Atenolol, or Tenormin, is a beta-blocker that is often prescribed for dogs with heart conditions, and although it is not registered with the FDA as a drug for dogs, it has proven very effective in treating our canine friends. But, like any drug, it has side effects.
Allergic Reaction
If your pet has taken Atenolol and has difficulty breathing, hives or swelling of the lips, tongue or face, he's probably having an allergic reaction, and you should take him to your veterinarian immediately.
Shortness of Breath
Shortness of breath is considered a serious side effect. If your pet has a history of asthma or other breathing difficulties, be sure to tell you veterinarian before your pet uses Atenolol.
Slow or Irregular Heart Beat
Because it is a beta-blocker, Atenolol can cause the heart to beat too slowly or irregularly, lowering blood pressure. Be sure to tell your veterinarian if you dog has had heart problems or low blood pressure in the past before beginning use.
Leg Pain
Leg pain or cramping can be a side effect of Atenolol, and is normally a sign of a more immediate problem like heart irregularities.
Weight Gain
If your pet suddenly gains a notable amount of weight, it may be a side effect of taking Atenolol. Be sure to contact your veterinarian immediately.
Fatigue
Fatigue in a dog can be caused by a great many things, but if your dog has just begun taking Atenolol, be careful to note it. If this side effect occurs with any of the other side effects, it may be something to worry about.
Digestive Issues
Although considered a rather minor side effect, digestive issues are fairly common in dogs taking Atenolol. Digestive issues related to Atenolol use may include diarrhea, constipation, gas, nausea or vomiting.
