Less serious side effects include: 1  Loss of appetite. 2  Weight loss. 3  Nausea. 4  Vomiting. 5  Diarrhea. 6  Frequent urination. 7  Muscle cramps, painful and swollen joints. 8  Excessive tiredness. 9  Difficulty falling asleep. 10  Headache, nervousness, dizziness. 11  Depression, mood swings. 12  Vivid dreams.
Nausea can occur in dogs for many reasons, particularly when the digestive tract and nervous systems are out of balance. Stress can certainly play a role in nausea.
1 Weight gain; this can be managed with a healthy diet and regular exercise. 2  Bad breath (it is salmon oil); this can be resolved by regularly cleaning their teeth.  Stomach pain, dizziness and nausea; not all dogs have this reaction, but you should watch your dog to be sure that s/he is compatible with salmon oil.