Hypothyroidism in dogs as a baseline of different clinical signs and laboratory results
Date Issued
2020-10-03
Author(s)
Atanaskova Petrov, Elena
Abstract
Introduction: Hypothyroidism is the most common endocrinopathy in dogs. It is clinical
condition with decrease serum level concentration of thyroid hormones, resulting with
different clinical signs. As a common subclinical and clinical condition, hypothyroidism can
be congenital and acquired, as well as primary, secondary and tertiary (the last mentioned is
very rare). This clinical condition is sometimes hard for diagnosis, but it is very easy for
treatment.
Aims: The main purpose of this clinical study is interpretation of serum concentration of
fT4 in correlation with other laboratory findings (hematology and biochemistry) and clinical
manifestation. For that purposes 5 clinical cases will be describe with history data, clinical
manifestation and laboratory findings such as clinical condition after treatment protocol.
Material and methods: Clinical research was performed in 5 clinical cases admitted in the
University clinic. According anamnestic data from the owners, dogs presented different
clinical signs, reported at the personal files of the patients. Hematology was performed
immediately after sampling on veterinary hematology analyzer Exigo (Sweden), as well as
biochemistry status: enzyme serum concentration (ALT, AST, ALKP), degradation profile
(urea and creatinine), protein status (albumin, total protein), lipid parameters (cholesterol,
triglycerides), according manufacture instruction (Human, Germany) with colorimetric
procedure on automatized analyzer Chem Well 2910 (USA). Cytology (Diff Quick staining)
was performed only in cases with dermatological lesions. ELISA laboratory method was
used for measurement serum concentration of free thyroxin (fT4), on BDLS ELISA reader.
Results and Discussion: First case was 6 year female mix breed neutered dog, with
progressive skin lesion with hyperpigmentation and episodes of epileptiphormic seizures.
Hematology presented mild normocytic, normochromic anemia (5.09 1012/L), and
biochemistry results presented only mild increase of ALT (69 U/L) and mild hyperlipidemia
(cholesterol 6.89 mmol/l and triglycerides 2.05 mmol/l). Anticonvulsive therapy protocol
(phenobarbital 1mg/kg) was not responsive, epileptiformic seizures continue with the same
frequency. Cytology finding show non-pruritic non-inflammatory alopecia, with low
cellularity of superficial cornified epithelial cells. Serum level concentration fT4 presentedsevere hypothyroidism of 0.29 ng/dl. Initial treatment with levothyroxine started with 10
μcg/kg BID and after one month the treatment dose was increased of 22 μcg/kg BID.
Clinical signs of epileptiformic seizures disappeared and laboratory findings corrected
within reference ranges. Skin lesions recurrence in irregular intervals. After 5 years of
treatment the patient developed hepatic fibrosis. Second case was 5 year male Samoyed, with
no specific clinical signs only with polyphagia and increased body condition score.
Laboratory finding presented only moderate elevation of degradation profile (urea 18.24
mmol/l and creatinine 174.54 μmol/l). Renal supportive and protective protocol combined
with intravenous fluid crystalloid therapy did not give satisfactory results. Serum
concentration of fT4 (0.51 ng/dl) show moderate decrease level. Initial treatment with
levothyroxine 15 μcg/kg BID give satisfactory results with correction of degradation profile,
regular appetite and normal body condition score. Third case was 10 year female Maltese,
with history of chronic caught, collapse trachea, intolerance of physical exercise and
congestive heart failure with mitral dysplasia. Cardiotonic (0.25 mg/kg pimobendan BID)
and diuretic (2 mg/kg furosemide and spironolactone 1 mg/kg SID) treatment was not
completely effective protocol, didn’t give satisfactory results. There were intermittent
remission of subcutaneous myxedema. Serum concentration of fT4 (0.34 ng/dl) presented
marked hypothyroidism. There is no evident dermatology lesions or alterations in laboratory
results. Initial treatment of levotiroxine in dose of 22 μcg/kg BID give satisfactory results.
Fourth case is a 4 year male cocker spaniel presented marked dermatology clinical signs with
symmetric bilateral alopecia, “rat tail” and superficial exfoliate dermatitis. Cytology findings
present low cellularity of epithelial cells, intact inflammatory cells predominant neutrophils,
less small lymphocytes and telogen defluxion of hair. Dermatology cosmetically products,
topically used, was not effective treatment. Biochemistry lipid parameters
(hypercholesterolemia 7.15 mmol/l and hypertriglyceridemia 2.84 mmol/l) were indicators
for measurement of fT4. Moderate serum concentration of 0.54 ng/dl indicate
hypothyroidism. Treatment protocol of levothyroxine 15 μcg/kg BID together with dermal
supportive supplements give better condition of the skin and normal values of the lipid
parameters. Fifth case: 5 year male Labrador retriever, with bradycardia, myxedema,
seborrhea sicca, obtain laboratory results have shown increase serum level of ALT (105.3
U/L). Unclear clinical symptoms and elevated ALT were suspected indicators for
hypothyroidism. Serum concentration of fT4 of 0.61 ng/dl confirm diagnosis. Treatment
with levothyroxine 20 μcg/kg BID improve better condition of the patient.
Conclusion: Decreased serum concentration of fT4 can be used as baseline of many
different clinical conditions, non-responsive of regular conventional protocols. Clinical and
subclinical hypothyroidism correlated with the degree of clinical manifestation and altered
laboratory results.
condition with decrease serum level concentration of thyroid hormones, resulting with
different clinical signs. As a common subclinical and clinical condition, hypothyroidism can
be congenital and acquired, as well as primary, secondary and tertiary (the last mentioned is
very rare). This clinical condition is sometimes hard for diagnosis, but it is very easy for
treatment.
Aims: The main purpose of this clinical study is interpretation of serum concentration of
fT4 in correlation with other laboratory findings (hematology and biochemistry) and clinical
manifestation. For that purposes 5 clinical cases will be describe with history data, clinical
manifestation and laboratory findings such as clinical condition after treatment protocol.
Material and methods: Clinical research was performed in 5 clinical cases admitted in the
University clinic. According anamnestic data from the owners, dogs presented different
clinical signs, reported at the personal files of the patients. Hematology was performed
immediately after sampling on veterinary hematology analyzer Exigo (Sweden), as well as
biochemistry status: enzyme serum concentration (ALT, AST, ALKP), degradation profile
(urea and creatinine), protein status (albumin, total protein), lipid parameters (cholesterol,
triglycerides), according manufacture instruction (Human, Germany) with colorimetric
procedure on automatized analyzer Chem Well 2910 (USA). Cytology (Diff Quick staining)
was performed only in cases with dermatological lesions. ELISA laboratory method was
used for measurement serum concentration of free thyroxin (fT4), on BDLS ELISA reader.
Results and Discussion: First case was 6 year female mix breed neutered dog, with
progressive skin lesion with hyperpigmentation and episodes of epileptiphormic seizures.
Hematology presented mild normocytic, normochromic anemia (5.09 1012/L), and
biochemistry results presented only mild increase of ALT (69 U/L) and mild hyperlipidemia
(cholesterol 6.89 mmol/l and triglycerides 2.05 mmol/l). Anticonvulsive therapy protocol
(phenobarbital 1mg/kg) was not responsive, epileptiformic seizures continue with the same
frequency. Cytology finding show non-pruritic non-inflammatory alopecia, with low
cellularity of superficial cornified epithelial cells. Serum level concentration fT4 presentedsevere hypothyroidism of 0.29 ng/dl. Initial treatment with levothyroxine started with 10
μcg/kg BID and after one month the treatment dose was increased of 22 μcg/kg BID.
Clinical signs of epileptiformic seizures disappeared and laboratory findings corrected
within reference ranges. Skin lesions recurrence in irregular intervals. After 5 years of
treatment the patient developed hepatic fibrosis. Second case was 5 year male Samoyed, with
no specific clinical signs only with polyphagia and increased body condition score.
Laboratory finding presented only moderate elevation of degradation profile (urea 18.24
mmol/l and creatinine 174.54 μmol/l). Renal supportive and protective protocol combined
with intravenous fluid crystalloid therapy did not give satisfactory results. Serum
concentration of fT4 (0.51 ng/dl) show moderate decrease level. Initial treatment with
levothyroxine 15 μcg/kg BID give satisfactory results with correction of degradation profile,
regular appetite and normal body condition score. Third case was 10 year female Maltese,
with history of chronic caught, collapse trachea, intolerance of physical exercise and
congestive heart failure with mitral dysplasia. Cardiotonic (0.25 mg/kg pimobendan BID)
and diuretic (2 mg/kg furosemide and spironolactone 1 mg/kg SID) treatment was not
completely effective protocol, didn’t give satisfactory results. There were intermittent
remission of subcutaneous myxedema. Serum concentration of fT4 (0.34 ng/dl) presented
marked hypothyroidism. There is no evident dermatology lesions or alterations in laboratory
results. Initial treatment of levotiroxine in dose of 22 μcg/kg BID give satisfactory results.
Fourth case is a 4 year male cocker spaniel presented marked dermatology clinical signs with
symmetric bilateral alopecia, “rat tail” and superficial exfoliate dermatitis. Cytology findings
present low cellularity of epithelial cells, intact inflammatory cells predominant neutrophils,
less small lymphocytes and telogen defluxion of hair. Dermatology cosmetically products,
topically used, was not effective treatment. Biochemistry lipid parameters
(hypercholesterolemia 7.15 mmol/l and hypertriglyceridemia 2.84 mmol/l) were indicators
for measurement of fT4. Moderate serum concentration of 0.54 ng/dl indicate
hypothyroidism. Treatment protocol of levothyroxine 15 μcg/kg BID together with dermal
supportive supplements give better condition of the skin and normal values of the lipid
parameters. Fifth case: 5 year male Labrador retriever, with bradycardia, myxedema,
seborrhea sicca, obtain laboratory results have shown increase serum level of ALT (105.3
U/L). Unclear clinical symptoms and elevated ALT were suspected indicators for
hypothyroidism. Serum concentration of fT4 of 0.61 ng/dl confirm diagnosis. Treatment
with levothyroxine 20 μcg/kg BID improve better condition of the patient.
Conclusion: Decreased serum concentration of fT4 can be used as baseline of many
different clinical conditions, non-responsive of regular conventional protocols. Clinical and
subclinical hypothyroidism correlated with the degree of clinical manifestation and altered
laboratory results.
Subjects
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