Here is some information from the Material Safety Data Sheet for DMSO -
Potential Health Effects
Eye: May cause mild eye irritation. Two drops of >50% DMSO in the rabbit eye caused a temporary burning sensation and vasodilatation, but concentrations of <50% exhibited no effect. DMSO produced slight erythema of the conjunctiva over the first 3 days of the study, and a low level of key scoring was also recorded for chemosis, iritis and corneal opacity. The degree of eye injury described by these key scores would not result in DMSO being labelled as an eye irritant according to EEC classification. (ECB - Elf Aquitaine)
Skin: DMSO readily penetrates skin and may significantly enhance the absorption of numerous chemicals. Increased absorption of these other chemicals could lead to their increased toxicity. Skin sensitization was not observed with DMSO in human volunteers or in guinea pigs. Non-immunological whealing and flaring have been observed in animals and humans following short-term contact. Skin absorption of DMSO may result in a garlic-like breath and body odor, and CNS effects such as headache, nausea and dizziness. Undiluted DMSO applied topically to mice twice a week for 30 weeks failed to produce dermal injury. (EBC - Elf Aquitaine) Skin sensitization has not been reported in hundreds of human volunteers participating in a DMSO clinical trial. DMSO's ability to increase the absorption of other chemicals is its most significant occupational hazard.
Ingestion: May cause gastrointestinal irritation with nausea, vomiting and diarrhea. May cause central nervous system effects. May cause garlic smell on the breath and body.
Inhalation: Material has a very low vapor pressure at room temperature, so inhalation exposures are not expected unless material is heated or misted.
Chronic: Long-term skin application of 80-90% DMSO has produced CNS effects (such as fatigue, nausea, vomiting, sedation, dizziness and headache), and dermatitis (such as redness, dryness and scaling) in volunteers. A garlic-like breath odor has been noted.
If you are going to try this on your dog, consider the possible ingestion effects, since if the dog can reach the area of application she may lick it. I would use it very sparingly if it were me. (And I use the solvent occasionally in my job, but wear gloves to avoid skin contact.)