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Why Is My Dog or Cat Loosing Its Hair ?

Hair Loss Problems in Dogs And Cats












You might also want to read my article on flea-bite and other allergies. You can view it here

Or another one on lick (acral) dermatitis which you can view here
If the problem is hormonal, you may want to read about hypothyroidism here
If the problem is a "blown" coat, you can read about alopecia X here
If you are considering giving your dog Atopica, go here
If you are thinking about allergy tests for your pet, go here
If you are thinking about trying Apoquel, go here
For Cytopoint, go here

Ron Hines DVM PhD

Hair loss is one of the most common problems that bring pets to animal hospitals. There are an enormous number of possible causes for hair loss. I am going to go over a few of the more common ones and explain how veterinarians might go about deciding which one of them it is.


When your pet with hair loss comes to a veterinarian's office for the problem, these are some of the the observations and questions
that will probably be asked

What is your pet's age? Young pets often loose hair for different reasons than older ones.
What breed is your pet ? Certain breeds are prone to specific causes of hair loss.
How long has the problem been present and has it occurred before?
If it occurred before, how was it diagnosed and treated the last time? Was that treatment effective?
Is it a single patch that is affected or is it a generalized skin problem?
Is it on the trunk of the body itself or on the face or limbs?
Is the hair missing or broken or chewed off short?
Is the area itchy to your pet?
Is the hairless area raw and inflamed?
Is it dry and crusty?
Are the areas a particular shape?
What other pets do you have? Are any of them also affected?
What do they feed your pet?
What changes have occurred in your pet’s environment or life recently ?
Are you also itching?
Do the webs of your pet’s feet itch? Is the hair there discolored?
Does your pet also scoot?
Are fleas or flea dirt present?
What do you bathe your pet in and how often?
Is yours an emotional, nervous or easily frightened pet?

What medications worked or did not work if the condition was treated in the past ?

What are some of the most common causes of hair loss that veterinarians encounter ?

Flea-associated dermatitis

Read more about this here. This is a very common problem in all of the Southern USA. Even a single flea can cause this problem in some dogs and the flea and the waste it may leave behind on the pet's body can be very tough to find. This is particularly true in dark haired pets.

One give-away is the distribution of the problem. For reasons unknown, fleas prefer the area just anterior to the base of the pet's tail. A brittle, broken hair coat in this area with a characteristic musty (seborrheic) odor and/or the presence of pepper-like granules that stain rust colored when dampened on a wet paper towel are sure signs of flea involvement. So are the presence of the most common tapeworm's segments surrounding the animal's anus or on its stools.

In other cases, the bite of a single flea will set off itching of the entire body – but especially the webs between the pet's toes. Those pets have a flea-bite allergy. Read more about that here. Eventually, bacteria and yeast become involved. The best treatment is to apply advanced topical flea-control medicine such as Advantage®, Frontline®, or Revolution®. Oral flea control medications work well too. Read about them here. But I prefer to use topicals when they do the trick. The cheap stuff you see in supermarket pet isles doesn't work.

Canine and Feline Atopy (Allergy)

This is itching caused by general allergies. Although fleas are almost always included in the list of things that affect allergic pet, pollens, molds and other things in the are cause itching and scratching in these pets as well. That pet's scratching causes it's hair to break off or fall out. If you have allergies, it is your nose and respiratory tract that gets irritated. But in dogs, it is their skin that becomes itchy. Cats can go either way - itchy skin or respiratory problems.

Unfortunately, antihistamines that are moderately effective in humans are much less so in our pets. There is no full cure for pets that are allergic to things they breathe or come in contact with. If you move to a new area of the country, your pet will be better for a while. But then it will become allergic to new things.

Canine and Feline Atopy is an inherited disease. It occurs in families of dogs and cats. If your pet has the problem, one or both of it parents did too. Pets are generally a year or so old when the scratching begins. The younger in life it begins, generally the more severe the problem becomes.

Eventually, bacteria and yeast invade the broken skin and the pet develops a musty odor. Treatment will make the problem more bearable to the pet - but it will not cure it. Treatments include antihistamines, soothing topical shampoos used weekly or biweekly, soothing anti-inflammatory topical ointments, bathing agents that keep bacteria and yeast in check and tranquilizers that lessen itching.Some owners even resort to mechanical collars that prevent chewing.

I am not a believer in the accuracy of blood-sample-based allergy testing. Traditional skin testing - as a human allergist would perform on you - is somewhat more accurate. But avoiding the many things that most pets become allergic to is rarely possible. Two newer medications are available that block allergic itching. Read about Cytopoint® here and Apoquel® here. I am not a fan of Atopica® which will also stop itching, but you can read about it here.

When all else fails, judicious use of cortisone-like products are our last defense. All cortisones (corticosteroids), like prednisone, have serious side effects. They are safest when they are applied to the skin as a mist, spray or lotion rather than taken internally. When they must be given orally , we try to give them at the lowest possible dose, as infrequently as possible. I do not recommend that they be given by injection for itching. The only exception might be in pets that are very difficult to give oral medications to. None of the steroids in pill or tablet form are particularly unpleasant tasting.

Hot Spots (Pyotraumatic Dermatitis)

This is a problem in, long-coated thick-haired breeds of dogs with rich oily coats. Usually these pets are 2 years old or older. Often, these are northern dogs, which have recently moved to southern climates. Golden Retrievers, Cocker Spaniels, Spitz, Samoyed, Chows, Akitas, and Pyrenees are some breeds that come to mind as over- represented among dogs with this problem. It is a rarer problem in cats and when it does occur in cats, it is often during or after major emotional stress. Pets with hot spots develop Intense itching in one or two isolated area of the trunk of the body. These areas becomes inflamed, raw and oozy with serum within a matter of hours. Some people think that an insect bite starts the problem. But I have never seen an insect bite in a hot spot area. I believe that the nerves of sensation in the area are somehow falsely stimulated.If the dog is muzzled or restrained during the initial period, the problem passes in 24-72 hours. If not, when the area is painful enough, the pet will cease biting at the area. Hot spots may reoccur every 4-8 months or never again. It is treated with a topical astringent/cortisone agent and often with an injection of anti-inflammatory drug as well. Antibiotics are generally not required. Because the pets get better after almost any form of veterinary treatment, I am not certain that any of those products are the reason the problem goes away.

Acral Lick Granulomas

Somewhat like a chronic hot spot. Read about them here.

Demodectic and Sarcoptic Mange

The first form, demodectic mange, is a disease of young dogs or those that have become immunosuppressed. This parasite, which lives in hair follicles of your pet's skin is common in low numbers in all dogs, it only becomes a problems when it begins to multiply out of control. This is a genetically-based disease that is caused by the pet's defensive cells (immune cells) ignoring the parasite.

Demodectic mange runs in certain bloodlines and breeds of dogs. It causes no itching but the involved areas are subject to secondary bacterial infections. Until recently, veterinarians treated this form of mange with amitraz (Mitaban®) dips or with ivermectin (ivermectin can be very toxic to cats and some collie and herding-type dogs). More recently, it was found that the oral flea control medications for dogs cure demodex disease as well. (ref) Small (dime-size) demodectic mange lesions often disappear without treatment as the pet's own immune system learns to recognize and kill the parasites.

Sarcoptic mange is due to a transmissible mite that burrows through the layers of the pet's skin causing intense itching. Read about it here. This parasite passes from pet to pet through direct contact and contaminated bedding. It will attack humans as well, where it earned the name "The Seven Year Itch". It is easily cured in your pet with ivermectin given orally or by injection. Selamectin (Revolution®), flea and heartworm control product will also eliminate and prevent sarcoptic mange, as will the products that are effective against demodectic mange.


Read more about ringworm here. Ringworm is a fungus – not a worm. It is transmitted by contact or through some object – such as grooming clippers and combs. It is not itchy. It is often circular or oval in shape. The hair in the area is broken off – due to the fungus weakening the hair shafts. It is often located on a leg, ear or the face. It often glows in the dark under an ultraviolet light source (Woods lamp). It may spontaneously disappear (especially in cats). But the animal often remains a silent carrier of the fungus. It is usually treated with oral fluconozole or itraconazole. Topical iodine preparations inhibit the fungus but take much longer to be effective. Griziofulvin is effective, but it is no longer frequently used. Ringworm can spread to you - so wash well after handling pets with ringworm. Preferably, wear gloves. Do not let your children play with or fondle pets with this problem.

Nervousness Or Stress/Boredom Induced dermatitis

High strung breeds and pets tend to react to itchy skin problems more forcefully - damaging their skin more in the process. So do pets with time on their hands. This is more common in dogs than cats and more common when both members of a couples work and the pet must be left alone.

Older, obese and lame pets also tend to over groom more. Once these habits ares established, they are hard to cure. Some treatments include topical bitters mists (which almost never work) and relieving boredom in any way possible. Some pets do better in a fenced yard while their owners are away. Others do better in air conditioning or with the TV left on. Anti-obsessive/compulsive drugs such as chlomipramine sometimes help. Making the licked area inaccessible with taping and a protective covering always works well. But when the protection is removed, the problem generally returns.

When this problem occurs in cats, stress between multiple cats is a common underlying cause. A cat pheromone product called Feliway sometimes helps in these situations (However, a 2017 study did not find Feliway-type products very helpful in combating stress in cat shelter situations [ref]). When it occurs in a non-stressed cat, another internal, underlying health problem is usually present.

Food Allergies

Food allergies are over-diagnosed in pets. Food intolerances causing digestive disturbances are much more common. Pets with food allergies itch all over, all the time. Pets that are allergic to food or food-treat ingredients have cells in their skin that release histamine when the pet eats certain proteins. The best way to diagnose this problem is to place the pet on a 60 – 90 day hypoallergenic trial diet and feed no treats. These special diets either contain ingredients that the pet has never eaten before; or they contain protein molecules that have been made so small that the pet's immune system can no longer recognize them. These modified protein diets can be fed indefinitely. Diets prepared from novel (new) protein and carbohydrate sources (like duck and potato) may help for 6 months to a year. But eventually, the pets become allergic to them too and a new formula must be tried.

Non-skin Health Issues

Your pet's hair coat is also a mirror of the health of its internal organs. So diseases of almost any organ or gland can cause poor hair coat quality, broken hairs and a thin coat. I know of none that cause itching directly. Examination of blood-test results are the way your veterinarian usually discovers these root causes.


No matter what the underlying cause of itching is in your pet, boredom, inactivity and unoccupied time will make it worse. It is not unusual for the underlying cause of itching to be eliminated by your veterinarian only to have the pet continue to scratch and lick itself from force of habit. To minimize this, give your pets plenty of distractions. Hidden food morsels, toys and chew toys, walks, play time, other pets, and view through a porch, kennel or window all take your pet's mind off of its skin. Try these distractions, and others you might think of, before you resort to tranquilizers and mood-altering medications.