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Why is my Border Collie suddenly losing hair? What could it be?

Updated On September 23rd, 2025

Pet's info: Dog | Border Collie | Female | spayed | 10 years and 1 month old | 120 lbs

My Border Collie is suddenly losing her hair, why?

2 Answers

Most Helpful Answer

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Answered By Destini R. Holloway, DVM

Veterinarian

Published on July 23rd, 2017

That is a loaded question. Older pets can lose their hair for several reasons including undergoing Hypothyroidism, Cushings disease (an adrenal gland problem), flea allergies, Demodexx mites (can be seen in older dogs who have a weakened immune system) or even a seasonal alopecia is possible. I would start with a good examination, thyroid test and potential bloodwork if Cushing disease is suspected (based on the orientation of the alopecia and overall health of Sugar). I hope you are able to sort things out and hopefully get your answer as to why Sugar is losing her hair. Best wishes and take care.

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    Answered By Rodrigo Roca, DVM

    Veterinarian

    Published on

    Hello, dogs shed their hair normally at least 2 times per year. However, there are other conditions that can cause hair loss in dogs such as cushings disease, hypothyroidism, lupus, parasites, skin infections, and alopecia x to name a few. I would consult with your veterinarian to have Sugar evaluated thoroughly for any underlying disease that may be causing her hair loss. Hope this helps.

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