very hard to tell different causes of canine pruritus apart – you’ll likely need help from your veterinarian, or even a specialist canine dermatologist.
• Although not all causes of itching can be treated, relief is possible!

Why Dogs Itch: The Big Picture

There are loads of reasons dogs can be itchy. And although where they itch (ears, feet, or all over) can give us some clues about why your dog is so itchy, it’s not an exact science. Special nerves feel the itch, and the dog scratches (or licks or chews) in response. The only problem? When it’s constant, their claws and teeth break the skin, letting in bacteria, allergens, and yeasts. Plus, the damaged skin becomes inflamed, making your dog even itchier. We call this the itch-scratch cycle.

This cycle can confuse the clinical picture when it comes to causes. Dogs can have underlying allergies and an infection on top. Or fleas can complicate the picture. Or, to confuse things further, dogs can be allergic to fleas! In the next section, I’ll go through the most common causes of itching – although of course there are other less common causes too.

Why Is My Dog So Itchy: Common Causes of Itching in Dogs

1. Fleas and Parasites

Fleas are a very common cause of dog itching, but your dog doesn’t have to have these little parasites for them to be the cause. You see, dogs can also be hypersensitive to flea saliva, meaning just one bite sets them off scratching like they are going for a world record. It’s similar to how some humans react badly to mosquito bites. We call this ‘flea allergy dermatitis’ (FAD), and it’s a very common cause of itching in dogs.

There are plenty of other parasites that cause itching, too - mites and lice can both cause severe itching to unlucky pets harboring an infestation.

The nice thing about parasites (there’s something you never thought you’d read!) is that they are easy enough to diagnose and treat, meaning this cause of pruritus is less likely to cause ongoing problems for your pets. Make sure all the animals in the house are on consistent flea control, and check you’re using the product as often as necessary to make sure there are no gaps in cover – your vet can explain which product is the best option for your pet.

2. Environmental Allergies (Atopy)

Environmental allergies (aka atopy or atopic dermatitis) are unfortunately very common. If this is the reason your dog is so itchy, it’s because their immune system is over-reacting to pollen, dust mites, or molds in the air, making them itch furiously. In fact, it’s the doggy equivalent of eczema. Some dogs react to just one allergen; others are allergic to just about everything – and what they’re allergic to will often determine how badly they itch and how frequently it’s a problem for them. I once saw a dog we eventually decided was allergic to Christmas trees, as he only itched in December! That dog was lucky, though - the most common allergies are to the dust mites that live in your house, meaning many unlucky dogs itch year-round. I use the word ‘itch’ loosely here – recurring ear infections, anal gland problems, and foot licking are very common symptoms of atopy in dogs.

While environmental allergies can’t be cured, there are lots we can do to manage them. From allergy testing and immunotherapy (which does carry a very small chance of a cure) through to medicated shampoos, injections, and daily medication, there are many options for your vet to discuss with you if your dog is diagnosed with atopy.

3. Food Allergies or Sensitivities

Food allergies are to blame in only about 20% of itchy dogs, but they’re the thing everyone focuses on when we talk about allergies. I suppose it’s easier to think of an allergy being something your dog has eaten, rather than something they were unlucky enough to be near while on a walk! Still, food allergies do exist in dogs and do need to be ruled out when considering itchy dogs. Although food allergies can cause itching as their only symptom, these dogs often have chronic or recurrent tummy upset.

Contrary to popular opinion, most canine food allergies are to proteins such as chicken and beef, with only a very few dogs being allergic to grain, and gluten intolerance only being found in a very few family lines. Dogs become allergic to foods over time, so even if they haven’t had a new food recently, food allergies could still be the reason your dog is itchy. Unlike environmental allergies, it’s possible to avoid the allergen once you know what it is, which can make your dog’s life a whole lot more comfortable, but don’t get sucked into buying a useless allergy test (they don’t work for food allergies) or switch their diet hoping you’ll hit on the right food out of sheer luck – a vet-supervised strict diet trial followed by controlled exposure is the only way to diagnose food allergies.

4. Skin Infections (Bacterial or Fungal)

Skin infections cause some of the worst pruritus we vets see, but they’re always secondary to something else. Maybe your dog has underlying allergies, and skin inflammation and constant itching allow the infection to take hold – any flare-up in a previously controlled allergic dog holds suspicion for an infection. Or maybe parasites have damaged the skin’s protective barrier and let the bacteria and yeasts in. Or maybe they have an underlying hormonal imbalance – like hypothyroidism or Cushing’s disease – that means their immune system just isn’t strong enough to keep infections at bay. As well as itching, you might notice a sour smell, warm, red skin, or excessive greasiness.

Whatever the underlying cause, the offending bacteria and/or yeast will set up shop and won’t leave without a serious kick out the door. You’ll need vet-prescribed medicated shampoos or even antibiotics, depending on how deep the infection is.

5. Dry Skin or Overbathing

Shampooing dogs is good. Overbathing is bad. Frequent baths strip natural oils, leading to dry skin, which can be itchy. Moisturizing shampoos and diets high in omega-3 fatty acids are worth looking at if this could be a cause of your dog’s itching.

6. Stress and Behavioral Causes

While stress can’t actually cause itching, it can cause dogs to lick repeatedly as though they’re itchy. Licking is inherently calming for dogs, so this can feel soothing – except it can make skin sore, and even allow an infection to set in. If your dog is the anxious type, or there have been recent changes in their life that could have triggered some stress, consider a behaviorist consultation. And try to redirect the licking to something else – a lick mat is a good idea!

How to Tell When It’s Serious

Frequent scratching or constant licking is a red flag that something’s not right – but when should you head to the vet? While itching is rarely life-threatening, it can be extremely uncomfortable, impacting your dog’s quality of life. I’d recommend heading to the vet if you notice:

• Persistent scratching, chewing, or licking (noticed more than twice a day)
• Sore skin, redness, or scabs
• Head shaking and scratching at the ears
• A foul smell to the skin

Your vet can help you diagnose the cause and get suitable treatment to help your dog feel more comfortable.

Diagnosis: How Vets Find the Cause

You may be at the vets to find the answer to “why is my dog so itchy?” but there’s never a simple answer. First, your vet will do a thorough physical exam and take a detailed history of your dog’s itchiness and other health concerns. The first step is to rule out parasites and infections, so they usually take some samples to check in the lab.

Once those are ruled out, a food elimination trial is the best bet – while food allergies are relatively uncommon, they do need ruling out before your vet can consider other diagnoses, like environmental allergies. Your vet may also recommend allergy testing at this step – while these don’t work well for food allergies, testing your dog’s blood for reactivity to environmental allergens works well. Even more accurate is an intradermal skin test, where small amounts of allergen are injected under the skin, and your dog is monitored for over-reaction. Finding environmental allergies on these tests doesn’t rule out food allergies, though, and a diet trial is still recommended as some unlucky dogs will have both!

Treatment and Relief Options

Parasites and infections can usually be cleared completely, bringing fast and effective itch relief. You might be given prescription flea control or medicated shampoo, and once the treatment is underway, your dog will usually feel a lot better.

Allergies are a little more complex. While avoiding the allergen is ideal, it’s rarely practical, and most allergic dogs need some sort of regular medication. There are plenty of options, including an itch-blocking injection, daily medications, or immunotherapy treatment (which aims to teach the body to tolerate the allergen). Many people want to use human antihistamines for their dogs – I don’t recommend this unless your vet suggests trying it, as they rarely help and can complicate the clinical picture. Similarly, you should avoid human creams, which can be toxic when ingested, and instead stick to vet-recommended allergy relief.

In all cases of recurring itch, including dry skin, moisturizing shampoos and supplementing omega-3 fatty acids can help the skin to be healthier and better able to fight off allergens, parasites, and infections.

Home Care Tips for Itchy Dogs

If you’re here on the internet, you probably aren’t going to like my first bit of advice, which is to schedule an appointment with your veterinarian. You can’t start treatment until you know what’s wrong, and until then, anything you try could be a waste of money.

That said, there are some general things that most owners can try while they await a diagnosis:

• Make sure your dog has a high-quality, complete and balanced diet, and supplement Omega-3s for optimal skin health
• Check out your bathing routine – unless otherwise recommended by your veterinarian, every 1-2 weeks is sufficient
• Wash your dog’s feet down after a walk to remove allergens – they can also wear dog coats and boots out on walks, which should be washed regularly
• Buying smaller bags of dry food and/or freezing the food in small portions can help to discourage storage mites from setting up shop
• Double check their flea control – they need continuous protection year-round if they’re prone to being itchy
• Try an air purifier to reduce allergen load in the house

FAQs

Conclusion

Itching is annoying to witness, but it’s outright distressing for your dog. And the more they itch, the itchier they’ll become – that itch-scratch cycle has a lot to answer for! The number one mistake dog parents make is to try treating their dog’s itchy skin at home first, but this wastes time and money – getting the root cause diagnosed and treated is the best way to get your dog lasting relief. Sometimes, this is best done by a canine dermatologist – while they’re more expensive to visit, it’s often cheaper in the long run because they deal with these problems day in, day out, and will be most up to date about the current tests and treatments, meaning they can get your dog comfortable faster, with fewer false starts.

Bio

Dr Joanna Woodnutt BVM BVS MRCVS

After graduating from the University of Nottingham, Dr Woodnutt initially worked in companion animal practice in the Midlands, UK, where she developed a love for chronic conditions. Since moving home to Alderney in the Channel Islands, Dr Woodnutt does less clinical work, and now mostly writes articles about pets – including writing a column for the local newspaper, writing articles to help educate other vets, and writing for several websites across the internet.

Feature image: Istockphoto