The dog faints what to do. Why a dog loses consciousness and how to help it Why does a dog lose consciousness
It is generally accepted that impressionable and nervous people tend to faint. It is all the more unexpected to find out that our pets can also do the same. What to do if your dog fainted, and what could this unusual phenomenon indicate?
The term "fainting" refers to a short period of unconsciousness due to insufficient oxygen supply to the brain. It lasts from a few seconds to a couple of minutes. What are the causes of fainting in dogs?
Most of the fainting occurs due to hypoxia, often this happens at reduced pressure. This phenomenon is not a disease, but often indicates the presence of some kind of pathology. So, if your dog is constantly “turning off” for no apparent reason, this may indicate the presence in his brain.
Blood pressure indicators depend on the state of the heart and the vascular bed. Accordingly, diseases of the heart or blood vessels (cardiovascular system) are the most common causes of fainting. It is not uncommon for a dog to “walk away” due to problems with the conduction structures of the heart (bundle block). Some structural pathology of the heart () or pericardial disease, which interferes with the normal process of cardiac contraction, may also be to blame.
Please note! Fainting of cardiac etiology is extremely dangerous, as it can lead to severe morphological and functional disorders of the brain (they last a long time).
Like the people some dogs are different increased nervous excitability, and fainting in their case may be due to "physiological" causes. So, some dogs faint with joy. Of course, such cases are rare, but they should not be completely ruled out.
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Other causes that can lead to fainting in dogs include: severe respiratory illness (in some cases even a severe cough may be to blame), metabolic diseases, endocrine gland disorders, vegetative dystonia (this is a very common predisposing factor) and some medications. drugs. The less the dog is in a faint, the less dangerous it is for the animal's body.
Symptoms and identification of causes
What can be observed for a dog that, for one reason or another, is prone to cases of fainting? There are no specific symptoms, but predisposed pets often behave somewhat strangely:
- Sudden weakness. Syncope often begins with sudden weakness, which in some cases reaches (uncoordinated movements are observed). If your dog exhibits any of these, take it to the veterinarian. It certainly won't be redundant.
- In some dogs, “musical abilities” erupt before fainting: the dog begins to squeal, whine, wheeze. It looks scary, especially in those cases when, immediately before the “dumping”, the animal literally eyes roll.
- Rigidity of the neck muscles. Simply put, the muscles are greatly relaxed so that the dog’s head literally “falls through”. Sometimes it looks as if the pet has begun, after which the dog faints.
- In many cases of fainting or pre-syncope, the dog unconsciously emptying the intestines and bladder. You should not blame the dog for this, since he cannot control his actions at the moment of turning off the cerebral cortex.
Read also: Causes and remedies for bloating in dogs
As you can understand, the diagnosis of "fainting" does not exist. The veterinarian will have to figure out what kind of pathology causes the animal's brain to turn off for a short time. To do this, you need to conduct a comprehensive examination of the dog:
- Disease history(including treatment history). A thorough physical examination is performed, with emphasis on listening to the heart and lungs.
- Information is collected from the owners: what their pet was sick with, whether he had craniocerebral injuries, poisoning, or other serious pathologies.
- Blood measurement. Moreover, this should be done not once, but several times a day, for at least three to four days. During this time, the dog will get used to the veterinarian, stop being nervous, and the research results will become more “adequate”.
- Are taken. In particular, it is very important to determine the level of glucose (again, for at least three days). The fact is that it can easily lead to fainting hyperglycemia characteristic of
Fainting (syncope) is a condition that is characterized by a temporary loss of consciousness and spontaneous recovery.
The reasons
The main reason is a temporary decrease in cerebral blood supply, leading to a deterioration in the delivery of oxygen and nutrients to the brain. Fainting is not common in dogs and is not always caused by a lack of normal blood flow to the brain, there are other medical causes that lead to fainting in both humans and animals.
Fainting in dogs is usually associated with one of two causes (major problems): neurological (brain or spinal cord) or cardiac (eg, cardiac arrhythmias, etc.).
Neurological problems may include:
- epilepsy;
- disruption of brain activity.
Cardiac problems may include:
- cardiac arrhythmias (for example, atrial fibrillation, atrioventricular blockade, sick sinus syndrome, etc.);
- ventricular tachycardia;
- ventricular fibrillation.
Fainting in dogs needs to be differentiated from the more general problem of total loss of energy. When severely weakened, unconsciousness usually does not occur, in other words, your dog may be weak and unable to stand up, but he is still conscious. There are numerous reasons for general weakness: shock, severe hypotension, internal bleeding, severe anemia, heat stroke, low blood sugar, etc. This requires immediate veterinary care.
Symptoms
Nausea, vomiting, incoordination, lips, eyelids turn pale, pulse weakens, paw pads get cold.
What to do if your dog faints?
Remember, if the brain does not receive oxygen for only a few minutes, then an irreversible disruption of its activity occurs, so prolonged fainting can cause sudden death.
- First aid: lay the dog on its side, remove the collar, pull out the tongue, open the airways, put a cold compress on the head, and position the dog itself so that the head is lower than the body - this ensures blood flow to the brain. When the dog regains consciousness, give him cold water.
- After giving first aid during the episode, put your hands over your pet's heart, you can feel the heartbeat. Try noticing the heart is contracting very, very slowly or extremely fast. This will help your veterinarian determine if the cause of the syncope is cardiac in origin.
- Try videotaping the episode. This can help your veterinarian or veterinary specialist (neurologist, cardiologist) determine the physical cause of the attack.
- See your veterinarian as an untreated cause of fainting can be a potential life threat.
Examination of a dog in a veterinary clinic
Once you get to the veterinarian, the doctor will need to check the heart rate on an ECG to detect the presence of arrhythmias (they may not be present if your pet has recovered from an episode of syncope) and take a blood test to make sure there are no metabolic causes (for example, due to a violation of the liver, kidneys, etc.), or hypoglycemia (decrease in blood glucose levels) that causes an episode.
If neurological problems are found, further evaluation by a neurologist is necessary, and an MRI or spinal tap may be required.
If cardiac abnormalities are found, your pet will be referred to a cardiologist for an ultrasound of the heart (ECHO), chest x-rays, and may need a Holter monitor (to monitor the heart rhythm).
Fainting is a temporary and reversible phenomenon that occurs when a dog wakes up shortly after an episode of unconsciousness. However, if the underlying cause is not treated, it can lead to more episodes of syncope and worsening of other symptoms related to the disease. Consult your veterinarian, remember, your pet's health is in your hands.
The article was prepared by the doctors of the neurological department "MEDVET"
© 2015 SVTS "MEDVET"
It is generally accepted that impressionable and nervous people tend to faint. It is all the more unexpected to find out that our pets can also do the same. What to do if your dog fainted, and what could this unusual phenomenon indicate?
GENERAL INFORMATION
The term "fainting" refers to a short period of unconsciousness due to insufficient oxygen supply to the brain. It lasts from a few seconds to a couple of minutes. What are the causes of fainting in dogs?
Most syncope occurs due to hypoxia, often this happens with reduced pressure. This phenomenon is not a disease, but often indicates the presence of some kind of pathology. So, if your dog is constantly "turning off" for no apparent reason, this may indicate the presence of a tumor in his brain.
Blood pressure indicators depend on the state of the heart and the vascular bed. Accordingly, diseases of the heart or blood vessels (cardiovascular system) are the most common causes of fainting. It is not uncommon for a dog to “walk away” due to problems with the conduction structures of the heart (bundle block). Some structural pathology of the heart (cardiomyopathy) or pericardial disease that interferes with the normal process of heart contraction may also be to blame.
Please note! Fainting of cardiac etiology is extremely dangerous, as it can lead to severe morphological and functional disorders of the brain (they last a long time).
Like people, some dogs are characterized by increased nervous excitability, and fainting in their case may be due to "physiological" reasons. So, some dogs pass out with joy. Of course, such cases are rare, but they should not be completely ruled out.
Other causes that can lead to fainting in dogs include: severe respiratory illness (in some cases even a severe cough may be to blame), metabolic disease, endocrine gland dysfunction, vegetative dystonia, anemia (this is a very common predisposing factor), and some medications. The less the dog is in a faint, the less dangerous it is for the animal's body.
SYMPTOMS AND CAUSE IDENTIFICATION
What can be observed for a dog that, for one reason or another, is prone to cases of fainting? There are no specific symptoms, but predisposed pets often behave somewhat strangely:
Sudden weakness. Syncope often begins with sudden weakness, which in some cases reaches ataxia (uncoordinated movements are observed). If your dog exhibits any of these, take it to the veterinarian. It certainly won't be redundant.
In some dogs, “musical abilities” erupt before fainting: the dog begins to squeal, whine, wheeze. It looks scary, especially in those cases when, immediately before the “stall”, the animal literally rolls its eyes.
Rigidity of the neck muscles. Simply put, the muscles are greatly relaxed so that the dog’s head literally “falls through”. Sometimes it looks like the pet has an epileptic seizure, after which the dog faints.
In many cases of fainting or pre-syncope, the dog unknowingly empties his bowels and bladder. You should not blame the dog for this, since he cannot control his actions at the moment of turning off the cerebral cortex.
INFORMATION ABOUT TREATMENT AND PREVENTION
The treatment of fainting is to find and eliminate the root cause. Unfortunately, this is not always possible. Often, fainting in an animal is recognized as idiopathic. In this case, the owner can only rely on some possibilities to prevent seizures. In particular, try to keep your dog stress free, deworm regularly, etc.
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Jorg M. Steiner MedVet, DrMedVet, DiplACVIM, DiplECVIMCA A&M University, Texas, USA
Jörg M. Steiner works in the laboratory of gastroenterology. Department of Veterinary Medicine and Small Animal Surgery, A&M University, Texas, USA
MAIN PROVISIONS
- Collapse is the sudden fall of the dog, associated with loss of consciousness.
- There are three types of collapse: seizures, fainting and narcolepsy.
- The most common cause of seizures in older dogs is intracranial neoplasia or hypoglycemia.
- Hypoglycemia, as the main cause of seizures, can be due to many pathologies, but in older dogs it is usually caused by insulinoma.
- The diagnosis of insulinoma can be made on the basis of an abnormally high serum insulin concentration during episodes of hypoglycemia.
- Fainting can be caused by both glycopenia and cerebral hypoxia. Hypoxia can occur for various reasons, the most common cause of transient hypoxia is cardiac arrhythmia.
- For the diagnosis and characterization of cardiac arrhythmias leading to syncope, it is necessary to conduct constant or periodic monitoring.
INTRODUCTION
The term "collapse" is used ambiguously in veterinary medicine. In this article, this term refers to the sudden fall of a dog, associated with loss of consciousness. It should be noted that there are a number of other conditions associated with an acute attack of weakness in which consciousness is not lost. Examples of such conditions are malignant myasthenia gravis, acute herniated disc or cataplexy. These states are not covered in this article.
In general, 3 types of manifestation of collapse can be distinguished (Figure 1) (1):
- fit,
- fainting,
- narcolepsy
The most common type of collapse in dogs at any age is seizures, which can be either generalized or partial. Generalized seizures are in most cases tonic-clonic (convulsive) in nature, but psychomotor epileptic seizures (sometimes called petit mal seizures or absences) also occur. Fainting is also often observed in older dogs. Narcolepsy is rare in dogs and, as it is more common in young animals, is not discussed further.
Figure 1. Classification of types of collapse in a dog.
The initiation of work with a patient suffering from a manifestation of collapse should at least include a thorough neurological and ophthalmological examination; immediate determination of the content of glucose in the blood and the cellular formula of the blood; biochemical analysis of serum; general clinical analysis of urine. Patients suffering from fainting or psychomotor seizures should have electrocardiography (ECG).
convulsions
A seizure is the result of a paroxysmal disturbance of the electrical activity of the brain. Seizures are initiated by a group of neurons called the “paroxysmal focus”. These neurons have a reduced excitability threshold or loss of the necessary control from inhibitory neurotransmitters. Under the action of these neurons, neighboring neurons depolarize and, depending on the extent of this process, partial or generalized seizures occur (2).
The etiology of seizures is diverse. The causes of these conditions are given in Table 1 (1,2). Some of these are unimportant in older dogs (eg lisencephaly), others may be important at any age (eg trauma or toxicosis). In the following, special attention will be paid to several of the causes that cause seizures in older dogs. These include primarily primary intracranial neoplasms, followed by hypoglycemia and hepatoencephalopathy.
Intracranial neoplasms
Intracranial neoplasms by origin can be primary or secondary. Brain damage from metastases is quite common in humans with cancer, and as therapies for primary tumors improve and the lifespan of animals with such tumors improves, it is increasingly seen in dogs (Figures 2 and 3) (3). Among the primary intracranial neoplasms detected in dogs, meningiomas are in the first place in terms of frequency of detection (Figure 4), and gliomas are in the second place (4). clinical manifestations
Differential diagnosis of the causes of seizures
Causes of seizures that are more common in older than younger dogs are shown in bold even though they are rare overall.
Causes of intracranial localization
Degenerative processes
- Lysosomal storage disease
congenital anomalies
- congenital hydrocephalus
- Lisencephaly
Neoplasms of the brain
- Primary tumors
- Metastases
idiopathic
- Idiopathic epilepsy
infections
- Viral (e.g. rabies, plague)
- Rickettsial (e.g. Rocky Mount spotted fever)
- Bacterial (rare)
- Fungal (for example, cryptococcosis, blastomycosis and others, more rare)
- Protozoan (e.g. toxoplasmosis)
- Helminthic (for example, with impaired migration of larvae)
Inflammatory
- Granulomatous meningoencephalitis
- Steroid sensitive meningoencephalitis
Toxic (poisoning)
- ethylene glycol
- Heavy metals (eg lead, etc.)
- Phosphorus organic compounds and others
traumatic
Causes of extracranial localization
- hypoglycemia
- Hepatoencephalopathy (eg, portosystemic shunting, liver failure)
- Uremia
- Hypothyroidism
- Hypocalcemia
- Hyperlipoproteinemia
- Severe hyper or hyponatremia
- Hypertension
- Polycythemia
- Hyperviscosity syndrome Diabetic ketoacidosis
Many patients with intracranial neoplasms experience seizures. In practice, more than 50% of patients with brain tumors localized in the rostrum, seizures were the first clinical symptom (5). However, many coac patients initially present with other neurologic symptoms, such as loss of vision, characteristic head tilt, impaired filtration, and disturbances in pain sensitivity or behavior, which may reflect the specific location of the brain tumor lesion.
Diagnostics
At the initial stage of diagnosis of old dogs prone to seizures, one should undergo a neurological and ophthalmological examination, analyze the cellular formula of the blood, the chemical composition of the serum, the determination of thyroid hormones and urine analysis. All of these tests are very significant, because. can detect hypoglycemia, liver failure and other causes of seizures. In addition, the obtained data provide information on the most frequently affected organs in dogs during aging.
It should be noted that a normal blood glucose level does not exclude hypoglycemia from among the possible causes of seizures.
Intermittent hypoglycemia is detected only after a period of fasting. If liver failure is suspected (eg, unexplained weight loss or intermittent vomiting), blood bile acid levels should be measured before and after feeding.
To identify a possible source of metastases, an x-ray examination of the chest in three projections of the left lateral, right lateral and ventrodorsal should also be performed. If, after all the above tests, the most likely diagnosis is intracranial mass, the next step is to perform a CT scan or MRI of the brain (6,7). Since, in practice, in most cases, MRI equipment is not available to veterinarians, it is possible to use a tomograph in the nearest medical facility. X-ray of the skull is seldom useful, except in those few cases where the bone tissue is largely affected.
After computed tomography or MRI, a lumbar puncture should be performed. This is due to the fact that in some cases, inflammatory processes of the granulomatous type or fungal infections can give very similar symptoms in neoplasms. In the cerebrospinal fluid of patients with brain tumors, the protein content is usually mildly or moderately increased, and the number of leukocytes is slightly increased in about 60% of cases (8). Tumor cells themselves are rare in the cerebrospinal fluid. If an increase in intracranial pressure is expected, then appropriate measures should be taken to prevent infringement of the brain.
The possibilities of anticancer therapy for intracranial neoplasms are very limited. In some cases, surgical intervention is possible, but this requires that the veterinary clinic has a qualified neurosurgeon.
Other therapeutic approaches are largely determined by the type of tumor, which is not fully known until a biopsy is performed. Radiation therapy partially suppresses the development of some types of neoplasms (9). Treatment with anticancer drugs is usually less effective (except in cases of lymphosarcoma). Control studies are very important to evaluate different therapeutic approaches for the treatment of specific neoplasms.
For many patients, symptomatic anti-inflammatory therapy with glucocorticoids is effective, at least for a short period of time. If seizures are frequent, prolonged, severe, or intermittent, treatment with anticonvulsants should be considered.
hypoglycemia
Insulinoma-induced hypoglycemia is the second most common cause of seizures in older dogs. However, hypoglycemia as the cause of these seizures may be of another origin (Table 2). To clarify the causal relationship between hypoglycemia and seizures, the Wipple triad must be followed:
- to establish a reduced concentration of glucose in the blood,
- identify clinical symptoms of hypoglycemia,
- ensure the disappearance of clinical symptoms after normalization of blood glucose levels.
If a triad occurs, then an attempt should be made to establish the cause of hypoglycemia. In the majority of cases in older dogs, insulinoma is the cause, but hypoglycemia can also result from tumors outside the pancreas, liver failure, or sepsis.
Figure 2. Metastasizing neoplasm: metastatic brain lesions (black areas) in a dog with splenic hemangiosarcoma.
Contributed by Dr. David Waters, Purdue University
Figure 3. Computed tomography result of intracranial lesions with metastases in the same dog as in Figure 2. The massiveness of the lesion, characteristic of metastatic neoplasms or granulomatosis, is obvious. Contributed by Dr. David Waters, Purdue University
Figure 4 Meningioma in the pituitary region. Affected animals with this neoplasm rarely suffer from seizures.
Contributed by Dr. S. Schelling, Veterinary Hospital. Angela, Boston
Primary diagnosis
In all cases of collapse, it is necessary to conduct a thorough neurological and ophthalmological examination, determination of the cellular formula of the blood, the chemical composition of the serum and the general clinical analysis of urine. If a patient has hypoglycemia during an attack, the concentration of insulin in the blood serum should also be determined. However, some dogs may not detect low blood glucose during an attack due to hormonal imbalance. Such animals are shown serial determination of blood glucose for 48 hours against the background of starvation. If the glucose concentration falls below 50 mg/dL (2.8 mmol/L), the serum insulin level should be measured and then fed. Since insulinoma cells secrete insulin autonomously, a patient with insulinoma in the serum against the background of hypoglycemia has an abnormally high level of insulin. On the contrary, if hypoglycemia is associated with neoplasms of non-pancreatic origin or other causes, the detected insulin level is low.
Neoplasms of non-pancreatic origin as a cause of hypoglycemia
Hepatocarcinomas are the most common cause of hypoglycemia, but other types of tumors can also cause it (10,11). When identifying a tumor in an animal with hypoglycemia, a histopathological examination of the biopsy specimen should be performed to clarify the diagnosis and establish the stage of the disease. To select the appropriate therapy, the reader is referred to the specialized literature on the treatment of specific types of tumors in each individual case.
Sepsis as a cause of hypoglycemia
Sepsis is rarely the cause of hypoglycemia. However, it should be kept in mind if, with a normal serum insulin level, clinical symptoms and changes in the blood composition characteristic of sepsis are detected (12). In such cases, a microbiological blood culture should be done and a thorough antibiotic treatment should be initiated.
Insulinoma as a cause of hypoglycemia
Dogs with insulinoma may exhibit neuroglycopenic syndromes (seizures, weakness, ataxia, depression) or symptoms of increased sympathetic tone (changes in behavior, trembling, staggering gait, muscle atrophy). Clinical symptom data from a sample of 113 dogs with insulinoma are shown in Table 3(13).
In most animals with insulinoma, symptoms are intermittent. Therefore, it is not always easy to recognize during the usual therapeutic examination. Only a few patients show signs of epilepsy or develop a coma. In some older dogs, a number of geriatric anomalies may not be associated with insulinoma, such as symptoms of peripheral polyneuropathy (14).
The most common causes of hypoglycemia
Causes more common in older than younger dogs are in bold.
False hypoglycemia
- Incorrect separation of serum from whole blood
- Lab error
Decreased glucose intake
- Hypoglycemia in puppies
- Chronic starvation
- chronic malnutrition
Decreased gluconeogenesis
- Adrenal insufficiency
- Portosystemic anastomosis
- Liver failure
- adrenocortical insufficiency
Glucose storage disorders
- Hypoglycemia in puppies
- Hypoglycemia in toy breed dogs
- Liver failure
- Portosystemic anastomosis
- Liver failure
Enhanced glucose utilization
- insulinoma
- Neoplasm outside the pancreas
- Sepsis
- Hypoglycemia in hunting dogs
iatrogenic
- Overdose of exogenous insulin
Chest and abdominal radiographs are rarely helpful in diagnosing insulinoma, and there are no reports that lung metastases can be detected in pets using this approach. However, such studies may be useful to rule out other causes of hypoglycemia. Abdominal ultrasonography is a valuable tool for the patient with suspected insulinoma. Although ultrasonography can only detect insulinoma in a small number of cases, this procedure is very helpful in identifying its metastases to various organs or mesenteric lymphadenopathy.
In medicine and veterinary practice, many diagnostic tests are used when insulinoma is suspected. The most important of these is the detection of abnormally high levels of insulin in the blood serum against the background of hypoglycemia (insulinglucose pair). Serum to determine the concentration
Table 3
Clinical signs of insulinoma based on observations of 113 dogs
The amount of insulin should be received during hypoglycemia. In this case, it is necessary to conduct a serial measurement of blood glucose in a starving animal.
Several ratios were used to estimate elevated insulin levels: glucose/insulin, insulin/glucose, and adjusted insulin/glucose ratio (15). Unfortunately, none of them improves diagnosis due to the high number of false positives (16). Therefore, in practice, the definition of these relationships is not recommended. The use of provocative tests to detect insulinoma is also not recommended; they are lengthy, expensive and potentially sleepy for the patient, because promote hypoglycemia.
Safe treatment should be aimed at eliminating hypoglycemia and overcoming its consequences. If hypoglycemia is detected, the animal should be given an intravenous injection of dextrose (0.5 g/kg of body weight in the form of a 25% solution for 1 a), and then begin the administration of glucose through a dropper. The goal in one case is to eliminate the symptoms rather than to normalize the concentration of glucose in the blood. In the presence of symptoms of hypoglycopenia, cerebral edema is possible. In such cases, treatment with mannitol and glucocorticoids may be indicated (15).
In the early stages, insulinomas in dogs can be surgically removed. During surgery, continuous monitoring of the patient's blood glucose level should be carried out. In order to determine the stage of tumor development during the walkie-talkie, a thorough examination of the abdominal cavity is necessary, taking biopsy specimens from suspicious lymph nodes and those close to the liver. In a study (13), which analyzed the results of survey laparotomies in 129 dogs with insulinoma, metastases were detected in 66 cases (51%) (Figure 5). Identification of an insulinoma can be quite difficult. In the work mentioned above (13), in 26 cases out of 129, the pancreas had no visible pathology. However, further development of the technique for determining the localization of tumors allows us to rely on the success of its use in dogs with insulinoma. A huge number of these methods have been developed for humans and are too complex or not readily available in veterinary medicine. The most acceptable method for veterinary medicine is ultrasound of the pancreas during surgery.
When manipulating the tissue of the pancreas, you should be extremely careful. The preferred type of intervention is partial pancreectomy (Figure 6) I). If the tumor cannot be localized on abdominal examination, a pancreatic biopsy should be performed to assess for diffuse neoplastic infiltrates, and pancreatic tissue should not be arbitrarily removed. The most common postoperative complication is acute pancreatitis, but its risk is reduced by careful handling of the pancreas during surgery and appropriate postoperative care. Another frequent postoperative complication is prolonged hypo- or hyperglycemia.
Figure 5. Dogs with liver metastases from insulinoma. A severe case of liver injury by metastases is evident in this dog.
According to Dr. T. VanWinkle, Pennsylvania State University. Published with the permission of the author (13).
Figure 6. Insulinoma in a dog after removal by partial pancreectomy.
Other cancer therapies, such as chemotherapy or radiation therapy, are used in human medicine but are rarely used in veterinary medicine. Therefore, it is impossible to give specific recommendations on their use.
- Symptomatic treatment is prescribed in the following cases:
- refusal of the owner to undergo surgery,
- intolerance to anesthesia in animals,
- inoperability of insulinoma,
- surgical failure,
- recurrence of symptoms after surgical treatment of insulinoma.
Feed the dog 46 times a day, using high-protein, high-fat foods containing a large amount of complex carbohydrates. Such a diet can in principle be prepared at home on the advice of a nutritional veterinarian. However, now there is a sufficient amount of dry high-calorie feed intended for growing animals, which are quite applicable in this case. When signs of weakness, the dog should immediately be given a small portion of food. The owner is advised to give the dog a dextrose solution (in the form of syrup or honey) to act on the mucous membranes and contact the veterinarian in case of seizures. Exciting the dog should be avoided, and physical activity should be limited to a short walk on a leash (15).
If frequent feeding alone is insufficient to prevent clinical manifestations of hypoglycemia, treatment with glucocorticoids should be initiated. Prednisone or prednisolone can be used at a dose of 0.25 mg/kg per os 2 times a day. If clinical signs of hypoglycemia persist, the hormone dose may be increased up to a maximum of 23 mg/kg twice daily. Contraindications to steroid therapy are the appearance of iatrogenic hyperadrenocorticism and side effects from the gastrointestinal tract (gastritis, stomach ulcers, colitis).
Diazoxide benzothiadiazine with hypertensive and hyperglycemic action, which does not have a diuretic effect, does not inhibit insulin synthesis and does not have a toxic effect on beta cells. The recommended dose of diazoxide is 5 mg/kg per os 2 times a day. If small doses of the drug are ineffective, the dosage can be gradually increased, bringing up to 30 mg / kg 2 times a day. To reduce the chance of gastrointestinal side effects, diazoxide should be given to the dog with the food (18).
Somatostatin reduces the content of several polypeptide hormones produced by the gastroenteropancreatic system, including insulin, glucagon, gastrin, secretin, motilin, and several others. Octreotide, a long-lived derivative of somatostatin, reduces the blood insulin levels of people with insulinoma by about 50% and significantly improves their clinical condition in 65% of cases. The efficacy of octreotide was studied in 5 dogs with recurrent beta cell tumor. A dose of 1020 micrograms of octreotide was administered to dogs 23 times a day. Two dogs survived for 9 and 12 months, respectively (19). However, one of these dogs was treated with octreotide for only one week, followed by glucocorticoid therapy. There were no visible side effects at the above doses of octreotide (19). Clearly, more research is needed to optimize dosage and frequency of octreotide in dogs.
The long-term prognosis for dogs with insulinoma is poor, but the short-term prognosis may be quite good. Based on the results of evaluating the effectiveness of surgical treatment of insulinoma and subsequent symptomatic treatment in the event of its recurrence in a sample of 114 dogs, the average life expectancy of animals was 11.5 months, and 12 months in 25 dogs (13). It should be noted that animals with non-metastatic insulinoma (MO stage) live much longer than dogs with metastatic insulinoma (Ml stage) (20).
Liver failure
Hepatoencephalopathy can trigger seizures in dogs at any age. However, in older dogs, hepatoencephalopathy usually develops as a result of liver failure (with or without secondary portosystemic anastomosis). Liver failure can occur under the influence of a large number of various etiological factors (infection, inflammation, toxicosis or neoplasms). However, in older dogs, the most common causes of liver failure are chronic idiopathic hepatitis, anticonvulsant drug toxicity, and metastatic liver tumors rather than primary tumors (21).
Before the onset of the first clinical symptoms of hepatoencephalopathy, the liver must lose a significant part of its functional reserve (Figure 7). Often in animals for a long time there is weight loss, anorexia, periodic vomiting. Depression, diarrhea and bloating are also common clinical symptoms. Seizures and neurological symptoms often appear after a long course of the disease. Rarely, seizures are the only symptom.
Older dogs with seizures and other clinical signs suggestive of liver failure should undergo a thorough neurological and ophthalmological examination. In addition, it is also necessary to determine the cellular formula of the blood (including platelets), the chemical composition of the serum, prescribe a urine test and measure the content of bile acids in the blood before and after feeding. Most dogs with end-stage liver disease have some degree of hypoalbuminemia, hypoglycemia, hypocholesterolemia, and decreased serum urea nitrogen. The activity of liver enzymes is slightly increased, and the content of bile acids in the blood is sharply increased both before and after feeding.
If, as a result of the studies performed, there is reason to assume the presence of liver failure, liver function should be studied in more detail. In particular, radiography and ultrasound of the abdominal cavity are useful in this case. In most cases, an accurate diagnosis and specific treatment require a liver biopsy. Cytological examination of aspirates obtained with fine needles may be useful in hepatic lymphosarcoma. However, it is preferable to perform a biopsy with an ultrasound-guided instrument. Such biopsy specimens give more accurate results in cytological and histopathological examination. To prevent hemorrhagic complications, it is necessary to check the blood for clotting and, if it is impaired, take appropriate measures.
Figure 7. Cirrhosis of the liver: This portion of the liver was obtained from a post-mortem autopsy of a dog suffering from liver failure. Multiple nodes of regeneration and general clarification of the organ are visible. Contributed by Dr. Catharine Scott Moncrief, Purdue University.
If the cause of liver failure is established, specific therapy is possible. For example, in liver failure caused by the toxic effects of anticonvulsants such as phenobarbital, they should be replaced with alternative anticonvulsants. Potassium bromide is the drug of choice and should be used according to a known protocol. In some cases, only symptomatic and supportive therapy is possible. Clinical symptoms of hepatoencephalopathy can often be corrected by the use of protein-reduced diets in conjunction with oral lactulose and similar administration of the antibiotics neomycin or metronidazole (22). Ursodeoxycholic acid has also been shown to be useful in the treatment of chronic hepatopathy (22). Colchicine or other similar drugs can be used to suppress liver fibrosis (23).
Other causes of seizures
In old dogs, pathologies such as hypothyroidism, end-stage renal failure, polycythemia, diabetic ketoacidosis, hyperviscosity syndrome and electrolyte imbalance are much more common than in young dogs. However, all these pathologies rarely cause seizures in these animals. The reader is therefore referred to the specialized literature for more information on these and other rare causes of seizures in older dogs.
Fainting
Syncope is a sudden loss of consciousness caused by a temporary severe lack of oxygen or glucose in the brain (hypoxia or glycopenia) (1). Old dogs prone to fainting should be carefully examined for psychomotor seizures. At the beginning, the concentration of glucose in the blood should be determined, then a careful neurological and ophthalmological examination, a complete analysis of the cellular blood count, determination of the chemical composition of the serum and urine analysis should be carried out. In addition, an EKG should be performed. If possible and in cases of frequent recurrence of syncope, the ECG should be recorded over a long period.
Glycopenia of the brain
The entry of glucose into the brain is insulin-independent. Therefore, brain glycopenia is a direct consequence of hypoglycemia. Hypoglycemia is much more likely to cause seizures than fainting (this has already been discussed above).
Hypoxia of the brain
Hypoxia of the brain can be caused by various reasons. However, only some of them are temporary. For example, intracranial neoplasms, cerebral thromboembolism, cardiac tamponade, or anemia can cause hypoxia, but with them it is not transient.
In this work, attention will be focused on those causes of cerebral hypoxia that are transient in nature, causing only recurring attacks.
Cardiac arrhythmia as a cause of cerebral hypoxia
The most common causes of transient cerebral hypoxia are cardiac arrhythmias, most often sinus rhythm disturbances, weakened sinus pacemaker syndrome (Figure 8), severe second and third degree atrioventricular blocks (Figure 9), sinus blockade and other types of bradyarrhythmias (24, 25). Severe forms of tachyarrhythmia may also be accompanied by fainting. Diagnosing cardiac arrhythmias can be difficult because many forms of arrhythmias are transient and difficult to detect with an ECG. For example, the sympathetic excitation of a patient associated with admission to a hospital is often sufficient for the disappearance of bradyarrhythmia.
Figure 8. Sick sinus syndrome in a miniature schnauzer bitch at 8 years of age. This dog had fainting spells. Note the heterogeneity of the ECG. Visible gastric extrasystoles (1), the imposition of ECG waves (2), atrial asystole (3) and periods of supraventricular tachycardia (4).
Contributed by Dr. T. DeFrancesco, North Carolina State University.
Figure 9. Third-degree atrioventricular block in a 1-year-old neutered male English Spaniel. The dog has fainted. Ventricular rhythm is shown (large arrows) without atrial suppression (small arrows).
In patients with suspected cardiac arrhythmia, at least 4-lead ECG should be recorded. If the ECG is normal, the above examinations do not reveal psychomotor epileptic seizures or syncope associated with brain glycopenia, a chest x-ray should be taken and an echocardiogram should be recorded.
If cardiac abnormalities cannot be detected and the animal does not experience cardiac arrhythmia and/or syncope during the hospital stay, long-term ECG monitoring using a Holter monitor or other similar device should be used. The duration of an ECG recording using a Holter monitor is 24 hours (26). Anomalies in the resulting record are detected using computer analysis. When using a conventional portable cardiograph, the ECG recording time is limited by the supply of tape for recording. Therefore, when using it, the owner must observe the animal for the necessary time in order to initiate an ECG recording during syncope, recording it during the last few minutes of syncope and a few minutes after it ends. A portable cardiograph for monitoring is especially useful in cases where syncope is rare, and it is necessary to observe for several days until fainting occurs.
Although some forms of bradyarrhythmias are associated with specific heart conditions and are treated with specific drugs, most of them are idiopathic in nature. In some cases, especially in the initial stages, weakened sinus node syndrome and atrioventricular blockade of the third
degrees respond well to medical treatment. The most effective is probantheline bromide, which has a parasympatholytic effect with antimuscarinic activity. Another agent that may be effective is terbutaline sulfate, a betasympathomimetic. Unfortunately, many patients do not respond to these drugs; in some, the therapeutic effect is observed only for a short period.
In the absence of the effect of drug therapy, the installation of a pacemaker is necessary. In most cases, electrodes to set the heart rate are inserted into the heart through the jugular vein, and the stimulator itself is fixed subcutaneously in the dorsolateral region of the neck (27,28). Pacemaker insertion in dogs is a routine procedure, and unless the animal has serious heart disease, the prognosis for pacemaker patients is very good.
Other causes of cerebral hypoxia
Another cause of transient hypoxia of the brain may be periodic profuse internal bleeding, leading to a sharp hypotensive crisis and fainting. These symptoms are most commonly seen in dogs with splenic hemangiosarcoma, which causes acute bouts of hemorrhage (29). In many such patients, the bleeding stops spontaneously, and the sick animal looks healthy. These diseased animals are fairly easy to diagnose based on pale mucous membranes, low hematocrit, and a well-palpable tumor in the cranial abdomen.
Hemangiosarcoma is best treated with supportive care following splenectomy and possibly chemotherapy. In general, however, the prognosis for such animals is unfavorable.
Hypovolemic crises with spontaneous recovery have also been observed in dogs with bleeding gastric ulcers. In most of these patients, however, bleeding does not spontaneously stop and requires active intervention. There is no consensus on the methods of treatment of such conditions yet. Supportive therapy with transfusion of blood or its substitutes is indicated, in some cases surgical intervention is required.
Thanks
I would like to thank dramas Catharine ScottMoncrieff, David Williams, Phil March, and Teresa DeFrancesco for their contributions to the selection of literature for selected sections of this work and assistance in preparing this manuscript.
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Fainting is a sudden loss of consciousness that occurs in a dog due to insufficient filling of cerebral vessels with blood (hypoxia) combined with a decrease in blood pressure.
This condition may be short-term or long-term.
Causes of fainting in dogs
There are many reasons that can lead to fainting. So,
- overwork (especially as a result of long-term transportation in a stuffy and cramped car),
- hypothermia,
- stuffiness,
- hunger for over a week
- or intoxication
lead to vascular disorders. The vessels of the brain expand or narrow sharply and fainting occurs. Other causes of fainting in a dog may be neurogenic changes in the central nervous system or a sudden drop in blood sugar levels. In any case, the causes of fainting must be sought in the work of blood vessels, heart or blood.
The most dangerous are fainting, which occurs as a result of a violation of cardiac activity. They can be quite long (up to half an hour), which often leads to the sudden death of the animal.
Symptoms
It may be a harbinger of fainting.
- The dog can't stand
- impaired coordination,
- the animal becomes weak and lies down.
- Mucous membranes turn pale
- breathing becomes shallow, barely noticeable,
- limbs get cold
With a sudden fainting, the dog falls, a weak pulse is felt in it, the animal does not respond to commands and the nickname.
First aid for a dog with a faint
The owner of the dog must be able to provide first aid for fainting, as it is needed very quickly. If the dog has fainted, it must be immediately moved to fresh air, in a cool place or in the shade. If this happened in winter, you can’t put it on bare ground, you need to lay something or find a wooden bench, platform or something like that.
- The animal must be freed from the collar, muzzle, harness, leash and put on its side.
- You need to lay the dog so that the head is lower. This will ensure blood flow to the brain.
- To ensure this position, you need to raise the back of the body and put rolled up clothes under it.
- It is also urgent to pull out the tongue and check for vomit in the airways. If they are found, then you need to clean the mouth with your finger.
- You can put a cold damp cloth on the dog's head, and in winter - snow or ice wrapped in a scarf or towel.
- In the heat, you can simply pour water on the head of the animal.
- After the dog comes to his senses, he should be allowed to drink cold water.
- If she is too weak and cannot drink on her own, then water should be poured over the cheek in small portions. After moving the animal to a more convenient place, it should be given warm sweetened water to drink.
You can feed no earlier than an hour after the restoration of a normal state. To stimulate the work of the heart and breathing, if the animal has a heart disease, it can be given corvalol, cordiamine and other similar drugs. Even if the dog fainted once, it must be examined, since such a condition could be caused not only by environmental factors (transportation, stuffiness, etc.), but also by serious pathologies and diseases of the heart.