How to Dye a Dog's Fur
To dye a dog's fur, use natural food coloring or a dog-friendly hair dye, and never use human hair dye or permanent dye since it can be toxic for dogs and irritate their skin. Also, make sure your dog doesn't have any wounds or skin issues or else dying its fur could make them worse. If you plan on dying the fur on your dog's face, get some sterile ophthalmic ointment and apply it to your dog's eyes beforehand in case any dye gets in them.
Avoid hair dye for humans. Hair dye that is designed for humans can have chemicals that are toxic for dogs and can harm their skin. Dogs have a different pH skin balance than humans, so avoiding human hair dye is essential to ensuring your dog's comfort and safety. Instead, seek out alternative dyes that can be found naturally. The less synthetic the dyes, the better they will be for your dog. Look for wounds or skin irritations. Do not dye your dog's fur if they have any healing wounds or present skin irritations. Dyeing your dog's fur will more than likely cause further irritation, and can even cause more serious infections. Be sure to check your dog's body for nicks or healing wounds while you groom them before you begin applying the dye. Avoid using any permanent dye. Using permanent dye on your dog's fur can cause harm as they almost always contain chemicals that can be harmful to your dog's health. Permanent dyes can not only cause damage to your dog's fur and skin, but pose serious health risks as your dog will be grooming themselves. There are many alternatives to dyeing your dog's fur, from impermanent dyes to semi-permanent dyes. Use edible foods. Edible foods, that are safe for your dog to eat, will produce light hair dyes. These dyes can be made in a variety of ways , from juicing fresh vegetables to boiling and dehydrating. However, the sugar in many fruits can also cause your dog's fur to become sticky, and can also cause mild skin irritations. Try to stick to vegetables or fruits with low sugar contents. Try using vegetables like carrots, beets, and spinach, or spices like turmeric. Although fruit dyes should try and be avoided, they do often produce the most vibrant color. Try to thin or dilute any dyes made from juice to avoid skin irritation. Most dyes made from edible foods are impermanent and will begin to fade within a week. Try natural food coloring. Natural food coloring can be purchased at almost any supermarket and is generally free of harmful chemicals. Some food dyes are made with artificial dyes that have been linked to negative health effects if congested on a daily basis for many years. However, these dyes should not pose any problems when used in dyeing dog fur. Try using all natural organic food coloring to avoid unwanted artificial colors, like India Tree. Food coloring will be semi-impermanent and hold color longer than dyes made from edible foods. Purchase dog-friendly hair dye. There are a few dog-friendly hair dyes that are available in both pet stores and online vendors. Pet hair dyes range from sprays to gels to chalks, and most avoid using harmful chemicals. Dog friendly hair dyes are generally the best option for more permanent dyeing with reduced irritation. Try purchasing dog-friendly hair dyes by brand, like PetPeri . Consult a salon. There are many high-end or boutique salons that are devoted entirely to grooming and treating dogs. These salons will often have many options for dyeing your dog's fur, many of which will be hold longer and be more permanent. Be sure to ask about hair dyes that are dog-friendly and that will not harm or irritate your dog. Most dog salons will also be equipped to check various elements that are included in the dyeing process, like color bleed and color depth. Ask questions like “Do you have any dog-friendly hair dyes?” “Do your hair dyes contain any ingredients that could be harmful if my dog ingests them?” or “How permanent are your hair dyes?” Wash their fur. Wash your dog's fur in a bath with shampoo. Work up a thick lather all over their body and rinse. Once they have been washed, dry them with a towel so that their fur is still slightly damp. Damp fur will hold dye more effectively than completely dry fur. Use shampoos specifically designed for dog fur, like Apply ointment to your dog’s eyes. Apply a sterile ophthalmic ointment to your dog's eyes, especially if you plan on dyeing the fur around their eyes or on their face. Ophthalmic ointments will help prevent any dye irritating their eyes and will reduce the chance of infection in case dye invariably does get in their eye. Although using ointment is a good idea regardless of where you are dyeing, it won't be essential if you are dyeing minimal parts of their body, like the tail. Each ointment will come with a set of directions for applying the ointment in your dog's eye. Mix the dye. If you are using a homemade dye, you will need to mix it with water and place it into a spray bottle. Use half the amount of water as you are using day. If you are using one cup of dye then you will need to use half a cup of water. Most store bought dyes will give you mixing and application instructions. Comb or brush their fur. Once your dog is clean and relatively dry, use a comb or brush to prepare their fur for the application of the hair dye. Simply brush the area you plan on dyeing with a comb to straighten their fur so that the dye can be applied as evenly as possible. The better and more thorough their hair is brushed the easier it will be to evenly apply the hair dye. Apply the dye evenly on the desired areas. If you are applying dye made from food coloring or foods you'll need to mix the dye with water and apply it with a spray bottle. Hair chalk can be rubbed directly into your dog's fur, whereas bottle dyes will need to be applied by hand with gloves. However you are applying the dye, be sure to do so evenly so that your dog's fur isn't patchy. Make sure to cover the entire area you are dying before going over it with a second coat. Most dyes that you purchase will come with instructions and best practices for applying dye to your dog's fur. Let dry. Let your dog's fur dry so that the dye can set. You'll need to let your dog's fur dry for varying amounts of time depending on whether or not you used a dry or wet dye. Dry dyes, like chalk, will only need to be left for a few minutes before they set, whereas dyes that have been sprayed on will need to sit for around 15-20 minutes. You can use a hairdryer on a low setting to decrease your dog's drying time. 
Avoid hair dye for humans. Look for wounds or skin irritations. Avoid using any permanent dye. Use edible foods. Try natural food coloring. Purchase dog-friendly hair dye. Consult a salon. Wash their fur. Apply ointment to your dog’s eyes. Mix the dye. Comb or brush their fur. Apply the dye evenly on the desired areas. Let dry. 