We all know how upsetting it is to suffer from a headache. Luckily, as humans, we can verbalise how we feel and hopefully take measures to alleviate our own pain. However, dogs cannot verbalise how they feel. It is easier to spot a sore paw, manifested as lameness, or dental pain if they refuse to eat and have strange jaw movements, however, something as non-specific as a headache can be difficult to guess, no matter how much clues our canine friends can try to give us.
But, do dogs really get headaches like we do?
The short answer is that we do not really know for sure. There are certain conditions that can be linked to headache: for instance, dogs with head trauma, brain tumours or meningitis are at risk of suffering pain in the head, as the layers of the brain (meninges) are inflamed or stretched out. Other conditions such as certain endocrine disorders or electrolyte imbalances could potentially have the same effect. In these cases, a low head carriage, semi-closed eyes, avoid bright light, quiet behaviour or vocalisation can be perceived as signs of undefined pain that may resemble those of people suffering a headache. Dogs can also manifest “head pressing”, leaning the head against a wall or a corner. The use of painkillers, such as paracetamol, and the treatment of the underlying condition usually result in an improvement of the signs observed, making us think that the pain they were experiencing was similar in many ways to a human headache.
Outside of these pathologies as potential causes for headaches, we do not know if dogs suffer “primary” headaches, or “without any obvious underlying cause” as humans do.
According to the Mayo clinic, primary headache is caused by overactivity of pain-sensitive structures in the head, and it does not come as a consequence of an underlying disease. There are different factors that can play a role in the development of a primary headache, such as different chemical activity in the brain, or changes in the nerves, blood vessels or muscles in the skull head or neck. Some primary headaches can be triggered by lifestyle factors, including alcohol, processed meats, lack of sleep or stress.
Some people may also carry genes that make them more likely to develop headaches. In that aspect, migraines (a particularly bad type of primary headaches considered to be typically hereditary) can be a really challenging condition to live with for many people. Migraine in people is deﬁned as recurrent headache disorder manifesting in attacks lasting 4–72 hours, and it is classified by the WHO as the number 19th among disabling diseases¹. There is one case report that describes a migraine-like episodic pain behaviour in one dog²: from 6 months of age, this dog suffered from episodes of vocalisation, fear and low head carriage, that could last from hours to days. Occasionally, she would show signs of nausea as well. In one of the episodes, the signs appeared to be worsened by light and noise. Routine veterinary examinations and most common painkillers used in dogs fail to alleviate the episodes, which progressed from twice a year to almost twice a month. The dog was examined at a specialist referral centre and underwent extensive diagnostic investigations, including MRI of the brain and spine and cerebrospinal fluid analysis. All tests performed were normal.
A treatment trial with phenobarbital was initially instigated to rule out seizures as a cause for the episodes but failed to alleviate the vocalisation and other clinical signs. Later, another trial consisting of paracetamol, codeine and pregabalin was given for 4 weeks, but also failed to improve her apparent pain.
Then, suspecting pain arising from the head area, and without any evidence of underlying pathologies, the veterinary specialists tried Topiramate, a medication usually prescribed to treat migraines. The dog improved markedly on this treatment.
The authors of this case study concluded that the episodes most likely resemble painful behaviour, arising from the head area, and that some of the features the dog exhibited could be comparable to those experienced by people who suffer migraines.
Migraines can be a diagnostic challenge in humans, and the diagnosis criteria to differentiate migraines from other types of headaches are strict¹. Migraine and seizures share some common clinical features and underlying mechanisms, and this makes even more challenging to diagnose migraines in dogs. All efforts should be placed on ruling out underlying pathologies first.
Topiramate is a drug used for chronic and episodic migraine in people, through various mechanisms of action³. There are other drugs used to treat migraines in people such as ergotamine, triptans or valproate. Special care should be taken when using any drug not intended for use in dogs.
It is possible that our canine friends suffer headaches in a similar way that we experience them. The first step is to check with your veterinarian to see if there are any signs of identifiable pain in any other anatomical areas, such as the neck, teeth, or any other anatomical structure. Dogs with unlocalised pain that does not respond to typical painkiller treatment should be referred for specialist input. In this cases, a thorough assessment will be carried to ensure that no underlying pathologies are the cause of the pain. Specialist care will focus on ruling out intracranial problems such as meningitis, brain tumours or other infectious or inflammatory condition of the brain, its blood vessels and its meninges. This is particularly important as some of these conditions can be fatal if left untreated.
If no underlying cause if found, empirical treatment with paracetamol or other drugs can be tried. If this fails, topiramate use can be attempted, although the evidence for this drug as a treatment modality for suspected headache in dogs is only anecdotical and it must always be used under veterinary supervision.