Canine cognitive dysfunction (CCD) can be likened to Alzheimer’s disease in humans. Senior dogs with CCD may experience confusion, anxiety, disorientation and other symptoms that can impair their quality of life.
The pathophysiology of CCD involves a series of degenerative changes within the brain. There is no cure for CCD at this time, but transcranial photobiomodulation therapy (tPBMT) has been showing promising results as a treatment option for this condition.
Let’s explore this condition, and the research on tPBMT.
The pathophysiology of canine cognitive dysfunction
CCD is a progressive degenerative condition affecting the brain in dogs. It is characterised by an increase in oxidative stress that results in mitochondrial dysfunction, impairing the ability of neurotransmitters to fire and therefore disrupting neural pathways.
Some of the changes that take place in the brain include:
- compromise of the brain vasculature with reduced blood flow;
- dysfunction of the neuronal mitochondria;
- β-amyloid protein deposition around neurons and blood vessels;
- oxidative stress in the brain;
- increased inflammation in the brain.
Signs and symptoms of canine cognitive dysfunction
Signs of CCD develop gradually and can often be mistaken for normal signs of aging, going undiagnosed and unrecognized until it has significantly progressed. Common signs include:
- confusion
- disorientation
- excessive panting
- disrupted sleep cycles
- anxiety
- phobias
- irritability
- vocalisation
The DISHAA scoring system allows owners to evaluate the severity of these symptoms in their dogs, and to monitor the progression of the condition.
tPBMT (laser therapy) to treat canine cognitive dysfunction
Laser therapy or photobiomodulation is a phenomenal modality when our goals are to stimulate mitochondrial function and reduce oxidative stress, making it a good modality to consider in the treatment of CCD. In people with Alzheimer’s disease, tPBMT has been shown to produce the following mechanisms or changes:
- increased neuronal mitochondrial energy production;
- improved brain blood flow;
- reduced β-amyloid load and deposition;
- reduced dendrite and neuronal loss;
- reduced inflammation;
- reduced oxidative neuronal injury.
Red light in the 665 nm to 810 nm range has been shown to be effective in humans.
A closer look at the mechanisms of tPBMT
Mitochondrial stimulation
Neuronal mitochondria produce energy in the form of adenosine triphosphate (ATP) and reduce the toxic effects of β-amyloid plates within the brain. This makes their correct and optimal function essential to a healthy brain.
ATP production can be increased when we stimulate the mitochondria – or, more specifically, when we stimulate the electron transport chain within the mitochondria – with light wavelengths at 660 nm to 810 nm.
tPBMT can stimulate the generation of new mitochondria within the cells, increasing the number of available mitochondria for energy production.
Finally, when a cell experiences oxidative stress, the intracellular fluid within the inner mitochondrial membrane becomes more viscous, slowing down the electron transport chain. Wavelengths of 670 nm can decrease the viscosity of this fluid layer and support more efficient ATP synthesis.
β-amyloid load
β-amyloid is a neurotoxic protein that collects in the brain when there is an increase in inflammation and a decrease in blood flow, as well as secondary to gut dysbiosis. An increase in β-amyloid load increases the production of free radicals and proinflammatory cytokines that will lead to damage and death of the neural cells, as well as damage to the mitochondria. tPBMT may decrease β-amyloid load by increasing blood supply and stimulating β-amyloid phagocytosis.
Brain-derived neurotrophic factor (BDNF)
BDNF is a signalling peptide involved in neurogenesis and the maintenance of neural synapses within the central nervous system. It protects against the damage caused by β-amyloid load and toxicity.
632.8 nm wavelengths can upregulate BDNF allowing it to restore damage from β-amyloid toxicity.
Increased vascularisation
Early in the development of CCD, cerebral blood flow decreases. tPBMT increases nitric oxide (NO) production and angiogenesis, thus promoting and increasing blood circulation.
Does laser penetrate through the skull?
800 nm and 808 nm wavelengths have been shown to penetrate through the human skull to a brain depth of 40–50 mm. There is an inverse relationship between the amount of photons that penetrate the skull and the thickness of the bone (Tedford et al., 2015; Lapchak et al., 2015).
Dosage and treatment parameters for tPBMT in canine cognitive dysfunction
Dewey et al. (2024) found that the following tPBMT parameters effectively improved the clinical signs of canine cognitive dysfunction by 30–45% over a two-month treatment period.
Application: My Pet 2 Laser, Multi Radiance Medical with a 4 cm squared aperture applied to the caudal aspect of the temporal fossa and aimed toward the opposite orbit.
Energy: 64 J administered on either side of the head.
Wavelengths: 660, 850, 905 nm
Frequency: 1000–3000 Hz
Total power: 0.3564 W;
Power density: 0.0891 W/cm2;
Energy density: 16.04 J/cm2.
Time: 6 minutes (3 minutes per side)
Treatment frequency: 3 X per week for 30 days, 2 X per week for the next 30 days.
In their study, Dewey et al. (2024) found that owners could easily use the modality at home.
This provides us with a valuable starting point for the treatment of these patients. Treatment parameters need to be further studied to determine what the optimal dosage and treatment parameters are.
Conclusion
tPBMT shows promise as a treatment modality for canine cognitive disorder. We look forward to further research on this condition and the optimal treatment parameters to treat it.
Client Educational Resources
If you would like to provide your clients with a resource on CCD that includes recommendations on environmental adaptations, diet, and additional management and monitoring strategies, you can.
We have created a fully customizable template on this condition, that you can use for your clients. Fully editable and brandable, this resource can help your clients and patients while increasing your brand awareness and credibility as a professional.
Resources
- For resources on veterinary neurology, visit Web-Vet Neurology Specialists
- Nutritional support of dogs with canine cognitive dysfunction
- Dewey CW, Brunke MW, Sakovitch K. (2022).Transcranial photobiomodulation (laser) therapy for cognitive impairment: A review of molecular mechanisms and potential application to canine cognitive dysfunction (CCD). Open Vet J.
- Dewey CW, Rishniw M, Brunke M W, Gerardi J & Sakovitch K. (2024) Transcranial photobiomodulation therapy improves cognitive test scores in dogs with presumptive canine cognitive dysfunction (CCD): A case series of five dogs.Open Vet J. doi:10.5455/OVJ.2024.v14.i5.11
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