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ADHD Like Behavior in Dogs
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'''''Authors''''' : Muzykant-Turchin Tali, Garrido-Andersson Linnéa, Fima Eden
'''''Supervisor'' ''': Dr. Kiss Dávid Sándor
Physiology Department, University of Veterinary Medicine, Budapest
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''' Attention deficit hyperactivity disorder (ADHD) ''' is a [[https://en.wikipedia.org/wiki/Neurodevelopmental_disorder|neurodevelopmental type disorder]] which is characterized mainly in attention deficit, concentration difficulties, hyperactivity and impulsivity. The disorder is typically related to humans, but the signs can be manifested in dogs as well. Exactly like humans, dogs are social mammals. They share social qualities and keep social bonds. Moreover, there is a similarity between kids and dogs in the aspect of their association with social environments and their response to it. Those are the reasons for dogs suitability as modeling physiological diseases in humans.
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== Causes ==
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Nowadays there is no absolute answer to what might cause ADHD, but it seems like an interaction between genetics, social behavior and physical condition.
=== Genetic ===
|| {{attachment:Dopamine processing in a synapse.png|Cilia|width="500 height=500"}} <
>'''Fig 1.'''<
>'' Dopamine synthesis and degradation.'' ||
ADHD is a neurobiological disorder that is associated to dysfunctions of [[https://en.wikipedia.org/wiki/Neurotransmitter|neurotransmitters]]. Genetic studies indicate that the disorder can be related to a [[https://en.wikipedia.org/wiki/Gene_polymorphism|polymorphism]] in tyrosine hydroxylase (TH) gene that directly affects the dopamine neurotransmission ([[http://www.wiki.vetphysiol.hu/ADHD_Dogs?action=AttachFile&do=get&target=Dopamine+processing+in+a+synapse.png|Fig.1]]) and to a DRD4 gene polymorphism which is responsible for [[https://en.wikipedia.org/wiki/Dopamine_receptor_D4|D4 dopamine receptor]] coding.
In a case study that has been performed by [[https://www.jstage.jst.go.jp/article/jvms/66/7/66_7_815/_article/-char/ja/|Ito et al. (2004)]], 23 breeds were divided based on their [[https://en.wikipedia.org/wiki/Allele_frequency|allele frequency]]. Dogs belonging to group A showed frequency in 435 and 447a alleles while the 447b, 498 and 549 were frequent in group B. The phenotype of the dog was analyzed by a questionnaire to the owner and it was possible to see that group B had a higher score in aggressiveness and a lower value of reactivity and trainability compared to group A. Another similar case study [[https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2052.2007.01657.x|(Hejjas et al., 2007)]] was conducted but it focused on a single breed- German Shepherd dog. The results correlated with the [[https://www.jstage.jst.go.jp/article/jvms/66/7/66_7_815/_article/-char/ja/|Ito et al. (2004)]] study and showed that a frequency of specific and same alleles will result in ADHD like behavior traits such as social impulsivity, activity impulsivity and inattention.
Another theory that has been tested is a connection between [[https://en.wikipedia.org/wiki/Tyrosine_hydroxylase|tyrosine hydroxylase]] (TH) polymorphism and the activity impulsivity trait [[https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0030271|(Kubinyi et al., 2012)]]. TH is a catalyzer of the conversion of the dopamine precursor (dihydroxyphenylalannin, DOPA), dopamine is the precursor of [[https://en.wikipedia.org/wiki/Catecholamine|catecholamines]] epinephrine and norepinephrine. As neurotransmitters, [[https://en.wikipedia.org/wiki/Dopamine|dopamine]] and norepinephrine are involved in many physiological processes such as attention and focus, movement control, cognition and etc., so they may be implicated in ADHD. German Shepherd dogs were investigated for the effect of TH repeat polymorphism on the activity impulsivity trait that was determined earlier by an owner questionnaire and a behavior test. The results showed that the dog group, who possessed at least one short allele (instead of homozygotes with only longer allele) was previously reported as active and impulsive by their owner and the behavior test that can be shown in[[http://www.wiki.vetphysiol.hu/ADHD_Dogs?action=AttachFile&do=get&target=47.png|Fig. 4.]]
=== Social and physical ===
|| {{attachment:125.png|Cilia|width="350 height=350"}} <
>'''Fig 2.'''<
>''Thyroid-adrenal axis .'' ||
In addition to genetic factors, physical and social factors seem to have an important effect on the ADHD like behavior in dogs. [[https://openventio.org/wp-content/uploads/Correlates-of-Attention-Deficit-Hyperactivity-Disorder-ADHD-Like-Behavior-in-Domestic-Dogs-First-Results-from-a-Questionnaire-Based-Study-VMOJ-2-122.pdf|Hoppe et al. (2017)]] found a correlation between certain factors and their effect on ADHD like behavior based on different questionnaires.
• Inattention can be caused by lack or a small amount of affectional behavior after adoption and by the sleeping pattern of the dog (alone/ with owner/ with other pets).
• How fast the dog will gain or lose interest and other concentration problems with games or tasks may be affected by the number of social contacts the dog experienced (dog-dog or dog-human).
• Problems with keeping itself calm can indicate on a long lasting separation periods. Another study might support this claim- Weller and Fuller (1961) found out that puppies who were separated from other puppies and had only limited access to them, displayed an excessive activity in social situations.
• Motor activity - castrated dogs seems to present a significantly higher motor activity, the explanation for that was shown by [[https://www.sciencedirect.com/science/article/abs/pii/S0003347211000078?via%3Dihub|Lisberg and Snowdon (2011)]] and [[https://www.frontiersin.org/articles/10.3389/fvets.2018.00018/full|Farhoody et al. (2018)]] and claims that dogs who have been castrated have an increased risk for development of fear, hyperactivity and anxiety duo to decrease in [[https://en.wikipedia.org/wiki/Testosterone|testosterone]] levels.
[[https://en.wikipedia.org/wiki/Hypothyroidism|Hypothyroidism]]- since the human medicine shows correlation between a hypothyroid function and a wild range of behavioral symptoms, where aggression is one of them, [[http://www.dogs4dogs.com/JR_Articles/dog-thyroid-and-behavior.htm|L.P Aronson (2008)]] suggested to test this theory also on dogs. Of the 1500 dogs that shown behavioral problems, 61.4% suffered from low or sub-optimal thyroid function. 54% of the diagnosed dogs showed a significant relationship between hypo-function of the thyroid gland and aggression, both, to human and to other dogs. There is not a clear understanding about how low thyroid function may affect the behavior however it might be linked to the fact that low levels of [[https://en.wikipedia.org/wiki/Thyroid_hormones|thyroid hormones]] may affect the dog's hypothalamic-pituitary-adrenal axis which controls the reaction of the dog to stress. Moreover elevated levels of [[https://en.wikipedia.org/wiki/Cortisol|cortisol]], that might be found in dogs, may cause it to feel a constant stress. High levels of cortisol will also suppress the production of thyroid stimulation hormone [[https://en.wikipedia.org/wiki/Thyroid-stimulating_hormone|(TSH)]], reduce the conversion of T4 to T3 and have a direct effect on the thyroid gland itself. Therefore, the thyroid-adrenal axis ([[http://www.wiki.vetphysiol.hu/ADHD_Dogs?action=AttachFile&do=get&target=125.png|Fig.2]]) might affect the behavior.
== Symptoms ==
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ADHD in canines seems to be with similar pathology as in humans. Dogs with ADHD show several behavioral signs. They manifest spontaneous activity without any stimulation and they simply can't relax. In addition, they have an elevated body temperature, heart and respiratory rate which stay high while in rest and during an activity. Dogs with ADHD are more difficult to train since their attention span is decreased and they also show signs of aggressive behavior.
In addition to these factors there are other details to be considered, especially the breed of the dog. Different dog breeds have different genes, and these carry different behaviors which we need to consider whether they are normal or abnormal for the specific dog. For example – [[https://en.wikipedia.org/wiki/Terrier|Terriers]] naturally have high levels of energy, excitement and boldness and with certain environmental factors one may think that a dog may be hyperactive while he is just acting as he is supposed to. Four important traits relating to dog behavior are trainability, calmness, sociability and boldness. The amount of the trait that each dog expresses has a great dependence on the breed – herding dogs are more trainable than toy dogs and non-sporting dogs, terriers are bolder than [[https://en.wikipedia.org/wiki/Hound|hounds]]. Using these descriptions of traits for each dog breed, we can create breed clusters as [[http://www.wiki.vetphysiol.hu/ADHD_Dogs?action=AttachFile&do=get&target=00.png|Fig.3]] shows and use them to group dogs together based on their typical behavior [[https://www.sciencedirect.com/science/article/abs/pii/S0168159111000864?via%3Dihub|(Turcsán et al., 2011)]]. Using these clusters, if a dog breed is known for a certain type of behavior, the traits it expresses can be somewhat predictable. This can help in noticing symptoms of ADHD since a dog owner can look for large discrepancies between how his dog behaves and what the dog breed usually behaves like. For example- if an Alaskan Malamute, which are usually calm and easy to train according to the cluster of breeds, is hyperactive and difficult to train, this might be an indication for an ADHD behavior. We can compare it to a Chihuahua that is naturally not calm and hard to train and doesn’t necessarily expresses ADHD symptoms, but just behaves normally.
|| {{attachment:00.png|Cilia|width="500 height=600"}} <
>'''Fig 3.'''<
>'' Clusters of breeds.'' ||
== Diagnosis ==
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The main question that might be asked is how can we differentiate between a normal behavior of a dog to an ADHD-like behavior.
=== Pre-diagnosis by the owner ===
Behavioral phenotype identification is a complicated thing to do, but a pre-diagnosis by the owner is possible through different means. Owners can primarily lean on the ADHD-Rating Scale, generally established on the human one, showing if the animal has ADHD-like symptoms. High boldness, low trainability, low calmness and low sociability are the main ones. The questionnaire will start with basic information about the dog- breed, age, living area and etc. Later on specific questions regarding the inattention and hyperactivity- impulsivity will be asked:
► It’s easy to attract your dog’s attention, but your dog loses interest easily.
► Your dog barks endlessly, seemingly at nothing important.
► Even if your dog knows someone is speaking to him/her, your dog doesn’t seem to pay any attention.
► Your dog often has difficulties performing tasks, even if your dog has practiced them often.
► Your dog’s attention can be easily distracted.
► Your dog cannot wait as it has no self-control.
(Questions from the ADHD Rating Scale [[https://journals.sagepub.com/doi/10.1177/0734282905285792|Du-Paul (1998)]] and [[https://www.sciencedirect.com/science/article/abs/pii/S0168159106000955?via%3Dihub|Vas et al. (2007)]], modified by [[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2823640/|Lit et al. (2010)]] for American dog owners)
Owners can also base their research on their dog’s breed, as there is evidence to suggest that some breeds seem to be predisposed to ADHD. Regarding genetic relatedness, breeds with ancient Asian or African origin seem to be less trainable than other breed groups[[https://www.sciencedirect.com/science/article/abs/pii/S0168159111000864?via%3Dihub|(Turcsán et al., 2011)]].
=== Diagnosis by a professional ===
|| {{attachment:47.png|Cilia|width="450 height=450"}} <
>'''Fig 4.'''<
>'' '' ''Behavioral test determining whether the dog posses an active & impulsive behavior.'' ||
In a study of the computational analysis of movement patterns of dogs with ADHD-like behaviors [[https://www.mdpi.com/2076-2615/9/12/1140|(Bleuer-Elsner et al., 2019)]] , 12 movement parameters were analyzed. This led to the identification of 3 dimensions after an observation of the most significant differences between the sample models : high speed, large coverage of the room space, and constant re-orientation in space, the 3 of them being easily observable by the clinicians.
Furthermore, examinations can be done, especially urine investigations, in order to notice the presence or not of the metabolites of [[https://en.wikipedia.org/wiki/Serotonin|serotonin]], related to behavioral inhibition, and dopamine, related to behavioral activation. The link between the renal system and the central nervous system remains unclear, but it has been demonstrated that individuals with a higher level of impulsivity in the DIAS (Dog Impulsivity Assessment Scale) would demonstrate a lower level of those metabolites in the urine. Aggressive behavior, characteristics of ADHD in dogs, is also characterized by reduced monoaminergic levels in the cerebrospinal fluid. The detection of these metabolites in the urine represents a non-invasive alternative suitable for the veterinary practice. Finally, a test can also be realized by giving the dog [[https://en.wikipedia.org/wiki/Methylphenidate|methylphenidate]] or [[https://en.wikipedia.org/wiki/Dextroamphetamine|D-amphetamine]] under clinical control. If the heart rate, respiratory rate and general ADHD symptoms are reduced, the dog can be diagnosed with ADHD.
== Management ==
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=== Behavioural therapies ===
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|| {{attachment:11.jpg|Figure 5: Impulse control - teaching the dog calm and polite manners. (YouTube video)|width="300"}} ||
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