
==== Front
Vet Med Sci
Vet Med Sci
10.1002/(ISSN)2053-1095
VMS3
Veterinary Medicine and Science
2053-1095
John Wiley and Sons Inc. Hoboken

39254119
10.1002/vms3.70015
VMS370015
Case Report
DOGS
Case Report
Suspected paroxysmal dyskinesia in four small‐breed dogs: Clinical presentation, diagnosis, management and prognosis
KIM et al.
Kim Minji 1
Cho Heesoo 1
Kim Unghui 1
Choen Sangkyung 2
Yun YoungMin 1 3
Song Woo‐Jin https://orcid.org/0000-0002-9195-551X
1 3 ssong@jejunu.ac.kr

1 Laboratory of Veterinary Internal Medicine College of Veterinary Medicine Jeju National University Jeju South Korea
2 Department of Surgical and Radiological Sciences School of Veterinary Medicine University of California Davis California USA
3 The Research Institute of Veterinary Science College of Veterinary Medicine Jeju National University Jeju South Korea
* Correspondence
Woo‐Jin Song, Laboratory of Veterinary Internal Medicine, College of Veterinary Medicine, Jeju National University, Jeju, 63243, Korea.
Email: ssong@jejunu.ac.kr

10 9 2024
9 2024
10 5 10.1002/vms3.v10.5 e7001522 7 2024
12 2 2024
23 8 2024
© 2024 The Author(s). Veterinary Medicine and Science published by John Wiley & Sons Ltd.
https://creativecommons.org/licenses/by-nc/4.0/ This is an open access article under the terms of the http://creativecommons.org/licenses/by-nc/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Abstract

This case report details the clinical presentation, diagnosis, management and prognosis of paroxysmal dyskinesia (PD) in four small‐breed dogs, each weighing under 6 kg: A 7‐year‐old spayed female Pomeranian, an 8‐year‐old female mixed breed, a 1‐year‐old female Pomeranian and a 9‐year‐old castrated male Poodle. These dogs were referred to our hospital due to movement disorders. Diagnosis was facilitated by video recordings of the episodes, assessing motor activity, consciousness, episode duration, any pre‐ or post‐episodic behaviour as well as the presence of autonomic signs. Magnetic resonance imaging conducted on two of the dogs returned unremarkable results. Treatment trials included a gluten‐free diet for all four dogs, with two also receiving acetazolamide. This intervention led to a decrease in the frequency of abnormal movement in all patients. Our findings suggest that PD in dogs can be effectively diagnosed through detailed symptom description using videos and questionnaires. Furthermore, once diagnosed, a combination of nutritional and medical management can be beneficial.

This case report details the clinical presentation, diagnosis, management and prognosis of paroxysmal dyskinesia (PD) in four small‐breed dogs. Our findings suggest that PD in dogs can be effectively diagnosed through detailed symptom description using videos and questionnaires. Furthermore, once diagnosed, a combination of nutritional and medical management can be beneficial.

canine
limb dystonia
movement disorder
paroxysmal dyskinesia
seizure
National Research Foundation of Korea 10.13039/501100003725 RS‐2023‐00252033 RIBS/NRF2019R1A6A1A10072987 source-schema-version-number2.0
cover-dateSeptember 2024
details-of-publishers-convertorConverter:WILEY_ML3GV2_TO_JATSPMC version:6.4.8 mode:remove_FC converted:10.09.2024
Kim, M. , Cho, H. , Kim, U. , Choen, S. , Yun, Y. M. , & Song, W.‐J. (2024). Suspected paroxysmal dyskinesia in four small‐breed dogs: Clinical presentation, diagnosis, management and prognosis. Veterinary Medicine and Science, 10 , e70015. 10.1002/vms3.70015 39254119
==== Body
pmc1 INTRODUCTION

Paroxysmal dyskinesia (PD) represents a category of movement disorders marked by episodic, self‐limiting abnormal and involuntary movements (Bhatia, 2011; Cerda‐Gonzalez et al., 2021). In human medicine, PD is categorized into three distinct types based on what triggers the symptoms (Bhatia, 2011). These categories include paroxysmal kinesigenic dyskinesia, which presents upon sudden movement or the start of exercise; paroxysmal non‐kinesigenic dyskinesia, occurring during periods of rest; and paroxysmal exertion‐induced dyskinesia, which emerges during prolonged physical activity (McGuire et al., 2018). These classifications are associated with different genetic variants (Erro et al., 2014; McGuire et al., 2018).

Translating these classifications to veterinary medicine presents challenges due to the diverse genetic backgrounds of different dog breeds and the variability in symptoms and anatomy between species (Cerda‐Gonzalez et al., 2021; Kolicheski et al., 2017; Mandigers et al., 2021; Nessler et al., 2020; Packer et al., 2010; Richter et al., 2015). Consequently, veterinary professionals categorize PD as either primary or secondary PD, depending on its origin (Cerda‐Gonzalez et al., 2021). Primary PD is attributed to genetic variants resulting in functional irregularities in the basal ganglia, while secondary PD arises from structural brain changes or hypersensitivity to external factors, such as drugs or dietary components like gluten (Cerda‐Gonzalez et al., 2021). A key clinical feature of PD is that affected animals do not experience loss of consciousness or display autonomic signs, such as hypersalivation, involuntary defecation or urination during the onset of episodes (Lowrie & Garosi, 2017).

Previously, differentiating PD from seizures based on owner reports proved challenging. However, the widespread use of smartphones and video data has facilitated the differentiation of clinical signs (Cerda‐Gonzalez et al., 2021; Lowrie & Garosi, 2017). This case report describes the diagnosis, management and prognosis of PD in four small‐breed dogs through the use of video data and questionnaires filled out by the owners, as well as dietary and pharmacological interventions.

2 CASE DESCRIPTION

2.1 Case 1

A 7‐year‐old neutered female Pomeranian dog, weighing 4 kg, was referred to us with a 6‐year history of intermittent episodes of sudden involuntary movements. These episodes were often triggered by stress and excitation, beginning with the dog walking with a hunched back or a displaying stiff, high‐stepping gait. Importantly, the patient showed no loss of consciousness or autonomic signs during this episode. Initially, episodes occurred once or twice a year from the age of one, but the frequency increased over time to two or three times daily. The average duration of each episode was 1–5 min.

Detailed information on the episodes was gathered using a previously described questionnaire (Polidoro et al., 2020), which was completed by the owner (Table 1). Interestingly, the dog experienced an episode while waiting in the hospital (Supporting Information S1). During the clinical examination, the patient exhibited panting and mild hyperthermia (39.7°C), which was attributed to stress, but otherwise appeared normal. A comprehensive neurological examination, along with a complete blood count (CBC; IDEXX ProCyte Dx Hematology Analyzer; IDEXX Laboratories), serum chemistry including ammonia and C‐reactive protein (CRP), electrolyte analysis (IDEXX Catalyst One Chemistry Analyzer; IDEXX Laboratories), plasma cortisol concentration (Vcheck cCortisol; Bionote) and canine Pancreatic Lipase (Vcheck cPL; Bionote), all returned unremarkable results. Urine analyses, including urine‐specific gravity and urine dipstick testing, also yielded normal results, and no significant changes were observed on radiographic examination or abdominal ultrasonography.

TABLE 1 Results of questionnaires of the dogs.

	Case 1	Case 2	Case 3	Case 4	
Age of onset	6 years	8 years	4 months	8 years	
Trigger able to elicit the episodes	Stress	Rest	Rest	Random	
Time of the day	Random	Random	Random	Random	
Frequency of the episodes	2–3 times in a day	2–3 times in a day	2–3 times in a day	2–3 times in a year	
Possible to predict	No	No	No	No	
Conscious during the episodes	Yes	Yes	Yes	Yes	
Aware of surroundings during the episode	Yes	Yes	Yes	Yes	
Attempt to come to the owner during the episode	Yes	Yes	Yes	Yes	
Can the owner get the dogs’ attention during the episode	Yes	Yes	Yes	Yes	
Salivation/defecation/urination during the episode	No	No	No	No	
Normal after/before the episodes	Yes	Yes	Yes	Yes	
Which limbs are mainly affected during the episodes	All limbs	Hind limbs	Front limbs	Front limbs	
Average length of an episode	<5 min	<5 min	<5 min	<5 min	
John Wiley & Sons, Ltd.

Based on the history and clinical findings, the patient was suspected to have PD. Magnetic resonance imaging (MRI) was performed to exclude the possibility of secondary PD due to intracranial lesions, which showed no evidence of brain disease. Considering the significant impact of episodes on the patient's quality of life, a lifelong gluten‐free diet and 2‐week trial of acetazolamide at 5 mg/kg orally every 12 h were initiated. Shortly after the diet change, the patient remained symptom‐free even without medication. Subsequent follow‐up visits confirmed a reduction in episode frequency to approximately once every few months.

2.2 Case 2

An 8‐year‐old female mixed‐breed dog weighing 5.8 kg was referred for intermittent episodes of sudden involuntary limb movements with dystonic posture and head tremors (Supporting Information S2). The episodes began immediately after adoption from a shelter and persisted for 2 weeks, occurring two to three times per day. Each episode lasted no longer than 5 min, without any loss of consciousness or autonomic symptoms. The patient's condition was normal before and after each episode (Table 1).

A comprehensive clinical and neurological assessment did not identify any abnormalities. Laboratory tests, including a CBC (IDEXX ProCyte Dx Hematology Analyzer), serum chemistry including ammonia and electrolyte analysis (IDEXX Catalyst One Chemistry Analyzer), were all within normal ranges. Additionally, thoracic and abdominal radiographs, as well as abdominal ultrasonography, did not reveal any abnormalities associated with the observed clinical signs.

Based on these findings, PD was suspected. An MRI was recommended to exclude the possibility of secondary PD caused by intracranial lesions. However, the owner decided against pursuing this diagnostic step. Treatment options included a gluten‐free diet and oral administration of 5 mg/kg acetazolamide every 12 h. At the owner's discretion, only the diet was modified. Following the dietary change, there was a significant increase in the duration between episodes, with the patient eventually remaining free of episodes for months and no need for medication.

2.3 Case 3

A 5‐month‐old female Pomeranian dog weighing 1.6 kg was referred for intermittent and repetitive dystonic postures along with involuntary limb movements occurring two or three times a day (Supporting Information S3). Each episode lasted no longer than 5 min, and notably, the patient exhibited no loss of consciousness or autonomic signs during these episodes.

Upon thorough clinical and neurological examination, no significant abnormalities were identified. Laboratory tests, including a CBC (CBC; IDEXX ProCyte Dx Hematology Analyzer), serum chemistry including ammonia and electrolyte analysis (IDEXX Catalyst One Chemistry Analyzer), were all within normal ranges. Considering the patient's young age, a distemper kit (Bionote) test was also performed, which yielded normal results. Radiographic examination and abdominal ultrasonography showed no remarkable findings.

Based on these findings, and in conjunction with the owner‐provided questionnaire information, PD was suspected (Table 1). Although an MRI scan was advised to rule out the presence of intracranial lesions, an initial dietary change was suggested due to the patient's young age, with the option to perform an MRI if symptoms did not improve. After transitioning to a gluten‐free diet, there was an immediate reduction in the frequency of episodes. Subsequent follow‐up assessments revealed that the patient's episodes decreased to approximately once every 2–3 months, eliminating the need for medication.

2.4 Case 4

A 9‐year‐old castrated male Poodle weighing 5.4 kg was referred due to two episodes of postural abnormalities, which occurred 6 months apart. Each episode lasted less than 5 min and was marked by rigidity of the front limbs, including notable elevation of the right front limb and neck dropping. No loss of consciousness, hypersalivation, defecation or urination was observed during these episodes (Table 1).

Physical and neurological examinations revealed no remarkable findings. Laboratory tests, including a CBC (IDEXX ProCyte Dx Hematology Analyzer), serum chemistry including ammonia, electrolyte analysis (IDEXX Catalyst One Chemistry Analyzer) and CRP (Vcheck CRP), were all within normal ranges. Additionally, thoracic and abdominal radiography, as well as abdominal ultrasonography, revealed no relevant abnormalities.

Based on these findings, PD was suspected. MRI confirmed the absence of structural disorders. In this case, we determined that treatment was not necessary based on the interval of symptom occurrence. However, since the owner desired proactive management, we decided to switch to a gluten‐free diet. Following this change, no symptoms were observed for at least 5 months.

3 DISCUSSION

Collapse in dogs is typically categorized into two types: Syncopal collapse, caused by a decrease in cardiac output, and non‐syncopal collapse, caused by other factors (Wray, 2005a). Specifically, diseases leading to non‐syncopal collapse include brachycephalic syndrome, which results in hypoxia, metabolic disorders such as hypoglycaemia, and neurological conditions such as seizures and movement disorders (Posporis et al., 2018; Wray, 2005a, 2005b, 2005c). The diagnosis of PD involves recognizing that patients’ symptoms may occur intermittently and that they are unable to maintain their posture without loss of consciousness (Lowrie & Garosi, 2017; Richter et al., 2015). Additionally, an inclusive assessment including physical examinations, neurological evaluations and blood tests is required to rule out syncopal collapse or metabolic dysfunctions, particularly when diagnosing primary PD (Park et al., 2014). The four cases we report also employed questionnaires (Polidoro et al., 2020) and video documentation as preliminary steps in the PD diagnosis process. This approach aimed to exclude conditions that could cause intermittent collapse with loss of consciousness. Furthermore, these cases demonstrated a favourable response to management strategies designed for PD, underscoring its significance in the differential diagnosis of non‐syncopal collapse.

Nevertheless, diagnosing PD based solely on clinical signs captured in videos and questionnaires has inherent limitations (Whittaker et al., 2022). Specifically, distinguishing PD from focal epileptic seizures poses considerable challenges (Posporis et al., 2018; Rogers et al., 2023; Yu et al., 2022). Although secondary PD accompanied by structural brain disorders is uncommon, utilizing MRI to detect structural lesions can aid in the differentiation process (Whittaker et al., 2022). However, distinguishing idiopathic focal epileptic seizures from PD in the absence of structural lesions remains challenging (Thomas, 2010). Nonetheless, MRI scans are recommended due to their value in prognosis (Fredsø et al., 2014), especially when differentiating PD from focal epileptic seizures based on the presence of intracranial lesions. Among the four case reports presented, two confirmed PD without intracranial lesions, highlighting the diagnostic challenge presented with the unavailability of MRI scans.

Cerebrospinal fluid analysis to rule out the possibility of infection was not conducted in any of the patients. In Case 3, who was younger, a kit test was performed; however, its reliability is questionable (Amude et al., 2006; Sarchahi et al., 2022). Nonetheless, considering that symptoms of distemper infection typically include gradually progressing paralysis, vestibular signs, seizures, and dementia (Amude et al., 2007; Koutinas et al., 2002), the likelihood of distemper infection was deemed low.

Using electroencephalography (EEG) would be greatly beneficial in diagnosing PD, as unlike focal epileptic seizures, PD typically does not exhibit seizure activity on EEG (Musteata et al., 2023; Packer et al., 2010; Polidoro et al., 2020). However, none of the four cases in our study underwent EEG due to the limited availability of equipment and the technical challenges of conducting EEG during events. In addition, there is a recent study suggesting that measuring the concentrations of gliadin peptide immunoglobulin G and tissue transglutaminase‐2 immunoglobulin A in serum could aid in the diagnosis and management of PD; however, we were unable to evaluate these parameters (Rogers et al., 2023). Despite this, considering that all four cases improved symptomatically without the use of antiseizure medications, solely through nutritional changes and a trial of acetazolamide, PD could be strongly suspected.

Treatment for PD is generally not pursued unless the symptoms are severe and significantly impact the quality of life of either the owner or the patient, because of the potential for self‐limiting remission (Lowrie & Garosi, 2016). However, if quality of life is affected or if symptoms occur more than once a week, intervention becomes essential (De Risio et al., 2016; Royaux et al., 2016). Notably, a gluten‐free diet has been identified as beneficial to patients diagnosed with PD (De Risio et al., 2016; Lowrie et al., 2018; Polidoro et al., 2020; Stassen et al., 2017), and there is evidence supporting the efficacy of acetazolamide in symptom management, making it a viable treatment option (Polidoro et al., 2020; Royaux et al., 2016).

In our case series, we approached treatment by first introducing a gluten‐free diet, reserving acetazolamide for cases where dietary changes did not yield sufficient improvement (Cases 3 and 4). Case 2 saw the addition of acetazolamide when the diet adjustment alone was ineffective. For one patient, we adopted a simultaneous approach of dietary changes and immediate acetazolamide administration from the outset (Case 1).

However, should these initial strategies prove inadequate, further treatment options include selective serotonin reuptake inhibitors such as fluoxetine (Geiger & Klopp, 2009; Polidoro et al., 2020) and antiepileptic drugs such as levetiracetam (Green & Olby, 2021), diazepam (Green & Olby, 2021; Stassen et al., 2017) and phenobarbital (Harcourt‐Brown, 2008; Stassen et al., 2017). These alternatives, however, were not explored in our cases due to observed improvements in symptoms with the primary interventions of dietary changes and acetazolamide administration.

According to a retrospective study (Lowrie & Garosi, 2016), PD can go into spontaneous remission without treatment in Labrador Retrievers and Jack Russell Terriers. In this context, since we cannot exclude the possibility that the four cases in our study experienced clinical remission without treatment, it is challenging to attribute their improvement solely to the efficacy of nutritional changes. Additionally, we cannot entirely rule out the potential for a placebo effect resulting from either the nutritional changes or the administration of acetazolamide. Therefore, a longer follow‐up period is necessary to further investigate and understand the outcomes of the cases in our study.

4 CONCLUSION

This case series has illustrated that PD can be effectively diagnosed through detailed symptom descriptions, supplemented by video documentation and owner‐completed questionnaires, in dogs presenting with movement disorders. Furthermore, it underscores the significance of nutritional and medical management trials not only in managing PD but also in facilitating its diagnosis. These insights highlight the importance of comprehensive, non‐invasive diagnostic approaches and underscore the potential for specific treatment regimens to improve the quality of life for affected patients.

AUTHOR CONTRIBUTIONS

Minji Kim: Conceptualization; Investigation; Methodology; Writing ‐ original draft. Heesoo Cho: Conceptualization; Investigation; Methodology. Unghui Kim: Investigation; Methodology. Sangkyung Choen: Investigation; Methodology. Youngmin Yun: Investigation; Methodology. Woo‐Jin Song: Conceptualization; Data curation; Funding acquisition; Writing ‐ original draft; Writing ‐ review & editing.

CONFLICT OF INTEREST STATEMENT

The authors declare no conflicts of interest.

ETHICS STATEMENT

The dogs described in this report were client‐owned patients presented for care at the veterinary medical teaching hospital of Jeju National University. Informed owner consents were received for any possible research use of all diagnostic samples acquired from the dogs.

PEER REVIEW

The peer review history for this article is available at https://www.webofscience.com/api/gateway/wos/peer-review/10.1002/vms3.70015.

Supporting information

Supporting information 1. Video image of clinical presentation of the dog in case 1.

Supporting information 2. Video image of clinical presentation of the dog in case 2.

Supporting information 3. Video image of clinical presentation of the dog in case 3.

ACKNOWLEDGEMENTS

This study was funded by the National Research Foundation (NRF) of Korea grant funded by the Korean government (MSIT) (RS‐2023‐00252033), and also by Basic Science Research Program to Research Institute for Basic Science (RIBS) of Jeju National University through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2019R1A6A1A10072987).

DATA AVAILABILITY STATEMENT

Data sharing is not applicable—no new data are generated.
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