In a masked field study assessing effectiveness and safety of Zenrelia for the control of atopic dermatitis in dogs, 181 Zenrelia-treated dogs and 87 placebo-treated dogs diagnosed with atopic dermatitis were evaluated for safety up to 112 days. By Day 112, 66.7% of placebo-treated dogs and 22.1% of Zenrelia-treated dogs exited the study. Adverse reactions seen during the field study are summarized in Table 1 below.
Table 1. Adverse Reactions through Day 112
Abnormal hematology results likely related to Zenrelia treatment included thrombocytopenia, leukopenia, neutropenia, lymphopenia, eosinopenia, monocytopenia, and decreased red blood cell count.
Abnormal serum chemistry results likely related to Zenrelia treatment included increased hepatobiliary parameters (alanine transaminase, aspartate aminotransferase, alkaline phosphatase, gamma-glutamyl transferase, and total bilirubin), increased blood urea nitrogen (concurrently with an increase in creatinine for one dog), hypertriglyceridemia, hypercholesterolemia, hypoalbuminemia (without a concurrent hyperglobulinemia), and hypoglobulinemia (with or without a decrease in total protein).
Twelve Zenrelia-treated dogs withdrew from the study early due to an adverse reaction, nine of which were considered likely related to Zenrelia treatment. These reactions included repeated episodes of vomiting, leukopenia, neutropenia, worsening of pre-existing lymphocytosis, enlargement of a non-resolving histiocytoma, eyelid mass with bacterial blepharitis, otitis interna with vestibular disease, urinary tract infection, and upper respiratory infection. Five placebo dogs withdrew from the study early due to an adverse reaction (i.e., lethargy, worsening of pre-existing lymphocytosis, occurrence of nystagmus, skin infection, and teat infection).
One Zenrelia-treated dog was diagnosed with splenic and liver masses on Day 112. Histopathologic diagnosis after euthanasia one month later confirmed metastatic splenic and hepatic hemangiosarcoma. Another Zenrelia-treated dog experienced traumatic tendonitis and a puncture wound four days prior to study completion, which progressed to a serious infection. The owner elected amputation after study completion. A third Zenrelia-treated dog experienced a moderate neutropenia on Day 28 associated with a pre-existing subclinical urinary tract infection (UTI) that had progressed into a clinical UTI. The neutrophil count normalized seven days later while still receiving Zenrelia, prior to exiting the study to receive antibiotics.
Control of Pruritus Associated with Allergic Dermatitis
In a masked field study assessing effectiveness and safety of Zenrelia for the control of pruritus associated with allergic dermatitis in dogs, 206 Zenrelia-treated dogs and 100 placebo-treated dogs diagnosed with allergic dermatitis were evaluated for safety up to 112 days. By Day 112, 84% of placebo-treated dogs and 49.5% of Zenrelia-treated dogs exited the study. Adverse reactions seen during the field study are summarized in Table 2 below.
Table 2. Adverse Reactions through Day 112
Abnormal hematology results likely related to Zenrelia treatment included thrombocytosis, leukopenia, neutropenia, eosinopenia, and monocytopenia.
Abnormal serum chemistry results likely related to Zenrelia treatment included increased hepatobiliary parameters (alanine transaminase, aspartate aminotransferase, alkaline phosphatase, gamma-glutamyl transferase, and total bilirubin), increased blood urea nitrogen, increased creatinine, hypertriglyceridemia, hypercholesterolemia, hypoproteinemia, and hypoglobulinemia (with or without a decrease in total protein).
Seven Zenrelia-treated dogs withdrew from the study early due to an adverse reaction, four of which were considered likely related to Zenrelia treatment. These reactions included vomiting, lethargy, soft stool, neutropenia, increased liver enzymes, fever, abdominal discomfort, coughing, and wheezing. Four placebo treated dogs also withdrew from the study early due to an adverse reaction (i.e., splenic hemangiosarcoma, restlessness, abdominal pain, lethargy, and vomiting).