Sleep Disorders in Dogs and Cats
Patients often ask if there are any treatments available for sleep disorders in pets. Many have described how their cat or dog snores so loud they can’t hear the TV, paediatric patients giggle as they recall their pet trying to run in their sleep, and videos of narcoleptic animals are a popular You Tube search for those slow night shifts.
It therefore comes as no surprise that dogs and cats can suffer from obstructive sleep apnoea (OSA). In fact the English Bulldog has been used as a natural model for sleep disordered breathing (SDB) for many years.1 These dogs have a short snout and neck, with a narrow oropharynx and enlarged soft palette. The result is a dog breed that is genetically predisposed to OSA: they snore, become hypoxic in response to apnoeas, have increased arousals and are hypersomnolent. By observing this model, researchers have been able assess how abnormal upper airway anatomy contributes to the development of SDB and its association with cardiac, metabolic and neurological impairment.
Obesity is also associated with an increased risk of OSA, and weight-loss is one of the recommended treatments. However for some dogs or cats where weight is not the issue, surgery can help alleviate the obstruction, especially if life-threatening cardiac, metabolic or neurological complications start to emerge. Surgical examples include shortening the palette or widening the airways via CO2 laser surgery to improve the flow of air. Tracheostomies have also been performed but this is usually reserved for serious cases, e.g. when associated with loss of consciousness or hyperthermia.
Information regarding pet-friendly CPAP therapy was (as I expected) difficult to find. However a very recent study did use CPAP therapy to reverse severe OSA in cats.2 On average, supine REM in six feline subjects resulted in an AHI of 82 with a highly fragmented sleep pattern. Two of the cats were then conditioned (not sedated) to use a modified CPAP mask. In response to the CPAP treatment, arousal frequency decreased, total REM sleep increased and their sleep was more consolidated.
Narcolepsy has also been documented in canine populations (particularly Doberman Pinschers), and research focused on narcoleptic dogs has helped determine the role of the neurotransmitter orexin (or hypocretin) in cataplexy.3 Dogs that suffered from cataplexy were found to have a degeneration of the hypothalamic neurons that produced orexin, or mutations in their orexin receptors, both resulting in defective orexin-modulated signalling. As observed in humans, multiple sleep latency tests conducted on narcoleptic dogs show a shorter sleep latency and higher sleep onset REM compared to normal dogs.4 Veterinarians assess the severity of cataplexy by exposing the animal to their trigger (e.g. food or play). Blood tests and scans are also performed to rule out any underlying medical conditions that may cause similar symptoms (such as tumours, seizures or muscular disorders). In a scientific setting cataplexy severity is assessed by arranging 12 pieces of food 30cm apart in a semicircle.5 The length of time it takes the dog to eat all the food is then recorded. For a non-narcoleptic dog it takes an average of 10 seconds to complete the task. Narcoleptic dogs, however, exhibit paralysis before completion.
Treatment for infrequent narcolepsy in cats and dogs is to avoid their triggers. However, if the disorder interferes with quality of life and safety, medications are often prescribed. Currently the recommended treatment is tricyclic antidepressants to decrease the severity and frequency of periodic paralysis. Stimulants such as Modafonil and Ritalin are also prescribed to combat hypersomnolence.
Pets twitching, running, or vocalising in their sleep are common observations described by patients (google Bizkit the sleepwalking dog) but do pets suffer from REM behaviour disorder? Unfortunately due to limitations accessing veterinary journals, the scientific information obtained on this topic was minimal, however it does appear that pets can suffer from the disorder, or something similar. In the 1980’s researchers assessed a group of cats and dogs that appeared to have movement disorders during REM.6 They then tried to treat the disorder with pharmacological agents, with clonazepam (an anticonvulsant and muscle relaxant) responding most favourably. However the study also showed, that out of the eight animals observed, only three appeared to have no underlying medical condition. Of the other five animals, three had disorders of the central nervous system and two had thyroid tumours.
A more recent study evaluated a Labrador Retriever that had ‘seizure like episodes’ both during sleep and awake.7 An EEG confirmed the sleep associated episodes were not seizures and occurred during REM sleep. In contrast the day episodes were diagnosed as seizures as they responded to anti - seizure medication. Treatment for this dog was a prescription of tricyclic antidepressants.
As illustrated above, sleep disorders have been observed in the canine and feline populations. They have also contributed to the understanding of sleep disorders in humans. Treatment for narcolepsy and OSA in pets is also similar to humans with the use of prescription medications, surgery and weight loss. To answer the question I get asked time and time again, there is no pet-friendly CPAP therapy available for commercial use, and personally I don’t see that changing any time soon. If I tried to put a CPAP mask on my Border collie it would be chewed beyond recognition by morning. And if I tried it on our cat – my face would be beyond recognition in 5 minutes. Needless to say, if anyone is concerned about their pet’s sleeping habits they should seek advice from a veterinarian to exclude medical conditions such as seizure activity or tumours, and to assess for complications that may be associated with a sleep disorder.
1.Hendricks JC., Kline LR., Kovalski RJ., O'Brien JA., Morrison AR, Pack AI. The English bulldog: a natural model of sleep-disordered breathing. Journal of Applied Physiology. 1987; 63(4): 1344-1350.
2. Neuzeret, PC., Gormand F, Reix P, Parrot S, Sastre JP, Buda C, Guidon G, Sakai K, Lin JS. A new animal model of obstructive sleep apnea responding to continuous positive airway pressure. Sleep. 2011; 34(4): 541-548.
3. Hungs M, Mignot E. Hypocretin/orexin, sleep and narcolepsy BioEssays. 2001; (5): 397-408.
4. Toth LA, Bhargava P. Animal Models of Sleep Disorders. Comparative Medicine. 2013; 63(2): 91-104.
5. Reid MS, Tafti M, Geary JN, Nishino S, Siegel JM, Dement WC, Mignot E. Cholinergic mechanisms in canine narcolepsy—I. Modulation of cataplexy via local drug administration into the pontine reticular formation. Neuroscience. 1994; 59(3): 511-522.
6. Hendricks JC., Lager A, O'Brien D, Morrison AR. Movement disorders during sleep in cats and dogs. J Am Vet Med Assoc. 1989; 194(5): 686-689.
7. Bush W,. Barr CS, Stecker M, Overall KL, Bernier NM, Darrin EW, Morrison AR. Diagnosis of rapid eye movement sleep disorder with electroencephalography and treatment with tricyclic antidepressants in a dog. J Am Anim Hosp Assoc . 2004;40(6): 495-500.
Veterinary information predominately from: http://www.petwave.com/