Why Is My Dog or Cat Loosing Its Hair?
Hair Loss Problems in Dogs And Cats
Ron Hines DVM PhD
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Hair loss is one of the most common problems that bring pets to my animal hospital. There are an enormous number of causes for hair loss. I am only going to go over a few of the more common ones and how I go about deciding which one it is.
When a pet with this problem enters my office, I make a few simple observations and ask a few simple questions:
Is this a young or an old pet?
What breed is it?
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?
Is it a single patch or on various areas?
Is it on the body itself or on the face or limbs?
Is the hair missing or broken or chewed off short?
Is the area itchy to the pet?
Is the hairless area raw and inflamed?
Is it dry and crusty?
Are the areas a particular shape?
What other pets do the owners have?
What do they feed this pet?
What changes have occurred in this pet’s recent past?
Are the owners themselves itching?
Do the webs of the pet’s feet itch?
Does it also scoot?
Are fleas or flea dirt present?
What is the pet bathed in?
Is this an emotional or nervous pet?
What medications worked or did not work if the condition was treated in the past?
What follows are some common causes of hair loss, presented in order of frequency that I see them in Florida and Texas:
1) Flea-associated dermatitis:
This is a common problem in all of the Southern USA. Even a single flea can cause this problem and the flea or its waste can be very tough to find. This is particularly true in dark haired pets. You can read more about the problem in another article on this site on fleas.
One give-away is the distribution of the problem. For reasons unknown to me, fleas prefer the area just anterior to the base of the 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 a wet paper towel are sure signs of flea involvement.
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. Eventually, bacteria and yeast become involved. The best treatment
is to apply a topical flea-control medicine such as Advantage Frontline
or Revolution. The stuff you see in the supermarket doesn't work.
This is itching caused by allergies. The 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 so effective in us are much less effective in our pets. There is no cure for pets that are allergic to things they breathe. 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.
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 impossible to give oral medications to.
3) 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.
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 them are the reason the
problem goes away.
The first form, Demodectic mange, is a disease of young dogs. This parasite, which lives in hair follicles of the skin of all dogs, begins to multiply out of control. This is a genetically-based disease that causes the pet's defensive cells to ignore the parasite. The mites that are found on normal dogs are kept in check by the pet's immune system.
Demodectic mange runs in certain bloodlines and breeds of dogs and (see article on mange). It causes no itching but the involved areas are subject to secondary bacterial infection. We treat this form of mange with Mitaban (amitraz) dips or with ivermectin. Ivermectin is very dangerous to use in cats and collie-type dogs. Small demodectic mange lesions often disappear without treatment as the pet's own immune system learns to kill the parasites.
Sarcoptic mange is due to a transmissible mite that burrows through
the layers of the pet's skin causing intense itching. It 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
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 treated with fluconozole, itraconazole, griziofulvin and topical iodine preparations. It can spread to you - so wash well after handling a pet with ringworm.
6) Nervous or Stress/Boredom Induced dermatitis:
This is quite common in terrier and other high strung breeds. It is more common in dogs than cats and more common when both couples work and the pet is left alone.
It also occurs due to persistent licking of an area in older, obese or lame pets. Dogs with this type of problem are usually adults.
Once the habit is established, It is hard to cure. Some treatments include topical bitters mists (which almost never works) 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.
When this problem occurs in cats, stress between multiple cats is the 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.
7) Food Allergies:
Pets with this problem 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.
Your pet's external hair coat is also a mirror of the health of its internal body. So diseases of almost any organ or gland can cause poor hair coat quality. 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.