Dog shedding: normal coat blow versus real hair loss, and what changes by coat type

Quick answer

The question is never how much hair. It is whether the skin underneath is normal and whether the loss is symmetrical.

Shedding is normal and dogs do a lot of it. What separates a heavy moult from a medical problem is not the volume of hair on the floor but three other things: whether the skin underneath looks normal, whether the pattern is symmetrical, and whether the hair grows back.

The trigger for seasonal shedding is day length rather than temperature, which is why a dog living under artificial light in a heated house sheds moderately all year instead of dramatically twice a year, and why moving between climates changes the pattern.

• Look at the skin, not the hair. Redness, scale, odour, thickening, black spots or bare patches change the answer.
• Symmetrical loss on both flanks, both thighs or the tail is a hormonal pattern, not a moult.
• Hair that is being scratched or chewed out is a different problem from hair that is falling out.
• A double coated dog should never be shaved to reduce shedding. It does not help and it damages the coat.
• Hair loss that follows an illness, a season, whelping or an anaesthetic by several weeks is often a delayed shed, not a new disease.

Decide in 60 seconds

How the coat actually works

A dog's coat is not one thing. Guard hairs are the long, coarse, often pigmented outer hairs that shed water and block sun. Undercoat is the short, soft, dense wool beneath them, and it is what provides insulation by trapping still air.

Each follicle runs its own cycle: a growth phase, a brief transition, a resting phase where the hair is held in place but no longer growing, and a release phase where it falls. Because follicles are not synchronised in dogs, hair is normally lost continuously and evenly, and the coat never looks patchy.

Two things synchronise them. The first is season. Changing day length shifts a large proportion of follicles into the resting and release phases at the same time, and the result is a coat blow: undercoat coming out in visible sheets and tufts over a few weeks. Temperature has some influence, but light is the main signal, which is why a dog under household lighting sheds year round at a moderate level rather than twice a year at a dramatic one.

The second is a systemic event. A fever, a serious illness, a general anaesthetic, whelping, or a season in an entire bitch can push many follicles into the resting phase simultaneously. The hair does not fall immediately, because resting hairs are still held in place. It falls when the next growth phase pushes it out, which is typically weeks to months later. That is why owners so often report their dog losing coat long after it recovered from something, and why the timeline confuses people.

Coat type changes the answer

The tools matter less than the technique, but the wrong tool on the wrong coat does real damage. An undercoat rake on a double coat, a slicker used lightly, and nothing with a blade used repeatedly on the same spot.

Double coated breeds. Nordic breeds, herding breeds, retrievers and many others. They blow coat seasonally in large quantities, and the correct approach is to remove the loosened undercoat mechanically rather than to shorten the coat. Undercoat rake, then a bath, then a thorough blow dry, repeated through the moult.

Single coated breeds. Sighthounds, boxers, dobermanns, dalmatians, bull breeds, many small companion breeds. They shed steadily and modestly, without a dramatic seasonal blow, and their short stiff hairs weave into fabric more than fluffy undercoat does. Bare patches in a single coated dog are more obvious and more likely to be significant.

Continuously growing coats. Poodles, bichons, some terriers and their crosses. Hair grows for a long period before shedding, so very little falls out. Instead it tangles with itself and with the undercoat and forms mats close to the skin. These dogs need clipping and daily line brushing, and their problem is matting rather than shedding.

Wire coats. Many terriers, schnauzers and some gundogs. The harsh outer coat is designed to be plucked out when mature, either by hand stripping or by carding. Clipping cuts the harsh hair rather than removing it, and over time the soft undercoat dominates and the coat texture and often the colour change permanently.

Hairless and near hairless breeds. No shedding to speak of, but they need skin care, sun protection and warmth.

When shedding is a disease

Itchy hair loss. If the dog is scratching, chewing, licking or rubbing, the hair is coming out because the dog is removing it. Fleas and flea allergy remain the most common cause everywhere fleas exist, and a single flea can maintain an allergic dog. Atopic dermatitis, food responsive skin disease, bacterial folliculitis, yeast overgrowth and contact reactions all produce itch. Sarcoptic mange is exceptionally itchy, favours ear margins, elbows and hocks, and is transmissible to people, so it deserves separate mention.

Non itchy symmetrical loss. This is the pattern that points at hormones or at a follicular disorder, and the symmetry is the clue. Hypothyroidism classically produces a dull thin coat, loss along the flanks and tail, weight gain, lethargy, heat seeking and a thickened facial expression. Hyperadrenocorticism produces thin skin, a pot belly, muscle loss, panting, increased drinking and urination, and hair that fails to regrow. Sex hormone related alopecia occurs in some entire and some neutered dogs.

Breed specific alopecias. Alopecia X in Pomeranians, chow chows, keeshonds and malamutes produces symmetrical loss of the guard coat with a woolly appearance and darkened skin. Seasonal flank alopecia in boxers, bulldogs, airedales and others produces well demarcated pigmented bare patches on the flanks that come and go with the season and are directly linked to day length. Colour dilution alopecia affects blue and fawn coats, most notably in dobermanns, staffordshire bull terriers and dilute retrievers, and produces thinning and broken hairs only in the diluted colour areas.

Post clipping alopecia. Coat that fails to regrow for months after clipping, most commonly in Nordic breeds. This is a real phenomenon and it is one of the reasons not to clip these coats.

Localised loss. Ringworm produces scaly, often circular patches and is transmissible. Demodex produces patchy loss, often around the face and feet, and is usually not itchy unless it becomes infected. Pressure calluses, injection sites and scars produce loss in one specific location.

Nutritional causes. Genuine deficiency is uncommon on a complete commercial diet but occurs on home prepared diets that have not been formulated properly, and on very poor quality food. Zinc responsive skin disease occurs in Nordic breeds and in rapidly growing large breed puppies and produces crusting around the face and pressure points. Malabsorption from gut disease can produce the same picture with a normal diet.

Anything chronic. Long standing illness, pain, parasitism and liver disease all show in the coat because hair is expensive to make and is the first thing the body economises on.

What to look at, in order

Part the coat and look at the skin, not just at what comes off on the brush. Redness, scale, black spots, a greasy feel or an odour all move this out of the grooming category.

Is the dog itchy? Watch it for a while rather than asking yourself. Scratching, chewing at the feet or flanks, rubbing on furniture, licking one area, head shaking. Itch changes the whole differential list.

Is it symmetrical? Compare left to right. Almost all hormonal and follicular disorders are symmetrical; almost all infections and traumas are not.

What does the skin look like? Part the coat in several places. Look for redness, scale, greasiness, black comedones, thickening, darkening, pustules and circular scaling.

Does it smell? A yeasty or a sour smell means infection.

Does the hair come out easily? Gently take a small tuft between finger and thumb and pull lightly. In a normal coat between moults, few hairs come away. In an active moult, many do, easily and painlessly. Hair that comes out with resistance, or that snaps rather than releases, is different.

Is it regrowing? Look at a bare area over weeks. Fine new hairs are a good sign. Nothing at all is not.

What else has changed? Weight, appetite, thirst, energy, heat and cold tolerance, panting, and the shape of the abdomen. Coat is often the visible part of a systemic problem.

When did it start relative to anything? A season, a litter, an illness, a surgery, a house move, a diet change, a new parasite product, or a clip.

The grooming that actually reduces shedding

Remove loosened undercoat mechanically. An undercoat rake worked through in sections is the core tool for a double coat. It reaches the loose wool without cutting the guard hairs.

Use a slicker lightly and in one direction. Repeated hard passes over the same spot cause slicker burn on the skin.

Be careful with bladed deshedding tools. They work well used occasionally and gently, and they cut and thin guard hairs when used hard or often. If you can see cut hair ends rather than whole hairs with root ends, you are cutting the coat rather than removing shed hair.

Bathe, then dry properly. A bath loosens dead undercoat, and a high velocity dryer blows it out. This is the single most effective way to get through a coat blow quickly, and it is what makes professional deshedding appointments worth the money in a heavy moulting breed.

Line brush a continuously growing coat. Work in sections from the skin outward. Brushing the top of the coat leaves mats forming underneath it.

Groom in short sessions, often. A brief daily session beats a long weekly battle, for the coat and for the dog's tolerance.

Feed a complete diet, and consider omega 3 fatty acids after a vet has ruled out disease rather than instead of doing so.

Control parasites year round. Flea allergy is the most common skin disease of dogs in most regions and it does not require a visible flea.

What the vet will want

What never to do

Never shave a double coated dog for summer or to reduce shedding.

Never clip a wire coated breed if you want to keep the coat texture.

Never assume a bald patch is seasonal. Season causes thinning, not bare skin.

Never treat a coat problem with supplements before it has been diagnosed. Several months on fish oil is several months for a thyroid or an adrenal problem to progress.

Never bathe repeatedly with a harsh shampoo to control shedding. It strips the coat and irritates skin.

Never use a deshedding blade hard, repeatedly, or on a coat that is not shedding.

Never ignore a rash on a person in the household. Two of the causes of canine hair loss are transmissible to people, and that information changes what the vet does first.

Never assume a dog cannot have fleas because you have not seen one.

When to get help

Book a veterinary appointment for any bare patch, any change in the skin, any symmetrical loss, any itching that is affecting the dog, and any hair loss that comes with weight change, increased thirst, lethargy or panting.

Book sooner if anyone in the household has developed an itchy rash, since sarcoptic mange and ringworm both transmit to people.

Book a grooming appointment rather than a veterinary one for a heavy but normal seasonal blow in a healthy dog with normal skin. A bath and a high velocity dry through a moult saves weeks of hair in the house.

Bring your photographs, your timeline and your parasite prevention record. Between them they usually narrow the list before the dog is examined.

A coat in good condition lies flat, feels dense rather than sparse, and covers evenly. That is what you are comparing against every month.