Irregular heat cycle in dogs results from many causes which include obesity, inadequate nutrition, infections and metabolic diseases like hypothyroidism or ovarian problems or simply imbalance in sex hormones. Some dogs under two years of age may experience irregular cycles. Although rare, some dogs experience a condition called silent heat in which they do ovulate but the characteristic signs of being in heat, such as vulvar swelling and discharge are not observed.
Question by - Manish Rawat, Rishikesh