There are many different ways to help your dog gain weight. One simple method is to add more high-calorie foods to his diet, such as fatty meats, cheese, or full-fat dairy products like whole milk and yogurt. You can also try feeding him more frequently throughout the day so that he gets a chance to eat more calories each mealtime.
In most cases, the ant trap will pass through your dog's system without any problems. However, it's always best to err on the side of caution and get professional medical help right away.
Constipation in dogs usually manifests as irregular and infrequent passing of stool and pain while doing so. The reasons for the problem range from dietary deficiencies like insufficient water and fiber to digestive tract diseases like volvulus. Whatever the case, it is highly uncomfortable for the dog and should be addressed as soon as possible.