A dog's first heat: when it arrives and how to handle it calmly

There is no single date that fits every female, because the timing of the first heat depends mostly on size and on the individual dog. As a general rule, small dogs tend to come into heat earlier, while large and giant breeds may reach it later. Knowing the expected range helps you avoid alarm at either an early or a late start within certain limits.

The first cycles can be irregular, both in the interval between one heat and the next and in the intensity of the signs, and this is usually normal as the body settles. If, however, the first heat is much later than expected for the size, or if the cycles stay very disordered over time, it is worth discussing it with the vet to rule out hormonal causes.

Heat is not a single event but a cycle with distinct phases, each with different signs and meanings. Understanding them helps you recognise where the dog is and, above all, when she is in the genuinely fertile period when vigilance must be at its highest.

• Proestrus: the opening phase, with vulval swelling and a bloody discharge. The female attracts males but usually does not yet accept them. It lasts around ten days on average, with great variability.
• Estrus: the truly fertile phase. The discharge often lightens, the female accepts mating and can become pregnant. This is the period needing the most attention.
• Diestrus: the following phase, in which the body gradually returns toward quiet, whether the female is pregnant or not.
• Anestrus: the long period of sexual rest until the next cycle.

Besides the physical signs, many females show behavioural changes: more demand for attention or, conversely, irritability, a tendency to urinate more often to leave messages, reduced focus on walks and sometimes a temporary drop in appetite. These are normal variations tied to the hormonal state and tend to settle as the heat ends.

The practical management of heat revolves around two goals: cleanliness and comfort at home, and above all the prevention of unwanted mating outside. With a few precautions daily life stays almost unchanged.

1. 1

   Prepare the home for the discharge

   Many females keep themselves clean and the discharge stays modest. If needed, there are purpose-made hygiene pants, to alternate with free time for hygiene. Protect beds and sofas with washable covers.

2. 2

   Always keep the dog on lead outside

   Throughout the heat, give up off-lead dog areas and the long line left loose. Even a usually obedient female can wander off following instinct, and males can travel considerable distances drawn by the scent.

3. 3

   Choose quieter routes and times

   Prefer outings in places and at times with fewer dogs, to reduce encounters and tension. If you meet an interested male, calmly change direction without creating panic.

4. 4

   Watch the house and the garden

   Check that fences, gates and windows do not allow escapes or intrusions. During the fertile weeks do not leave the dog alone in the garden unsupervised.

5. 5

   Keep a reassuring routine

   Adequate exercise, mental games and attention help release restlessness. Avoid excessive effort and stressful situations, though, in an already delicate phase.

If a female in heat and an unneutered male share the home, complete physical separation is the only truly reliable measure for the whole fertile period, because improvised barriers and occasional supervision almost never suffice. In case of an accidental mating, contact the vet as soon as possible to discuss the options.

The first heat is often when the family seriously asks the question about spaying. It is an important decision, with benefits and risks to be weighed for the individual dog, and there is no single answer that fits every female. A few general points, though, help set the reasoning in the right direction.

• Spaying ends the heats and the possibility of unwanted pregnancies, and prevents some diseases of the reproductive tract.
• The best time for surgery depends on size, breed and lifestyle, and in recent years the reasoning about when to operate has become more individualised than in the past.
• As a rule surgery is not performed during the heat itself, because the tissues are more vascular: it is preferably scheduled away from that phase.
• The choice should be discussed with the vet, considering the dog's health, the family's goals and the up to date evidence for that kind of dog.

Whatever the choice, keeping track of the start and end dates of each heat is very useful: it lets you predict the next cycles more precisely, schedule any surgery at the right time and give the vet a clear timeline. A simple log of events turns something experienced as unpredictable into something readable and manageable.

Most heats pass without problems, but some signals mean it is worth seeking advice. Recognising them avoids overlooking situations that, behind an ordinary appearance, call for attention.

• Very heavy, foul-smelling discharge, or one containing pus, which is not typical of a normal heat.
• Signs of general malaise in the weeks after heat, such as greatly increased thirst and urination, dullness, fever or marked loss of appetite, which need urgent assessment.
• A first heat much later than expected for the size, or cycles that stay chronically irregular.
• A marked or prolonged false pregnancy, with obvious distress in the dog.
• Any accidental mating, to discuss the available options in good time.

One condition in particular is worth knowing about: pyometra, an infection of the uterus that can appear in the weeks after a heat in unspayed females and that is an emergency. Its signs, such as increased thirst and urination, dullness and sometimes a vulval discharge, must be taken seriously: faced with a doubt, an extra phone call is better than a late one.