Feline Fur-Mowing

WHAT IS FUR-MOWING?

Nadia Holly Fur MowingIn short, the cat is licking off all his or her hair. Often the belly is nearly as bald as if it were shaved. Sometimes a Mohawk of normal fur makes a stripe down the back, surrounded by bald spots on either sides. Sometimes it is the lower back itself that is bald. Often the owner thinks the hair is falling out. Often the veterinarian wonders if the problem is really psychological. The good news is that most cats that mow do not have mental illness. The answer is almost always much simpler: cats lick off their hair because they itch and it is important not to launch into treatment with psychoactive drugs until causes of itching have been ruled out. For example, in a recent study of 21 cats referred to the University of Guelph Veterinary Teaching Hospital Behavior Service because of excessive hair licking, only two cats were ultimately believed to have a psychological reason for hair licking, sixteen cats were found to have a true medical basis for itching, and three cats had both.

But let us go back to the beginning: the cat with a big bald spot.

HOW DO WE KNOW THE CAT’S HAIR IS NOT SIMPLY FALLING OUT?

A truly observant owner will actually see the cat licking the area but cats, being private creatures, often do their licking when no one is watching. One might wonder why it is that the itchy dog creates moist, red, oozy, unpleasant looking “hot spots” while the itchy cat cleanly licks away only the hair leaving the skin itself not in the least bit scabbed, red, or even raw. This turns out again to be the feline nature: refined. Private and refined.

The truth is simple:  that there are only a few rare diseases that actually will lead a cat to lose hair in great patches but, if someone still remain skeptical, there is a test called a “trichogram”which will confirm the answer.

 

A trichogram involves the plucking of a hair from the affected area. There are most likely at least a couple of hairs in the area but if there are not, hairs from the margin may do as well. Under the microscope, the end of the hair is flat from having been broken off. A hair shedding from the skin will have a tapered, natural end

hair with a normal tip

chewed off hair tip

hair with a normal tip

chewed off hair tip

OBVIOUS REASONS TO ITCH

Before embarking on a large battery of tests it is important to rule out obvious causes of itching. The easiest such cause to rule out is a flea infestation. If live fleas or flea dirt are seen in the coat, then the answer is obvious. If fleas are not seen in the coat, one cannot assume there are no fleas to be found particularly if the lower back is one of the balding areas. Cats are very efficient groomers and can lick away all traces of fleas so we may need to go by the pattern of hair loss (lumbar, possibly including scabbing around the neck), seasonality of the hair loss, and response to flea control. The first step is virtually always going to be insuring immaculate flea control.

FIGURING OUT THE NOT-SO-OBVIOUS CAUSES

A step-by-step process is important in ruling out hidden allergies, parasites, and even ringworm.

First, the non-invasive tests are performed:

  • Several skin scrapes (ideally, if feline Demodex mites are present, they will be found, though sometimes this is not the case. Notoedres or Cheylitiella mites generally produce more obvious skin damage).
     
  • A fecal flotation test for parasites (occasionally intestinal worms will create itching in the skin. Also, Demodex mites sometimes show up in the fecal test rather than the skin scrape because the cat has been so efficient at licking them up.)
     
  • Checking the ears with otoscope (even if the itchy areas are distant from the ears sometimes ear mite travel out of their normal homes in the ear canal).
     
  • Inspection of the cat with a Wood’s light (a fluorescent light – hairs infected with ringworm fungus often glow in the dark) plus a culture for ringworm. The culture will require approximately 10 days to grow.
     
  • Thorough inspection of the cat for evidence of fleas. (The only evidence may be the mowing pattern on involving the lower back). Cats with fleas should have a seasonal aspect to their mowing (i.e. mow primarily Spring and Summer) but there are many geographic areas where seasonal climate differences are not dramatic enough to use this as a diagnostic point.

If these non-invasive procedures have not yielded the answer then there are some choices to make in the approach. Your veterinarian may have a preference as to the order but the following are several possibilities that might be chosen, each answering different questions:

SKIN BIOPSY

This can likely be accomplished the same day as the initial visit and yield results as soon as 48 hours later. It is important that the samples be read by a pathologist who specializes in reading skin tissue so your veterinarian may need to request a special expert or use a special laboratory. In this procedure, a local anesthetic is injected into selected areas of skin and an instrument called a “punch biopsy” (which resembles a tiny cookie cutter) is used to remove small plugs of skin. The cat will probably have a stitch in each area where a sample was taken.

  • The absence of abnormalities in the tissue virtually confirms a psychological (the more correct term is “psychogenic”) cause of the mowing. (In the Guelph study mentioned above, 3 cats had both psychogenic mowing AND medical disease).
     
  • Ringworm can be confirmed more quickly than with the culture (the culture sometimes picks up ringworm when the biopsy does not, though, so doing both tests is very reasonable.)
     
  • The presence of allergy should be readily identified (though it will not be possible to tell what type of allergy: insect-related, food, or airborne).

FOOD ALLERGY TRIAL

Food allergy commonly produces non-seasonal mowing in cats. This mowing may or may not be responsive to cortisone-type medications. The only way to determine if the cat has a food allergy is to put the cat on a trial diet that the cat could not possibly be allergic to (either a hydrolyzed protein diet or a novel protein diet) for a long period of time and see if the mowing stops. How long? Many cats respond in 3-4 weeks but some require a good 2 months, so to be sure, a 2 month trial is typically recommended.

  • The advantage of this test is that it not only can make the correct diagnosis, it also provides treatment.
     
  • There are two important disadvantages of this test. The first is that no results will be available for potentially 2 months. The second is that many cats are picky about the diet food and it may be hard to find one the patient likes. If the cat goes outside, it will not be possible to do a food trial as it will not be possible to control what the cat eats.

See our related page on Food Allergy for more details.

FLEA CONTROL TRIAL

As mentioned immaculate flea control is very important in ruling out fleas as a cause of the mowing.  To be sure about fleas, a reliable flea product such as Frontline, AdvantageRevolution, Promeris or Vectra. If Advantage or Frontline is used, these products must have been purchased from a veterinary office to be reliable. Advantage and Frontline applications tend to wane in the last 10 days of their use allowing fleas to bite before they are killed by the product. For this reason, to maintain adequate skin levels of product for the trial, some experts recommend using the product more frequently than labeled by the manufacturer. Using flea products extra frequently over long time periods will ultimately create a resistant flea population but for a short period (6-8 weeks) for the trial this is reasonable. Your veterinarian will instruct you.

  • This trial only answers the question of whether or not the problem is flea-related and it takes approximately 2 months to do so.
     
  • To properly determine if there are fleas in the household, a flea comb should be used, ideally on a pet that is not itchy or mowing. Flea combs have special narrow teeth that can trap live fleas and flea dirt.

IN AN EFFORT TO SAVE TIME, THE FOOD TRIAL AND
FLEA CONTROL TRIAL CAN BE DONE AT THE SAME TIME.

IF, AFTER TWO MONTHS, THE CAT HAS NOT RESPONDED,
ANOTHER DISEASE / CONDITION CAN BE PURSUED.

IF THE CAT HAS RESPONDED, AFTER TWO MONTHS,
THE CAT CAN BE CHALLENGED WITH THE ORIGINAL DIET.
IF MOWING RECURS (WHICH GENERALLY TAKES
TWO WEEKS ON THE ORIGINAL DIET AT THE MOST),
THEN FOOD ALLERGY IS THE ANSWER.

IF THE CAT CONTINUES NOT MOWING AFTER THE ORIGINAL FOOD
IS INTRODUCED, THEN THE PROBLEM WAS FLEA RELATED.

DEMODECTIC MANGE DIPPING TRIAL

LymdypDemodectic mange mites can be difficult to find in the cat. One option is to treat for them and see if the mowing stops. The treatment involves 6 weekly dips using lime sulfur which is particularly smelly and will stain clothing and jewelry.

  • This trial is often left as one of the last as it is fairly unpleasant and the parasite is not that common. This is, however, likely to be the only way to rule this parasite out as the cause once and for all.

STEROID TRIAL

For this trial, patient receives some kind of cortisone-type treatment for 3-4 weeks. At the end of that time one can tell if the mowing has improved (and the mowing is said to be “steroid responsive”) or the mowing has not improved at all (and the mowing is said to be “steroid non-responsive.”) Knowing whether or not the mowing is steroid responsive helps classify possible causes. For example, seasonal steroid responsive mowing is most likely to be from fleas (technically allergy to the flea bite) or an airborne allergy. Non-seasonal steroid responsive mowing is most likely going to be from a food allergy. Steroid non-responsive mowing is most likely to be from a parasitic or fungal problem or a food-allergy. Many experts like to do the steroid trial at the beginning of the work up while others wait until more results are in.

  • The use of steroids can make ringworm worse so many experts prefer to hold off steroids until the ringworm culture is finished.
     
  • The use of steroids will interfere with skin biopsy. If biopsy is being considered, it should be performed prior to steroid use.
     
  • The use of steroids will interfere with food trials or flea control trials.
     
  • The steroid trial is very inexpensive and one of the least labor intensive tests that can be done.

WHAT IF THE CAT REALLY HAS MENTAL ILLNESS?

This is generally called “psychogenic” mowing. We don’t imply that we know if cats are licking out of obsession or out of anxiety or even boredom. We simply say that there is nothing wrong with the skin. Psychoanalysis is generally unnecessary; the approach is aimed at environmental enrichment. This means the cat gets more toys, more games (feeding in a different location daily to create a hide-and-seek sort of cat entertainment), more attention. Clomipramine, has both anti-anxiety as well as anti-compulsive effects and has been helpful though it does not come in a convenient feline size and may have to be compounded. Amitriptyline has both anti-anxiety properties as well as anti-histamine properties and is sometimes used to cover both the medical and psychogenic causes of mowing simultaneously.

Page last updated: 11/27/10