Apply pure, commercially prepared aloe vera gel to your dog's scrapes or minor skin irritations with peace of mind; any amount he would consume by licking it off his skin is typically too nominal to create any internal disturbances. Additionally, most reputable brands of aloe vera gel are prepared without the toxic component. You do need to be concerned about him eating an aloe vera plant or leaf, or consuming too much aloe vera juice.
Prepared Aloe Gel
Always check with your vet if your dog has a serious wound such as a puncture, or if a wound is red and painful to the touch. Applying aloe vera gel to minor scrapes and sores, however, can safely hasten their healing. Check the label on your commercially prepared aloe gel to ensure it doesn't have any additives that can irritate your dog's skin, or isn't harmful if ingested -- pure aloe gel formulas should contain just the gel.
Applying from the Aloe Leaf
Rinse the aloe vera leaf with water and peel back to reveal the clear or green-tinted gel. Scrape off the gel only and apply directly to your dog's wound. Do not apply the white or yellowish substance around the edge of the leaf; this is called sap, or latex, and is potentially toxic to your dog, depending on his size and how much he consumes if he were to lick it.
Internal Use of Aloe Vera
Never give your dog aloe vera or a derivative, such as juice or tincture, without consulting your veterinarian; she may have cause to administer a small dose internally, but excessive doses can cause diarrhea and vomiting. While the aloe vera plant is not considered highly palatable to most dogs, if your dog is the exception he may experience severe gastrointestinal side effects from eating it, as the leaf sap is a laxative. Severe diarrhea in dogs can be life threatening. Contact your veterinarian immediately if you know your dog has chewed on an aloe vera plant, if he starts vomiting excessively, has diarrhea, stops eating or begins to shake or tremble.
Medicinal Properties of Aloe Vera
Your dog's minor scrapes and wounds may heal faster with topical aloe vera gel treatment. Aloe vera contains a compound called acemannan, believed to stimulate cells into boosting the body's own immunity responses. Some veterinarians -- with the blessing of the US Department of Agriculture -- use acemannan to treat certain cancers in dogs and cats. It also may improve vaccine effectiveness. Acemannan is extremely nontoxic but should never be administered without a veterinarian's prescription or counsel, particularly if your dog has a serious illness.