Silent Heat in Dogs

Sexual-cycle abnormalities are an important cause of infertility in bitches. Although most dogs experience their heat cycle at regular intervals after their cycles begins, sometimes dogs experience abnormal cycling. Abnormal heat in dogs can include silent, absent, split, or irregular cycles.

Silent heat is defined as the maintenance of ovarian functions without the presence of vulvar edema, serosanguinous vaginal discharge, and charm for male dogs.

In a silent heat, all external physical signs (like vaginal bleeding, discharge, or swollen vulva) are so minimal that you don’t see them. Not only that, but her behavior might not change—she may show absolutely no interest in male dogs, either.

Toy breeds like Yorkies, may be prone to having a slightly different heat cycle compared to larger breeds. Their first heat might be barely noticeable compared to subsequent heats. If your toy breed dog has therefore gone into heat only at 1 year of age, it’s likely that she had her first heat about 6 months ago but you missed it because it was silent.

It is also very hard to figure out if there is vaginal bleeding because the female will usually lick herself clean. It’s a habit, most dogs do it and sometimes they will also lick the floor for any drop of blood.

Signs of a Dog in Heat

So, you don’t see any bleeding and you certainly can’t smell the pheromones. What other signs are there? Some of the signs you might notice are that your dog might:

• Urinate more often
• Raise her leg differently while urinating or when a male dog happens to pass by
• Pay more attention to male dogs
• Become lazier or more aroused
• Show signs of anxiety
• Run away, to practice hiding from male dogs 

Diagnosing Silent Heat in Dogs

Bitches that are thought to have silent heat can be diagnosed by taking monthly progesterone assays or conducting weekly vaginal smear investigations. If the progesterone level rises above 2 nmol/ml or vaginal smears show an increasing number of cornified cells the bitch is diagnosed to have a silent oestrous.

Treating Silent Heat in Dogs

First, you should consult with your veterinarian to identify any health issues that may be causing irregular heat cycles. Your vet will probably run a variety of tests. He will also come up with a treatment plan to resolve any underlying health issues.

Using vaginal cytology and progesterone measurements, your vet will be able to accurately tell you whether the bitch is cycling or not.

In most cases, male dogs are capable of detecting a silent heat. Housing her with another intact female who is approaching proestrus may help. There are many cases, where a cycling dog may induce heat in another female dog living alongside.