What Causes Excessive Canine Hair Loss?

According to Holly Nash, DVM, MS of Pet Education.com, 59 canine conditions and diseases can cause a dog to lose varying amounts of hair coat. While not all of these conditions and diseases cause excessive hair loss, any loss you consider unusual for your dog should be investigated by a veterinarian.

  1. Seasonal Shedding

    • Seasonal hair loss is not normal in a purebred poodle.

      It is normal for double coated breeds to shed their undercoats in the spring. If you live in an area where abrupt seasonal changes are common, loss of coat may seem sudden and excessive. More gradual shedding is typical where seasonal temperatures stay consistent. Seasonal shedding in a breed that typically does not shed, like the poodle or Portuguese water dog is not common and should be mentioned to your veterinarian.

    Parasitic Infestations

    • Keeping your dog on insect preventatives may keep parasites at bay.

      Healthy skin promotes beneficial shedding. Skin compromised by parasites has a difficult time supporting a healthy coat. Fleas and a variety of mange causing mites can damage the skin and trigger excessive loss of the coat.

    Allergic Reactions

    • Allergies may cause a consistent propensity for hair loss.

      As noted by contributing veterinarians on Pet Education.com, dogs can develop inhalant, food borne and slightly less common, contact allergies. Allergies can cause your dog to scratch or chew at itchy skin which in turn creates a loss of coat. Based on the type of allergy your dog may have, shedding symptoms may be seasonal or constant.

    Infections, Disease and Conditions

    • Excessive thinning hair on short-coated breeds may signify a medical condition.

      Bacterial infections of the skin, dermatitis, fungal infections, and canine disease can cause excessive hair loss. Hair loss can be prevalent in dogs afflicted with thyroid abnormalities, Cushing's disease, diabetes, folliculitis or those undergoing chemotherapy treatments. It is common for a pregnant or nursing dog to drop an excessive amount of coat.