Male dog lost weight when female in heat.

Dr. Marie replied:

Hmmm...interesting question.

It is definitely common for an unneutered male to lose weight when there is a female in heat nearby. This is one of the reasons why I recommend neutering males - because it is so frustrating for them to have the desire to breed and then not be able to go through with the act. The frustration is so stressful that many dogs don't eat.

It's really hard to say why he has not gained his weight back though. Sometimes when a dog is trying to eat everything in sight it can be because of nausea. My theory is that they seem to know that if they fill their stomach up then they will be able to vomit and then somehow feel better.

There are lots of possible reasons for nausea including ingestion of something that has irritated the intestinal tract, a foreign object in the intestines or stomach, an infection, a problem with the liver or kidneys or more.

While parasites are possible, most dogs don't lose weight with parasites unless they are severely infested.

If this were my case I would be doing a good physical exam and likely do some bloodwork as well as a fecal exam for parasites.

If he does not start to gain weight soon, I think a vet visit is definitely in order.

Dr. Marie.

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