Case of the Stunted Puppies

A 4 year old rat terrier bitch had a litter of pups and 3 were stunted in growth and quite developmentally delayed. The pups were much smaller than "normal" littermates (see Photo 1). They also were difficult to house train. The haircoat of these puppies even at 6 months of age was dominated by guard hairs (i.e. the "puppy coat" was maintained). The haircoat was also lighter in color than the "normal" pups. Please see the photographs which come with the text introduction to the case. There were no serum biochemical abnormalities in the bitch and yet the puppies had an elevated serum cholesterol and a mild anemia with no evidence that immature red blood cells were being produced by the bone marrow in response. Thyroid function tests were performed and are shown below. One of the puppies was such a "poor doer" according to the breeder that the decision was made to euthanize it. The second photo in the case introduction shows the thyroid gland on the lefthand side compared with the kidney on the righthand side.

Photo 1: Rat Terrier Litter: 3 stunted puppies with 1 normal littermate

Photo of Litter

Photo 2: Gross Cross-Section of Thyroid lobe (left; both glands are grossly enlarged) compared to Kidney

Comparision of Thyroid (left) to Kidney (right) Size

Summary of literature data on diagnostic characteristics of individual and dual combinations of thyroid hormone testing.

Thyroid Diagnostic Test Characteristics

from Ferguson, D.C.: Testing for hypothyroidism in dogs. Veterinary Clinics of North America Small Animal 37: 647-669, 2007.

Endocrine Tests for Pup and Bitch

CASE ANALYSIS

In outline form, develop an analysis of this case which highlights the connection of case clinical signs and test results to physiology. Highly suggested elements of your analysis should include answers to the following questions. You are encouraged to copy from elements within the case and include multimedia resources in your analysis, but the most important feature for your reviewers will be the extent to which you individualize your explanation, that is use your own words to demonstrate synthesis of the information you found relevant and its connection to normal or perturbed physiology.

• Significant Historical and Physical Exam Findings in Bitch consistent or inconsistent with thyroid dysfunction
• Does the Bitch have normal thyroid function? Why or why not?
• Significant Historical and Physical Exam Findings in Pup consistent or inconsistent with thyroid dysfunction
• Does the pup have normal thyroid function? Why or why not?
• Identify one or more possible causes of the pup's condition and explain how all of the clinical features of the pup's case would be explained. At least one of the causes described should be a genetic abnormality (i.e. congenital cause of disease).