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The important points, first
- Dogs and cats shed more in early spring and early autumn: it is the natural renewal of the coat.
- Brush regularly to remove dead hair and prevent mats; brush cats daily while they shed to limit hairballs.
- Do not cut mats out with scissors: it is easy to cut the skin.
- Bald patches, symmetrical hair loss, itching, redness or scaling are not shedding: contact your veterinarian.
Why dogs and cats shed
The Merck Veterinary Manual explains that hair growth depends on nutrition, hormones and the change of season: dogs and cats normally shed more in early spring and early autumn, and may also shed in response to changes in temperature or daylight. In a study of beagle dogs, peaks of hair combed from the coat coincided with spring and autumn, when most follicles were in the resting phase.
Growing a winter coat does not in itself call for more food. The FEDIAF nutritional guidelines indicate that it is cold that raises energy expenditure: a dog kept outdoors in winter may need 10 to 90% more calories than in summer, depending on coat, size, activity and acclimatisation. For a pet living indoors, it is better to monitor weight and body condition and agree any change in portions with your veterinarian.1289
How to brush during shedding season
Regular brushing removes loose hair and prevents mats, especially in dogs with thick or long coats. Mats irritate the skin and can lead to infections: do not cut them out with scissors, as it is easy to cut the skin, and if they are too tight ask a groomer or veterinarian, who will use clippers.
For cats, Cornell recommends getting them used to daily brushing and combing, particularly while they shed: less hair swallowed during grooming means fewer hairballs. Long-haired cats such as Persians and Maine Coons are most at risk; if a cat will not accept brushing, a haircut by a veterinarian or groomer once or twice a year can help. While brushing, look at the skin too.567
Hairballs in cats: when to worry
Cats swallow a lot of hair while grooming, because the papillae on the tongue push it towards the throat. Most passes out in the faeces, but some can build up in the stomach. According to Cornell it is not unusual for a cat to bring up a hairball every week or two, and that alone is nothing to worry about; hairballs are more frequent during shedding seasons and in adult cats, which spend a lot of time grooming.
A hairball that grows too large may fail to pass, or become lodged in the intestine: this is uncommon but serious. A cat that is lethargic, has not eaten for more than a day or two or retches repeatedly without producing anything should be examined without delay; frequent hacking can also be caused by other conditions, such as asthma. Do not give laxatives or change the diet on your own, and remember that excessive licking can point to a skin problem worth assessing.6
When hair loss is not shedding
Merck notes that the growth of new hair is always accompanied by the shedding of old hair: if hair loss does not leave bald patches and is not symmetrical on both sides of the body, it is most likely the normal renewal of the coat.
It is different when bald areas, symmetrical hair loss, red, thickened or scaly skin, changes in skin colour or itching appear. Common causes include infections, parasites and allergies, as well as friction from a poorly fitted collar. These cases need a visit: the veterinarian will examine skin and coat, comb for parasites and, if needed, take samples for testing.34
Sources and checks
Numbers in the text lead to the exact source. Commercial blogs and social posts are not used as evidence.
- 1Peer-reviewed veterinary manual
Structure of the Skin in Dogs
Merck Veterinary Manual · Dog Owners · Hair growth linked to nutrition, hormones and season; shedding in early spring and early autumn.
Link checked on 15 Sept 2026 - 2Peer-reviewed veterinary manual
Structure of the Skin in Cats
Merck Veterinary Manual · Cat Owners · Cats shed in early spring and early autumn, also in response to temperature and daylight.
Link checked on 15 Sept 2026 - 3Peer-reviewed veterinary manual
Hair Loss (Alopecia) in Dogs
Merck Veterinary Manual · Dog Owners · Normal shedding versus abnormal loss (patches, symmetry), common causes and skin examination.
Link checked on 15 Sept 2026 - 4Peer-reviewed veterinary manual
Hair Loss (Alopecia) in Cats
Merck Veterinary Manual · Cat Owners · In cats, as in dogs, shedding without bald patches or symmetrical loss is normal coat renewal.
Link checked on 15 Sept 2026 - 5Peer-reviewed veterinary manual
Routine Health Care of Dogs
Merck Veterinary Manual · Dog Owners · Regular brushing to remove loose hair and prevent mats; no scissors on mats.
Link checked on 15 Sept 2026 - 6University veterinary centre
The Danger of Hairballs
Cornell Feline Health Center · How hairballs form, frequency considered normal, signs that need a visit, daily brushing.
Link checked on 15 Sept 2026 - 7University veterinary centre
A Hairy Dilemma
Cornell Feline Health Center · Daily brushing against hairballs and, if the cat will not accept it, a haircut once or twice a year.
Link checked on 15 Sept 2026 - 8Peer-reviewed research article
Hair follicle cycle and shedding in male beagle dogs
American Journal of Veterinary Research (1977) · PubMed PMID 879559 · Shedding peaks in spring and autumn, matching the follicle resting phase (study of 9 beagles).
Link checked on 15 Sept 2026 - 9European labelling code
Nutritional Guidelines for Complete and Complementary Pet Food for Cats and Dogs (2025)
FEDIAF EuropeanPetFood · Thermoregulation: dogs kept outdoors in winter may need 10 to 90% more calories.
Link checked on 15 Sept 2026
This guide provides general information about coat renewal. Abnormal hair loss, itching or digestive problems should be assessed by a veterinarian.